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Status, Distribution, Habitat Requirements, and Foraging Ecology of the Jabiru Stork (Jabiru mycteria) in Northern and C...


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STATUS, DISTRIBUTION, HABITAT REQUIREMENTS, AND FORAGING ECOLOGY OF THE JABIRU STORK ( Jabiru mycteria ) IN NORTHERN AND CENTRAL BELIZE, CENTRAL AMERICA By ALEJANDRO JOSE PAREDES BORJAS A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLOR IDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2004

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Copyright 2004 by Alejandro Jos Paredes Borjas

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ACKNOWLEDGMENTS The successful completion of this project was due to the support of family, friends, professors, and organizations in Central America and the United States. Firstly, I feel indebted to Omar Figueroa and his parents, Don Azuceno and Doa Jeannette, for giving me their support while I was conducting field research in Belize. The Figueroa family kindly provided me with a warm, hospitable place from the moment I arrived in their country. Omar, in particular, helped me arrange logistics and provided useful technical and contact information. Their support was key to the success of this project. I would also like to thank Wilver Martinez, Raynold Cal and Mario Tehul for their help, peer support, and long-lasting coffee breaks. I also thank pilot Frank Plett, whose experience, skills and motivation have been instrumental for conservation of waterbirds in Belize. Thanks also go to the Belize Audubon Society, who granted me permission to do research in Crooked Tree Wildlife Sanctuary. I am grateful to my friends in Graduate school: Santiago Espinosa, Amy Duchelle, Rafael Reyna and Edith Rojas, Mutsuo Nakamura, Ivan Diaz, Olga Montenegro, Luis Ramos, Percy Peralta, Sonia Canavelli and Marcela Machicote, who assisted me with data analyses and provided feedback that proved extremely useful for the development of this project. Special thanks go to Charlotte Skov and Debra Anderson for their encouragement and unconditional support. iii

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Thanks go to my committee members (Dr. Peter Frederick, Dr. George Tanner and Dr. Ken Meyer) for providing ideas and revising the manuscript. This thesis was possible thanks to financial support provided by the Compton Foundations grant for Tropical conservation and development. Finally, I would like to thank my family: my mother, Martha; my sister Martha Judith; and my brother, Ricardo. They have always encouraged me to find a balance between the consistent mind and the kind heart. All my endeavors are kindly dedicated to them. iv

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TABLE OF CONTENTS Page ACKNOWLEDGMENTS ................................................................................................iii LIST OF TABLES............................................................................................................vii LIST OF FIGURES.........................................................................................................viii LIST OF OBJECTS.............................................................................................................x ABSTRACT.......................................................................................................................xi CHAPTER 1 INTRODUCTION........................................................................................................1 Threats to Central American Wetlands.........................................................................1 Influence of Wetland Hydrology in the Natural History of Wading Birds..................2 Influence of Spatial Heterogeneity and Hydrological Fluctuations on the Natural History of Wading Birds..........................................................................................4 The Study Species: The Jabiru Stork............................................................................8 2 STUDY AREA AND METHODS.............................................................................13 Study Area..................................................................................................................13 Methods......................................................................................................................16 Landscape Data and Population Estimates..........................................................16 Microhabitat data and Observations on Foraging Behavior................................19 Analysis of Data..................................................................................................20 3 RESULTS...................................................................................................................24 Abundance of Jabiru Storks........................................................................................24 Spatial Distribution.....................................................................................................24 Habitat Use.................................................................................................................26 Habitat Use According to Ecosystem Classification...........................................26 Habitat Use According to Land Use Classification.............................................28 Use of Water Bodies............................................................................................28 Features of Foraging Microhabitat......................................................................29 Diet Composition........................................................................................................29 Foraging Behavior......................................................................................................30 v

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Walking and Searching for Food.........................................................................30 Capturing and Handling Prey..............................................................................32 Prey Piracy...........................................................................................................34 Loafing and Social Interactions...........................................................................35 4 DISCUSSION.............................................................................................................50 Rainfall Pattern in Central and Northern Belize.........................................................50 Abundance of Storks in Response to Local Hydrology..............................................50 Spatial Distribution and Habitat Use..........................................................................53 Foraging Ecology........................................................................................................55 Conservation...............................................................................................................57 5 CONCLUSIONS........................................................................................................60 APPENDIX A MAPS OF STUDY AREA.........................................................................................62 B ROUTES OF SURVEY FLIGHTS............................................................................65 LIST OF REFERENCES...................................................................................................69 BIOGRAPHICAL SKETCH.............................................................................................75 vi

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LIST OF TABLES Table page 1 Total number of Jabirus observed in survey flights.................................................47 2 Number of Jabirus in relation to habitat types.........................................................48 vii

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LIST OF FIGURES Figure page 1 Map of Belize...........................................................................................................21 2 Map showing the components of the hydrological system in central Belize...........22 3 Map of study area.....................................................................................................22 4 Map showing of foraging areas................................................................................23 5 Variation of foraging sociality of Jabiru..................................................................36 6 Spatial distribution of Jabirus: survey 1...................................................................37 7 Spatial distribution of Jabirus: survey 2...................................................................38 8 Spatial distribution of Jabirus: survey 3...................................................................39 9 Spatial distribution of Jabirus: survey 4...................................................................40 10 Spatial distribution of Jabirus: survey 5...................................................................41 11 Summary of spatial distribution of Jabiru................................................................42 12 Readings of water levels recorded from 6 water stages...........................................43 13 Ecosystems used by foraging Jabirus.......................................................................44 14 Habitat used by Jabirus............................................................................................45 15 Water bodies used by foraging Jabirus....................................................................46 16 Proportion of prey items of the Jabiru......................................................................46 17 Satellite image of CTWS and New River Lagoon area............................................62 18 Map of ecosystems of Belize, northern Belize.........................................................63 19 Map of ecosystems of Belize, central Belize...........................................................64 20 Map of ecosystems of Belize, southern Belize........................................................64 viii

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21 Route of survey flight 1, northern and central Belize..............................................66 22 Route of survey flight 1, central Belize....................................................................66 23 Route of survey flight 2, northern and central Belize..............................................67 24 Route of survey flight 2, central Belize....................................................................67 25 Route of survey flight 3, northern and central Belize..............................................68 26 Route of survey flights 4 and 5, northern and central Belize...................................68 ix

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LIST OF OBJECTS Objects page 1 Video clip of Jabiru walking in Northern Lagoon. ................................................. 30 2 Video clip of searching for food. ............................................................................31 3. Video clip of Jabiru searching for food in mudflat. ................................................31 4 Video clip of Jabiru dismembering a large prey. ....................................................33 5 Video clip of Jabiru searching, handling and eating eels. .......................................33 6 Video clip of Jabiru handling a large prey and then harrased by conspecific. ........34 7 Video sequence of monthly water level fluctuation in Northern Lagoon from March to July 2003. ................................................................................................. 50 x

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Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science STATUS, DISTRIBUTION, HABITAT REQUIREMENTS, AND FORAGING ECOLOGY OF THE JABIRU STORK (Jabiru mycteria) IN NORTHERN AND CENTRAL BELIZE, CENTRAL AMERICA By Alejandro Jos Paredes Borjas August 2004 Chair: Peter Frederick Major Department: Wildlife Ecology and Conservation Mesoamerica hosts an impressive diversity of species and ecosystems. However, the explosive population growth in the region is threatening the integrity of functions, composition and structure of pristine ecosystems. Several wildlife species are intimately linked to the fluctuating physical and biological processes occurring in some of these ecosystems. Seasonally flooded wetlands and waterbirds dependent on fluctuating water levels are a good example of this close relationship. I explored the effects of hydrological fluctuations on the ecology of one of the largest birds in the Western Hemisphere: the Jabiru Stork. The research was carried out in the central and northern region of the Central American country of Belize. Since little is known about Central American populations of this bird species, the research was aimed, firstly, at answering basic conservation questions regarding population size, distribution, habitat used for feeding, diet, and foraging behavior. Secondly, the research tries to provide a picture of the influence of weather and wetlands water levels on variables xi

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already mentioned. To answer these questions, I performed five aerial surveys over central and northern Belize from April to June 2003, during the dry-down and dry stage of wetlands and beginning of rains. During air surveys, I counted the number of individuals and flocks of Jabirus, and recorded positions and foraging habitat type. I also performed ground surveys aimed at measuring the physical characteristics of foraging habitat, recording size of foraging flocks, diet and behavior of the Jabiru Stork. Results show that the mean number of storks counted during the air surveys was 65.17 (SD = 24.28), while the maximum number of Jabirus ever recorded was 116 individuals. During the study, most Jabirus used inner areas, especially, around New River lagoon and Crooked Tree Wildlife Sanctuary (CTWS). In most occasions (91%), Jabirus used open areas: mainly freshwater wetlands subject to periodic flooding; the rest used lowland savanna, lowland broadleaf forest and agricultural fields. There were no recordings of Jabirus in coastal areas or rice fields. The Jabirus diet consisted mainly of fish, Swamp Eels (Symbranchus marmoratus) and snails. Weather affected the wetlands water levels. This, in turn, influenced foraging sociality, distribution of Jabirus in the landscape, and common prey items consumed. The CTWS may guarantee the protection of some critical foraging habitat for the Jabiru Stork. However, the CTWS and other foraging areas are dependent on the extent and quality of hydrological processes occurring outside its boundaries. It is therefore recommended that conservation efforts target the protection of the Belize River and other lotic bodies feeding wetlands. Scientific studies should also address the ecology of some of the Jabirus main prey, especially the Swamp Eel. xii

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CHAPTER 1 INTRODUCTION Threats to Central American Wetlands Natural environments and the species associated with them are disappearing at an alarming rate (due in great part, to an accelerated growth in human population). Mesoamerica (the land bridge that extends from southern Mexico to Panama), one of the hotspots of biological diversity in the planet (Myers et al. 2000, Brooks et al. 2002) is currently facing an explosive human population growth rate (reaching almost 3%/year). This is one of the highest growth rates for the Western Hemisphere, and human population in the region is expected to double in the next 15 years. Therefore, pressures for development are intense, and will be much accelerated in the near future, as expanding societies demands for goods and services increase. In this spatial conflict, wetlands are among the most vulnerable ecosystems. Many of the Central American wetlands remain relatively undeveloped; and maintain local communities by providing them with clean water, fisheries, and wood for fuel or construction. However, in some areas, population pressures are resulting in rapid deterioration of wetlands and, therefore, the quality and quantity of goods and services provided by wetlands (e.g., fuel wood, fresh water, and fisheries) is also decreasing. Wetland wildlife is often strongly dependent on vegetation cover, water quality, and natural fluctuations in water levels. Alteration of any of these variables by human activities can have severe effects on the wetland ecology, even when the wetlands have not been developed. Water birds are among the most vulnerable wildlife groups 1

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2 because of their location in the aquatic trophic web. Responses of waterbird populations to changing environments are difficult to predict, because much of the basic natural history of many species is largely unknown. This is particularly true for the Jabiru Stork (Jabiru mycteria), the largest bird in Central American wetlands. A gap of knowledge exists regarding its abundance, its distribution and the effects of environmental variables on its foraging and nesting ecology. Jabiru Storks were chosen for this study because they are large, conspicuous birds, potentially dependent on the wetlands hydrological characteristics; and because they can serve as flagship species that may help us identify key habitat features for the protection of other equally vulnerable waterbird species. Influence of Wetland Hydrology in the Natural History of Wading Birds Hydrological conditions play an important role in the natural history of many wetland birds. This is especially true for wading birds (order Ciconiiformes) whose foraging ecology is often responsive to and dependent on water levels. In tropical and subtropical wetlands with marked wet/dry seasons, water-depth fluctuations can be dramatic (Ogden et al. 1980, Frederick and Collopy 1989), and this dynamism affects both the production and availability of prey animals to birds. Studies in the subtropical south Florida environment have shown that during the wet season, prey production is strongly affected by the expansion and contraction of ponds into surrounding marshes and swamps. When water levels recede, high densities of prey are usually found in deeper ponds (Kushlan 1980, Collopy and Jelks 1987). This hydrological mechanism that regulates concentration of prey is called the dry-down model. Even though environmental factors have a strong influence in the foraging ecology of wading birds, the response of each species to hydrological changes is variable, depending on how each species exploits the niche of prey availability. Gawlik (2002)

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3 showed the effects of food availability on the numerical response of wading birds species by manipulating water depth and fish density in artificial ponds. Diverse reactions were found for all species: Wood Stork (Mycteria americana), White Ibis (Eudocimus albus), Snowy Egret (Egretta thula), Glossy Ibis (Plegadis falcinellus), Great Egret (Ardea albus), Tricolored Heron (Egretta tricolor), Great Blue Heron (Ardea herodias) and Little Blue Heron (Egretta caerulea). Some of these species were more responsive to water depth, some to fish density, some to both, and others to neither of them. However, it should be noted that prey availability is a composite factor that involves a number of environmental, physiological, behavioral, and morphological variables of both prey and wading bird, rather than prey density alone. It also seems apparent that, at patch level, short-term availability of resources may be more important than resource depletion for predators of active prey, as shown by Erwin (1985) for Snowy (Egretta thula) and Great (Ardea albus) Egrets. Additionally, several other factors may determine wading bird foraging success, as suggested by Surdick (1998) who found that vegetation, prey density and prey composition were related to wading bird capture rate in unmodified Everglades habitats. This shows that responses on each species are driven to maximize their use of aquatic niches, and shows the difficulty of applying a single set of predictions to all wading bird species. Changes in water levels can also influence the reproductive biology of wading birds (Ogden et al. 1980, Frederick and Collopy 1989) by affecting the amount of food available in the system (Cezilly et al. 1995). For some wading bird species, the number of nesting individuals can be responsive to changes in food resources (Bildstein et al. 1990, Frederick and Collopy 1988), and even nesting success and nesting productivity have

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4 been linked to prey availability (Frederick 2002). Wading birds reproductive activity can be synchronized with external phenomena (namely, the amount of rainfall and its effects on local wetlands). As shown in the Everglades of Florida, some wading birds typically nest during the dry season when water levels are receding allowing birds to take advantage of prey concentration (Bancroft et al. 1990). Ogden (1994) observed relationships among these seasonal hydrological fluctuations, availability of prey, and date of nest initiation in Wood Storks (Mycteria americana). Also, Ogden et al. (1980) found that in several species of wading birds, total number of nesting pairs and location of nest colonies varied in response to rainfall across the Florida peninsula. Similarly, in the French Camargue, Cezilly et al. (1995) found a positive correlation among water depth, the number of breeding pairs, and the body condition of fledglings of the Greater Flamingo (Phoenicopterus ruber roseus). In their study, water levels determined the extent of flooded surfaces; and this, in turn, reflected the abundance and availability of invertebrates produced in temporary, seasonal, and semi permanent wetlands (Kushlan 1989). Water levels and storms have also been related to complete abandonment of nest colonies or heavy attrition of birds in the freshwater Everglades of Florida (Frederick and Collopy 1988). This shows that the interaction of both biotic and abiotic factors at landscape and/or patch level may play an important role in the foraging ecology, energy acquisition, and consequently, the nesting behavior and nesting success of wetland birds. Influence of Spatial Heterogeneity and Hydrological Fluctuations on the Natural History of Wading Birds Landscapes are defined as aggregations of habitat patches differing spatially and temporally (Turner and Gardner 1991, Dunning et al. 1992). In this context, wetlands are interesting ecosystems, because they contain a wide array of habitat types and/or patches,

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5 sometimes complexly arranged within the landscape. Wetlands also have an important temporal component which includes seasonal fluctuations in water levels, which can have profound effects on the ecology of wetland biota. Hydroperiod (the amount of time that an area is covered with water) can determine density and composition of a wetland vegetation community (Gunderson 1994). Hydroperiod, depth of water, and drought frequency can drastically alter the spatial distribution, population dynamics, inter/intraspecies interactions, and food webs of both terrestrial and aquatic organisms (Urban et al. 1993, Newman et al. 1996, Turner et al. 1999, Liao et al. 2001). The latter implies that, for many vertebrate species, availability of food, shelter, water, and space will vary greatly in response to fluctuations of water levels, and that fulfillment of wildlife needs will also change according to patch dynamics. As a consequence of landscape heterogeneity and dynamism, habitat needs will often be fully covered in a given patch/habitat type for only a limited period. When these patches/habitats currently under use are no longer available, the species will be driven to search and use new suitable patches/habitats, until these do not offer appropriate resources for survival. A species will then return to patches formerly used when they become available. This is typical of many waterbirds, which are obligately tied to wetlands, and are dependent on characteristics of individual patches (Haig et al.1998) for which they have developed morphological and behavioral adaptations that maximize the exploitation of available resources (Weller 1999). Since fluctuation of water levels determines the spatial distribution of aquatic habitat, it will, therefore, influence the distribution of prey animals available to wading birds. This (and water depths) can determine the distribution of wading birds across the

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6 landscape. Powell (1987) found that seasonal changes in water levels in a shallow marine embayment were responsible for seasonal abundances and distribution of wading birds, largely according to leg length. Bancroft et al. (2002) showed that water depth had the largest effect on distribution and abundance of wading birds in the Northern Everglades. This hydrological mechanism (triggered by seasonal changes of precipitation rates) has ecological repercussions in wetlands within temperate and subtropical latitudes. Few studies addressing the effects of hydrological fluctuations on wetlands biota have been carried out in tropical wetlands. One of these studies, in the Venezuelan Llanos, reported a significant shift in prey composition, habitat use and foraging behavior of Wood Storks (Mycteria americana), as a result of the change from rainy to dry seasons (Gonzalez 1997). Like Florida, during the beginning of the rainy season streams and lagoons overflowed and inundated extensive marshes that became preferred habitats for storks. Similarly, in the coastal wetlands of the Yucatn Peninsula, Mexico, Arengo and Baldassarre (1999) reported seasonal differences in the number of feeding Flamingos (Phoenicopterus ruber ruber) according to water level fluctuation and its influence on food variability. The latter scientists believed that fluctuating environmental conditions lead to variation in food resources and determined spatial shifts in the availability and quality of foraging habitat. This study demonstrated that the landscape needs of the Flamingo are fulfilled by availability of multiple foraging sites within the 8,000-Km2 coastal wetlands of the Yucatn Peninsula. Rainfall seasonality and its effects on wetland hydrology seem to be dominant factors in determining distribution, abundance and behavior of wading birds in subtropical and perhaps, tropical wetlands. Therefore similar environmental mechanisms

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7 may influence the ecology of wading birds in Central America, even though the dry-down model described above has been derived almost exclusively from observations on wetlands in Florida and the Venezuelan Llanos. It is not clear that, predictions from these extremely large, open, and sometimes heavily modified wetlands, are pertinent to other types of wetlands and their biota. This is especially true given the large differences in niche exploitation and mechanisms affecting both, foraging success and breeding, that seem to be apparent for different species of wading birds (Gawlik 2002). One possible model for determining the impact of rainfall and hydrological variation on Jabirus in Central America can be obtained from observations made on one of the Jabirus closest relatives: the Wood Stork. In the Sian Kaan Biosphere Reserve, eastern Yucatn peninsula, interruptions in the wetlands drying pattern due to heavy rainfall during the nesting season have led to a decrease of food supply for Wood Storks and, consequently, disrupting their nesting activity (Ramo and Busto 1992). Additional evidence can be obtained by observing the relationship between rainfall and the Wood Storks egg-laying period. In south Florida, southeastern Mexico and Honduras, the egg-laying period is almost the same, approximately January to March (Hancock et al. 1992), as are the rainfall pattern and the pronounced dry seasons. The Wood Storks seem to be clearly adapted to the drying trend throughout most of their range, and nesting is not known to occur outside of the period of decreasing water levels, since any appreciable rise of water levels seems to be associated with nest abandonment and nestling mortality (Kahl 1964, Hancock et al. 1992). In contrast, other wading birds seem to be less influenced by water conditions. White Ibises (Eudocimus albus) can feed effectively on rising or decreasing water levels (Kushlan 1979), and therefore, its nesting activity is not

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8 strictly dependent on water levels. As a consequence, the nesting period of the White Ibis is quite variable throughout its range. In the Florida Everglades, nesting occurs during the dry season, while along the eastern coast of North America, nesting occurs on rising water levels; along the coast in South America, nesting seems less influenced by climatic conditions and takes place mostly during the wet season (Hancock et al. 1992). Therefore, it is very important to emphasize that, as Gawlik (2002) pointed out, even though some wading bird species might provide a general idea regarding the ecological responses to environmental changes of the entire wading bird group, specific responses to these changes will vary from species to species. For this reason, I am not attempting to use the Jabirus ecology as a model for other wading birds, although, I believe that the Wood Storks ecology can provide a congruent model for the Jabirus foraging and nesting ecology due to their close phylogenetic relationship. The Study [AP1]Species: The Jabiru Stork Together with the Maguari (Exenura galeata) and Wood Stork (Mycteria americana), the Jabiru (Jabiru mycteria, Lichtenstein 1819) is one of only three species of New World storks (Ciconiidae). It is also the largest flying bird in the Americas, and one of the largest birds on the planet, reaching 1200 mm tall, 625-715 mm wing length (males) and an average culmen length of 284 to 328 mm (Blake 1977). Adults are commonly described as having entirely white plumage, black legs and bill, naked head and neck with a broad red collar around base of neck. Juveniles are characterized by their pale gray upper parts, whitish lower parts with silvery grey-brown edged feathers, downy dusky head and neck with feathering lost within a few weeks (Howell and Webb 1995). Jabirus occur in extensive freshwater marshes, savanna lagoons and ranchland with ponds (Hilty and Brown 1986) where they search for fish, eels, mollusks and reptiles. Jabirus

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9 usually nest solitarily in pine savannas or in high trees in broadleaf forests in open wetland savannas from southern Mexico to Northern Argentina, Uruguay and Paraguay. Three distinct populations are believed to occur throughout the Jabirus range, with the largest two located in northern South America and south-central South America (Luthin 1987), and the smallest in Central America. Studies aimed at estimating population size and characteristics of their natural history have been carried out mostly in Venezuela (Thomas 1985a, Gonzalez 1997), Surinam (Spaans 1975), and Argentina (Kahl 1969). Smaller numbers of storks may occur in Uruguay, Paraguay, Bolivia and Peru. In the South American part of the range, Jabirus inhabit extensive wetlands like the Pantanal of Brazil, the Pampas in Argentina, and the Venezuelan Llanos. However, in Central America, wetlands are generally smaller, more isolated, and less extensive than in South America. Thus, it is believed that the Central American population is much smaller and more localized than the other two populations, perhaps containing no more than 150 individuals (Luthin 1984). Because of its small size, this Central American population may be more vulnerable to external threats, and therefore, prone to decline. For instance, in Panama, the last known record of a Jabiru was that of a male shot in Bocas del Toro in 1927 (Wetmore 1965); after this, there have not been further sightings or reports. Ridgley and Gwynne (1989) did not believe that Jabirus will ever occur again in Panama, partly because of their recent decline in neighboring Costa Rica. This might suggest that, in spite of the Jabirus natural potential for dispersion due its ability to sustain long range flights, local populations could have been already extirpated from the vicinity and that similar trends might be expected elsewhere in Central America. Despite the natural rarity and vulnerability of the species in the region, few descriptions or scientific studies have

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10 been carried out in order to determine basic traits of its natural history, demographics or habitat requirements. The ecology of the species remains largely undescribed for many of the Central American countries. Some of the earliest references addressing the presence of the storks can be traced back to the nineteenth century, when British expeditions documented many of Central Americas species of flora and fauna, including the Jabiru, in a series of scientific publications known as Biologia Centrali-Americana (Salvin and Goodman 1904). More recently, a few estimates of population and some biological descriptions have been obtained for southern Mexico (Ogden et al. 1988, Correa and Luthin 1988, Lopez Ornat et al. 1989), the lowlands of the Honduran and Nicaraguan Moskitia (Frederick et al. 1997) and the lower Tempisque River basin in Costa Rica (Villareal 1997). To date, there have been no rigorous estimates of population size of Jabirus in Belize, even though this country may host the largest breeding population in the region (Luthin 1984). It has been suggested that Belize breeders move to the Usumacinta drainage in Mexico during July and that they travel back to Belize in November or early December (Miller 1995, Howell and Webb 1995), when most wetlands in both areas are drying and food is available. If it is true that regular movements occur across country borders, a strategic plan with bipartisan or multinational efforts must be developed to ensure conservation of the Jabirus foraging and nesting habitat across Mesoamerican countries. Nevertheless, before starting the policymaking process, it seems imperative to acquire accurate and reliable scientific data regarding the natural history and ecological requirements of the species. To date, pieces of information from some of these countries provide rough indication of sites where Jabirus occur in Central America. Information

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11 addressing the status and distribution of the species is lacking for, what is believed, one of the most important bastions of suitable foraging and nesting habitat for Jabirus in the region: Belize. In this thesis I present a picture of the ecological needs of the Jabiru Stork in the hope that this can serve as baseline information for rapid conservation action and encourage future scientific research on wetlands, storks and other water birds in Central America. Since it is still unknown whether these birds move widely across Central American wetlands in response to rainfall and its influence on water levels and food availability, or if they are largely sedentary, I attempted to investigate the influences of rainfall and the dry-down model on the abundance, local movements and distribution of the Jabiru in central and northern Belize. Assuming that the dry-down model is correct, I predicted that fewer Jabirus would be observed when water levels increased during the rainy season. In contrast, larger numbers of Jabirus should be recorded during the dry season. I also predicted that Jabirus would occur in interior wetlands that are more susceptible to strong hydrological variations, as opposed to coastal regions where water level fluctuations are buffered by the stability of sea level. I also investigated the effects of water levels on habitat used for foraging purposes as a means to discover any linkage between hydrology and reproductive biology. I predicted that larger prey items would be captured when water was receding, especially during the dry period, when fish should have been concentrated in ponds. I recorded locations of Jabirus in the landscape through five systematic aerial surveys. Using this information, I explored the variations in the number of Jabirus according to rainfall, and their distribution and habitat use at the

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12 landscape and local levels. Observations made from the ground helped me describe their foraging behavior and identify and quantify the prey items captured.

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CHAPTER 2 STUDY AREA AND METHODS Study Area I studied the Jabiru Stork in Belize, the second smallest country in Central America, from March to July 2003 (Figure 1). The entire country is influenced by a tropical weather pattern with two clearly distinct seasons. The dry season usually extends from November to June, and the rainy season lasts for the remaining 5 months. In El Nio/La Nia years, the weather pattern exhibits a drastic deviation from the one found in neutral years. Before and during El Nio events the entire region is usually dry. In La Nia years, the climatic conditions are much more variable (Curtis 2002) and they can include increased monsoon rains during the dry season, like the ones recorded across Central America and Mexico from October to December 1998 (Bell et al. 1999). At the national scale, weather parameters are slightly affected by local topographic features since most of the country lacks mountain ranges, with the exception of the Maya Mountains located in the southwest quadrant. A great proportion of the countrys surface is at low elevation; almost half of it lies between 0 and 100 m above sea level. This has allowed the development of several types of wetland ecosystems, which account for nearly 10% of the countrys total area (Meerman and Sabido 2001). Most of my research was performed in the northern half of Belize. Ground observations were made in the Crooked Tree Wildlife Sanctuary (hereafter CTWS). CTWS is a 6,639-Ha reserve located at the center of Belize, between 17 and 18 north, 88 and 88 west. The entire area encompasses freshwater wetland systems 13

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14 consisting of seasonally flooded lagoons, marshes, creeks, and pine savannas. The reserve can be divided into 5 main lagoons. The Northern, Western and Southern Lagoons are interconnected and comprise one of the reserves hydrological systems, while the Mexico and Jones lagoons comprise the second hydrological system (Figure 2). The elongated basins of the Northern and Western Lagoons are approximately 16 km long and run parallel to each other separated by a 3 km wide land fringe, and are connected in CTWS northernmost limit. In contrast, the Southern Lagoon represents CTWS southernmost boundary, separated from the Northern Lagoon throughout 3.5 km of anastomosed creeks. The dominant vegetation differs slightly in each lagoon. graminoids (Eleocharis spp) cover most of Western Lagoons basin, especially its northern portions, while little or no emergent vegetation characterizes the basins in the Northern and Southern Lagoons. One to two meter-high shrubs (Bucida buceras) fringe the Northern Lagoons shores, especially the east shore, and cover some portions on its northern boundary. In this hydrological system Spanish Creek connects the Belize River to the Western and Southern Lagoons; meanwhile Black Creek connects the Southern and Northern Lagoons to the Belize River. During the rainy season, the water level in the Belize River increases and its flow discharges directly to the Northern, Southern and Western Lagoons through the Black and Spanish Creeks, respectively. During this time of the year the current flows in a south to north direction. The pattern is reversed during the dry season, when the water levels in the Belize River decrease, and, therefore, Spanish Creek and Black Creek decrease, limiting their contribution to the main lagoons. By this time a significant amount of water has been stored in the lagoons, and, especially, in the reserves

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15 northernmost portion, in the Backlanding/Revenge area. Due to differential pressure between lagoons and creeks, the flow gradually drains from this expanse directly to the creeks from north to south. By the end of the dry season, the lagoons are almost entirely dry, and only a few small ponds and creeks retain some of the water available in the system. Mexico and Jones Lagoons are located approximately 12 km east from the Northern Lagoon, apart from CTWS main hydrological system. These two lagoons are approximately 1 km long, and are connected to the Belize River through Mexico Creek. Like in Northern-Western-Southern Lagoons, similar processes define the mechanics of the Mexico-Jones hydrology throughout the year. Crooked Tree village (CT), located on the land strip between the Northern and Western Lagoons, is the only human settlement that has been developed within the reserves boundaries. This 300-person community has traditionally depended upon the resources provided from the Northern and Southern Lagoons, and fishing is currently an important income-producing activity for local villagers, fishermen from outside the influence of the CTWS area and for few fishermen that come from Guatemala. However, during the dry season, when the lagoons have almost or entirely dried down, their basins are frequently used for cattle ranching or game hunting. Other relevant human settlements are located along the Northern highways and around the largest cities, especially nearby Belize City, approximately 45 km southeast, and Orange Walk town 35 km to the north. Unplanned urban sprawl and extensive agricultural production are the major threats to wetlands around the large towns.

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16 Methods Landscape Data and Population Estimates I obtained population estimates, spatial distribution and habitat use of the Jabiru Stork by air-surveying northern and central Belize from March to mid June 2003 (Figure 3). One initial reconnaissance flight was made over CTWS on March 22. The goals of this flight were to identify type and location of wetlands, determine actual water levels, distribution of water bodies and other relevant hydrological features, identify vegetation types and their arrangement within the landscape, determine habitat preferences of Jabirus, and to refine surveying techniques and datasheets. Five additional surveys were performed on a bi-weekly basis beginning on April 12, and the final flight was made on June 21. The flights encompassed three stages according to weather and hydroperiod: a dry-down stage (March 15 to April 30) that occurred when waters levels in most water bodies were receding, a dry stage (May 1 to May 31) occurred when all major water bodies were almost or completely dry, and beginning of rains which consisted of a short period of rainfalls that occurred from June 1 to July 15. Depending on weather conditions, flights started between 15:00 and 15:30 and finished after 2 to 2.75 h of surveying time. A total of 2,400 km were flown during six flights combined, at an approximate surveying altitude of 60 m and average speed of 150 km/h. At this altitude, the distance from the aircraft at which Jabirus could be sighted and accurately distinguished from similar birds, was estimated at 1.5 km on each side of the aircraft. Each flight path was planned using one 1:350,000 scale map that depicted Belizes northern and central region and two 1:50,000 scale maps that showed, with greater detail, biophysical features around New River lagoon, CTWS and adjacent areas

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17 of interest. The Belizes Ecosystem Map produced by Meerman and Sabido (2001) was also useful at identifying major vegetation types, prioritizing surveying areas and identifying the type of habitat used by Jabirus. I modified the routes for each flight in an adaptive way, using information about the vegetative communities and the location of storks that were recorded in previous flights. In this way, I avoided resampling areas of unsuitable foraging habitat (e.g., broadleaf woodlands) and focused on habitat where Jabirus were previously recorded (e.g., freshwater wetlands) or where they had a reasonable likelihood of occurrence (e.g., savannas, coastal wetlands). Even so, the surveys encompassed a relatively large variety of suitable and unsuitable habitat for the storks. Because I found the greatest concentration of Jabirus within New River Lagoon and CTWS, I surveyed these areas in all flights with approximately the same intensity; therefore the surveying routes over these two areas remained relatively unmodified. Most modifications made to the routes affected areas outside the New River Lagoon and CTWS systems. Initially, the first survey flight was aimed at making observations of Jabirus within CTWS, while the second one was aimed at counting individuals in CTWS and to survey coastal wetlands in eastern and northern Belize. The third and longest flight surveyed New River Lagoon and CTWS, coastal wetlands in eastern and northern Belize and sugar cane crops and rice fields located on northwest Belize, bordering Guatemala and Mexico. The fourth and fifth flights were planned to survey the New River Lagoon and CTWS and other wetlands around and north from Mexico and Jones Lagoons and between the New and Old Northern highways.

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18 Two or three observers, including the pilot, sighted the Jabirus during each survey. On each survey, one person entered the data related to the animals surrounding habitat features, noted positions, flock size and bird activity. In some cases, digital photographs of flocks in foraging sites also aided to clarify doubtful counts. Positions of individuals and flocks and flock size were recorded on a tape recorder and plotted on 1:50,000 scale maps. The GPS readings were taken when the aircraft was positioned exactly above the target group. In some cases, the storks position could not have been determined using this procedure, either because the airplane traveled in a straight line or because of a pronounced turn. In these cases, I recorded GPS readings and estimated distance and bearing from each group to the aircraft. This type of situations occurred in approximately half of all observations. I defined a group of Jabirus as an aggregation of two or more individuals standing within 50 m from each other. If an individual was located outside this distance, then it was considered as a separate individual or flock. However, there were occasions in which the groups of Jabirus were distributed in rows, and often, the distance from one end of the row to the other was greater than 50 m. In these situations I estimated the maximum distance between birds and recorded them as an entire group only if they were aggregated within 50 m from each other. Relative water depths were noted from the air, but supplemental information during the dates in which the surveys were performed was obtained by taking weekly readings on staff gauges that I had installed. These staff gauges were made out of PVC pipes marked at 1 cm intervals and were placed in several isolated ponds and large catchments within and around CTWS. I categorized the water bodies found in the landscape as

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19 ponds, lagoons or creeks. Ponds were small and shallow (length < 500m, depth < 1m) water bodies with nearly circular geometry, containing still water, and could be connected or not to lotic water bodies. Lagoons were large and deep (length > 500m, depth > 50cm) lentic water bodies, generally connected to creeks that provide inflow and outflow of water. Creeks were narrow and shallow (width < 50m, depth < 1m) running water bodies (Figure 4). Microhabitat data and Observations on Foraging Behavior I recorded foraging behavior on the ground during the dry-down stage, dry stage and beginning of rains. Most observations were performed between 15:00 and 18:30 h, although sporadic encounters were made in the morning or midday. I used the Focal Animal Sampling Method, in which a single foraging individual is randomly selected from the flock and observed during a pre-established amount of time. In the current study, observation time comprised no more than 30 minutes. However, if the selected bird stopped foraging or left the area before the pre-established time, then, the observation and data recording ceased, in which case, a new individual was randomly selected and data recording continued. Observations were made using a 25-56x telescope and a pair of 10x46 binoculars. Data were recorded on a cassette tape, timed by stopwatch and entered on datasheets after every daily session. I recorded general environmental variables (weather, date, time of day, location, length of observation), social and behavioral data (e.g., size of foraging flock, number of steps, probes, prey type, prey size) and habitat data (type, water depth, vegetation height, % cover) for each foraging individual under observation. During observation periods, vegetation height and water depth was estimated in fractions of tarsometatarsal length (Frederick and Bildstein 1992). Prey items were identified by

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20 direct observation and prey size was estimated in fractions of culmen length, and then converted to metric units using the culmen measurements compiled by Thomas (1985b). Foraging behavior was recorded during the dry-down, dry and beginning of rains. Preliminary observations on the storks foraging behavior were made during the last week of March and, when possible, quantified within basic behavioral categories (e.g., steps, probes) based on the descriptions developed by Meyerriecks (1962), Kushlan (1976, 1978), Kelly et al. (2003). Direct measurements of habitat features were made when accessibility permitted it. First, I randomly selected foraging individuals and established circular plots (15-m diameter) around selected individuals. If present, emergent vegetation height was recorded by direct measurement and percentage cover (%) was sampled using a 1 m2 PVC frame thrown 10 times in random directions. The frame was divided into a grid of 100 squares (10 x 10 cm/square) using monofilament strings, and vegetation cover was estimated by counting the number of cells covered. Vegetation composition and height, type of substrate and water depth were estimated using graduated poles in each different foraging patch. Analysis of Data Routes, locations and size of groups of Jabirus recorded on each survey flight were entered into a Geographic Information System (ArcViewGIS, ver. 3.2). Aerial survey routes were drawn into the Belize ecosystems map (Meerman and Sabido 2001), buffered at 1.5 km on each side and clipped accordingly to obtain total surveyed areas and the proportions of each habitat surveyed. The storks location and group size were also plotted onto the map, allowing identification of habitat type used. I used the Belize ecosystems map to identify the biophysical features of ecosystems used by storks. I added

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21 one category, seasonally flooded basins, to the vegetation map and assigned it to those areas covered by the major lagoons. I did this because I considered lagoons as important areas for Jabirus and because in the map of vegetation there are no detailed biophysical descriptions of areas subject to hydrological fluctuation. I also used the land use base map to identify the major categories where Jabirus occurred. Differences in habitat use were determined using the chi-squared test (Gonzalez 1997). Figure 1. Map of Belize, Central America. Adapted from ESRI. ( http://www.esri.com/data/online/index.html )

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22 Figure 2. Map showing the components of the hydrological system in central Belize. CTWS (shadowed) encompasses four of the major lagoons: Northern, Western, Southern and Jones. Light blue: wetlands, Dark blue: water bodies, Red: Urban areas and highways. Figure 3. Map showing the study area divided according to differential sampling effort. Inner square: CTWS and New River lagoon, Middle size area: central Belize, larger area: northern Belize.

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23 Figure 4. Map showing designated survey areas according to foraging relevance for Jabiru Storks, central and norther n Belize. Areas: I=New River Lagoon, II=Western Lagoon, III=Revenge Area/ Bight Swamp, IV=Northern Lagoon, V=Southern Lagoon, VI=Black Creek/ May Pen and adjacent wetlands, VII=Mexico and Jones lagoon, VIII=N ew and Old Northern Highways, IX=Dobloon Lagoon, X=Shipyard and surrounding agricultural lands.

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CHAPTER 3 RESULTS Abundance of Jabiru Storks I made a total of 391 sightings of individual Jabiru Storks during six aerial surveys in central and northern Belize. Overall, I recorded an average of 65 storks/flight or 0.16 storks/km, a mean of 4.46 individuals/group, and an average of 15 flock sightings/flight or 0.04 flock/km. The largest number of storks (n = 116) was recorded on May 10 (survey 3), while the smallest number (n = 49) was recorded on April 12 (Table 1). Singletons were recorded more frequently during the dry down (n = 11, survey 1) and dry stages (n = 8, survey 3), while the frequency of Jabirus foraging in pairs seemed to remain constant throughout the entire study period. Very large aggregations (n = 31-50, n > 50) were recorded only in the dry stage (surveys 3 and 4). Conversely, intermediate-sized groups (n = 3-10, n = 11-30) were rarely observed at this date although they were relatively frequent in the next four surveys (Figure 5). Spatial Distribution Jabiru Storks were frequently sighted in central Belize, between southern New River Lagoon and Dobloon Lagoon, from latitude 17 to 18N, and from longitude 88 to 88 West. The area encompasses approximately 2000 km2. I saw no Jabirus in coastal areas, or in Belizes northernmost areas. Similarly, few storks were recorded from the countrys western areas, mainly from agricultural lands located close to New River Lagoons wetlands in central Belize. CTWS and wetlands associated with the New River Lagoon contained the highest densities of Jabirus. Sightings in both systems 24

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25 accounted for 76% of recordings in all surveys, while only a small proportion of the total number of observations were recorded from wetlands located between the Old and New Northern Highways, and few of them from within and around Dobloon Lagoon in northern Belize. Stork distribution varied according to wetlands water level fluctuations. During the dry down stage, the highest concentrations of storks were observed around New River Lagoon, Revenge/Backlanding Area/Bight Swamp, and, especially in CTWS Northern Lagoon (areas I, III and IV respectively). Around 78% of the total number of storks recorded during the first survey on April 12 (Figure 6) and 45.6% of birds sighted during the second survey (April 26, Figure 7) foraged in the Northern Lagoon area, all of them distributed almost exclusively along a 5 km-long strip that runs from Crooked Tree village to Bight Swamp, in the lagoons northernmost limits. By May 10, most of the largest impoundments had receded to the point that they formed scattered ponds across the landscape. By this date, most Jabirus occupied the Revenge Area/Bight Swamp (26% of total) and Northern Lagoon (35%, Figure 8). These proportions were at least 6 times greater than those recorded from other large impoundments (May Pen, Southern and Western Lagoons) where most of the basins were almost entirely dry. By May 24, the dry weather still prevailed; Jabirus foraged on remnant ponds at Northern Lagoon, and then shifted towards Bight Swamp approximately 1.5 km north, even though the ponds that they formerly used in the Northern Lagoon still held water (Figure 9). Approximately 67% of total observations made during survey 4 were recorded from Bights Swamp ponds and creeks.

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26 May Pens wetlands and Western Lagoon (58 and 28% respectively) show the highest densities of storks by June 21 (Survey 5). Few birds were seen in the Northern Lagoon; this due to the rise of water levels in this lagoon as result of 38 hours of continuous rain that fell over central Belize. Thus, most of this habitat, which was used in previous weeks, was then completely unavailable. At the same time, water levels increased on the dry basins of Western Lagoon and most wetlands in May Pen Area (Figure 10). Figure 11 summarizes the spatial distribution of the Jabiru Storks recorded during the five surveys in central and northern Belize. Habitat Use Habitat Use According to Ecosystem Classification A total of 9 ecosystem types were sampled during air surveys, although, only 4 of them were used by Jabirus. Overall I found that 85.75% of Jabirus used Seasonally Flooded Basins, 9.26% used Tropical Lowland Tall Herbaceous Swamps, 3.56% used Tropical Evergreen Seasonal Broadleaf Lowland Swamp Forest: Low Variant and only 1.43% were recorded on Tropical Evergreen Broadleaf Forest over Calcareous Soils. When plotted onto the ecosystem map of Belize, 7 % of locations of Jabirus corresponded to Short-Grass Savanna with Needle-Leaved Trees or Short-Grass Savanna with Shrubs. However, based on observations made in the field, these ecosystem types were, in many occasions, complex mosaics of several ecosystem types. Large ecosystem sometimes appeared as ecosystem matrices with several smaller patches of different ecosystem types embedded within the matrix. The immediate habitat type surrounding Jabirus observed in Short-Grass Savanna with Needle-Leaved Trees or Short-Grass Savanna with Shrubs corresponded small patches of, either, Seasonally Flooded Basins or Tropical Lowland Tall Herbaceous Swamp. Therefore, during data analysis, records from

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27 these locations were pooled together with Seasonally Flooded Basins or Tropical Lowland Tall Herbaceous Swamp types. The Jabirus use of ecosystem did not vary much during the time that this study was done. When compared across the dry-down and dry stages and beginning of rains, the majority of Jabirus preferred Seasonally Flooded Basins. For instance, during the dry down stage (March to May 1), around 89% of observations on storks were made from Seasonally Flooded Basins and only a few of them (6.5%) in the Tropical Evergreen Seasonal Broadleaf Lowland Swamp Forest: Low Variant, or the Tropical Lowland Tall Herbaceous Swamp (1.5%). Similarly, during the late dry season (May 1 to May 30) when most lagoons were already dry, 86.3% of the storks were observed foraging in remnant ponds formed by the New River Lagoon and the receding waters of the Northern Lagoon. Nine percent of the total number of observations were recorded on Tropical Lowland Tall Herbaceous Swamp, 3.7 % on Tropical Evergreen Seasonal Broadleaf Lowland Swamp Forest: Low Variant, and only 2 observations were made on Tropical Evergreen Broadleaf Lowland Forest over Calcareous Soils (Western Variant), representing 1% of the observations for this season. By the first week of May, the area in which the main gauge was installed at the Northern Lagoon was completely dry. By this date, PVC gauges dispersed among two remnant ponds at the Western Lagoon, one of the areas with high occurrence of Jabirus, showed a mean decrease of 3.0 and 6.5 cm/week (Figure 12). By the beginning of June, mild and scattered rains arrived at certain areas in Belize and water levels recorded at the stages increased rapidly. For instance, the gauge located at the Northern Lagoon reached 110 cm following 36 hours of continuous rains. During

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28 this period Jabirus used two ecosystem typesat least 82% of storks used Seasonally Flooded Basins and 17% of the storks were foraging in Tropical Lowland Tall Herbaceous Swamp (Figure 13). Most of the locations were recorded from small marshes close to CTWS and from small ponds surrounded by Pine-Palmetto savannas located between Belizes Old and New main highways. Habitat Use According to Land Use Classification The data obtained from land use maps indicated that a total of 9 different land use categories were sampled during all 5 flights but only 4 of them were used by Jabirus (Table 2). The storks were found using wetlands (open areas subject to seasonal floods) out of proportion to other available habitat. Overall, 91% of total observations on individuals (n = 415) were recorded from wetlands, significantly higher (X2= 975.8, P < 0.001, df = 3) than in any other habitat. The proportion of birds using vegetation types was relatively similar across the dry-down, dry stages and beginning of rains, with the highest number of birds foraging in wetlands and the lowest observed in agricultural areas (Figure 14). I found no Jabirus using any coastal habitat, even though other wading birds such as the Wood Stork were found aggregated in colonies along coastal savannas and mangrove forests within the Shipstern Reserve, in Belizes north-easternmost area. Similarly, there were no records of any Jabiru from rice fields in northwest Belize. Use of Water Bodies Jabirus foraged in lagoons and ponds more frequently than in creeks, although the proportion of storks using these habitats changed drastically across seasons. During survey 1 most Jabirus (87%) foraged in lagoons, mainly around New River and the Northern Lagoon and, in fewer cases, in ponds and creeks. Observations made from the next 3 surveys showed that the use of remnant ponds increased drastically; the proportion

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29 of storks in these habitats rose from 6% in survey 1 to 56, 99 and 92% in surveys 2, 3 and 4 respectively. The frequent use of ponds was due to decrease of water levels and reduction of lagoon habitat. Jabirus rarely used creeks (< 6% of total) with an exception during survey 2, when 44% of the storks were found there (Figure 15). Features of Foraging Microhabitat In both aerial and ground surveys, Jabirus were generally observed in open spaces (free of trees or shrubs) and in drying-down or already dry basins and marshes. In 96% (n = 336) of the observations made from the ground, individuals foraged in locations with little or no emergent or submerged aquatic vegetation. However, when present, graminoids and sedges, mainly spike rush (Eleocharis spp) and Cyperus spp, were the most common species composing the emergent plant cover, reaching an average height of 1.28 cm (SD = 35.26) and mean coverage of 39.67% (SD = 22.07). The mean depth of water at which foraging occurred was 16.26 cm (n = 351 observations, SD = 12.30) but fluctuated from 0 to 50 cm. Foraging in open waters and along shorelines was common in all seasons. Foraging on mudflats in the Northern Lagoon occurred only during the dry down period, when receding waters allowed the formation of extensive mud banks where the storks searched for buried eels. Diet Composition I recorded a total of 782 prey items collected by Jabirus in the period of March to June. I was unable to identify 80% of these items due to difficulties observing details of small-sized prey at long distances. Ninety eight percent of these unidentified items (n = 563, 72% of total) were recorded from a single group of 5 foraging storks in the Northern Lagoon after heavy rains fell over central Belize on June 18, flooding all the lagoons and many small wetlands. Due to the small prey size (< 2 cm), their substrate, location, and

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30 the speed at which they were captured by the Jabirus, it is very likely that these small items were aquatic insects. Of the 162 remaining prey items that I was able to identify, 95% were aquatic animals. Small fish, with approximate standard length (sl) below 15 cm, were the most abundant prey type consumed, accounting for 73%, followed by Swamp Eels (Symbranchus marmoratus, 13%), Apple Snails (Pomacea spp, 6%) and large fishes (sl > 30 cm, 3%) including cichlids (Tilapia spp. among others) and catfishes (Ariidae). Terrestrial prey comprised only 5% of the items collected; they were represented only by amphibians and lizards. Although identification of these terrestrial prey items was often inconclusive, several clues led me to believe that they were terrestrial prey. The storks were frequently searching the vegetation on a narrow strip of land (5 x 150 m) located in the middle of the lagoon, and picking up small items from the ground. Later visits to the foraging patch revealed an abundance of anurans, mainly toads (Bufo spp.) and lizards (Norops spp.) that probably serve as food items for the storks (Figure 16). Foraging Behavior I recorded a cumulative of 800 minutes of foraging behavior from 53 Jabiru Storks in CTWS and adjacent wetlands from March to July 2003, from 53 individuals. Walking and Searching for Food Overall, the stepping rate during search periods averaged 23.14 step/min and the step length, as compared with leg length, was estimated at between 50 to 60 cm { Object 1. Video clip of Jabiru walking in Northern Lagoon. AVI file. (Jabiru_steps.avi, 18 seconds, 2.79 Mb )}. Shorter, faster steps were used when prey were sighted, commonly at distances as far as 20 to 30 m.

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31 I observed Jabirus using two main types of searching behavior. First, the birds inclined their head and neck towards the water, and introduced their bills into the water. As the bill was introduced, they opened and closed it several times in a way that resembled biting or tasting the water, as described by Thomas (1985b). The depth of water at which they performed this behavior was variable but typically ranged from the tip to half-length of bill (2 ~ 15 cm) and it was more frequent in shallow areas. Captures of fish were common using this method, but most of the time, it seemed like the Jabiru was probing repeatedly trying to detect the fish hitting the bill { Object 2. Video clip of searching for food. AVI file (Jabiru_feeding_behavior.avi, 15 seconds, 2.33 Mb )}. In a different behavior, the birds inclined their head and neck at an angle that ranged between 45 and 90 degrees below the horizontal, slowly introduced their bill into the water, and, consequentially, into the mud. Normally, one to four bill strokes on the same location followed the first insertion, and, often, subtle probing was seen as the bill was about to be taken out of the water. These movements seemed to be more useful for tactolocation, especially detection and capture of infauna, mainly eels and mollusks. Jabirus used this behavior on shallow areas in the lagoon or around ponds (1 cm to 15 cm), and it seemed exclusively used to locate and excavate buried eels from mudflats { Object 3. Video clip of Jabiru searching for food in mudflat. AVI file. (Jabiru_feeding behavior1 1 minute 29 seconds, 3.18 Mb)}. A third behavior, which I did not see during the dry down stage, was observed in the dry season, when most foraging Jabirus formed groups around shallow remnant ponds scattered throughout CTWS. In this behavior, the birds swayed their neck from side to side of the body, while simultaneously pivoting their head approximately 45 degrees

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32 above and below the horizontal. During these movements the birds bill almost reached the tarsus, when the neck was positioned at its lowest level at either side of the body; the head was lifted until reached its highest peak, and then pulled back down at the other side of the body, describing a movement through the water that resembled an inverted V. Repetitions were always performed as the bird walked across the water body, and were sometimes violent enough that water was lifted when the bill was raised. This behavior was not observed in shallow water (depth < 10 cm), mudflats, or dry shorelines. No prey items were captured, nor were any type of intra or interspecific aggression evident during these episodes. This behavior was very infrequent, perhaps not recorded in more than 5 occasions; the reasons that explain it still remain unclear. Capturing and Handling Prey Capture rate of all observations was 0.62 prey/min (SD = 1.33). Preys were captured using the two searching behaviors described above. Small and large fish were always captured by probing (inserting the bill into the substrate, water or mud, opening and closing the bill), either while actively chasing prey or by stalking. Especially during the dry down period, Jabirus often stopped foraging, stood still, and then stretched their neck, keeping the head as high as possible and staring from one side of the head, switching to the other to scan nearby areas. Once the type of prey and its distance was determined, the stork ran towards the preys location, often flapping its wings 1 to 3 times and leaping 0.5 to 1 m above water. The bird then searched actively, inclining its head and neck with its bill placed perpendicular to the waters surface and catching the fish at the first or second strike. Both stalking and tactolocation were used in dry down and dry periods. However, during the dry period stalking occurred mostly on small dead fish which were picked up from the ponds surface and quickly discarded.

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33 The manner in which fish were handled before ingestion varied according to the size of fish. Small fish were captured and eaten rapidly, while longer periods were spent manipulating and consuming large prey, generally larger than 30 cm. Following capture, Jabirus usually used their bills to stab violently at large fishes captured, which seemed to stun or dismember the fish. Stabbing was often coupled with neck shaking while the prey was held in the bill. Several repetitions of this behavior occurred, interspersed with periods where the storks dropped the prey into the water and picked it up again. Remnants of the preys body floating on the surface were then consumed. Large fish eaten whole by Jabirus were rarely seen. The storks dismembered fish prey on all but one occasion, when a 30-cm fish was eaten whole { Object 4. Video clip of Jabiru dismembering a large prey. MPEG. (Jabiru_handling_prey.mpeg, 1 minute 29 seconds, 10 Mb)}. Eels were captured after long searches across the lagoons very shallow waters, shorelines and mudflats. Generally, the stork dug repeatedly into the same location by introducing the bill several times, until the eel was unburied. Then, the prey was picked up from mid body, moved along the bill, and then swallowed. On rare occasions, captured eels were held in the bill for several minutes (5 to 10) before being consumed, dropped repeatedly to the ground to be stabbed a few times, picked up and eaten. Unlike large fishes, eels were not dismembered completely when stabbed, and apparently, these strikes were an attempt at stopping further contortions of large eels, by either killing or stunning them before ingestion { Object 5. Video clip of Jabiru searching, handling and eating eels. MPEG file. Jabiru_eating_eels.mpeg, 1 minute 21 seconds, 8.37 Mb )}.

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34 Snails were collected from shallow waters (depth < 30 cm). Once captured, the snail was retained in the tip of the bill, and the shell was broken into pieces by applying bites of the bill, leaving the mollusk ready to be swallowed. During the process the shell was not ingested. Prey Piracy Intraspecific prey piracy was seldom observed, but occurred more frequently and intensely when storks captured large prey items. For instance, on March 29, I observed one Jabiru capturing a large eel (sl > 30 cm), and then be harassed and briefly chased in the air for nearly one minute by another stork. The chase finished when the prey was dropped into the water. The manner in which robbing or robbing attempts occurred was variable. During some incidents, the intruder stork approached the other at a normal stepping rate (1 step/s) and as close as 5 to 10 meters radius. In these cases, the intruder may have attempted to approach and pick up remnants of a fishs body without disturbing the other Jabiru. On other occasions the prey was brought to the shoreline, where one or two other Jabirus stalked, ran and/or flew immediately towards the stork and its prey { Object 6. Video clip of Jabiru handling a large prey and then harrased by conspecific.MPEG file. (Jabiru_large_prey.mpeg, 39 seconds, 4.19 Mb)}. Sometimes the storks used brief attack-defense displays to threaten each other, which involved opening the bill 10 to 15 cm and spearing 2 or 3 times without touching the rival and then quickly pulling the head back. Interspecific prey piracy, though infrequent, occurred exclusively during the dry down stage. On one of two occasions, a Snail Kite (Rosthramus sociabilis) carrying a fish was chased by a Jabiru for nearly one minute, and ended with the kite retaining the fish. Similarly, on another occasion the Jabiru chased a Snowy Egret (Egretta thula) with a

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35 fish on the ground and the stork obtained the fish. I did not observe any species making attempts to rob the Jabirus prey. Loafing and Social Interactions Storks foraging in the Northern Lagoon during the dry down stage usually moved from their foraging location to the lagoons east shoreline typically by the end of the afternoon, between 17:30 and 18:30. Groups rather than singletons were more common, usually containing between 5 and 20 individuals. During these periods, some storks remained inactive while others (young and adults), walked around the area and played with bushes by pulling dry branches or picked up sticks from the ground. They often engaged in sham disputes with conspecifics and between Wood Storks. This type of interaction was more frequently observed in the dry-down period, especially in the Northern Lagoon. Conversely, they were less frequently seen in the dry season, however, all of them were observed in Western Lagoon and remnant ponds at Northern Lagoon. Interaction between Jabirus and Wood Storks were seen only during the dry season in Western Lagoon and remnant ponds of the Northern Lagoon. Regardless of the species, these disputes were characterized by two individuals pulling one end of a twig. However, I never observed aggressive displays at any moment during these interactions.

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36 1168556561064461512103001000001002468101212345Date of survey flightFrequenc y 1 2 3-10 11-30 31-50 >50Group size June 21 May 10 April 26 April 12 Ma y 24 Figure 5. Variation of foraging sociality of Jabiru Storks observed in 5 survey flights.

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N Legend 1 2-5 6 10 11 30 37 15 Kms Figure 6. Spatial distribution of Jabirus during survey 1 (April 12, 2003).Light blue= Tropical Lowland Tall Herbaceous Swamp, Dark blue= water bodies/ Seasonally Flooded Basins, Pink= Short Grass Savanna, Green: Broadleaf forest, Yellow= Agriculture/rural communities.

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20 Kms N 11 30 6 10 1 2-5 Legend 38 Figure 7. Spatial distribution of Jabirus during survey 2 (April 26, 2003). Light blue= Tropical Lowland Tall Herbaceous Swamp, Dark blue= water bodies/ Seasonally Flooded Basins, Pink= Short Grass Savanna, Green: Broadleaf forest, Yellow= Agriculture/rural communities.

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N Legend 1 2 3 10 11 30 31 50 39 Figure 8. Spatial distribution of Jabirus during survey 3 (May 10, 2003). Light blue= Tropical Lowland Tall Herbaceous Swamp, Dark blue= water bodies/ Seasonally Flooded Basins, Pink= Short Grass Savanna, Green: Broadleaf forest, Yellow= Agriculture/rural communities.

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20 Kms Legend 1 2 3 5 6 30 N 40 Figure 9. Spatial distribution of Jabirus during survey 4 (May 24, 2003). Light blue= Tropical Lowland Tall Herbaceous Swamp, Dark blue= water bodies/ Seasonally Flooded Basins, Pink= Short Grass Savanna, Green: Broadleaf forest, Yellow= Agriculture/rural communities.

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N Le g end 1 2 3 5 6 30 41 20 Kms Figure 10. Spatial distribution of Jabirus during survey 5 (June 21, 2003). Light blue= Tropical Lowland Tall Herbaceous Swamp, Dark blue= water bodies/ Seasonally Flooded Basins, Pink= Short Grass Savanna, Green: Broadleaf forest, Yellow= Agriculture/rural communities.

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4610630216028813146350460695412465960126030010672678010203040506070809010012345Survey flight% Observations/are a New River lagoon Western lagoon Bight swamp Northern Lagoon Southern lagoon May pen and adj Mexico and Jones lagoons Old-New NHgwy Dobloon lagoon Shipyard and surroundings 42 Figure 11. Summary of spatial distribution of Jabiru Storks recorded from 5 survey flights over central and northern Belize.

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0204060801002831017243081522305111925211172431 MarAprilMayJuneJuly DateWater depth (cm) NLn,s BB WLn WLs MP AGc 43 Figure 12. Readings of water levels recorded from 6 water stages: NLn,s=Northern Lagoon north and south portions, BB=Burrell Boom, WLn= Western Lagoon north stage, WLs=Western Lagoon south stage, MP=May Pen area, AGc=Aguacaliente Lagoon (Southern Belize).

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88.682.03.51.00.03.70.01.59.018.086.36.50102030405060708090100Dry down stageDry stageBeginning of rainsSeason% of Observation s Seasonally flooded basin Tropical evergreenbroadleaf forest overcalcareous soils Tropical evergreen seasonalbroadleaf lowland swampforest-low variant Tropical lowland tallherbaceous swampEcosystem type 44 Figure 13. Ecosystems used by foraging Jabiru Storks in central and northern Belize, from March to July, 2003.

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45 a )91.332.895.540.240.0010.0020.0030.0040.0050.0060.0070.0080.0090.00100.00FRESHWATERWETLANDLOWLANDBROADLEAF FORESTOWLAND SAVANNAAGRICULTURE b96.463.540.000.000.0010.0020.0030.0040.0050.0060.0070.0080.0090.00100.00FRESHWATERWETLANDLOWLAND BROADLEAFFORESTLOWLAND SAVANNAAGRICULTURE c) 86.702.959.85 0.490.0010.0020.0030.0040.0050.0060.0070.0080.0090.00100.00FRESHWATERWETLANDLOWLAND BROADLEAF FOREST LOWLAND SAVANNA AGRICULTURE d) 94.952.023.03 0.000.0010.0020.0030.0040.0050.0060.0070.0080.0090.00100.00FRESHWATERWETLANDLOWLAND BROADLEAF FOREST LOWLAND SAVANNA AGRICULTURE L ) Figure 14. Habitat used by Jabiru Storks according to land use classification; northern and central Belize: a= All flights combined, b=dry down, c=dry, and d=beginning of rains.

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46 8700574656999224644132010203040506070809010012345Date of survey flight% sightings... Lagoons Ponds CreeksType of water body May 10 April 26 April 12 Ma y 24 June 21 Figure 15. Water bodies used by foraging Jabiru Storks in central and northern Belize, from March to July, 2003. 1002006001000191074402221201020304050607080Dry down stageLate dryBeginning of rainsSeasonPrey items captured ( %) Lizards Shells Anurans Snails Freshwater eels Small fish Large fishType of prey Figure 16. Proportion of identified prey items (n=160) of the Jabiru Stork in CTWS, from March to June 2003.

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Table 1. Total number of Jabirus counted during one reconnaissance and six survey flights made over Central and Northern Belize, from April to June, 2003. Survey No. Week Date Season Distance flown (km) Time (h) Total Number of Foraging Jabirus Total number of sightings (number of groups) Mean number of individuals/group Pre 1 April 5 Reconnaissance 240 2.1 69 1 3 April 12 300 2.5 49 21 2.30 2 5 April26 Dry down season 800 2.7 68 16 4.30 3 7 May 10 400 2.6 116 22 5.30 4 9 May24 Late dry season 315 2.5 89 17 5.20 5 13 Jun 21 Beginning of rains 500 2.3 99 19 5.20 Total 2055 12.34 391.00 76.00 Mean 411 2.46 65.17 15.20 4.27 Standard deviation 204.36 0.12 24.28 2.55 1.26 47

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Table 2. Number of Jabirus in relation to habitat types (Land-use classification). Survey flight 1 2 3 Area Number of Jabirus Area Number of Jabirus Area Number of Jabirus Land use type km 2 % n % km 2 % n % km 2 % n % Agricultural uses 88.82 9.93 0 0.00 99.4 9.68 0 0.00 73.38 11.55 1 0.86 Coastal savanna 53.63 6.00 0 0.00 112.58 10.96 0 0.00 0.00 0.00 0 0.00 Lowland broadleaf forest 383.58 42.88 0 0.00 365.74 35.61 4 6.06 342.62 53.93 4 3.45 Lowland pine forest 0.02 0.00 0 0.00 0.00 0.00 0 0.00 0.00 0.00 0 0.00 Lowland savanna 158.69 17.74 0 0.00 131.51 12.81 0 0.00 93.80 14.76 11 9.48 Mangrove and littoral forest 68.28 7.63 0 0.00 101.04 9.84 0 0.00 0.83 0.13 0 0.00 Rice 0.00 0.00 0 0.00 13.69 1.33 0 0.00 0.00 0.00 0 0.00 Water 47.73 5.34 0 0.00 88.42 8.61 0 0.00 33.07 5.2 0 0.00 Wetland 93.82 10.49 47 100.00 114.54 11.15 62 93.94 91.67 14.43 100 86.2 Total 894.57 100.00 47 100.00 1026.90 100.00 66 100.00 635.36 100.00 116 100.00 48

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Table 2. Continued Survey flight 4 5 All flights combined Area Number of Jabirus Area Number of Jabirus Area Number of Jabirus Land use type km 2 % n % km 2 % n % km 2 % n % Agricultural uses 92.54 14.51 0 0.00 92.54 14.51 0 0.00 446.68 11.65 1 0.24 Coastal savanna 0.00 0.00 0 0.00 0.00 0.00 0 0.00 166.21 4.34 0 0.00 Lowland broadleaf forest 306.34 48.02 4 4.49 306.34 48.02 2 2.02 1704.62 44.48 14 3.36 Lowland pine forest 0.00 0.00 0 0.00 0.00 0.00 0 0.00 0.02 0.00 0 0.00 Lowland savanna 106.25 16.66 9 10.1 106.25 16.66 3 3.03 596.51 15.56 23 5.52 Mangrove and littoral forest 0.83 0.13 0 0.00 0.83 0.13 0 0.00 171.81 4.48 0 0.00 Rice 0.00 0.00 0 0.00 0.00 0.00 0 0.00 13.69 0.36 0 0.00 Water 33.66 5.28 0 0.00 33.66 5.28 0 0.00 236.54 6.17 0 0.00 Wetland 98.32 15.41 76 85.4 98.32 15.41 94 95.00 496.67 12.96 379 90.89 Total 637.93 100.00 89 100.00 637.93 100.00 99 100.00 3832.70 100.00 417 100.00 49

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CHAPTER 4 DISCUSSION Rainfall Pattern in Central and Northern Belize Typically, during neutral years (without presence of El Nio/La Nia effects), rains in Belize start in early May and end in the first weeks of November. There is a slight decrease in the amount of rainfall between June and July, and then, the maximum peaks occur in September and October. Data obtained from the closest weather stations around CTWS (Phillip SW Goldson Airport and Tower Hill Station) indicate that the mean monthly rainfall peaks in September and October at 275 mm, while the lowest rainfall rates are recorded during March (mean = 52.50 mm, n = 43). The weather during 2003 was abnormally dry and warm; I did not observe any rains for most of the first half of the year. According to anecdotal information, the wetlands water levels found during the first half of 2003 were much lower than those typical of preceding years. Heavy but brief storms were observed by the end of May although these rains were a consequence of tropical storm Claudette that affected central and northern Belize. No rains followed and the landscape remained relatively dry; heavy rains did not occur until the end of August { Object 7. Video sequence of monthly water level fluctuation in Northern Lagoon from March to July 2003. MPEG. (Dry_down_sequence.mpeg, 1 minute 17 seconds, 8.95 Mb )}. Abundance of Storks in Response to Local Hydrology My population surveys did not suggest any effects of climatological events on the number of foraging storks. As opposed to my prediction, I did not observe a decrease in 50

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51 the number of foraging Jabirus in response to the change from dry-down to dry to the beginning of rains. However, it was not clear that I had a good chance of observing the required range of conditions. This was due, in part, to the drought experienced in Belize during 2003 that extended until the end of August, delayed the rainy season, and therefore, did not allow a clear comparison between both dry and rainy seasons. Even though a decrease in the number of Jabirus was not evidenced throughout seasons, I observed that the foraging sociality of the stork was clearly influenced by changes in available foraging habitat. Most of the storks observed during the dry-down period foraged alone, or in pairs, rarely in flocks larger than 15 individuals. In contrast, during the dry period, Jabirus foraged in flocks as large as 60 individuals, as water levels had decreased and receding surface waters formed pools and ponds where the storks concentrated. Later, when water levels increased as a result of rainfall activity, the storks were dispersed, usually alone, in pairs or in two groups of around 25 individuals. This pattern of aggregation was similar to the associations of foraging Jabirus found in the Venezuelan llanos, where larger flocks were recorded during the dry season while singletons and pairs were more frequent during the rainy season (Gonzalez 1996). My data suggest that Belize hosts the largest number of Jabiru Storks reported to date in Central America and southern Mexico, confirming the assertions made by Luthin (1987). The maximum number of storks ever recorded in one single survey over Belize (survey 3, n = 116) was 34% higher than the overall number of sightings and almost 8 times the estimated minimum size of the resident population reported for wetlands in the Usumacinta-Grijalva Delta, in southeast Mexico (Correa and Luthin 1988). The number

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52 of Jabirus counted in Belize is almost 55% higher than the minimum population size estimated for Jabirus in the Lower Tempisque Rivers basin, Costa Rica (Villareal 1997). Average density of Jabirus found in the four main habitat used in Belize reached 0.12 individuals/km2, which is twice the density of Jabirus found in the Honduran part of the Miskito coast and almost 25% lower than the density found in the wetlands of the Nicaraguan Miskito coast (Frederick et al 1997). Reports from villagers settled near wetlands located south of CTWS and records of storks at Aguacaliente Lagoon in southern Belize also suggest that at least 10 additional Jabirus occur there, and were not counted during aerial surveys. It should also be noted that some Jabirus might have been double-counted during survey 3, when 10 to 13 Jabirus moved in the same day, from wetlands already surveyed in CTWS to areas that were currently being sampled. I believe that a conservative estimate of the minimum number of Jabirus in Belize during the first half of 2003 was 130 to 140 individuals. It was not clear if these Jabirus were local, sedentary breeders or if they have came to Belize from other parts of Central America and/or southeastern Mexico, perhaps propelled by unusual dry weather and unavailable foraging habitat in those areas, as suggested by Correa and Luthin (1988). To date, there has not been any study aiming at corroborating the existence of these movements, identifying regional flying paths or determining the hydrological dynamics and synchronization of wetlands used by Jabirus across Central America. If it is assumed for a moment that other Jabirus are breeding in other Central American wetlands at the same time that those in Belize, I estimate that no more than 400 individuals may occur in Mexico and Central America.

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53 Spatial Distribution and Habitat Use During the extremely dry conditions in 2003, Jabirus spatial distribution followed closely the actual distribution of remaining surface freshwater in the landscape. Like many wading birds in tropical and temperate regions, Jabirus clearly responded to local hydrological fluctuations; their spatial distributions changed according to these fluctuations. This would not be surprising, since they foraged almost exclusively on aquatic prey. Although that Jabirus have been reported using coastal habitats in South America (Spaans 1975), in Belize, they used inland freshwater wetlands exclusively. The storks appeared to have a strong link to these ecosystems; the fact that an average of 13% of the surveyed area contained at least 76% of the overall sightings is a clear indication of selectivity for these habitats. Apparently, Jabirus did not seem to select wetlands haphazardly. They preferred large, unvegetated and shallow freshwater wetlands, subject to marked fluctuation of water levels, such as the Northern and Southern Lagoon in CTWS and wetlands associated to the New River Lagoon within central Belize. Perhaps, the relatively good quality flowing water and high influx of prey animals from major rivers into the larger water bodies offer a higher amount and variety of prey animals to the storks compared to small, isolated and heavily vegetated wetlands that were still available during the dry down period. Fluctuations of water levels in these large wetlands can be dramatic, perhaps reaching 150 cm. I observed that during the dry-down period, a vast area of aquatic habitat is drastically reduced; massive mortality of its fauna occurs, notably fishes, as water conditions change and inter/intraspecific relationships intensify. Additionally, reduced vegetation causing an extremely openness of these wetlands might increase the

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54 storks ability to identify and locate possible predators approaching while the stork is foraging. It was interesting to notice that during the dry down period, when water levels were falling; most Jabirus were distributed in the northernmost section of the Northern Lagoon. Perhaps, this peculiar distribution was related to the road that was built across the Northern Lagoon, which bisected the entire wetland into north and south portions and impeded the flow of aquatic fauna from one side to the other. During the rainy season, water flows from south to north and it is stored in the northern portion. The road functions as a dike reducing the flow of water back into the southern portion. During the flooding stage, fish and other aquatic species might follow the same pattern and become trapped in the northern portion, leaving a larger amount and variety of prey animals available to the storks in this area. Contrary to my prediction, there was not a shift in habitat used for foraging purposes when the dry-down period ended and most wetlands and some of the lagoons were completely dry. Instead, many Jabirus continued foraging on ponds and pools that were formed by the lagoons receding waters. Nevertheless, I believe that, like some other species of wading birds, a few Jabirus could have relied on altered habitats (e.g., agricultural grounds, aquaculture lagoons) but were not detected during surveys. Anecdotal reports from local people suggested that Jabirus often forage in the shrimp farm located near Belize City, the rice fields in Blue Creek area, northwestern Belize and ponds within the agricultural fields of Spanish lookout in central Belize. As the brief rainy season progressed, many of the lagoons were flooded and a considerable number of small ponds were completely filled with water. Jabirus continued foraging at the lagoons, although during this period, they occupied the wetlands around May Pen area. Some

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55 other small wetlands were available and used by very few Jabirus; these included those located along the Northern highway, near Sibun River, and around Aguacaliente Lagoon in southern Belize. Foraging Ecology I found Jabiru prey item selection very similar to that recorded by Thomas (1985b) in the Venezuelan Llanos and Villareal (1997) in Costa Rica. Unlike Venezuela, Jabirus in Belize were not seen ingesting any mammals or crustaceans. In Belize, Jabirus foraged in the same large basins for nearly all of the dry season. The lack of precipitation over the entire study area affected the foraging grounds of the Jabiru Stork by reducing the amount of surface area covered by water and altering the water quality. During the dry-down stage Jabirus in Northern Lagoon foraged more frequently in open waters and mudflats, and less frequently on shorelines and vegetation patches. During the dry season, Jabirus could forage only in open waters; there were no mudflats and the shoreline perimeter was substantially reduced. Unlike most wading bird species in these wetlands Jabirus used mudflats as foraging grounds, where they exclusively searched for Swamp Eels. Typically, these fishes live in clear to muddy waters in sluggish flowing streams, on sandy or muddy substrates (Martin 1972) where they build tunnels of about 0.3 to 1.2 m under water in which males guard the eggs (Greenfield and Thomerson 1997). Jabirus may have developed morphological adaptations for exploiting this prey item to an extent that other sympatric wading bird species in the area cannot. In Thomas (1985) paper, it was proposed that the peculiar curvature and length of the Jabirus bill can be a specialization for digging large Swamp Eels from the mud. If this is an adaptation for exploiting eels, it seems quite reasonable to expect that eels are a critical resource for the natural history and survival of the species.

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56 In fact, Swamp Eels may constitute a relatively large proportion of the Jabirus diet. I found that around 19 % of the total prey items captured by Jabirus were Swamp Eels; similar proportion has been recorded in the Venezuelan Llanos (Thomas 1985b) and almost twice this proportion has been recorded in Costa Rica (Villareal 1997). Apparently, the reason Jabirus preferred eels is that, Swamp Eels seem to be easier to handle than large fish, and perhaps, eels might be ingested entirely without much investment of time and/or energy compared to the time and energy invested to dismember large fishes. Another potential reason for preying on Swamp Eels is that, they might represent a considerable source of protein for the Jabirus diet as compared with other types of fish available in these wetlands. Perhaps, Swamp Eels might represent a considerable part of the fledglings diet, especially during late stages when rapid development is necessary to avoid predatory attacks. The dependence on the type and availability of specific food resources might be an indication that, like Wood Storks, the reproductive season and nesting success of the Jabiru are related to the amount of rainfall and its consequences on the wetlands water levels, availability and distribution of food, especially, that of Swamp Eels. Instead of relying entirely on fish to become concentrated, like the Wood Stork, the Jabiru Stork can take additional advantage of the dry-down stage by unburying Swamp Eels from large remnant mudflats predominantly available during the dry-down stage. This can suggest an alternative or additional mechanism to the classical dry-down model concentration of prey. Therefore, the extent and amount of mudflats and/or other areas available for dispersing Swamp Eels, and the abundance of Swamp Eels might influence the nesting phenology and nesting success of the Jabiru Storks. This is a potential explanation that

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57 may indicate why nesting Jabirus have not been recorded outside the dry-down/dry period, unlike other wading birds such as the White Ibis (Eudocimus albus). Conservation Belize still manages large, intact areas that might be crucial for survival of several wildlife species. Many of these key areas were designated as protected areas; the CTWS is one of these, and certainly, one of the most important feeding areas for Jabiru Storks. The establishment of CTWS has ensured protection of vital foraging habitat for this species. However, the quality of this habitat will not depend solely on the integrity of the Reserves vegetation cover alone, but on the quality and quantity of water available to the wetland system supplied in great extent by the Belize River. Unsustainable activities such as removal of forest cover along the Belizes River shores to clear areas for agriculture and the use of agrochemicals or spillage of urban wastewaters into rivers will eventually affect the physical and chemical characteristics of the Belize River and the wetland system, possibly changing the composition and structure of the aquatic community and its biological processes. Deforestation along the margins of the Belize River is currently taking place. During the aerial surveys, I observed that several areas along the Belize River have been drastically modified, mainly for agricultural purposes. In some areas the riparian forest is lacking, in some others, there is a 10 to 100 m wide forest cover fringing the river. In both cases, sediments and agrochemicals may be easily injected into the river as a consequence of actual land use and lack of environmental protection. As a consequence, populations of aquatic species, key for the survival of the Jabiru, such as Swamp Eels and other large fishes may be reduced if the actual water conditions are modified.

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58 Because the energetic requirements and reproductive success of Jabirus and other wading birds seem to be determined by different food resources available during the wetlands dry-down, dry and flooding stages, it is very important that the wetlands natural fluctuation of water levels remain unaltered. Construction of physical infrastructure such as dams, dikes, roads and bridges can alter hydroperiod or prevent water from entering into the wetland system. Any of the activities already mentioned have the potential to modify the water conditions in the wetland system and lead a decrease in populations or changes of foraging grounds. Changes in land use around the major cities-Belize City and Orange Walkare resulting in the loss of wetland habitat. Small, sparse human communities are settling within wetlands located along Belizes Northern Highway. In the north, around Orange Walk town, several areas have been deforested and replaced with sugar cane crops. No Jabirus were sighted in rice fields during air surveys. There are numerous studies (Czech and Parsons 2002, Lawler 2001) indicating that if appropriately managed, rice fields can help sustain local population of waterbirds, and therefore, rice fields in Belize can potentially be an important landscape feature for conservation of this taxa. Nevertheless, as Ma et al. (2004) caution, an over-emphasis on the benefits of artificial wetlands might encourage landowners to convert natural wetlands into artificial wetlands, resulting in a considerable loss of bird diversity. Therefore, policies must, above all, prioritize the conservation of natural wetlands and preserve the hydrologic processes that support them before encouraging the construction of artificial wetlands as a substitute for natural wetlands.

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59 Finally, many of the Jabirus nests seem to be located in unprotected, densily forested areas or pine savannas, away from already protected feeding habitat. Efforts must be made to incorporate these important nesting habitat into the current conservation schemes.

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CHAPTER 5 CONCLUSIONS Like wetlands in other tropical, subtropical and temperate regions, water depths and fluctuations clearly affected the distribution, habitat use, foraging behavior and diet of the Jabiru Stork in Belize during the first half of 2003. Several large and relatively open wetlands in Belize can be utilized by Jabirus as feeding grounds, probably when many in other areas of se Mexico are unavailable. The Northern and New River lagoons were preferred foraging grounds of Jabirus, probably due to their size, openness, lack of vegetation, and/or hydrological features. It is also possible that because these wetlands dry down more slowly than small wetlands, large wetlands might offer abundant food resources for a longer period of time. Like Wood Storks, the onset of the dry season and the relative abundance of food resources seem to trigger the breeding season of the Jabiru, although the mechanisms producing this abundance may be different. Watersheds especially that of the Belize River, must be protected in order to preserve appropriate water conditions for wetlands that support the major concentrations of Jabirus. Future research should be directed at determining the movements of Jabirus across countries, at identifying wetlands used during these movements, to study the relationship between rainfall, water levels and reproductive success of Jabirus, and at determining and quantifying the effects of human activities on the hydrological characteristics of wetlands used as foraging habitat by the Jabiru and other wading birds. It is also important to understand more about the ecology of the Jabirus prey items, especially the Swamp Eels, 60

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61 since little is known about this species which seems to constitute one of the main items in the diet of the Jabiru.

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APPENDIX A MAPS OF STUDY AREA Figure 17. Satellite image of CTWS and New River Lagoon Area. Red: water bodies, Green: Broadleaf forest, Purple/Pink: wetlands. 62

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63 Mapa de Ecosistemas de CentroamricaHoja ESC-01 Escala : 1:250,000Proyeccin Lambert AcimutalCentro 85W, 13NDatum WGS84Fuentes originales :Imgenes LANDSAT 1994-1999Definicin de polgonos finales porimgenes LANDSAT 1998-1999y trabajo de campo 1999 11528-NE966552-T856547659682115566511528-NE11574-L8211552-T5612952-T28-NE52-T52-T9628-NW65115112-VG52-T52-Sh1159674-L52-T52-Sh52-T12128-NE52-T52-T1154752-T74-L52-T11512952-T856565115115479612152-T52-T74-L31-16552-T52-T52-T12912752-T52-T75-211552-T651278512913652-T52-T28-NE52-T656528-NW11552-T52-T112-VG52-T112-VG52-T1366565112-VG65477052-T8512952-T112-VG52-T6552-T656528-NE28-NE52-T52-T6552-T52-Sh74-L52-T28-NW12912752-T115112-VG52-T13674-L112-VG74-L12974-L1271276574-L9665129824774-L6528-NE52-T52-T12774-L52-Sh12774-L28-NE52-T6512952-T656552-T28-NE74-L112-VG28-NE52-T12970112-VG654728-NE52-T8228-NW28-NE12928-NE656552-T28-NE112-VG74-L127115112-VG52-T52-T10552-T1056552-T52-T1296512956112-VG12774-L52-T11552-T11512952-T28-NE11512711552-T9674-L52-T65129112-VG112-VG6552-T966528-NE1159652-T52-T6565656512913665112-VG47112-VG656528-NE28-NE12765129112-VG10552-Sh65112-VG112-VG74-L9652-Sh74-L136129112-VG52-T659612928-NE112-VG11512712774-L28-NW112-VG74-L115129112-VG112-VG1294712996112-VG11512952-T471291299628-NE11174-L112-VG112-VG12996112-VG6552-Sh6511712995136651291156512910574-L12912711765129127136112-VG127112-VG11511512912752-T115127112-VG115129129EQUIPO DE CIENTIFICOS Y ASESORESIr. Daan Vreugdenhil, CoordinadorDouglas J. Graham, MSc., Especialista en Biodiversidad, Banco MundialLuis Diego Gmez, MSc., Cientfico de vegetacin OTSDr. Susan Felicity Iremonger, Cientfico de vegetacin WCMCDr. Jeffrey Jones, Director SIG CATIEDr. Douglas Muchoney, Cientfico SIG Universidad de BostonValery Kapos, MSc., Botnica WCMCIr. Rob Beck, Cientfico SIG/vegetacinIr. Peter Sloot, Cientfico SIG/suelosMaurice Carignan, MSc., Especialista SIG/Sensores Remotos EQUIPO DE CIENTIFICOS NACIONALESBelize: Wilber Sabido, BSc., Ing. Jan MeermanGuatemala: Prof. Ing. Juan Jos Castillo, Prof. MSc. Csar Castaeda,Ing. Francisco Leonel LpezEl Salvador: Prof. MSc. Nohemy E. Ventura, Tec. Ing. Agric. Ral.F. Villacorta, Ing. Francisco Delgado, Licdo. Csar AbregoHonduras: Lcda. Telma Meja, Ing. Cristbal Vsquez.Nicaragua: MSc. Alain Meyrat, MSc.,Alfredo Grijalva.Costa Rica: Lus Diego Gmez, MSc. Wilberth Herrera, Lic.Panam: Prof. Dra. Mireya Correa, Prof. Dr. Lus Carrasquilla, Mara Stapf, MSc., Martn Mitre, MSc. CCAD Comisin Centroamericana de Ambiente yDesarrollo Centro AgronmicoTropical deInvestigacin yEnseanzaDGIS(Holanda)Banco MundialWorld Institute forConservation andEnvironment Participantes Institucionales:Financiamiento : Banco Mundial/Pases Bajos/GEF/CBMAuspiciado por : Comisin Centroamericana de Ambiente y DesarrolloEjecucin : WICE (World Institute for Conservation and Environment) y CATIE (Centro Agronmico Tropical de Investigacin y Enseanza)Colaboracin : ANAM (Panam), AFE-COHDEFOR (Honduras), INAB (Guatemala), MINAE (Costa Rica), MARENA (Nicaragua),MARN (El Salvador), Land Information Center (Belize) 79352846134352520191213101411181615211724272341433240362830423922312633382937 Confiabilidad Falta sobrevuelo Imagenes viejas NubesLEYENDA 1 1-1 1-2 1-VG 1-ZA 1-CG 1-VT 1-C 1-ST 2-r 2-s 3 3-2 3-PN 3-VG 3-ZA 4 5 6 6-1 6-2 6-ND 6-CG 6-VG 6-ZA 7-r 7-s 8 9 9-1 9-A 9-ND 9-CG 9-VG 10-HCW 10-RP 11 12 12-2 12-A 12-KM 12-CG 13-CG 14-HCW 14-RP 14-ND 15 15-A 15-ND 16-HCW 17 17-2 17-Pr 18 19 19-C 19-VG 19-ZA 20 21 21-HC 21-HC-2 21-M 22 22-A 22-P 22-M 22-M-2 22-ST 22-PN 22-VR 22-VIT 23-r 23-s 23-s-M 24 25 26 26-2 27 28 28-NE 28-NW 28-CE 28-CW 28-BR 29 30 30-M 30-HC-2 31 31-1 31-2 32 33-s 34 34-VR 34-VT 34-ST 34-l 35-r 35-s 36 37 37-2 38 39 40 41 42 43 44 45 46 47 48-M 48-ES 49 50 51 52-T 52-Sh 52-SC 52-AC 53-M 53-M-2 54 55 56 56-1 56-2 56-PNVC 56-HCW 56-CAR 56-ISL-2 57-ISL 58-2 58-HC-1 58-HC-2 59 59-2 59-NC 60 61 61-PN 62 63 64 65 66 67 67-2 68 68-2 69-PN 69-2 70 71 71-s 72 138 73-MI 74-L 75 75-2 76 77 78 79 80 81 82 83 84 85 85-2 86-M 87 88-PN 89-VG 90 91 92 93 94 94-2 96 97 98-2 99 100 101 102 103 104 105 105-2 106 107 108 109 110 111 112-VG 112-ZA 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 10010203040Kilmetros 560000 560000 580000 580000 600000 600000 620000 620000 640000 640000 660000 660000 680000 680000 700000 700000 720000 720000 1560000 1560000 1580000 1580000 1600000 1600000 1620000 1620000 1640000 1640000 1660000 1660000 Figure 18. Map of ecosystems of Belize, northern Belize. Comisin Centro Americana de Ambiente y Desarrollo (CCAD)/Centro Agronmico Tropical de Investigacin y Enseanza (CATIE)/Government of the Netherlands/World Bank (WB)/World Institute for Conservation and Environment. ( http://wbln0018.worldbank.org/MesoAm/UmbpubHP.nsf/917d9f0f503e647e8525677c007e0ab8/c8e1288cde4801f585256a6c008050e3?OpenDocument ).

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64 Mapa de Ecosistemas de CentroamricaHoja ESC-04 Escala : 1:250,000Proyeccin Lambert AcimutalCentro 85W, 13NDatum WGS84Fuentes originales :Imgenes LANDSAT 1994-1999Definicin de polgonos finales porimgenes LANDSAT 1998-1999y trabajo de campo 1999 28-NW22-ST2828-CW82115368511528-CE23-r828534-VT23-r6582857711528-CE8528-BR37856552-T28-CE23-s22-VIT321153728-CE278565115653752-T8511552-Sh27828234-ST2832761151158252-Sh11512928-CW1158523-r115478552-T12912111523-s8565821152827282812965112-VG52-T23-r9665829665112-VG6574-L52-T2713313628368582967652-Sh52-T964711522-ST658577777523-r11511523-s52-T1271366531-16511565652752-T8252-T8511552-T1368552-T52-T73-MI74-L826552-T52-T22-VIT7752-T28826528112-VG6574-L11552-T9652-T23-r23-r1157528112-VG52-T8265278528-CW828252-Sh7752-T2775-275-23252-Sh11552-T65778227856522-VIT8273-MI52-T11531-12735-s8273-MI28-NW35-s758252-T129112-VG658552-Sh11552-Sh2875-26575-211523-r74-L22-VIT968528-NE8582121115112-VG9652-T75-2112-VG73-MI52-T115822752-T852811575-234-ST651158212711511552-Sh7534-ST74-L52-T52-T7731-152-T52-Sh74-L11552-T822773-MI96115656574-L52-T11535-s2752-Sh22-ST75-211532286511531-111511552-T52-SC2874-L73-MI11174-L12752-T112-VG34-ST75-28565115657531-1776552-T115658275-2282873-MI281292875-252-T286552-Sh22-VIT73-MI74-L6552-Sh23-s1051161157723-s52-T23-s11574-L2823-r12974-L769552-T23-s115271159611574-L74-L11528-NE75-252-SC73-MI75-252-T85826552-T2723-s23-s52-T52-T85112-VG52-T23-r73-MI35-s6512931-1652875-234-ST52-T112-VG28-NW2865115133651154711528-CW73-MI74-L7523-s658273-MI6528-NW657711565136751152413673-MI23-s6528-BR6552-Sh8273-MI52-T52-Sh12123-r8273-MI12111523-s52-Sh75-2287723-s52-Sh52-Sh74-L6523-r23-s11552-T6528-NW75-252-T11528-CW73-MI23-s772812722-VIT52-T34-ST1154728281152452-T966528-NW52-T284775-2112-VG73-MI7723-r776582129821157711552-T74-L112-VG52-Sh52-T6511531-123-s657575-234-ST13611523-s74-L657775-273-MI13628-CW10511552-T10511511575-252-Sh6513611552-Sh23-s35-r52-Sh1296528-NW651154773-MI2812923-s4752-Sh52-Sh286552-Sh28-CW112-VG1151156528-CE23-s276573-MI28111112-VG6531-19628-NW777728-BR1151152428112-VG23-s11552-T52-Sh52-T115658211510552-Sh476531-152-T105112-VG75-26552-Sh12998-29674-L73-MI6511531-111512152-Sh28-NW11552-Sh112-VG6552-Sh2728127136112-VG1211156575-231-174-L115112-VG98-2112-VG656573-MI6512123-s1361054711574-L28-BR74-L23-s112-VG4731-1961156575-2112-VG6574-L27112-VG11511522-VIT136651362847112-VG2823-s52-T12931-111565652822-VIT129656523-r65771156523-s65778210527115136112-VG74-L11552-T136105112-VG74-L96652852-T11547856511547286552-T112-VG4752-Sh65761051294711534-ST23-s7723-s1051219628-CW65129654752-T73-MI23-s6552-T6511513665471274713612934-ST776513628-NW52-T6531-1129651362775-2129112-VG12982112-VG37112-VG13613623-s73-MI136129969628112-VG10552-T6552-T65112-VG24105121827775-211576284711523-s115112-VG112-VG112-VG28-CE23-s11513612122-ST73-MI28-BR76112-VG52-Sh6528-CE2828115EQUIPO DE CIENTIFICOS Y ASESORESIr. Daan Vreugdenhil, CoordinadorDouglas J. Graham, MSc., Especialista en Biodiversidad, Banco MundialLuis Diego Gmez, MSc., Cientfico de vegetacin OTSDr. Susan Felicity Iremonger, Cientfico de vegetacin WCMCDr. Jeffrey Jones, Director SIG CATIEDr. Douglas Muchoney, Cientfico SIG Universidad de BostonValery Kapos, MSc., Botnica WCMCIr. Rob Beck, Cientfico SIG/vegetacinIr. Peter Sloot, Cientfico SIG/suelosMaurice Carignan, MSc., Especialista SIG/Sensores Remotos EQUIPO DE CIENTIFICOS NACIONALESBelize: Wilber Sabido, BSc., Ing. Jan MeermanGuatemala: Prof. Ing. Juan Jos Castillo, Prof. MSc. Csar Castaeda,Ing. Francisco Leonel LpezEl Salvador: Prof. MSc. Nohemy E. Ventura, Tec. Ing. Agric. Ral.F. Villacorta, Ing. Francisco Delgado, Licdo. Csar AbregoHonduras: Lcda. Telma Meja, Ing. Cristbal Vsquez.Nicaragua: MSc. Alain Meyrat, MSc.,Alfredo Grijalva.Costa Rica: Lus Diego Gmez, MSc. Wilberth Herrera, Lic.Panam: Prof. Dra. Mireya Correa, Prof. Dr. Lus Carrasquilla, Mara Stapf, MSc., Martn Mitre, MSc. CCAD Comisin Centroamericana de Ambiente yDesarrollo Centro AgronmicoTropical deInvestigacin yEnseanzaDGIS(Holanda)Banco MundialWorld Institute forConservation andEnvironment Participantes Institucionales:Financiamiento : Banco Mundial/Pases Bajos/GEF/CBMAuspiciado por : Comisin Centroamericana de Ambiente y DesarrolloEjecucin : WICE (World Institute for Conservation and Environment) y CATIE (Centro Agronmico Tropical de Investigacin y Enseanza)Colaboracin : ANAM (Panam), AFE-COHDEFOR (Honduras), INAB (Guatemala), MINAE (Costa Rica), MARENA (Nicaragua),MARN (El Salvador), Land Information Center (Belize) 79352846134352520191213101411181615211724272341433240362830423922312633382937 Confiabilidad Falta sobrevuelo Imagenes viejas NubesLEYENDA 1 1-1 1-2 1-VG 1-ZA 1-CG 1-VT 1-C 1-ST 2-r 2-s 3 3-2 3-PN 3-VG 3-ZA 4 5 6 6-1 6-2 6-ND 6-CG 6-VG 6-ZA 7-r 7-s 8 9 9-1 9-A 9-ND 9-CG 9-VG 10-HCW 10-RP 11 12 12-2 12-A 12-KM 12-CG 13-CG 14-HCW 14-RP 14-ND 15 15-A 15-ND 16-HCW 17 17-2 17-Pr 18 19 19-C 19-VG 19-ZA 20 21 21-HC 21-HC-2 21-M 22 22-A 22-P 22-M 22-M-2 22-ST 22-PN 22-VR 22-VIT 23-r 23-s 23-s-M 24 25 26 26-2 27 28 28-NE 28-NW 28-CE 28-CW 28-BR 29 30 30-M 30-HC-2 31 31-1 31-2 32 33-s 34 34-VR 34-VT 34-ST 34-l 35-r 35-s 36 37 37-2 38 39 40 41 42 43 44 45 46 47 48-M 48-ES 49 50 51 52-T 52-Sh 52-SC 52-AC 53-M 53-M-2 54 55 56 56-1 56-2 56-PNVC 56-HCW 56-CAR 56-ISL-2 57-ISL 58-2 58-HC-1 58-HC-2 59 59-2 59-NC 60 61 61-PN 62 63 64 65 66 67 67-2 68 68-2 69-PN 69-2 70 71 71-s 72 138 73-MI 74-L 75 75-2 76 77 78 79 80 81 82 83 84 85 85-2 86-M 87 88-PN 89-VG 90 91 92 93 94 94-2 96 97 98-2 99 100 101 102 103 104 105 105-2 106 107 108 109 110 111 112-VG 112-ZA 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 10010203040Kilmetros 580000 580000 600000 600000 620000 620000 640000 640000 660000 660000 680000 680000 700000 700000 720000 720000 740000 740000 1440000 1440000 1460000 1460000 1480000 1480000 1500000 1500000 1520000 1520000 1540000 1540000 Figure 19. Map of ecosystems of Belize, central Belize. (CCAD/CATIE/Government of the Netherlands/WB/World Institute for Conservation and Environment). Mapa de Ecosistemas de CentroamricaHoja ESC-07 Escala : 1:250,000Proyeccin Lambert AcimutalCentro 85W, 13NDatum WGS84Fuentes originales :Imgenes LANDSAT 1994-1999Definicin de polgonos finales porimgenes LANDSAT 1998-1999y trabajo de campo 1999 551155422-ST34-ST8252-s5212-r8821153482-r8211511535-r218535-s5192135-r82542817822722-ST2135-r1-VT34-VT2-s52-s66554211291156115827-r2-s172-s7-s20281-C6511535-r522-VIT1362-s105173734-VT822-s8221-M196511585271951-VT6531-1556-251155206511555527105-227906511585851912773-MI5136271723-r20435-s1331956851934-VT85902752-T65274121821152-s21452719761156585192-s34-VT17171731-11731-1281798-2112-VG761152-s534-ST22-VIT31-1121857-s657-s565115129272-r2-r27535-s851111517105-231-1112-VG31-11-VT1765822-s34-VT11558565411534-ST47191711511556576548582911555465192-r11531-16519412111531-135-r1362-r1058231-1410498-235-r31-11366582121477631-164652-s31-165112-VG31-18227171911586597851711552-AC31-177278212176517202731-11216573-MI1711552-SC57656-CAR2-s51332-r11565651-ST6531-131-120115112-r1-ST136115520651159719281161161156531-1121517115115276552-SC1-ST1152723-r91722-VIT76171291727112-VG82129531-1115756517656565761152-r82651731-1176535-s1151156512911613635-r1982171292711592115105112-VG65856510531-112711565652-s821211156531-11712965136116766565176531-131-1651156585201151051296551717116651056565276565136276575-21056511565115821151292-s12910511531-173-MI65112-VG10534-l6527652023-r112-VG73-MI105112-VG6576105171052071-s17277613665112-VG11571-s71-s71-s71-s11510571-s71-s6511571-s71-s71-s3871-s71-s10573-MI1052752-SC105272712131-173-MI761765EQUIPO DE CIENTIFICOS Y ASESORESIr. Daan Vreugdenhil, CoordinadorDouglas J. Graham, MSc., Especialista en Biodiversidad, Banco MundialLuis Diego Gmez, MSc., Cientfico de vegetacin OTSDr. Susan Felicity Iremonger, Cientfico de vegetacin WCMCDr. Jeffrey Jones, Director SIG CATIEDr. Douglas Muchoney, Cientfico SIG Universidad de BostonValery Kapos, MSc., Botnica WCMCIr. Rob Beck, Cientfico SIG/vegetacinIr. Peter Sloot, Cientfico SIG/suelosMaurice Carignan, MSc., Especialista SIG/Sensores Remotos EQUIPO DE CIENTIFICOS NACIONALESBelize: Wilber Sabido, BSc., Ing. Jan MeermanGuatemala: Prof. Ing. Juan Jos Castillo, Prof. MSc. Csar Castaeda,Ing. Francisco Leonel LpezEl Salvador: Prof. MSc. Nohemy E. Ventura, Tec. Ing. Agric. Ral.F. Villacorta, Ing. Francisco Delgado, Licdo. Csar AbregoHonduras: Lcda. Telma Meja, Ing. Cristbal Vsquez.Nicaragua: MSc. Alain Meyrat, MSc.,Alfredo Grijalva.Costa Rica: Lus Diego Gmez, MSc. Wilberth Herrera, Lic.Panam: Prof. Dra. Mireya Correa, Prof. Dr. Lus Carrasquilla, Mara Stapf, MSc., Martn Mitre, MSc. CCAD Comisin Centroamericana de Ambiente yDesarrollo Centro AgronmicoTropical deInvestigacin yEnseanzaDGIS(Holanda)Banco MundialWorld Institute forConservation andEnvironment Participantes Institucionales:Financiamiento : Banco Mundial/Pases Bajos/GEF/CBMAuspiciado por : Comisin Centroamericana de Ambiente y DesarrolloEjecucin : WICE (World Institute for Conservation and Environment) y CATIE (Centro Agronmico Tropical de Investigacin y Enseanza)Colaboracin : ANAM (Panam), AFE-COHDEFOR (Honduras), INAB (Guatemala), MINAE (Costa Rica), MARENA (Nicaragua),MARN (El Salvador), Land Information Center (Belize) 79352846134352520191213101411181615211724272341433240362830423922312633382937 Confiabilidad Falta sobrevuelo Imagenes viejas NubesLEYENDA 1 1-1 1-2 1-VG 1-ZA 1-CG 1-VT 1-C 1-ST 2-r 2-s 3 3-2 3-PN 3-VG 3-ZA 4 5 6 6-1 6-2 6-ND 6-CG 6-VG 6-ZA 7-r 7-s 8 9 9-1 9-A 9-ND 9-CG 9-VG 10-HCW 10-RP 11 12 12-2 12-A 12-KM 12-CG 13-CG 14-HCW 14-RP 14-ND 15 15-A 15-ND 16-HCW 17 17-2 17-Pr 18 19 19-C 19-VG 19-ZA 20 21 21-HC 21-HC-2 21-M 22 22-A 22-P 22-M 22-M-2 22-ST 22-PN 22-VR 22-VIT 23-r 23-s 23-s-M 24 25 26 26-2 27 28 28-NE 28-NW 28-CE 28-CW 28-BR 29 30 30-M 30-HC-2 31 31-1 31-2 32 33-s 34 34-VR 34-VT 34-ST 34-l 35-r 35-s 36 37 37-2 38 39 40 41 42 43 44 45 46 47 48-M 48-ES 49 50 51 52-T 52-Sh 52-SC 52-AC 53-M 53-M-2 54 55 56 56-1 56-2 56-PNVC 56-HCW 56-CAR 56-ISL-2 57-ISL 58-2 58-HC-1 58-HC-2 59 59-2 59-NC 60 61 61-PN 62 63 64 65 66 67 67-2 68 68-2 69-PN 69-2 70 71 71-s 72 138 73-MI 74-L 75 75-2 76 77 78 79 80 81 82 83 84 85 85-2 86-M 87 88-PN 89-VG 90 91 92 93 94 94-2 96 97 98-2 99 100 101 102 103 104 105 105-2 106 107 108 109 110 111 112-VG 112-ZA 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 10010203040Kilmetros 580000 580000 600000 600000 620000 620000 640000 640000 660000 660000 680000 680000 700000 700000 720000 720000 740000 740000 1320000 1320000 1340000 1340000 1360000 1360000 1380000 1380000 1400000 1400000 1420000 1420000 Figure 20. Map of ecosystems of Belize, southern Belize. (CCAD/CATIE/Government of the Netherlands/WB/World Institute for Conservation and Environment).

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APPENDIX B ROUTES OF SURVEY FLIGHTS

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Figure 21. Route of survey flight 1, northern and central Belize. Figure 22. Route of survey flight 1, central Belize. 66

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67 Figure 23. Route of survey flight 2, northern and central Belize. Figure 24. Route of survey flight 2, central Belize.

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68 Figure 25. Route of survey flight 3, northern and central Belize. Figure 26. Route of survey flights 4 and 5, northern and central Belize.

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LIST OF REFERENCES ARENGO, F. AND G.A. BALDASSARRE. 1999.Patch choice and foraging behavior of nonbreeding American Flamingos in Yucatn, Mexico. Condor. 104(2):452-457. BANCROFT, G.T., D.GAWLIK AND K. RUTCHEY. 2002. Distribution wading birds relative to vegetation and water depths in the northern Everglades of Florida, USA. Waterbirds. 25(3):265-277. BANCROFT, G.T., S.D. JEWELL AND A.M. STRONG. 1990. Foraging and nesting ecology of herons in the lower Everglades relative to water conditions. Final report prepared for Environmental Science Division, South Florida Management District. Ornithological Research Unit, National Audubon Society. 136 pp. BELL, G.D., M.S. HALPERT, C.F. ROPELEWSKI, V.E. KOUSKY, A.V. DOUGLAS, R.C. SCHNELL AND M.E. GELMAN. 1999. Climate assessment for 1998. Bulletin of the American Meteorological Society. 80(5):1-48. BILDSTEIN, K.L., P.W. JOHNSTON AND P. FREDERICK. 1990. Freshwater wetlands, rainfall, and the breeding ecology of White Ibises in coastal South Carolina. Wilson Bulletin. 102(1):84-98. BLAKE, E.R. 1977. Manual of neotropical birds. Volume I. The University of Chicago Press. Chicago. 674 pp. BROOKS, T.M., R.A. MITTERMEIER, C. MITTERMEIER, G.A. DE FONSECA, A.B. RYLANDS, W. R. KONSTANT, P. FLICK, J. PILGRIM, S. OLDFIELD, G. MAGIN, C. Hilton-Taylor. 2002. Habitat loss and extinction in the hotspots of biodiversity. Conservation Biology. 16(4):909-923. CEZILLY, F.V. BOY, R.E. GREEN, G.J. HIRONS, A.R. JOHNSON. 1995.Interannual variation in Greater Flamingo breeding success in relation to water levels. Ecology. 76(1):20-26. COLLOPY, M.W. AND H.L. JELKS. 1987. Distribution of foraging wading birds in relation to the physical and biological characteristics of freshwater wetlands in southwest Florida. Florida Game and Fresh Water Fish Commission. Final Report. 102 pp. 69

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72 LIAO, C.M., J.W. TSIAI AND M.C. LIN. 2001. A simple modeling approach towards hydroperiod effects on fish dynamics in a northern Taiwan wetland ecosystem. Journal of Environmental Science and Health part A-Toxic/Hazardous Substances and Environmental Engineering. 36(7):1205-1226. LOPEZ ORNAT, A., J.F. LYNCH AND B. MACKINNON. 1989. New and noteworthy records of birds from the eastern Yucatn Peninsula. Wilson Bull. 101(3):390-409. LUTHIN, C. 1984. World working group on storks, ibises and spoonbills. Report 2, 1984. ICPB-Brehm Fonds. Walsrode. . 1987. Status and conservation priorities for the worlds storks species. Colonial Waterbirds. 10(2):181-202. MA, Z.J., LI, B., ZHAO, B., JING, K., TANG, S.M. AND J.K. CHEN. 2004. Are artificial wetlands good alternatives to natural wetlands for waterbirds? Biodiversity and Conservation. 13(2):333-350. MARTIN, M. 1972. A biogeographic analysis of the freshwater fishes of Honduras. University of Southern California. PhD. Dissertation. 597 pp. MEERMAN J.C. AND W. SABIDO. 2001. Central American ecosystem map: Belize. Volumes 1 and 2. Programme for Belize-World Bank-The Government of the Netherlands-Central American Commission of Environment and Development. Belize. 58 pp. MEYERRIECKS, A. J. 1962. Diversity typifies heron feeding. Nat. Hist. 71:48-59. MILLER, C. 1995. 100 Birds of Belize. Wildlife Conservation Society. Belize. 157 pp. MYERS, N., R. MITTERMEIER, G.A. DE FONSECA AND J. KENT. 2000. Biodiversity hotspots for conservation priorities. Nature. 403(6772):853-858. NEWMAN, S., J.B GRACE AND J.W. KOEBEL. Effects of nutrients and hydroperiod on Typha, Cladium, and Eleocharis: Implications for Everglades restoration. Ecological Applications. 6(3):774-783 OGDEN, J.C., C.E. KNODER AND A. SPRUNT JR. 1988. Colonial waterbird populations in the Usumacinta delta, Mexico, p. 565-605, in Ecologa de los Ros Usumacinta y Grijalva. Instituto Nacional de Investigaciones sobre los Recursos Biticos. Tabasco, Mexico. OGDEN, J.C., H.W. KALE II AND S.A. NESBITT. 1980. The influence of annual variation in rainfall and water levels on nesting by Florida populations of wading birds. Transactions of the Linnaean Society of New York. 9:115-126. POWELL, G.V. 1987. Habitat use by wading birds in a subtropical estuary: implications of hydrography. Auk. 104:740-749.

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73 RAMO, C. AND B. BUSTO. 1992. Nesting failure of the Wood Stork in a neotropical wetland. Condor. 94:777-781. RIDGLEY, R. S. AND J.A. GWYNNE JR. 1989. A guide to the birds of Panama with Costa Rica, Nicaragua and Honduras. Princeton University Press. Princeton. 534 p. SALVIN, O. AND F.D. GOODMAN. 1897-1904. Biologia Centrali-Americana: AVES. Vol III (Text). Taylor and Francis. SPAANS, A.L. 1975. The status of the Wood Stork, Jabiru and Maguari Stork along the Surinam Coast, South America. Ardea. 63:116-130. SURDICK, J. A. 1998. Biotic and abiotic indicators of foraging site selection and foraging success of four cicioniiform species in the freshwater Everglades of Florida. Masters Thesis. University of Florida. THOMAS, B.T. 1985a. A colonial wading bird survey in the Central Llanos of Venezuela. Colonial Waterbirds. 8(1):23-31. . 1985b. Coexistence and behavior differences among the three western hemisphere storks, p. 921-931, In P.A. Buckley, M.S. Foster, E.S. Morton, R.S.Ridgley and F.G. Buckley, Eds. Neotropical ornithology. Ornithological monograph No. 36. American Ornithologists Union, Washington, D.C. TURNER, A.M., J.C. TREXLER, C. F. JORDAN, S.J. SLACK, P. GEDDES, J. CHICK AND W. F. LOFTUS. 1999. Targeting ecosystem features for conservation: standing crops in the Florida Everglades. Conservation Biology. 13(4):898-911. TURNER, M.G. AND R.H. GARDNER. 1991. Quantitative methods in landscape ecology: an introduction, In M.G. Turner and R.H. Gardner. Quantitative methods in landscape ecology. Springer-Verlag. New York 314 pp. URBAN, N. H., S.M DAVIS AND N.G. AUMEN. 1993. Fluctuations in sawgrass and cattail densities in Everglades-Water Conservation Area-2A under varying nutrient, hydrologic and fire regimes. Aquatic Botany. 46(3-4):203-223. VILLAREAL, J.A. 1997. Estado actual, presas y uso de habitat del Jabiru (Jabiru mycteria) en la cuenca del Ro Tempisque, Costa Rica. Universidad Nacional. Thesis. Heredia. 104 pp. WELLER, M.W. 1999. Wetland birds: habitat resources and conservation implications. Cambridge University Press. 271 pp. WETMORE, A. 1965. The birds of the republic of Panama-Part 1: TINAMIDAE (Tinamous) to RYNCHOPODIDAE (Skimmers). Smithsonian Institution. Washington. 483 pp.

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74 WITH, K.A., R.H. GARDNER AND M.G. TURNER. 1997. Landscape connectivity and population distributions in heterogeneous environments. Oikos. 78:151-169.

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BIOGRAPHICAL SKETCH Alejandro Paredes was born in 1976 in Tegucigalpa, Honduras, Central America. He obtained his bachelors degree from Universidad Nacional Autnoma de Honduras, majoring in biology with a minor in zoology. During his undergraduate studies, Alejandro had the opportunity to work in several scientific and conservation efforts in Honduras. After completing his undergraduate studies, Alejandro worked for the Honduran Ministry of Natural Resources and the Environment, for NGOs, and as freelance consultant, acquiring and analyzing data for several development projects. He decided to pursue further studies at the University of Florida because of his desire to find a balance between conservation and sustainable development. Now that Alejandro has been immersed in the field of biological conservation, he plans to pursue his doctoral degree and to continue working in sustainable development. 75


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Full Text












STATUS, DISTRIBUTION, HABITAT REQUIREMENTS, AND FORAGING
ECOLOGY OF THE JABIRU STORK (Jabiru mycteria) IN NORTHERN AND
CENTRAL BELIZE, CENTRAL AMERICA















By

ALEJANDRO JOSE PAREDES BORJAS


A THESIS PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE

UNIVERSITY OF FLORIDA


2004

































Copyright 2004

by

Alejandro Jose Paredes Borjas















ACKNOWLEDGMENTS

The successful completion of this project was due to the support of family, friends,

professors, and organizations in Central America and the United States. Firstly, I feel

indebted to Omar Figueroa and his parents, Don Azuceno and Dofia Jeannette, for giving

me their support while I was conducting field research in Belize. The Figueroa family

kindly provided me with a warm, hospitable place from the moment I arrived in their

country. Omar, in particular, helped me arrange logistics and provided useful technical

and contact information. Their support was key to the success of this project. I would also

like to thank Wilver Martinez, Raynold Cal and Mario Tehul for their help, peer support,

and long-lasting coffee breaks. I also thank pilot Frank Plett, whose experience, skills and

motivation have been instrumental for conservation of waterbirds in Belize. Thanks also

go to the Belize Audubon Society, who granted me permission to do research in Crooked

Tree Wildlife Sanctuary.

I am grateful to my friends in Graduate school: Santiago Espinosa, Amy Duchelle,

Rafael Reyna and Edith Rojas, Mutsuo Nakamura, Ivan Diaz, Olga Montenegro, Luis

Ramos, Percy Peralta, Sonia Canavelli and Marcela Machicote, who assisted me with

data analyses and provided feedback that proved extremely useful for the development of

this project. Special thanks go to Charlotte Skov and Debra Anderson for their

encouragement and unconditional support.









Thanks go to my committee members (Dr. Peter Frederick, Dr. George Tanner and

Dr. Ken Meyer) for providing ideas and revising the manuscript. This thesis was possible

thanks to financial support provided by the Compton Foundation's grant for Tropical

conservation and development.

Finally, I would like to thank my family: my mother, Martha; my sister Martha

Judith; and my brother, Ricardo. They have always encouraged me to find a balance

between the consistent mind and the kind heart. All my endeavors are kindly dedicated to

them.
















TABLE OF CONTENTS
Page

A C K N O W L E D G M E N T S ................................................................................................ iii

LIST OF TABLES .......... .. ....... .. .................... .... ......... .. vii

L IST O F F IG U R E S ......... ............................................................... ..... viii

LIST OF OBJECTS ................................. ...... ... ................. .x

ABSTRACT .............. .................. .......... .............. xi

CHAPTER

1 IN TR OD U CTION ............................................... .. ......................... ..

Threats to Central American Wetlands.................... ........ .....................
Influence of Wetland Hydrology in the Natural History of Wading Birds ................2
Influence of Spatial Heterogeneity and Hydrological Fluctuations on the Natural
H history of W ading B irds ........................................................................... ...... 4
The Study Species: The Jabiru Stork....................................... ......................... 8

2 STUDY AREA AND M ETHODS .................................... .......................... ......... 13

Study A rea ...................................................................................................... ....... 13
M eth o d s ............................. ..... ...... .............................16
Landscape Data and Population Estimates................................................... 16
Microhabitat data and Observations on Foraging Behavior.............................19
A analysis of D ata .................. ...................................... .. ........ .... 20

3 R E S U L T S .......................................................................... 2 4

Abundance of Jabiru Storks......................................................... ............... 24
Spatial D distribution ........ ................................................................. ...... .... ..... 24
H habitat U se ........................ ........................................ ....... .. ............... 26
Habitat Use According to Ecosystem Classification................................. 26
Habitat Use According to Land Use Classification................... ..............28
U se of W after B bodies ......................................... ..... ........ ....... .......... .. ..28
Features of Foraging Microhabitat .......................................... ...............29
D iet C om position .......... ..... ................................................................. ....... .. ....... .. 29
Foraging B behavior .................. ................................. ....... .. ............ 30









W walking and Searching for Food..................................................................... 30
Capturing and H handling Prey ........................................ ......................... 32
Prey Piracy............................................. 34
Loafing and Social Interactions ............ ... .......... .................. ............... 35

4 D ISCU SSION ........... .. ....... ........................................................... 50

Rainfall Pattern in Central and Northern Belize.......................... ................... 50
Abundance of Storks in Response to Local Hydrology .................... ...................50
Spatial D distribution and H habitat U se ........................................ ...................... 53
F oraging E cology ........... ...... ............................................ .............. ......... ........ 55
C on servation .................................................................................................57

5 CON CLU SION S .................................. .. .......... .. .............60

APPENDIX

A M APS OF STUD Y AREA ........................ ............... ................. ............... 62

B ROUTES OF SURVEY FLIGHTS ........................................ ........................ 65

LIST OF REFEREN CES .................................................................. ............... 69

BIOGRAPH ICAL SKETCH ...................................................... 75
















LIST OF TABLES

Table pge

1 Total number of Jabims observed in survey flights ...... ..... ................................. 47

2 Number of Jabirus in relation to habitat types. ........... .... ................... ............... 48
















LIST OF FIGURES

Figurege

1 M ap of B elize. .........................................................................2 1

2 Map showing the components of the hydrological system in central Belize...........22

3 M ap of study area. ......................... .......................... .... ...... .. ............22

4 M ap showing of foraging areas ......... ......... ................. .............. ......... 23

5 Variation of foraging sociality of Jabiru. ...............................................................36

6 Spatial distribution of Jabirus: survey 1 ............... .... ........... ............... .37

7 Spatial distribution of Jabirus: survey 2..................... ................... ............... 38

8 Spatial distribution of Jabirus: survey 3 .......................................... ................... 39

9 Spatial distribution of Jabirus: survey 4. .............. .............................................40

10 Spatial distribution of Jabirus: survey 5 ........................................ ..................... 41

11 Summary of spatial distribution of Jabiru. .............. ...................... .. ............ 42

12 Readings of water levels recorded from 6 water stages...................................43

13 Ecosystems used by foraging Jabirus ...................... ..... ...............44

14 H habitat used by Jabirus. ................................................ ............................... 45

15 W ater bodies used by foraging Jabirus. ...................................... ............... 46

16 Proportion of prey items of the Jabiru................... .. .... ................. 46

17 Satellite image of CTWS and New River Lagoon area........................... ........62

18 Map of ecosystems of Belize, northern Belize ...................................................63

19 M ap of ecosystems of Belize, central Belize. .................................. .................64

20 Map of ecosystems of Belize, southern Belize ....................................................... 64









21 Route of survey flight 1, northern and central Belize. ...........................................66

22 Route of survey flight 1, central Belize ............... ..................... .....................66

23 Route of survey flight 2, northern and central Belize. ...........................................67

24 Route of survey flight 2, central Belize ..................................... ......................67

25 Route of survey flight 3, northern and central Belize. ...........................................68

26 Route of survey flights 4 and 5, northern and central Belize ..................................68
















LIST OF OBJECTS


Objects p

1 Video clip of Jabiru walking in Northern Lagoon. ............................................30

2 Video clip of searching for food. ............................... ................................... 31

3. Video clip of Jabiru searching for food in mudflat. ...................... ............... 31

4 Video clip of Jabiru dismembering a large prey. ...................................................33

5 Video clip of Jabiru searching, handling and eating eels. ............. ...................33

6 Video clip of Jabiru handling a large prey and then harrased by conspecific. ........34

7 Video sequence of monthly water level fluctuation in Northern Lagoon from
M arch to July 2003 ............................ .................................... ..... .... ......... ..50














Abstract of Thesis Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Master of Science

STATUS, DISTRIBUTION, HABITAT REQUIREMENTS, AND FORAGING
ECOLOGY OF THE JABIRU STORK (Jabiru mycteria) IN NORTHERN AND
CENTRAL BELIZE, CENTRAL AMERICA

By

Alejandro Jose Paredes Borjas

August 2004

Chair: Peter Frederick
Major Department: Wildlife Ecology and Conservation

Mesoamerica hosts an impressive diversity of species and ecosystems. However,

the explosive population growth in the region is threatening the integrity of functions,

composition and structure of pristine ecosystems. Several wildlife species are intimately

linked to the fluctuating physical and biological processes occurring in some of these

ecosystems. Seasonally flooded wetlands and waterbirds dependent on fluctuating water

levels are a good example of this close relationship.

I explored the effects of hydrological fluctuations on the ecology of one of the

largest birds in the Western Hemisphere: the Jabiru Stork. The research was carried out in

the central and northern region of the Central American country of Belize. Since little is

known about Central American populations of this bird species, the research was aimed,

firstly, at answering basic conservation questions regarding population size, distribution,

habitat used for feeding, diet, and foraging behavior. Secondly, the research tries to

provide a picture of the influence of weather and wetlands' water levels on variables









already mentioned. To answer these questions, I performed five aerial surveys over

central and northern Belize from April to June 2003, during the dry-down and dry stage

of wetlands and beginning of rains. During air surveys, I counted the number of

individuals and flocks of Jabirus, and recorded positions and foraging habitat type. I also

performed ground surveys aimed at measuring the physical characteristics of foraging

habitat, recording size of foraging flocks, diet and behavior of the Jabiru Stork. Results

show that the mean number of storks counted during the air surveys was 65.17 (SD =

24.28), while the maximum number of Jabirus ever recorded was 116 individuals. During

the study, most Jabirus used inner areas, especially, around New River lagoon and

Crooked Tree Wildlife Sanctuary (CTWS). In most occasions (91%), Jabirus used open

areas: mainly freshwater wetlands subject to periodic flooding; the rest used lowland

savanna, lowland broadleaf forest and agricultural fields. There were no recordings of

Jabirus in coastal areas or rice fields. The Jabirus' diet consisted mainly offish, Swamp

Eels (Symbranchus marmoratus) and snails. Weather affected the wetlands' water levels.

This, in turn, influenced foraging sociality, distribution of Jabirus in the landscape, and

common prey items consumed. The CTWS may guarantee the protection of some critical

foraging habitat for the Jabiru Stork. However, the CTWS and other foraging areas are

dependent on the extent and quality of hydrological processes occurring outside its

boundaries. It is therefore recommended that conservation efforts target the protection of

the Belize River and other lotic bodies feeding wetlands. Scientific studies should also

address the ecology of some of the Jabiru's main prey, especially the Swamp Eel.














CHAPTER 1
INTRODUCTION

Threats to Central American Wetlands

Natural environments and the species associated with them are disappearing at an

alarming rate (due in great part, to an accelerated growth in human population).

Mesoamerica (the land bridge that extends from southern Mexico to Panama), one of the

hotspots of biological diversity in the planet (Myers et al. 2000, Brooks et al. 2002) is

currently facing an explosive human population growth rate (reaching almost 3%/year).

This is one of the highest growth rates for the Western Hemisphere, and human

population in the region is expected to double in the next 15 years. Therefore, pressures

for development are intense, and will be much accelerated in the near future, as

expanding societies' demands for goods and services increase. In this spatial conflict,

wetlands are among the most vulnerable ecosystems. Many of the Central American

wetlands remain relatively undeveloped; and maintain local communities by providing

them with clean water, fisheries, and wood for fuel or construction. However, in some

areas, population pressures are resulting in rapid deterioration of wetlands and, therefore,

the quality and quantity of goods and services provided by wetlands (e.g., fuel wood,

fresh water, and fisheries) is also decreasing.

Wetland wildlife is often strongly dependent on vegetation cover, water quality,

and natural fluctuations in water levels. Alteration of any of these variables by human

activities can have severe effects on the wetland ecology, even when the wetlands have

not been "developed". Water birds are among the most vulnerable wildlife groups









because of their location in the aquatic trophic web. Responses of waterbird populations

to changing environments are difficult to predict, because much of the basic natural

history of many species is largely unknown. This is particularly true for the Jabiru Stork

(Jabiru mycteria), the largest bird in Central American wetlands. A gap of knowledge

exists regarding its abundance, its distribution and the effects of environmental variables

on its foraging and nesting ecology. Jabiru Storks were chosen for this study because they

are large, conspicuous birds, potentially dependent on the wetlands' hydrological

characteristics; and because they can serve as flagship species that may help us identify

key habitat features for the protection of other equally vulnerable waterbird species.

Influence of Wetland Hydrology in the Natural History of Wading Birds

Hydrological conditions play an important role in the natural history of many

wetland birds. This is especially true for wading birds (order Ciconiiformes) whose

foraging ecology is often responsive to and dependent on water levels. In tropical and

subtropical wetlands with marked wet/dry seasons, water-depth fluctuations can be

dramatic (Ogden et al. 1980, Frederick and Collopy 1989), and this dynamism affects

both the production and availability of prey animals to birds. Studies in the subtropical

south Florida environment have shown that during the wet season, prey production is

strongly affected by the expansion and contraction of ponds into surrounding marshes

and swamps. When water levels recede, high densities of prey are usually found in deeper

ponds (Kushlan 1980, Collopy and Jelks 1987). This hydrological mechanism that

regulates concentration of prey is called the "dry-down model".

Even though environmental factors have a strong influence in the foraging ecology

of wading birds, the response of each species to hydrological changes is variable,

depending on how each species exploits the niche of prey availability. Gawlik (2002)









showed the effects of food availability on the numerical response of wading birds species

by manipulating water depth and fish density in artificial ponds. Diverse reactions were

found for all species: Wood Stork (Mycteria americana), White Ibis (Eudocimus albus),

Snowy Egret (Egretta thula), Glossy Ibis (Plegadisfalcinellus), Great Egret (Ardea

albus), Tricolored Heron (Egretta tricolor), Great Blue Heron (Ardea herodias) and

Little Blue Heron (Egretta caerulea). Some of these species were more responsive to

water depth, some to fish density, some to both, and others to neither of them.

However, it should be noted that prey availability is a composite factor that

involves a number of environmental, physiological, behavioral, and morphological

variables of both prey and wading bird, rather than prey density alone. It also seems

apparent that, at patch level, short-term availability of resources may be more important

than resource depletion for predators of active prey, as shown by Erwin (1985) for Snowy

(Egretta thula) and Great (Ardea albus) Egrets. Additionally, several other factors may

determine wading bird foraging success, as suggested by Surdick (1998) who found that

vegetation, prey density and prey composition were related to wading bird capture rate in

unmodified Everglades habitats. This shows that responses on each species are driven to

maximize their use of aquatic niches, and shows the difficulty of applying a single set of

predictions to all wading bird species.

Changes in water levels can also influence the reproductive biology of wading

birds (Ogden et al. 1980, Frederick and Collopy 1989) by affecting the amount of food

available in the system (Cezilly et al. 1995). For some wading bird species, the number of

nesting individuals can be responsive to changes in food resources (Bildstein et al. 1990,

Frederick and Collopy 1988), and even nesting success and nesting productivity have









been linked to prey availability (Frederick 2002). Wading birds' reproductive activity can

be synchronized with external phenomena (namely, the amount of rainfall and its effects

on local wetlands). As shown in the Everglades of Florida, some wading birds typically

nest during the dry season when water levels are receding allowing birds to take

advantage of prey concentration (Bancroft et al. 1990). Ogden (1994) observed

relationships among these seasonal hydrological fluctuations, availability of prey, and

date of nest initiation in Wood Storks (Mycteria americana). Also, Ogden et al. (1980)

found that in several species of wading birds, total number of nesting pairs and location

of nest colonies varied in response to rainfall across the Florida peninsula. Similarly, in

the French Camargue, Cezilly et al. (1995) found a positive correlation among water

depth, the number of breeding pairs, and the body condition of fledglings of the Greater

Flamingo (Phoenicopterus ruber roseus). In their study, water levels determined the

extent of flooded surfaces; and this, in turn, reflected the abundance and availability of

invertebrates produced in temporary, seasonal, and semi permanent wetlands (Kushlan

1989). Water levels and storms have also been related to complete abandonment of nest

colonies or heavy attrition of birds in the freshwater Everglades of Florida (Frederick and

Collopy 1988). This shows that the interaction of both biotic and abiotic factors at

landscape and/or patch level may play an important role in the foraging ecology, energy

acquisition, and consequently, the nesting behavior and nesting success of wetland birds.

Influence of Spatial Heterogeneity and Hydrological Fluctuations on the Natural
History of Wading Birds

Landscapes are defined as aggregations of habitat patches differing spatially and

temporally (Turner and Gardner 1991, Dunning et al. 1992). In this context, wetlands are

interesting ecosystems, because they contain a wide array of habitat types and/or patches,









sometimes complexly arranged within the landscape. Wetlands also have an important

temporal component which includes seasonal fluctuations in water levels, which can have

profound effects on the ecology of wetland biota. Hydroperiod (the amount of time that

an area is covered with water) can determine density and composition of a wetland

vegetation community (Gunderson 1994). Hydroperiod, depth of water, and drought

frequency can drastically alter the spatial distribution, population dynamics,

inter/intraspecies interactions, and food webs of both terrestrial and aquatic organisms

(Urban et al. 1993, Newman et al. 1996, Turner et al. 1999, Liao et al. 2001). The latter

implies that, for many vertebrate species, availability of food, shelter, water, and space

will vary greatly in response to fluctuations of water levels, and that fulfillment of

wildlife needs will also change according to patch dynamics. As a consequence of

landscape heterogeneity and dynamism, habitat needs will often be fully covered in a

given patch/habitat type for only a limited period. When these patches/habitats currently

under use are no longer available, the species will be driven to search and use new

suitable patches/habitats, until these do not offer appropriate resources for survival. A

species will then return to patches formerly used when they become available. This is

typical of many waterbirds, which are obligately tied to wetlands, and are dependent on

characteristics of individual patches (Haig et al. 1998) for which they have developed

morphological and behavioral adaptations that maximize the exploitation of available

resources (Weller 1999).

Since fluctuation of water levels determines the spatial distribution of aquatic

habitat, it will, therefore, influence the distribution of prey animals available to wading

birds. This (and water depths) can determine the distribution of wading birds across the









landscape. Powell (1987) found that seasonal changes in water levels in a shallow marine

embayment were responsible for seasonal abundances and distribution of wading birds,

largely according to leg length. Bancroft et al. (2002) showed that water depth had the

largest effect on distribution and abundance of wading birds in the Northern Everglades.

This hydrological mechanism (triggered by seasonal changes of precipitation rates) has

ecological repercussions in wetlands within temperate and subtropical latitudes. Few

studies addressing the effects of hydrological fluctuations on wetland's biota have been

carried out in tropical wetlands. One of these studies, in the Venezuelan Llanos, reported

a significant shift in prey composition, habitat use and foraging behavior of Wood Storks

(Mycteria americana), as a result of the change from rainy to dry seasons (Gonzalez

1997). Like Florida, during the beginning of the rainy season streams and lagoons

overflowed and inundated extensive marshes that became preferred habitats for storks.

Similarly, in the coastal wetlands of the Yucatan Peninsula, Mexico, Arengo and

Baldassarre (1999) reported seasonal differences in the number of feeding Flamingos

(Phoenicopterus ruber ruber) according to water level fluctuation and its influence on

food variability. The latter scientists believed that fluctuating environmental conditions

lead to variation in food resources and determined spatial shifts in the availability and

quality of foraging habitat. This study demonstrated that the landscape needs of the

Flamingo are fulfilled by availability of multiple foraging sites within the 8,000-Km2

coastal wetlands of the Yucatan Peninsula.

Rainfall seasonality and its effects on wetland hydrology seem to be dominant

factors in determining distribution, abundance and behavior of wading birds in

subtropical and perhaps, tropical wetlands. Therefore similar environmental mechanisms









may influence the ecology of wading birds in Central America, even though the "dry-

down" model described above has been derived almost exclusively from observations on

wetlands in Florida and the Venezuelan Llanos. It is not clear that, predictions from these

extremely large, open, and sometimes heavily modified wetlands, are pertinent to other

types of wetlands and their biota. This is especially true given the large differences in

niche exploitation and mechanisms affecting both, foraging success and breeding, that

seem to be apparent for different species of wading birds (Gawlik 2002).

One possible model for determining the impact of rainfall and hydrological

variation on Jabirus in Central America can be obtained from observations made on one

of the Jabiru's closest relatives: the Wood Stork. In the Sian K'aan Biosphere Reserve,

eastern Yucatan peninsula, interruptions in the wetlands' drying pattern due to heavy

rainfall during the nesting season have led to a decrease of food supply for Wood Storks

and, consequently, disrupting their nesting activity (Ramo and Busto 1992). Additional

evidence can be obtained by observing the relationship between rainfall and the Wood

Storks' egg-laying period. In south Florida, southeastern Mexico and Honduras, the egg-

laying period is almost the same, approximately January to March (Hancock et al. 1992),

as are the rainfall pattern and the pronounced dry seasons. The Wood Storks seem to be

clearly adapted to the drying trend throughout most of their range, and nesting is not

known to occur outside of the period of decreasing water levels, since any appreciable

rise of water levels seems to be associated with nest abandonment and nestling mortality

(Kahl 1964, Hancock et al. 1992). In contrast, other wading birds seem to be less

influenced by water conditions. White Ibises (Eudocimus albus) can feed effectively on

rising or decreasing water levels (Kushlan 1979), and therefore, its nesting activity is not









strictly dependent on water levels. As a consequence, the nesting period of the White Ibis

is quite variable throughout its range. In the Florida Everglades, nesting occurs during the

dry season, while along the eastern coast of North America, nesting occurs on rising

water levels; along the coast in South America, nesting seems less influenced by climatic

conditions and takes place mostly during the wet season (Hancock et al. 1992).

Therefore, it is very important to emphasize that, as Gawlik (2002) pointed out, even

though some wading bird species might provide a general idea regarding the ecological

responses to environmental changes of the entire wading bird group, specific responses to

these changes will vary from species to species. For this reason, I am not attempting to

use the Jabiru's ecology as a model for other wading birds, although, I believe that the

Wood Stork's ecology can provide a congruent model for the Jabiru's foraging and

nesting ecology due to their close phylogenetic relationship.

The Study [AP1]Species: The Jabiru Stork

Together with the Maguari (Exenura galeata) and Wood Stork (Mycteria

americana), the Jabiru (Jabiru mycteria, Lichtenstein 1819) is one of only three species

of New World storks (Ciconiidae). It is also the largest flying bird in the Americas, and

one of the largest birds on the planet, reaching 1200 mm tall, 625-715 mm wing length

(males) and an average culmen length of 284 to 328 mm (Blake 1977). Adults are

commonly described as having entirely white plumage, black legs and bill, naked head

and neck with a broad red collar around base of neck. Juveniles are characterized by their

pale gray upper parts, whitish lower parts with silvery grey-brown edged feathers, downy

dusky head and neck with feathering lost within a few weeks (Howell and Webb 1995).

Jabirus occur in extensive freshwater marshes, savanna lagoons and ranchland with ponds

(Hilty and Brown 1986) where they search for fish, eels, mollusks and reptiles. Jabirus









usually nest solitarily in pine savannas or in high trees in broadleaf forests in open

wetland savannas from southern Mexico to Northern Argentina, Uruguay and Paraguay.

Three distinct populations are believed to occur throughout the Jabiru's range,

with the largest two located in northern South America and south-central South America

(Luthin 1987), and the smallest in Central America. Studies aimed at estimating

population size and characteristics of their natural history have been carried out mostly in

Venezuela (Thomas 1985a, Gonzalez 1997), Surinam (Spaans 1975), and Argentina

(Kahl 1969). Smaller numbers of storks may occur in Uruguay, Paraguay, Bolivia and

Peru. In the South American part of the range, Jabirus inhabit extensive wetlands like the

Pantanal of Brazil, the Pampas in Argentina, and the Venezuelan Llanos. However, in

Central America, wetlands are generally smaller, more isolated, and less extensive than in

South America. Thus, it is believed that the Central American population is much smaller

and more localized than the other two populations, perhaps containing no more than 150

individuals (Luthin 1984). Because of its small size, this Central American population

may be more vulnerable to external threats, and therefore, prone to decline. For instance,

in Panama, the last known record of a Jabiru was that of a male shot in Bocas del Toro in

1927 (Wetmore 1965); after this, there have not been further sightings or reports. Ridgley

and Gwynne (1989) did not believe that Jabirus will ever occur again in Panama, partly

because of their recent decline in neighboring Costa Rica. This might suggest that, in

spite of the Jabiru's natural potential for dispersion due its ability to sustain long range

flights, local populations could have been already extirpated from the vicinity and that

similar trends might be expected elsewhere in Central America. Despite the natural rarity

and vulnerability of the species in the region, few descriptions or scientific studies have









been carried out in order to determine basic traits of its natural history, demographics or

habitat requirements. The ecology of the species remains largely undescribed for many of

the Central American countries. Some of the earliest references addressing the presence

of the storks can be traced back to the nineteenth century, when British expeditions

documented many of Central America's species of flora and fauna, including the Jabiru,

in a series of scientific publications known as Biologia Centrali-Americana (Salvin and

Goodman 1904). More recently, a few estimates of population and some biological

descriptions have been obtained for southern Mexico (Ogden et al. 1988, Correa and

Luthin 1988, Lopez Ornat et al. 1989), the lowlands of the Honduran and Nicaraguan

Moskitia (Frederick et al. 1997) and the lower Tempisque River basin in Costa Rica

(Villareal 1997). To date, there have been no rigorous estimates of population size of

Jabirus in Belize, even though this country may host the largest breeding population in

the region (Luthin 1984). It has been suggested that Belize breeders move to the

Usumacinta drainage in Mexico during July and that they travel back to Belize in

November or early December (Miller 1995, Howell and Webb 1995), when most

wetlands in both areas are drying and food is available. If it is true that regular

movements occur across country borders, a strategic plan with bipartisan or multinational

efforts must be developed to ensure conservation of the Jabiru's foraging and nesting

habitat across Mesoamerican countries.

Nevertheless, before starting the policymaking process, it seems imperative to

acquire accurate and reliable scientific data regarding the natural history and ecological

requirements of the species. To date, pieces of information from some of these countries

provide rough indication of sites where Jabirus occur in Central America. Information









addressing the status and distribution of the species is lacking for, what is believed, one

of the most important bastions of suitable foraging and nesting habitat for Jabirus in the

region: Belize.

In this thesis I present a picture of the ecological needs of the Jabiru Stork in the

hope that this can serve as baseline information for rapid conservation action and

encourage future scientific research on wetlands, storks and other water birds in Central

America. Since it is still unknown whether these birds move widely across Central

American wetlands in response to rainfall and its influence on water levels and food

availability, or if they are largely sedentary, I attempted to investigate the influences of

rainfall and the "dry-down" model on the abundance, local movements and distribution

of the Jabiru in central and northern Belize. Assuming that the dry-down model is correct,

I predicted that fewer Jabirus would be observed when water levels increased during the

rainy season. In contrast, larger numbers of Jabirus should be recorded during the dry

season. I also predicted that Jabirus would occur in interior wetlands that are more

susceptible to strong hydrological variations, as opposed to coastal regions where water

level fluctuations are buffered by the stability of sea level. I also investigated the effects

of water levels on habitat used for foraging purposes as a means to discover any linkage

between hydrology and reproductive biology. I predicted that larger prey items would be

captured when water was receding, especially during the dry period, when fish should

have been concentrated in ponds. I recorded locations of Jabirus in the landscape through

five systematic aerial surveys. Using this information, I explored the variations in the

number of Jabirus according to rainfall, and their distribution and habitat use at the






12


landscape and local levels. Observations made from the ground helped me describe their

foraging behavior and identify and quantify the prey items captured.














CHAPTER 2
STUDY AREA AND METHODS

Study Area

I studied the Jabiru Stork in Belize, the second smallest country in Central

America, from March to July 2003 (Figure 1). The entire country is influenced by a

tropical weather pattern with two clearly distinct seasons. The dry season usually extends

from November to June, and the rainy season lasts for the remaining 5 months. In El

Nifio/La Nifia years, the weather pattern exhibits a drastic deviation from the one found

in neutral years. Before and during El Nifio events the entire region is usually dry. In La

Nifia years, the climatic conditions are much more variable (Curtis 2002) and they can

include increased monsoon rains during the dry season, like the ones recorded across

Central America and Mexico from October to December 1998 (Bell et al. 1999).

At the national scale, weather parameters are slightly affected by local topographic

features since most of the country lacks mountain ranges, with the exception of the Maya

Mountains located in the southwest quadrant. A great proportion of the country's surface

is at low elevation; almost half of it lies between 0 and 100 m above sea level. This has

allowed the development of several types of wetland ecosystems, which account for

nearly 10% of the country's total area (Meerman and Sabido 2001).

Most of my research was performed in the northern half of Belize. Ground

observations were made in the Crooked Tree Wildlife Sanctuary (hereafter CTWS).

CTWS is a 6,639-Ha reserve located at the center of Belize, between 17030' and 1800'

north, 88o22' and 88035' west. The entire area encompasses freshwater wetland systems









consisting of seasonally flooded lagoons, marshes, creeks, and pine savannas. The

reserve can be divided into 5 main lagoons. The Northern, Western and Southern

Lagoons are interconnected and comprise one of the reserve's hydrological systems,

while the Mexico and Jones lagoons comprise the second hydrological system (Figure 2).

The elongated basins of the Northern and Western Lagoons are approximately 16

km long and run parallel to each other separated by a 3 km wide land fringe, and are

connected in CTWS' northernmost limit. In contrast, the Southern Lagoon represents

CTWS' southernmost boundary, separated from the Northern Lagoon throughout 3.5 km

of anastomosed creeks.

The dominant vegetation differs slightly in each lagoon. graminoids (Eleocharis

spp) cover most of Western Lagoon's basin, especially its northern portions, while little

or no emergent vegetation characterizes the basins in the Northern and Southern

Lagoons. One to two meter-high shrubs (Bucida buceras) fringe the Northern Lagoon's

shores, especially the east shore, and cover some portions on its northern boundary. In

this hydrological system Spanish Creek connects the Belize River to the Western and

Southern Lagoons; meanwhile Black Creek connects the Southern and Northern Lagoons

to the Belize River. During the rainy season, the water level in the Belize River increases

and its flow discharges directly to the Northern, Southern and Western Lagoons through

the Black and Spanish Creeks, respectively. During this time of the year the current flows

in a south to north direction. The pattern is reversed during the dry season, when the

water levels in the Belize River decrease, and, therefore, Spanish Creek and Black Creek

decrease, limiting their contribution to the main lagoons. By this time a significant

amount of water has been stored in the lagoons, and, especially, in the reserve's









northernmost portion, in the Backlanding/Revenge area. Due to differential pressure

between lagoons and creeks, the flow gradually drains from this expanse directly to the

creeks from north to south. By the end of the dry season, the lagoons are almost entirely

dry, and only a few small ponds and creeks retain some of the water available in the

system. Mexico and Jones Lagoons are located approximately 12 km east from the

Northern Lagoon, apart from CTWS main hydrological system. These two lagoons are

approximately 1 km long, and are connected to the Belize River through Mexico Creek.

Like in Northern-Western-Southern Lagoons, similar processes define the mechanics of

the Mexico-Jones' hydrology throughout the year.

Crooked Tree village (CT), located on the land strip between the Northern and

Western Lagoons, is the only human settlement that has been developed within the

reserve's boundaries. This 300-person community has traditionally depended upon the

resources provided from the Northern and Southern Lagoons, and fishing is currently an

important income-producing activity for local villagers, fishermen from outside the

influence of the CTWS area and for few fishermen that come from Guatemala. However,

during the dry season, when the lagoons have almost or entirely dried down, their basins

are frequently used for cattle ranching or game hunting. Other relevant human

settlements are located along the Northern highways and around the largest cities,

especially nearby Belize City, approximately 45 km southeast, and Orange Walk town 35

km to the north. Unplanned urban sprawl and extensive agricultural production are the

major threats to wetlands around the large towns.









Methods

Landscape Data and Population Estimates

I obtained population estimates, spatial distribution and habitat use of the Jabiru

Stork by air-surveying northern and central Belize from March to mid June 2003 (Figure

3). One initial reconnaissance flight was made over CTWS on March 22. The goals of

this flight were to identify type and location of wetlands, determine actual water levels,

distribution of water bodies and other relevant hydrological features, identify vegetation

types and their arrangement within the landscape, determine habitat preferences of

Jabirus, and to refine surveying techniques and datasheets. Five additional surveys were

performed on a bi-weekly basis beginning on April 12, and the final flight was made on

June 21.

The flights encompassed three stages according to weather and hydroperiod: a

"dry-down stage" (March 15 to April 30) that occurred when waters levels in most water

bodies were receding, a "dry stage" (May 1 to May 31) occurred when all major water

bodies were almost or completely dry, and "beginning of rains" which consisted of a

short period of rainfalls that occurred from June 1 to July 15.

Depending on weather conditions, flights started between 15:00 and 15:30 and

finished after 2 to 2.75 h of surveying time. A total of 2,400 km were flown during six

flights combined, at an approximate surveying altitude of 60 m and average speed of 150

km/h. At this altitude, the distance from the aircraft at which Jabirus could be sighted and

accurately distinguished from similar birds, was estimated at 1.5 km on each side of the

aircraft. Each flight path was planned using one 1:350,000 scale map that depicted

Belize's northern and central region and two 1:50,000 scale maps that showed, with

greater detail, biophysical features around New River lagoon, CTWS and adjacent areas









of interest. The Belize's Ecosystem Map produced by Meerman and Sabido (2001) was

also useful at identifying major vegetation types, prioritizing surveying areas and

identifying the type of habitat used by Jabirus.

I modified the routes for each flight in an adaptive way, using information about

the vegetative communities and the location of storks that were recorded in previous

flights. In this way, I avoided resampling areas of unsuitable foraging habitat (e.g.,

broadleaf woodlands) and focused on habitat where Jabirus were previously recorded

(e.g., freshwater wetlands) or where they had a reasonable likelihood of occurrence (e.g.,

savannas, coastal wetlands). Even so, the surveys encompassed a relatively large variety

of suitable and unsuitable habitat for the storks.

Because I found the greatest concentration of Jabirus within New River Lagoon

and CTWS, I surveyed these areas in all flights with approximately the same intensity;

therefore the surveying routes over these two areas remained relatively unmodified. Most

modifications made to the routes affected areas outside the New River Lagoon and

CTWS systems. Initially, the first survey flight was aimed at making observations of

Jabirus within CTWS, while the second one was aimed at counting individuals in CTWS

and to survey coastal wetlands in eastern and northern Belize. The third and longest flight

surveyed New River Lagoon and CTWS, coastal wetlands in eastern and northern Belize

and sugar cane crops and rice fields located on northwest Belize, bordering Guatemala

and Mexico. The fourth and fifth flights were planned to survey the New River Lagoon

and CTWS and other wetlands around and north from Mexico and Jones Lagoons and

between the New and Old Northern highways.









Two or three observers, including the pilot, sighted the Jabirus during each survey.

On each survey, one person entered the data related to the animals' surrounding habitat

features, noted positions, flock size and bird activity. In some cases, digital photographs

of flocks in foraging sites also aided to clarify doubtful counts.

Positions of individuals and flocks and flock size were recorded on a tape recorder

and plotted on 1:50,000 scale maps. The GPS readings were taken when the aircraft was

positioned exactly above the target group. In some cases, the storks' position could not

have been determined using this procedure, either because the airplane traveled in a

straight line or because of a pronounced turn. In these cases, I recorded GPS readings and

estimated distance and bearing from each group to the aircraft. This type of situations

occurred in approximately half of all observations.

I defined a group of Jabirus as an aggregation of two or more individuals standing

within 50 m from each other. If an individual was located outside this distance, then it

was considered as a separate individual or flock. However, there were occasions in which

the groups of Jabirus were distributed in rows, and often, the distance from one end of the

row to the other was greater than 50 m. In these situations I estimated the maximum

distance between birds and recorded them as an entire group only if they were aggregated

within 50 m from each other.

Relative water depths were noted from the air, but supplemental information during

the dates in which the surveys were performed was obtained by taking weekly readings

on staff gauges that I had installed. These staff gauges were made out of PVC pipes

marked at 1 cm intervals and were placed in several isolated ponds and large catchments

within and around CTWS. I categorized the water bodies found in the landscape as









ponds, lagoons or creeks. Ponds were small and shallow (length < 500m, depth < Im)

water bodies with nearly circular geometry, containing still water, and could be

connected or not to lotic water bodies. Lagoons were large and deep (length > 500m,

depth > 50cm) lentic water bodies, generally connected to creeks that provide inflow and

outflow of water. Creeks were narrow and shallow (width < 50m, depth < Im) running

water bodies (Figure 4).

Microhabitat data and Observations on Foraging Behavior

I recorded foraging behavior on the ground during the dry-down stage, dry stage

and beginning of rains. Most observations were performed between 15:00 and 18:30 h,

although sporadic encounters were made in the morning or midday. I used the Focal

Animal Sampling Method, in which a single foraging individual is randomly selected

from the flock and observed during a pre-established amount of time. In the current

study, observation time comprised no more than 30 minutes. However, if the selected

bird stopped foraging or left the area before the pre-established time, then, the

observation and data recording ceased, in which case, a new individual was randomly

selected and data recording continued.

Observations were made using a 25-56x telescope and a pair of 10x46 binoculars.

Data were recorded on a cassette tape, timed by stopwatch and entered on datasheets after

every daily session. I recorded general environmental variables (weather, date, time of

day, location, length of observation), social and behavioral data (e.g., size of foraging

flock, number of steps, probes, prey type, prey size) and habitat data (type, water depth,

vegetation height, % cover) for each foraging individual under observation. During

observation periods, vegetation height and water depth was estimated in fractions of

tarsometatarsal length (Frederick and Bildstein 1992). Prey items were identified by









direct observation and prey size was estimated in fractions of culmen length, and then

converted to metric units using the culmen measurements compiled by Thomas (1985b).

Foraging behavior was recorded during the dry-down, dry and beginning of rains.

Preliminary observations on the storks' foraging behavior were made during the last

week of March and, when possible, quantified within basic behavioral categories (e.g.,

steps, probes) based on the descriptions developed by Meyerriecks (1962), Kushlan

(1976, 1978), Kelly et al. (2003).

Direct measurements of habitat features were made when accessibility permitted it.

First, I randomly selected foraging individuals and established circular plots (15-m

diameter) around selected individuals. If present, emergent vegetation height was

recorded by direct measurement and percentage cover (%) was sampled using a 1 m2

PVC frame thrown 10 times in random directions. The frame was divided into a grid of

100 squares (10 x 10 cm/square) using monofilament strings, and vegetation cover was

estimated by counting the number of cells covered. Vegetation composition and height,

type of substrate and water depth were estimated using graduated poles in each different

foraging patch.

Analysis of Data

Routes, locations and size of groups of Jabirus recorded on each survey flight were

entered into a Geographic Information System (ArcViewGIS, ver. 3.2). Aerial survey

routes were drawn into the Belize ecosystems map (Meerman and Sabido 2001), buffered

at 1.5 km on each side and clipped accordingly to obtain total surveyed areas and the

proportions of each habitat surveyed. The storks' location and group size were also

plotted onto the map, allowing identification of habitat type used. I used the Belize

ecosystems map to identify the biophysical features of ecosystems used by storks. I added











one category, seasonally flooded basins, to the vegetation map and assigned it to those


areas covered by the major lagoons. I did this because I considered lagoons as important


areas for Jabirus and because in the map of vegetation there are no detailed biophysical


descriptions of areas subject to hydrological fluctuation. I also used the land use base


map to identify the major categories where Jabirus occurred. Differences in habitat use


were determined using the chi-squared test (Gonzalez 1997).


-90 89 48 87


MEXICO


P f. -


I .


BELIZE


1 17


CARIBBEAN
SEA


k I


-90 -89 -88

Figure 1. Map of Belize, Central America. Adapted from ESRI.
(http://www.esri.com/data/online/index.html)


1


; I
, /


. '.'L IF
PIT i


I'~~'''T




































Figure 2. Map showing the components of the hydrological system in central Belize.
CTWS (shadowed) encompasses four of the major lagoons: Northern,
Western, Southern and Jones. Light blue: wetlands, Dark blue: water bodies,
Red: Urban areas and highways.


Figure 3. Map showing the study area divided according to differential sampling effort.
Inner square: CTWS and New River lagoon, Middle size area: central Belize,
larger area: northern Belize.


88'45' 88'30' 8815' 8800'


18'30'


1 8'15'



18'00'


17'45'



17'30



17'15'











...t A



Jabi r Storks" --: if' ] \ y^ Tr ~ i f r n
V= 'SouthernLg l + a a
.-- ', ,i ,' '
I -
) I

,, '-- i a .






Figure 4. Map showing designated survey areas according to foraging relevance for
Jabiru Storks, central and northern Belize. Areas: I=New River Lagoon,
II=Western Lagoon, III=Revenge Area/Bight Swamp, IV=Northern Lagoon,
V=Southern Lagoon, VI=Black Creek/May Pen and adjacent wetlands,
VII=Mexico and Jones lagoon, VIII=New and Old Northern Highways,
IX=Dobloon Lagoon, X=Shipyard and surrounding agricultural lands.














CHAPTER 3
RESULTS

Abundance of Jabiru Storks

I made a total of 391 sightings of individual Jabiru Storks during six aerial surveys

in central and northern Belize. Overall, I recorded an average of 65 storks/flight or 0.16

storks/km, a mean of 4.46 individuals/group, and an average of 15 flock sightings/flight

or 0.04 flock/km. The largest number of storks (n = 116) was recorded on May 10

(survey 3), while the smallest number (n = 49) was recorded on April 12 (Table 1).

Singletons were recorded more frequently during the dry down (n = 11, survey 1) and dry

stages (n = 8, survey 3), while the frequency of Jabirus foraging in pairs seemed to

remain constant throughout the entire study period. Very large aggregations (n = 31-50,

n > 50) were recorded only in the dry stage (surveys 3 and 4). Conversely, intermediate-

sized groups (n = 3-10, n = 11-30) were rarely observed at this date although they were

relatively frequent in the next four surveys (Figure 5).

Spatial Distribution

Jabiru Storks were frequently sighted in central Belize, between southern New

River Lagoon and Dobloon Lagoon, from latitude 1730' to 18005'N, and from longitude

88o22' to 88o35' West. The area encompasses approximately 2000 km2. I saw no Jabirus

in coastal areas, or in Belize's northernmost areas. Similarly, few storks were recorded

from the country's western areas, mainly from agricultural lands located close to New

River Lagoon's wetlands in central Belize. CTWS and wetlands associated with the New

River Lagoon contained the highest densities of Jabirus. Sightings in both systems









accounted for 76% of recordings in all surveys, while only a small proportion of the total

number of observations were recorded from wetlands located between the Old and New

Northern Highways, and few of them from within and around Dobloon Lagoon in

northern Belize.

Stork distribution varied according to wetlands' water level fluctuations. During the

"dry down" stage, the highest concentrations of storks were observed around New River

Lagoon, Revenge/Backlanding Area/Bight Swamp, and, especially in CTWS' Northern

Lagoon (areas I, III and IV respectively). Around 78% of the total number of storks

recorded during the first survey on April 12 (Figure 6) and 45.6% of birds sighted during

the second survey (April 26, Figure 7) foraged in the Northern Lagoon area, all of them

distributed almost exclusively along a 5 km-long strip that runs from Crooked Tree

village to Bight Swamp, in the lagoon's northernmost limits.

By May 10, most of the largest impoundments had receded to the point that they

formed scattered ponds across the landscape. By this date, most Jabirus occupied the

Revenge Area/Bight Swamp (26% of total) and Northern Lagoon (35%, Figure 8). These

proportions were at least 6 times greater than those recorded from other large

impoundments (May Pen, Southern and Western Lagoons) where most of the basins were

almost entirely dry. By May 24, the dry weather still prevailed; Jabirus foraged on

remnant ponds at Northern Lagoon, and then shifted towards Bight Swamp

approximately 1.5 km north, even though the ponds that they formerly used in the

Northern Lagoon still held water (Figure 9). Approximately 67% of total observations

made during survey 4 were recorded from Bight's Swamp ponds and creeks.









May Pen's wetlands and Western Lagoon (58 and 28% respectively) show the

highest densities of storks by June 21 (Survey 5). Few birds were seen in the Northern

Lagoon; this due to the rise of water levels in this lagoon as result of 38 hours of

continuous rain that fell over central Belize. Thus, most of this habitat, which was used in

previous weeks, was then completely unavailable. At the same time, water levels

increased on the dry basins of Western Lagoon and most wetlands in May Pen Area

(Figure 10). Figure 11 summarizes the spatial distribution of the Jabiru Storks recorded

during the five surveys in central and northern Belize.

Habitat Use

Habitat Use According to Ecosystem Classification

A total of 9 ecosystem types were sampled during air surveys, although, only 4 of

them were used by Jabirus. Overall I found that 85.75% of Jabirus used Seasonally

Flooded Basins, 9.26% used Tropical Lowland Tall Herbaceous Swamps, 3.56% used

Tropical Evergreen Seasonal Broadleaf Lowland Swamp Forest: Low Variant and only

1.43% were recorded on Tropical Evergreen Broadleaf Forest over Calcareous Soils.

When plotted onto the ecosystem map of Belize, 7 % of locations of Jabirus

corresponded to Short-Grass Savanna with Needle-Leaved Trees or Short-Grass Savanna

with Shrubs. However, based on observations made in the field, these ecosystem types

were, in many occasions, complex mosaics of several ecosystem types. Large ecosystem

sometimes appeared as ecosystem matrices with several smaller patches of different

ecosystem types embedded within the matrix. The immediate habitat type surrounding

Jabirus observed in Short-Grass Savanna with Needle-Leaved Trees or Short-Grass

Savanna with Shrubs corresponded small patches of, either, Seasonally Flooded Basins or

Tropical Lowland Tall Herbaceous Swamp. Therefore, during data analysis, records from









these locations were pooled together with Seasonally Flooded Basins or Tropical

Lowland Tall Herbaceous Swamp types.

The Jabiru's use of ecosystem did not vary much during the time that this study

was done. When compared across the dry-down and dry stages and beginning of rains,

the majority of Jabirus preferred Seasonally Flooded Basins. For instance, during the dry

down stage (March to May 1), around 89% of observations on storks were made from

Seasonally Flooded Basins and only a few of them (6.5%) in the Tropical Evergreen

Seasonal Broadleaf Lowland Swamp Forest: Low Variant, or the Tropical Lowland Tall

Herbaceous Swamp (1.5%). Similarly, during the late dry season (May 1 to May 30)

when most lagoons were already dry, 86.3% of the storks were observed foraging in

remnant ponds formed by the New River Lagoon and the receding waters of the Northern

Lagoon. Nine percent of the total number of observations were recorded on Tropical

Lowland Tall Herbaceous Swamp, 3.7 % on Tropical Evergreen Seasonal Broadleaf

Lowland Swamp Forest: Low Variant, and only 2 observations were made on Tropical

Evergreen Broadleaf Lowland Forest over Calcareous Soils (Western Variant),

representing 1% of the observations for this season. By the first week of May, the area in

which the main gauge was installed at the Northern Lagoon was completely dry. By this

date, PVC gauges dispersed among two remnant ponds at the Western Lagoon, one of the

areas with high occurrence of Jabirus, showed a mean decrease of 3.0 and 6.5 cm/week

(Figure 12).

By the beginning of June, mild and scattered rains arrived at certain areas in Belize

and water levels recorded at the stages increased rapidly. For instance, the gauge located

at the Northern Lagoon reached 110 cm following 36 hours of continuous rains. During









this period Jabims used two ecosystem types- at least 82% of storks used Seasonally

Flooded Basins and 17% of the storks were foraging in Tropical Lowland Tall

Herbaceous Swamp (Figure 13). Most of the locations were recorded from small marshes

close to CTWS and from small ponds surrounded by Pine-Palmetto savannas located

between Belize's Old and New main highways.

Habitat Use According to Land Use Classification

The data obtained from land use maps indicated that a total of 9 different land use

categories were sampled during all 5 flights but only 4 of them were used by Jabirus

(Table 2). The storks were found using wetlands (open areas subject to seasonal floods)

out of proportion to other available habitat. Overall, 91% of total observations on

individuals (n = 415) were recorded from wetlands, significantly higher (X2= 975.8,

P < 0.001, df= 3) than in any other habitat. The proportion of birds using vegetation

types was relatively similar across the dry-down, dry stages and beginning of rains, with

the highest number of birds foraging in wetlands and the lowest observed in agricultural

areas (Figure 14). I found no Jabirus using any coastal habitat, even though other wading

birds such as the Wood Stork were found aggregated in colonies along coastal savannas

and mangrove forests within the Shipstern Reserve, in Belize's north-easternmost area.

Similarly, there were no records of any Jabiru from rice fields in northwest Belize.

Use of Water Bodies

Jabirus foraged in lagoons and ponds more frequently than in creeks, although the

proportion of storks using these habitats changed drastically across seasons. During

survey 1 most Jabirus (87%) foraged in lagoons, mainly around New River and the

Northern Lagoon and, in fewer cases, in ponds and creeks. Observations made from the

next 3 surveys showed that the use of remnant ponds increased drastically; the proportion









of storks in these habitats rose from 6% in survey 1 to 56, 99 and 92% in surveys 2, 3 and

4 respectively. The frequent use of ponds was due to decrease of water levels and

reduction of lagoon habitat. Jabirus rarely used creeks (< 6% of total) with an exception

during survey 2, when 44% of the storks were found there (Figure 15).

Features of Foraging Microhabitat

In both aerial and ground surveys, Jabirus were generally observed in open spaces

(free of trees or shrubs) and in drying-down or already dry basins and marshes. In 96% (n

= 336) of the observations made from the ground, individuals foraged in locations with

little or no emergent or submerged aquatic vegetation. However, when present,

graminoids and sedges, mainly spike rush (Eleocharis spp) and Cyperus spp, were the

most common species composing the emergent plant cover, reaching an average height of

1.28 cm (SD = 35.26) and mean coverage of 39.67% (SD = 22.07). The mean depth of

water at which foraging occurred was 16.26 cm (n = 351 observations, SD = 12.30) but

fluctuated from 0 to 50 cm. Foraging in open waters and along shorelines was common in

all seasons. Foraging on mudflats in the Northern Lagoon occurred only during the dry

down period, when receding waters allowed the formation of extensive mud banks where

the storks searched for buried eels.

Diet Composition

I recorded a total of 782 prey items collected by Jabirus in the period of March to

June. I was unable to identify 80% of these items due to difficulties observing details of

small-sized prey at long distances. Ninety eight percent of these unidentified items (n =

563, 72% of total) were recorded from a single group of 5 foraging storks in the Northern

Lagoon after heavy rains fell over central Belize on June 18, flooding all the lagoons and

many small wetlands. Due to the small prey size (< 2 cm), their substrate, location, and









the speed at which they were captured by the Jabirus, it is very likely that these small

items were aquatic insects. Of the 162 remaining prey items that I was able to identify,

95% were aquatic animals. Small fish, with approximate standard length (sl) below 15

cm, were the most abundant prey type consumed, accounting for 73%, followed by

Swamp Eels (Symbranchus marmoratus, 13%), Apple Snails (Pomacea spp, 6%) and

large fishes (sl > 30 cm, 3%) including cichlids (Tilapia spp. among others) and catfishes

(Ariidae).

Terrestrial prey comprised only 5% of the items collected; they were represented

only by amphibians and lizards. Although identification of these terrestrial prey items

was often inconclusive, several clues led me to believe that they were terrestrial prey.

The storks were frequently searching the vegetation on a narrow strip of land (5 x 150 m)

located in the middle of the lagoon, and picking up small items from the ground. Later

visits to the foraging patch revealed an abundance of anurans, mainly toads (Bufo spp.)

and lizards (Norops spp.) that probably serve as food items for the storks (Figure 16).

Foraging Behavior

I recorded a cumulative of 800 minutes of foraging behavior from 53 Jabiru Storks

in CTWS and adjacent wetlands from March to July 2003, from 53 individuals.

Walking and Searching for Food

Overall, the stepping rate during search periods averaged 23.14 step/min and the

step length, as compared with leg length, was estimated at between 50 to 60 cm {Object

1. Video clip of Jabiru walking in Northern Lagoon. AVI file. (Jabiru_steps.avi, 18

seconds, 2.79 Mb)}. Shorter, faster steps were used when prey were sighted, commonly

at distances as far as 20 to 30 m.









I observed Jabims using two main types of searching behavior. First, the birds

inclined their head and neck towards the water, and introduced their bills into the water.

As the bill was introduced, they opened and closed it several times in a way that

resembled "biting" or "tasting" the water, as described by Thomas (1985b). The depth of

water at which they performed this behavior was variable but typically ranged from the

tip to half-length of bill (2 15 cm) and it was more frequent in shallow areas. Captures

of fish were common using this method, but most of the time, it seemed like the Jabiru

was probing repeatedly trying to detect the fish hitting the bill {Object 2. Video clip of

searching for food. AVI file (Jabiru feeding behavior.avi, 15 seconds, 2.33 Mb)}.

In a different behavior, the birds inclined their head and neck at an angle that

ranged between 45 and 90 degrees below the horizontal, slowly introduced their bill into

the water, and, consequentially, into the mud. Normally, one to four bill strokes on the

same location followed the first insertion, and, often, subtle "probing" was seen as the

bill was about to be taken out of the water. These movements seemed to be more useful

for tactolocation, especially detection and capture of infauna, mainly eels and mollusks.

Jabirus used this behavior on shallow areas in the lagoon or around ponds (1 cm to 15

cm), and it seemed exclusively used to locate and excavate buried eels from mudflats

{Object 3. Video clip of Jabiru searching for food in mudflat. AVI file. (Jabiru feeding

behavior, 1 minute 29 seconds, 3.18 Mb)}.

A third behavior, which I did not see during the dry down stage, was observed in

the dry season, when most foraging Jabirus formed groups around shallow remnant ponds

scattered throughout CTWS. In this behavior, the birds swayed their neck from side to

side of the body, while simultaneously pivoting their head approximately 45 degrees









above and below the horizontal. During these movements the bird's bill almost reached

the tarsus, when the neck was positioned at its lowest level at either side of the body; the

head was lifted until reached its highest peak, and then pulled back down at the other side

of the body, describing a movement through the water that resembled an inverted "V".

Repetitions were always performed as the bird walked across the water body, and were

sometimes violent enough that water was lifted when the bill was raised. This behavior

was not observed in shallow water (depth < 10 cm), mudflats, or dry shorelines. No prey

items were captured, nor were any type of intra or interspecific aggression evident during

these episodes. This behavior was very infrequent, perhaps not recorded in more than 5

occasions; the reasons that explain it still remain unclear.

Capturing and Handling Prey

Capture rate of all observations was 0.62 prey/min (SD = 1.33). Preys were

captured using the two searching behaviors described above. Small and large fish were

always captured by "probing" (inserting the bill into the substrate, water or mud, opening

and closing the bill), either while actively chasing prey or by stalking. Especially during

the dry down period, Jabirus often stopped foraging, stood still, and then stretched their

neck, keeping the head as high as possible and staring from one side of the head,

switching to the other to scan nearby areas. Once the type of prey and its distance was

determined, the stork ran towards the prey's location, often flapping its wings 1 to 3

times and leaping 0.5 to 1 m above water. The bird then searched actively, inclining its

head and neck with its bill placed perpendicular to the water's surface and catching the

fish at the first or second strike. Both stalking and tactolocation were used in dry down

and dry periods. However, during the dry period stalking occurred mostly on small dead

fish which were picked up from the pond's surface and quickly discarded.









The manner in which fish were handled before ingestion varied according to the

size of fish. Small fish were captured and eaten rapidly, while longer periods were spent

manipulating and consuming large prey, generally larger than 30 cm. Following capture,

Jabirus usually used their bills to stab violently at large fishes captured, which seemed to

stun or dismember the fish. Stabbing was often coupled with neck shaking while the prey

was held in the bill. Several repetitions of this behavior occurred, interspersed with

periods where the storks dropped the prey into the water and picked it up again.

Remnants of the prey's body floating on the surface were then consumed. Large fish

eaten whole by Jabirus were rarely seen. The storks dismembered fish prey on all but one

occasion, when a 30-cm fish was eaten whole {Object 4. Video clip of Jabiru

dismembering a large prey. MPEG. (Jabiru_handling_prey.mpeg, 1 minute 29 seconds, 10

Mb)}.

Eels were captured after long searches across the lagoon's very shallow waters,

shorelines and mudflats. Generally, the stork dug repeatedly into the same location by

introducing the bill several times, until the eel was unburied. Then, the prey was picked

up from mid body, moved along the bill, and then swallowed. On rare occasions,

captured eels were held in the bill for several minutes (5 to 10) before being consumed,

dropped repeatedly to the ground to be stabbed a few times, picked up and eaten. Unlike

large fishes, eels were not dismembered completely when stabbed, and apparently, these

strikes were an attempt at stopping further contortions of large eels, by either killing or

stunning them before ingestion {Object 5. Video clip of Jabiru searching, handling and

eating eels. MPEG file. Jabiru_eating_eels.mpeg, 1 minute 21 seconds, 8.37 Mb)}.









Snails were collected from shallow waters (depth < 30 cm). Once captured, the

snail was retained in the tip of the bill, and the shell was broken into pieces by applying

"bites" of the bill, leaving the mollusk ready to be swallowed. During the process the

shell was not ingested.

Prey Piracy

Intraspecific prey piracy was seldom observed, but occurred more frequently and

intensely when storks captured large prey items. For instance, on March 29, I observed

one Jabiru capturing a large eel (sl > 30 cm), and then be harassed and briefly chased in

the air for nearly one minute by another stork. The chase finished when the prey was

dropped into the water. The manner in which robbing or robbing attempts occurred was

variable. During some incidents, the intruder stork approached the other at a normal

stepping rate (1 step/s) and as close as 5 to 10 meters radius. In these cases, the intruder

may have attempted to approach and pick up remnants of a fish's body without disturbing

the other Jabiru. On other occasions the prey was brought to the shoreline, where one or

two other Jabirus stalked, ran and/or flew immediately towards the stork and its prey

{Object 6. Video clip of Jabiru handling a large prey and then harrased by

conspecific.MPEG file. (Jabirularge_prey.mpeg, 39 seconds, 4.19 Mb)}. Sometimes the

storks used brief "attack-defense displays" to threaten each other, which involved

opening the bill 10 to 15 cm and spearing 2 or 3 times without touching the rival and then

quickly pulling the head back.

Interspecific prey piracy, though infrequent, occurred exclusively during the dry

down stage. On one of two occasions, a Snail Kite (Rosthramus sociabilis) carrying a fish

was chased by a Jabiru for nearly one minute, and ended with the kite retaining the fish.

Similarly, on another occasion the Jabiru chased a Snowy Egret (Egretta thula) with a









fish on the ground and the stork obtained the fish. I did not observe any species making

attempts to rob the Jabiru's prey.

Loafing and Social Interactions

Storks foraging in the Northern Lagoon during the dry down stage usually moved

from their foraging location to the lagoon's east shoreline typically by the end of the

afternoon, between 17:30 and 18:30. Groups rather than singletons were more common,

usually containing between 5 and 20 individuals. During these periods, some storks

remained inactive while others (young and adults), walked around the area and "played"

with bushes by pulling dry branches or picked up sticks from the ground. They often

engaged in sham disputes with conspecifics and between Wood Storks. This type of

interaction was more frequently observed in the dry-down period, especially in the

Northern Lagoon. Conversely, they were less frequently seen in the dry season, however,

all of them were observed in Western Lagoon and remnant ponds at Northern Lagoon.

Interaction between Jabirus and Wood Storks were seen only during the dry season in

Western Lagoon and remnant ponds of the Northern Lagoon. Regardless of the species,

these disputes were characterized by two individuals pulling one end of a twig. However,

I never observed aggressive displays at any moment during these interactions.











12
11
Group size
110
10

8
8 02

= 6 6 66 6
= 6- 3-10
S5 5 5 5

44 E 11-30
4

2 E3 31-50
2

o >50
0 0 00 00 0 0 0 [ >501

April 12 April 26 May 10 May 24 June 21

Date of survey flight


Figure 5. Variation of foraging sociality of Jabiru Storks observed in 5 survey flights.






















N Legend t MEMCO








a 2-5
6 10

Slt n 1 / BEUZE










I .* .








/1 15 Kms -".



Figure 6. Spatial distribution of Jabirus during survey 1 (April 12, 2003).Light blue= Tropical Lowland Tall Herbaceous Swamp, Dark
blue= water bodies/ Seasonally Flooded Basins, Pink= Short Grass Savanna, Green: Broadleaf forest, Yellow=
Agriculture/rural communities.





























BEUZE

If-


20 Kms


Figure 7. Spatial distribution of Jabirus during survey 2 (April 26, 2003). Light blue= Tropical Lowland Tall Herbaceous Swamp,
Dark blue= water bodies/ Seasonally Flooded Basins, Pink= Short Grass Savanna, Green: Broadleaf forest, Yellow=
Agriculture/rural communities.























-80 -89

MEIC ____ "<,





BEUZE


| //
i /f
0 I99


.4.
it


Figure 8. Spatial distribution of Jabirus during survey 3 (May 10, 2003). Light blue= Tropical Lowland Tall Herbaceous Swamp,
Dark blue= water bodies/ Seasonally Flooded Basins, Pink= Short Grass Savanna, Green: Broadleaf forest, Yellow=
Agriculture/rural communities.























-80 -89

MEIC ____ "<,





BEUZE ^ t

| /
.P



i ./"S
0


Figure 9. Spatial distribution of Jabirus during survey 4 (May 24, 2003). Light blue= Tropical Lowland Tall Herbaceous Swamp, Dark
blue= water bodies/ Seasonally Flooded Basins, Pink= Short Grass Savanna, Green: Broadleaf forest, Yellow=
Agriculture/rural communities.


r
f
.'


ki



















N Legend EXICO


6- 30 [iE-
11 1












Dark blue= water bodies/Seasonally Flooded Basins, Pink= Short Grass Savanna, Green: Broadleaf forest, Yellow=










Agriculture/rural communities.
Sr -o -aI













Figure 10. Spatial distribution of Jabirus during survey 5 (June 21, 2003). Light blue= Tropical Lowland Tall Herbaceous Swamp,
Dark blue= water bodies! Seasonally Flooded Basins, Pink= Short Grass Savanna, Green: Broadleaf forest, Yellow=
Agriculture/rural communities.






















90

78
80 l- New River lagoon


70 67 I Western lagoon

S59 Bight swamp
S60
U Northern Lagoon
50
46 E Southern lagoon

40 5 Maypenandadj


30 28 O Mexico and Jones lagoons
26
21 1 H E Old-New NHgwy
20
12 1 2 E Dobloon lagoon
10 9
10 8 10
4 4 Shipyard and surroundings

0I0000
0 F -.1 I 0 0---
1 2 3 4 5

Survey flight


Figure 11. Summary of spatial distribution of Jabiru Storks recorded from 5 survey flights over central and northern Belize.


















100 -



80 --- NLn,s
-BB






0
60 WLs



40 ....... AGc
i60------------ -------



"" 30 ----- -- -





28 3 10 17 24 30 8 15 22 30 5 11 19 25 2 11 17 24 31

Mar April May June July
Date


Figure 12. Readings of water levels recorded from 6 water stages: NLn,s=Northern Lagoon north and south portions, BB=Burrell
Boom, WLn= Western Lagoon north stage, WLs=Western Lagoon south stage, MP=May Pen area, AGc=Aguacaliente
Lagoon (Southern Belize).




















Ecosystem type


* Seasonally flooded basin





* Tropical evergreen
broadleaf forest over
calcareous soils



O Tropical evergreen seasonal
broadleaf lowland swamp
forest- low variant


* Tropical lowland tall
herbaceous swamp


Figure 13. Ecosystems used by foraging Jabiru Storks in central and northern Belize, from March to July, 2003.


Dry down stage Dry stage Beginning of rains
Season




















100 00


8670


FRESHWATER LOLAND
WETLAND BROADLEAFFOREST


AGRICULTURE


0 0 0 00

FRESHI\ATER LOLANDBROADLEAF LOVWANDS4VANNA AGRICULTURE
\ETLAND FOREST


FRESHWATER LOWLAND LOWLAND SAVANNA AGRICULTURE
WETLAND BROADLEAF FOREST


100001 9495

9000

8000

7000

6000

5000

4000

3000

2000

1000- 202 003
000000
FRESHWATER LOWLAND LOWLANDSAVANNA AGRICULTURE
WETLAND BROADLEAF FOREST


Figure 14. Habitat used by Jabiru Storks according to land use classification; northern

and central Belize: a= All flights combined, b=dry down, c=dry, and

d=beginning of rains.















99
92
87


6 61
0

April 12


0L 2


April 26


May 10

Date of survey flight


May 24


June 21


Figure 15. Water bodies used by foraging Jabiru Storks in central and northern Belize,

from March to July, 2003.






74
Type of prey



I Lizards


6 S h e l l s
50


4 _40 M Anurans


30 I Snails


20 19 I Freshwater eels

10 M Small fish
10

S0 0 0 1 0 0 00 Large fish

Dry down stage Late dry Beginning of rains
Season



Figure 16. Proportion of identified prey items (n=160) of the Jabiru Stork in CTWS, from

March to June 2003.


Type
of
water body


D Lagoons



Ponds



Creeks
















Table 1. Total number of Jabirus counted during one reconnaissance and six survey flights made over Central and Northern
Belize, from April to June, 2003.
Total
Number Total number Mean
Distance of of sightings number of
flown Time Foraging (number of individuals/
Survey No. Week Date Season (km) (h) Jabirus groups) group
Pre 1 April 5 Reconnaissance 240 2.1 69 -
1 3 April 12 Dry down season 300 2.5 49 21 2.30
2 5 April 26 800 2.7 68 16 4.30
3 7 May 10 Late dry season 400 2.6 116 22 5.30
4 9 May 24 315 2.5 89 17 5.20
5 13 Jun 21 Beginning of rains 500 2.3 99 19 5.20
Total 2055 12.34 391.00 76.00 -
Mean 411 2.46 65.17 15.20 4.27
Standard deviation 204.36 0.12 24.28 2.55 1.26




















Table 2. Number of Jabirus in relation to habitat types (Land-use classification).
Survey flight 1 2 3
Number of Number of Number of
Land use type Area Jabirus Area Jabirus Area Jabirus
km2 % n % km2 % n % km2 % n %
Agricultural uses 88.82 9.93 0 0.00 99.4 9.68 0 0.00 73.38 11.55 1 0.86
Coastal savanna 53.63 6.00 0 0.00 112.58 10.96 0 0.00 0.00 0.00 0 0.00
Lowland broadleaf forest 383.58 42.88 0 0.00 365.74 35.61 4 6.06 342.62 53.93 4 3.45
Lowland pine forest 0.02 0.00 0 0.00 0.00 0.00 0 0.00 0.00 0.00 0 0.00
Lowland savanna 158.69 17.74 0 0.00 131.51 12.81 0 0.00 93.80 14.76 11 9.48
Mangrove and littoral forest 68.28 7.63 0 0.00 101.04 9.84 0 0.00 0.83 0.13 0 0.00
Rice 0.00 0.00 0 0.00 13.69 1.33 0 0.00 0.00 0.00 0 0.00
Water 47.73 5.34 0 0.00 88.42 8.61 0 0.00 33.07 5.2 0 0.00
Wetland 93.82 10.49 47 100.00 114.54 11.15 62 93.94 91.67 14.43 100 86.2
Total 894.57 100.00 47 100.00 1026.90 100.00 66 100.00 635.36 100.00 116 100.00





















Table 2. Continued
Survey flight 4 5 All flights combined
Number of Number of Number of
Land use type Area Jabirus Area Jabirus Area Jabirus
km2 % n % km2 % n % km2 % n %
Agricultural uses 92.54 14.51 0 0.00 92.54 14.51 0 0.00 446.68 11.65 1 0.24
Coastal savanna 0.00 0.00 0 0.00 0.00 0.00 0 0.00 166.21 4.34 0 0.00
Lowland broadleaf forest 306.34 48.02 4 4.49 306.34 48.02 2 2.02 1704.62 44.48 14 3.36
Lowland pine forest 0.00 0.00 0 0.00 0.00 0.00 0 0.00 0.02 0.00 0 0.00
Lowland savanna 106.25 16.66 9 10.1 106.25 16.66 3 3.03 596.51 15.56 23 5.52
Mangrove and littoral forest 0.83 0.13 0 0.00 0.83 0.13 0 0.00 171.81 4.48 0 0.00
Rice 0.00 0.00 0 0.00 0.00 0.00 0 0.00 13.69 0.36 0 0.00
Water 33.66 5.28 0 0.00 33.66 5.28 0 0.00 236.54 6.17 0 0.00
Wetland 98.32 15.41 76 85.4 98.32 15.41 94 95.00 496.67 12.96 379 90.89
Total 637.93 100.00 89 100.00 637.93 100.00 99 100.00 3832.70 100.00 417 100.00














CHAPTER 4
DISCUSSION

Rainfall Pattern in Central and Northern Belize

Typically, during neutral years (without presence of El Nifio/La Nifia effects), rains

in Belize start in early May and end in the first weeks of November. There is a slight

decrease in the amount of rainfall between June and July, and then, the maximum peaks

occur in September and October. Data obtained from the closest weather stations around

CTWS (Phillip SW Goldson Airport and Tower Hill Station) indicate that the mean

monthly rainfall peaks in September and October at 275 mm, while the lowest rainfall

rates are recorded during March (mean = 52.50 mm, n = 43). The weather during 2003

was abnormally dry and warm; I did not observe any rains for most of the first half of the

year. According to anecdotal information, the wetlands' water levels found during the

first half of 2003 were much lower than those typical of preceding years. Heavy but brief

storms were observed by the end of May although these rains were a consequence of

tropical storm Claudette that affected central and northern Belize. No rains followed and

the landscape remained relatively dry; heavy rains did not occur until the end of August

{Object 7. Video sequence of monthly water level fluctuation in Northern Lagoon from

March to July 2003. MPEG. (Dry_down_sequence.mpeg, 1 minute 17 seconds, 8.95

Mb)}.

Abundance of Storks in Response to Local Hydrology

My population surveys did not suggest any effects of climatological events on the

number of foraging storks. As opposed to my prediction, I did not observe a decrease in









the number of foraging Jabirus in response to the change from dry-down to dry to the

beginning of rains. However, it was not clear that I had a good chance of observing the

required range of conditions.

This was due, in part, to the drought experienced in Belize during 2003 that

extended until the end of August, delayed the rainy season, and therefore, did not allow a

clear comparison between both dry and rainy seasons. Even though a decrease in the

number of Jabirus was not evidenced throughout seasons, I observed that the foraging

sociality of the stork was clearly influenced by changes in available foraging habitat.

Most of the storks observed during the dry-down period foraged alone, or in pairs, rarely

in flocks larger than 15 individuals. In contrast, during the dry period, Jabirus foraged in

flocks as large as 60 individuals, as water levels had decreased and receding surface

waters formed pools and ponds where the storks concentrated. Later, when water levels

increased as a result of rainfall activity, the storks were dispersed, usually alone, in pairs

or in two groups of around 25 individuals. This pattern of aggregation was similar to the

associations of foraging Jabirus found in the Venezuelan llanos, where larger flocks were

recorded during the dry season while singletons and pairs were more frequent during the

rainy season (Gonzalez 1996).

My data suggest that Belize hosts the largest number of Jabiru Storks reported to

date in Central America and southern Mexico, confirming the assertions made by Luthin

(1987). The maximum number of storks ever recorded in one single survey over Belize

(survey 3, n = 116) was 34% higher than the overall number of sightings and almost 8

times the estimated minimum size of the resident population reported for wetlands in the

Usumacinta-Grijalva Delta, in southeast Mexico (Correa and Luthin 1988). The number









of Jabirus counted in Belize is almost 55% higher than the minimum population size

estimated for Jabirus in the Lower Tempisque River's basin, Costa Rica (Villareal 1997).

Average density of Jabirus found in the four main habitat used in Belize reached 0.12

individuals/km2, which is twice the density of Jabirus found in the Honduran part of the

Miskito coast and almost 25% lower than the density found in the wetlands of the

Nicaraguan Miskito coast (Frederick et al 1997). Reports from villagers settled near

wetlands located south of CTWS and records of storks at Aguacaliente Lagoon in

southern Belize also suggest that at least 10 additional Jabirus occur there, and were not

counted during aerial surveys. It should also be noted that some Jabirus might have been

double-counted during survey 3, when 10 to 13 Jabirus moved in the same day, from

wetlands already surveyed in CTWS to areas that were currently being sampled. I believe

that a conservative estimate of the minimum number of Jabirus in Belize during the first

half of 2003 was 130 to 140 individuals. It was not clear if these Jabirus were local,

sedentary breeders or if they have came to Belize from other parts of Central America

and/or southeastern Mexico, perhaps propelled by unusual dry weather and unavailable

foraging habitat in those areas, as suggested by Correa and Luthin (1988). To date, there

has not been any study aiming at corroborating the existence of these movements,

identifying regional flying paths or determining the hydrological dynamics and

synchronization of wetlands used by Jabirus across Central America. If it is assumed for

a moment that other Jabirus are breeding in other Central American wetlands at the same

time that those in Belize, I estimate that no more than 400 individuals may occur in

Mexico and Central America.









Spatial Distribution and Habitat Use

During the extremely dry conditions in 2003, Jabirus' spatial distribution followed

closely the actual distribution of remaining surface freshwater in the landscape. Like

many wading birds in tropical and temperate regions, Jabirus clearly responded to local

hydrological fluctuations; their spatial distributions changed according to these

fluctuations. This would not be surprising, since they foraged almost exclusively on

aquatic prey. Although that Jabirus have been reported using coastal habitats in South

America (Spaans 1975), in Belize, they used inland freshwater wetlands exclusively. The

storks appeared to have a strong link to these ecosystems; the fact that an average of 13%

of the surveyed area contained at least 76% of the overall sightings is a clear indication of

selectivity for these habitats.

Apparently, Jabirus did not seem to select wetlands haphazardly. They preferred

large, unvegetated and shallow freshwater wetlands, subject to marked fluctuation of

water levels, such as the Northern and Southern Lagoon in CTWS and wetlands

associated to the New River Lagoon within central Belize. Perhaps, the relatively good

quality flowing water and high influx of prey animals from major rivers into the larger

water bodies offer a higher amount and variety of prey animals to the storks compared to

small, isolated and heavily vegetated wetlands that were still available during the dry

down period.

Fluctuations of water levels in these large wetlands can be dramatic, perhaps

reaching 150 cm. I observed that during the dry-down period, a vast area of aquatic

habitat is drastically reduced; massive mortality of its fauna occurs, notably fishes, as

water conditions change and inter/intraspecific relationships intensify. Additionally,

reduced vegetation causing an extremely openness of these wetlands might increase the









storks' ability to identify and locate possible predators approaching while the stork is

foraging. It was interesting to notice that during the dry down period, when water levels

were falling; most Jabirus were distributed in the northernmost section of the Northern

Lagoon. Perhaps, this peculiar distribution was related to the road that was built across

the Northern Lagoon, which bisected the entire wetland into north and south portions and

impeded the flow of aquatic fauna from one side to the other. During the rainy season,

water flows from south to north and it is stored in the northern portion. The road

functions as a dike reducing the flow of water back into the southern portion. During the

flooding stage, fish and other aquatic species might follow the same pattern and become

trapped in the northern portion, leaving a larger amount and variety of prey animals

available to the storks in this area.

Contrary to my prediction, there was not a shift in habitat used for foraging

purposes when the dry-down period ended and most wetlands and some of the lagoons

were completely dry. Instead, many Jabirus continued foraging on ponds and pools that

were formed by the lagoons' receding waters. Nevertheless, I believe that, like some

other species of wading birds, a few Jabirus could have relied on altered habitats (e.g.,

agricultural grounds, aquaculture lagoons) but were not detected during surveys.

Anecdotal reports from local people suggested that Jabirus often forage in the shrimp

farm located near Belize City, the rice fields in Blue Creek area, northwestern Belize and

ponds within the agricultural fields of Spanish lookout in central Belize. As the brief

rainy season progressed, many of the lagoons were flooded and a considerable number of

small ponds were completely filled with water. Jabirus continued foraging at the lagoons,

although during this period, they occupied the wetlands around May Pen area. Some









other small wetlands were available and used by very few Jabirus; these included those

located along the Northern highway, near Sibun River, and around Aguacaliente Lagoon

in southern Belize.

Foraging Ecology

I found Jabiru prey item selection very similar to that recorded by Thomas (1985b)

in the Venezuelan Llanos and Villareal (1997) in Costa Rica. Unlike Venezuela, Jabirus

in Belize were not seen ingesting any mammals or crustaceans.

In Belize, Jabirus foraged in the same large basins for nearly all of the dry season.

The lack of precipitation over the entire study area affected the foraging grounds of the

Jabiru Stork by reducing the amount of surface area covered by water and altering the

water quality. During the dry-down stage Jabirus in Northern Lagoon foraged more

frequently in open waters and mudflats, and less frequently on shorelines and vegetation

patches. During the dry season, Jabirus could forage only in open waters; there were no

mudflats and the shoreline perimeter was substantially reduced. Unlike most wading bird

species in these wetlands Jabirus used mudflats as foraging grounds, where they

exclusively searched for Swamp Eels. Typically, these fishes live in clear to muddy

waters in sluggish flowing streams, on sandy or muddy substrates (Martin 1972) where

they build tunnels of about 0.3 to 1.2 m under water in which males guard the eggs

(Greenfield and Thomerson 1997). Jabirus may have developed morphological

adaptations for exploiting this prey item to an extent that other sympatric wading bird

species in the area cannot. In Thomas (1985) paper, it was proposed that the peculiar

curvature and length of the Jabiru's bill can be a specialization for digging large Swamp

Eels from the mud. If this is an adaptation for exploiting eels, it seems quite reasonable to

expect that eels are a critical resource for the natural history and survival of the species.









In fact, Swamp Eels may constitute a relatively large proportion of the Jabirus diet. I

found that around 19 % of the total prey items captured by Jabirus were Swamp Eels;

similar proportion has been recorded in the Venezuelan Llanos (Thomas 1985b) and

almost twice this proportion has been recorded in Costa Rica (Villareal 1997).

Apparently, the reason Jabirus preferred eels is that, Swamp Eels seem to be easier to

handle than large fish, and perhaps, eels might be ingested entirely without much

investment of time and/or energy compared to the time and energy invested to dismember

large fishes. Another potential reason for preying on Swamp Eels is that, they might

represent a considerable source of protein for the Jabiru's diet as compared with other

types of fish available in these wetlands. Perhaps, Swamp Eels might represent a

considerable part of the fledglings' diet, especially during late stages when rapid

development is necessary to avoid predatory attacks.

The dependence on the type and availability of specific food resources might be an

indication that, like Wood Storks, the reproductive season and nesting success of the

Jabiru are related to the amount of rainfall and its consequences on the wetlands' water

levels, availability and distribution of food, especially, that of Swamp Eels. Instead of

relying entirely on fish to become concentrated, like the Wood Stork, the Jabiru Stork can

take additional advantage of the dry-down stage by unburying Swamp Eels from large

remnant mudflats predominantly available during the dry-down stage. This can suggest

an alternative or additional mechanism to the classical "dry-down model" concentration

of prey. Therefore, the extent and amount of mudflats and/or other areas available for

dispersing Swamp Eels, and the abundance of Swamp Eels might influence the nesting

phenology and nesting success of the Jabiru Storks. This is a potential explanation that









may indicate why nesting Jabirus have not been recorded outside the dry-down/dry

period, unlike other wading birds such as the White Ibis (Eudocimus albus).

Conservation

Belize still manages large, intact areas that might be crucial for survival of several

wildlife species. Many of these key areas were designated as protected areas; the CTWS

is one of these, and certainly, one of the most important feeding areas for Jabiru Storks.

The establishment of CTWS has ensured protection of vital foraging habitat for this

species. However, the quality of this habitat will not depend solely on the integrity of the

Reserve's vegetation cover alone, but on the quality and quantity of water available to the

wetland system supplied in great extent by the Belize River. Unsustainable activities such

as removal of forest cover along the Belize's River shores to clear areas for agriculture

and the use of agrochemicals or spillage of urban wastewaters into rivers will eventually

affect the physical and chemical characteristics of the Belize River and the wetland

system, possibly changing the composition and structure of the aquatic community and

its biological processes. Deforestation along the margins of the Belize River is currently

taking place. During the aerial surveys, I observed that several areas along the Belize

River have been drastically modified, mainly for agricultural purposes. In some areas the

riparian forest is lacking, in some others, there is a 10 to 100 m wide forest cover fringing

the river. In both cases, sediments and agrochemicals may be easily injected into the river

as a consequence of actual land use and lack of environmental protection. As a

consequence, populations of aquatic species, key for the survival of the Jabiru, such as

Swamp Eels and other large fishes may be reduced if the actual water conditions are

modified.









Because the energetic requirements and reproductive success of Jabirus and other

wading birds seem to be determined by different food resources available during the

wetlands' dry-down, dry and flooding stages, it is very important that the wetlands'

natural fluctuation of water levels remain unaltered. Construction of physical

infrastructure such as dams, dikes, roads and bridges can alter hydroperiod or prevent

water from entering into the wetland system. Any of the activities already mentioned

have the potential to modify the water conditions in the wetland system and lead a

decrease in populations or changes of foraging grounds.

Changes in land use around the major cities-Belize City and Orange Walk- are

resulting in the loss of wetland habitat. Small, sparse human communities are settling

within wetlands located along Belize's Northern Highway. In the north, around Orange

Walk town, several areas have been deforested and replaced with sugar cane crops. No

Jabirus were sighted in rice fields during air surveys. There are numerous studies (Czech

and Parsons 2002, Lawler 2001) indicating that if appropriately managed, rice fields can

help sustain local population of waterbirds, and therefore, rice fields in Belize can

potentially be an important landscape feature for conservation of this taxa. Nevertheless,

as Ma et al. (2004) caution, an over-emphasis on the benefits of artificial wetlands might

encourage landowners to convert natural wetlands into artificial wetlands, resulting in a

considerable loss of bird diversity. Therefore, policies must, above all, prioritize the

conservation of natural wetlands and preserve the hydrologic processes that support them

before encouraging the construction of artificial wetlands as a substitute for natural

wetlands.






59


Finally, many of the Jabiru's nests seem to be located in unprotected, densily

forested areas or pine savannas, away from already protected feeding habitat. Efforts

must be made to incorporate these important nesting habitat into the current conservation

schemes.
















CHAPTER 5
CONCLUSIONS

Like wetlands in other tropical, subtropical and temperate regions, water depths and

fluctuations clearly affected the distribution, habitat use, foraging behavior and diet of the

Jabiru Stork in Belize during the first half of 2003. Several large and relatively open

wetlands in Belize can be utilized by Jabirus as feeding grounds, probably when many in

other areas of se Mexico are unavailable. The Northern and New River lagoons were

preferred foraging grounds of Jabirus, probably due to their size, openness, lack of

vegetation, and/or hydrological features. It is also possible that because these wetlands

dry down more slowly than small wetlands, large wetlands might offer abundant food

resources for a longer period of time. Like Wood Storks, the onset of the dry season and

the relative abundance of food resources seem to trigger the breeding season of the

Jabiru, although the mechanisms producing this abundance may be different. Watersheds

especially that of the Belize River, must be protected in order to preserve appropriate

water conditions for wetlands that support the major concentrations of Jabirus. Future

research should be directed at determining the movements of Jabirus across countries, at

identifying wetlands used during these movements, to study the relationship between

rainfall, water levels and reproductive success of Jabirus, and at determining and

quantifying the effects of human activities on the hydrological characteristics of wetlands

used as foraging habitat by the Jabiru and other wading birds. It is also important to

understand more about the ecology of the Jabiru's prey items, especially the Swamp Eels,






61


since little is known about this species which seems to constitute one of the main items in

the diet of the Jabiru.



















APPENDIX A
MAPS OF STUDY AREA


Figure 17. Satellite image of CTWS and New River Lagoon Area. Red: water bodies,
Green: Broadleaf forest, Purple/Pink: wetlands.

























62


uE~uE
4i


*w


-s






63




























Figure 18. Map of ecosystems of Belize, northern Belize. Comisi6n Centro Ameriamecana
de Ambiente y Desarrollo (CCAD)/Centro Agron6mico Tropical de
Investigaci6n y Ensefianza (CATIE)/Government of the Netherlands/World
Bank (WB)/World Institute for Conservation and Environment.
(http://wbln0018.worldbank.org/MesoAm/UmbpubHP.nsf/917d9f0f503e647e
8525677c007e0ab8/c8el288cde480 f585256a6c008050e3?OpenDocument).































Figure 19. Map of ecosystems of Belize, central Belize. (CCAD/CATIE/Government of
the Netherlands/WB/World Institute for Conservation and Environment).


Figure 20. Map of ecosystems of Belize, southern Belize. (CCAD/CATIE/Govemment
of the Netherlands/WB/World Institute for Conservation and Environment).


...........














APPENDIX B
ROUTES OF SURVEY FLIGHTS










N
S Che~urnl BayI

SSlieml ec "osyshp
'- Coat wl satanra
L>II an bream leaf orew
L>l.InId piel frlsI
H Lolmanderabanna

ra lk r A ubmantene broedleal rm
Sub Mnte p* fors t
















Figure 21. Route of survey flight 1, northern and central Belize.










-ur ,i Low'and pi l t d nlao-i

Ii L i r t, .k1 -m r & bto ,um e Iroadrea' rvprni
5Urb-
pJ"MOimm )" ,i


Figure 22. Route of survey flight 1, central Belize.








66









67







Nmalmajor road
SAgricultur us"s
L LalAar4 lollnlarfort .
SIandrc erod htar I

i14W r emo an d arna4 tl'reL
ar 3, ^ lcC nl} y 8 a Anr ag ai learr n










mSD A r t










Figure 23. Route of survey flight 2, northern and central Belize.








rmr r rad


SBelize fcosys.shp

m clar. bmomlea usmaes
.deLen U n [I lawnd pin. *I mnI
SLow lan~oa sayva
M an'g ro a n d Iino aJ. f1r" .
Sub ama t broaleaf fers
SSubinaa pine forces
i4WII
WarN


15 0 16krm


Figure 24. Route of survey flight 2, central Belize.














N





S0 Roadsshp
A/ major road
ulme. cosyi shp
I Agdutural uses
m -Coastal savaa
LowIandlbroladlal lore
Lo-lrdp'r--. r f
] Lowland ra
Figue 2. 1. o csn M- Mmgrov and lihdral forest
Ri.0
Sub mor4 an buordliaf ereo
Submrnnne pane oreL
Urban

-6r as la : [1 ] Weland


















Figure 25. Route of survey flight 3, northern and central Belize.

"S~ll~rIf


Roads hp
mqoll load
BRltc .roqys ;rip
Agm0-naj-l u...
CEoill savnma
Low id brh-Ir, l- I.i- est
o tLow d pine i5e;l
S L-wl md anvrna
S MagMru- e ,ind Iinord foran
5 !Arorulans bhnieoad for lm
I SAlmlnlanre pire lorl
SUrban
Iwme
w aisd
Wlhand


Atr


Figure 26. Route of survey flights 4 and 5, northern and central Belize.

Figure 26. Route of survey flights 4 and 5, northern and central Belize.















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BIOGRAPHICAL SKETCH

Alejandro Paredes was born in 1976 in Tegucigalpa, Honduras, Central America.

He obtained his bachelor's degree from Universidad Nacional Aut6noma de Honduras,

majoring in biology with a minor in zoology. During his undergraduate studies,

Alejandro had the opportunity to work in several scientific and conservation efforts in

Honduras. After completing his undergraduate studies, Alejandro worked for the

Honduran Ministry of Natural Resources and the Environment, for NGO's, and as

freelance consultant, acquiring and analyzing data for several development projects. He

decided to pursue further studies at the University of Florida because of his desire to find

a balance between conservation and sustainable development. Now that Alejandro has

been immersed in the field of biological conservation, he plans to pursue his doctoral

degree and to continue working in sustainable development.