Front Cover

Group Title: Status and ecology of the American crocodile in Haiti (FLMNH Bulletin v.33, no.1)
Title: The Status and ecology of the American crocodile in Haiti
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00099064/00001
 Material Information
Title: The Status and ecology of the American crocodile in Haiti
Physical Description: 86 p. : ill., maps ; 23 cm.
Language: English
Creator: Thorbjarnarson, John B
Donor: unknown ( endowment )
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 1988
Copyright Date: 1988
Subject: Crocodiles -- Haiti   ( lcsh )
American crocodile   ( lcsh )
Genre: bibliography   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
Spatial Coverage: Haiti
Bibliography: Includes bibliographical references (p. 62-67).
General Note: Cover title.
General Note: Abstract in English and Spanish.
General Note: Bulletin of the Florida State Museum, volume 22, number 1
Statement of Responsibility: John B. Thorbjarnarson.
 Record Information
Bibliographic ID: UF00099064
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 19130188
issn - 0071-6154 ;

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Full Text

of the
Biological Sciences


Number 1


John B. Thorbjarnarson


Volume 33


SCIENCES, are published at irregular intervals. Volumes contain about 300 pages and are
not necessarily completed in any one calendar year.

OLIVER L. AUSTIN, JR., Editor Emeritus
RHODA J. BRYANT, Managing Editor

Communications concerning purchase or exchange of the publications and all manuscripts
should be addressed to: Managing Editor, Bulletin; Florida State Museum; University of
Florida; Gainesville FL 32611; U.S.A.

This public document was promulgated at an annual cost of $3150.00 or
$3.150 per copy. It makes available to libraries, scholars, and all interested
persons the results of researches in the natural sciences, emphasizing the
circum-Caribbean region.

ISSN: 0071-6154


Publication date: May 17, 1988

Price: $3.15


John B. Thorbjarnarson*


The American crocodile (Crocodylus acutus) is the most widely distributed of the New
World crocodiles. Due to a combination of hunting for its hide, habitat destruction, and
malicious killing, the American crocodile is currently in danger of extinction, with isolated
populations existing for the most part only in relatively undisturbed areas. Conservation and
management programs are sorely needed to protect this species, but are hampered by a lack
of knowledge concerning the current status of many of the extant populations and biological
data concerning many aspects of the crocodile's natural history.
In Haiti, crocodiles were once widely distributed throughout coastal and lowland areas
where suitable habitat was available. Today, the range of the crocodile in this country has
been greatly reduced, and the few extant populations have been severely depleted, remaining
only in those areas that have a combination of relatively low human population density and
sufficient mangrove habitat.
Presently, no commercial hide hunting is occurring, and the taking of crocodiles for
food or the use of their by-products are restricted to two areas bordering the Dominican
Republic. Habitat destruction and incidental killings, primarily by fishermen, represent the
greatest threat to crocodiles in Haiti today.
The largest remaining population is found in Etang Saumfitre, Haiti's largest lake (113
sq kin). Etang Saumftre is a brackish lake, located in a sparsely inhabited region only 30 km
from the capital of Port-au-Prince. The total crocodile population in the lake is estimated at
450. Over a 13-month period, various aspects of the demography, reproductive ecology, diet,
and habitat selection of these crocodiles were investigated. The results are discussed in the
light of other work which has been done on crocodilians.
The final section outlines several recommendations for the conservation of crocodiles
in Haiti.

* Florida State Museum and Department of Wildlife and Range Sciences, University of
Florida, Gainesville FL 32611.

THORBJARNARSON, J. B. 1988. The Status and Ecology of the American Crocodile in
Haiti. Bull. Florida State Mus., Biol. Sci. 33(1):1-86.



El cocodrilo americano (Crocodylus acutus) tiene la distribuci6n mis amplia entire las 4
species de los cocodrilos del Nuevo Mundo. Debido a la caza commercial para su piel,
destruci6n de su habitat, y a la simple matanza por maldad, el cocodrilo americano esta en
peligro de extinci6n, y hoy en dia solo quedan poblaciones aislados en zonas remotas. Se
necesitan urgentemente programs de conservaci6n y manejo para la protecci6n de esta
especie, pero el desarollo de estos programs es limitado por la falta de conocimiento sobre el
estado actual de la mayoria de las poblaciones, y muchos aspects de su historic natural.
En Haiti, cocodrilos tenian una distribuci6n amplia a lo largo de la costa. Hoy, esta
distribuci6n se ha reducido drasticamente, y las pocas poblaciones que quedan son my
pequefias, ubicadas en zonas despobladas donde hay sufficient habitat con manglares. Hoy
en dia, no existe una caceria commercial para cocodrilos en Haiti, y la gente los utilizan para
comida o remedios solamente en dos zonas al lado de la frontera con la Republica
Dominicana. Los dos peligros mayores para la supervivencia de los cocodrilos son la
destruci6n de habitat, y la muerte por inmersion al enredarse en redes de pescadores.
La mayor p9blaci6n de cocodrilos en Haiti esta en Etang Saumatre, el lago mas grande
del pais (113 km-). Etang Saumatre es de agua salobre, y esta ubicado en una zona semi-
arida a solamente 30 km de la capital; Puerto Principe. Approximadamente 450 cocodrilos
viven en este lago. Durante un period de 13 meses, se estudiaron aspects de la demografia,
reproduci6n, dieta, y uso de habitat de esta poblaci6n de cocodrilos. Los resultados estan
discutidos en relaci6n con otras investigaciones sobre cocodrilos.
La secci6n final present algunas recomendaciones para la conservaci6n del cocodrilo
en Haiti.


Introduction ...................................................................................................... ........................ . ..................3
A know ledgem ents ...................................................................................................................................... 4
M etho ds ......................................................... .......................................................................... ........... 5
Survey of Status and D istribution...................................................... ..............................5.......
Ecological Study: Etang Saum atre........................................................ ............................... 6
Present Status and D distribution in H aiti...................................................... .............................9.......
Introduction ......................................... ......................................................... 9
R esults..................................................................................................................... ......... . ........... 11
D iscussion................................................................................................................................. 17
Ecological Study: Etang Saum atre ......................................................... ....................................... 24
Introduction ............................................................................................................................ . 24
D em ography ..................................................................................................................... ........... 31
R productive E cology....................................................................... ...................................... 41
D iet............................................................................................................................................ . 51
H habitat Selection.............................................................................................................................53
C conservation ........................................................................................................................................ 58
D iscussion................................................................................................................................. 58
R ecom m endations ...................................................................................... ............................. 60


S u m m ary .......................................................................................................................................................6 1
L literature C ited ............................................................................................................. ................ 62
T ables.................................................................................................................................. . . ............. 68
A ppendices ............................................. .. . ..................................................................... .............. 82
I. D distribution of M angrove in H aiti...................................................... ............................ 82
II. Aquatic and Semi-aquatic Avifauna, native fish fauna................ .............................
and the Dry Forest Vegetative Association of Etang Saumatre .......................................84
III. Survey Correction Procedure .......................................... 86


The American crocodile (Crocodylus acutus) is the most widely
distributed of the four species of New World crocodiles. Although it may be
found well inland in freshwater habitats, the American crocodile lives
primarily in coastal areas, preferring brackish water habitats associated with
mangrove forests, coastal lagoons, and the estuarine sections of rivers. As
with most species of crocodilians, unregulated hide-hunting, malicious killing,
and habitat destruction have resulted in drastic population declines of the
American crocodile throughout its range. Today, these crocodiles exist
mostly in disjunct populations where past exploitation and habitat destruction
have not been overly severe. Although the general trend of local extirpations
and reductions in numbers clearly has been evident for some time (Barbour
1923, Moore 1953, Casas and Guzman 1970, Alvarez del Toro 1974), very
little is known about the status of existing populations. A recent review (King
et al. 1982) collated reports for C. acutus on a country by country basis.
Detailed information was available only for a few countries, and the review
pointed out the clear need for surveys to determine the present status and
distribution of the remaining populations. Data of this sort are needed for
the implementation of effective conservation and management schemes
designed to insure the continued survival of the species. Primarily a coastal
species, the range of the American crocodile includes southernmost Florida,
the Atlantic coast of Mexico south through Central America and northern
South America (east to the Peninsula de Paria in Venezuela), and the
Caribbean islands of Cuba, Jamaica, and Hispaniola. The American crocodile
is also found in Pacific Ocean drainages from northern Mexico (Sinaloa)
south to the Rio Tumbes in northernmost Peru. The northern distribution of
the American crocodile along the Atlantic coast of Mexico remains a
question. While crocodiles are known from the states of Tamaulipas and
Veracruz, all confirmed specimens from these areas are C. moreleti.
Nevertheless literature accounts of C. acutus exist for the Atlantic coast north
of the Yucatan. Further survey work is needed to determine the range of


these two species in Mexico. Very little was known about the status of
crocodiles on Hispaniola prior to the mid-1970's. In 1975 scientists from the
Museo Nacional de Historia Natural began an ecological study of crocodiles
in Lago Enriquillo, the largest lake in the Dominican Republic. This lake was
found to contain what may be the largest remaining C. acutus population
anywhere (Inchaustegui and Ottenwalder pers. comm.; pers. observ.). Coastal
populations in the Dominican Republic, however, appear to have been
eliminated completely with the exception of the Rio Massacre along the
northwestern border with Haiti. Today, both these populations are protected
by law (Decreto de Veda 861, June 1979). Prior to the present study,
however, the status of crocodiles in Haiti was completely unknown (Powell
1971, King et al. 1983). The objectives of this investigation were twofold: (1)
to determine the status and distribution of crocodiles in Haiti; and (2) to
record aspects of the ecology of this poorly known species. The findings of
the status survey are somewhat unexpected in that Haiti, a country with twice
the population density and a much lower standard of living than the
neighboring Dominican Republic, has several coastal crocodile populations as
well as a substantial population in Etang Saumatre, Haiti's largest lake. The
ecological study was done in Etang Saumatre, which is, at its closest, only 5
km from Lago Enriquillo in the Dominican Republic. The crocodile
population in this lake was somewhat unusual, as it was not found in typical
coastal wetland habitat. The crocodiles, however, were relatively easy to
locate and capture due to the limited amount of vegetative cover. In
addition, the lake represented a closed system, containing an easily defined
population. In contrast, coastal populations are often widespread over large
areas and are not easily delimited. The inaccessible nature of many of these
habitats also precludes any easily accomplished quantitative work on
population parameters. Based on the findings of the status survey and the
ecological investigation, the last section outlines several recommendations for
the conservation of crocodiles in Haiti.


Many people contributed to this project. Firstly, I am indebted to F. Wayne King, my
master's thesis chairman, for his continual support during the course of this project, and
Charles Woods, who first suggested the feasibility of work in Haiti and then provided many of
my initial contacts in that country. They, along with the other two members of my graduate
committee, J. Robinson and M. Collopy, read and made many constructive comments
concerning this thesis. My stay at Etang Saumitre was made possible through the generosity
of Pastor Wallace and Eleanor Turnbull and Pastor Eric and Irene Lange, who provided me
with a place to stay and store my equipment at Tete Source. The Langes provided constant
support and companionship, as well as many greatly appreciated home-cooked meals. Work in
Haiti was sponsored through the Institut de Sauvegarde du Patrimoine National, Albert


Mangones, Director. Paul Paryski especially provided a great deal of support. Permission to
conduct the work was obtained from Jean-Baptiste, Jean-Francois, and Edmond Magny of the
D6partement de l'Agriculture des Ressources Naturelles et du D6veloppment Rural
(DARNDR). Joseph Felix, also of DARNDR, kindly supplied permits for the export of some
specimens. Ekke Lempke provided a great deal of information concerning crocodiles and
first introduced me to Etang Saumatre. Jaques Durocher and Jimmy Stecher also supplied
much information on the current distribution of crocodiles in Haiti. Jimmy Stecher and Ted
Steinhauer provided logistical support for trips to the Laborieux region and La Gonave. Dan
Cordier and Brent Mitchell assisted during portions of the coastal surveys. Ragnar Arnesson
and Roland Roy, of the Organization of American States in Port-au-Prince, supplied
considerable assistance in attending to many of the problems which arise during work in
foreign countries. My assistants in Etang Saumfitre were Eldee Antoine and Tony Samveiss.
Pierre Milfort of DARNDR also helped during the early stages of the project. Others who
provided assistance were Peter Blanchard, Drew Kutchenreuter, Jim Keith, David Pulle, Tom
Greathouse, Mara McDonald, and Mike Binford. Identification of prey items was done by
Robert Woodruff (insects), G.B. Edwards (spiders), Mintor Westfall (dragonfly larvae),
Eleanor H. Stickney (birds), and George Burgess and Richard Franz (fishes). Plant
identifications were performed by David W. Hall, S. Davis, and D. Griffin. Expertise for the
step-wise discriminant analysis was provided by C. Abercrombie. Work in the Dominican
Republic was sponsored by the Museo Nacional de Historia Natural, in particular Lic. Jose
Alberto Ottenwalder, Lic. Sixto Inchaustegui, and David Robinson. I would also like to thank
Leslie D. Garrick for allowing me to cite some of his unpublished data from Jamaica.
Funding for work, both in Haiti and the Dominican Republic, was provided by the Wildlife
Conservation International (WCI) (formerly Animal Research and Conservation Center
[ARC]) of the New York Zoological Society. Research in Haiti was also funded through a
fellowship from the Organization of American States. Additional funding was provided by two
grants-in-aid of research from Sigma Xi, The Scientific Research Society. Reynolds
Aluminum kindly supplied the use of a pick-up truck over a 6-month period of time in Haiti.


Survey of Status and Distribution

Surveys of coastal areas and inland lakes (other than Etang Saumatre)
were conducted primarily during May-June 1983. Potential crocodile habitats
were initially identified on the basis of information provided by reliable
informants familiar with wildlife in Haiti. Next, 1:50,000 topographic maps
were used to pinpoint areas of possible crocodile habitat prior to visiting
those areas. The bulk of the information on the presence or absence of
crocodiles was obtained from conversations with knowledgeable local
residents (mostly fishermen). Areas were surveyed on foot or by boat during
the day to determine the quantity and the quality of the available habitat.
Whenever possible, night surveys were also made using a headlamp to spot
crocodiles or their reflected eyeshine. However, due to the limited amount of
time available to conduct the surveys and the frequent lack of a suitable boat,
night surveys were not conducted at all locations. The past distribution of
crocodiles in Haiti was reconstructed based on (1) historical accounts of
crocodiles in specific locations, (2) place names referring to "caiman," the


local word for crocodiles, and (3) the distribution of suitable crocodile habitat
in coastal areas. Regions containing extirpated and extant crocodile
populations were then compared on the basis of amount of mangrove habitat
(determined from 1:50,000 topographic maps) and human population density
based on recent population census (IHSI 1983).

Ecological Study: Etang Saumftre


Crocodiles were censused at night from a boat using a Q-Beam spotlight
(200,000 candle power) run off a 12-volt marine cell. Two censuses of the
entire lakeshore were performed, one requiring three nights (11, 17, 18
August 1983) and the other two nights (7, 8 January 1984). The August
survey was not conducted in consecutive nights because of boat trouble. It
appears, however, that crocodile movements between survey sections were
not sufficiently large to introduce significant error. Surveys were conducted
at an average speed of 7 km/hr, approximately 30 m from shore. The light
was swept along the shoreline and periodically out into the lake. Crocodiles
were spotted by their reflected eyeshine and approached to estimate size (0.3-
0.9 m, 0.9-1.8 m, 1.8-2.7 m, > 2.7 m). Because hatchlings did not form pods
and were frequently found in dense vegetation along with yearlings, it was
unfeasible to separate these two size classes during counts. If the crocodile
submerged before an accurate estimate of size could be made, it was placed
into one of the following categories: EO > 1.8 m (eyes only, greater than 1.8
m total length), EO < 1.8 m (eyes only, less than 1.8 m), or EO (eyes only).
The location of all crocodiles sighted was plotted on a map of the lake as they
were spotted. Surveys produced a base estimate of population size and size-
class distribution. These data were then corrected for: (1) reduced
sightability in areas of dense shoreline vegetation; (2) known animals that
were not seen during the survey; and (3) in the January 1984 survey, line
transects were conducted in two dense Conocarpus swamps to estimate the
number of crocodiles that could not be seen from the lake. A full description
of the correction procedures is given in Appendix III.
After determining the size-class distribution of the population, the EO,
EO < 1.8 m, and EO > 1.8 m sighting classes were divided proportionately
between the four known-length size classes. As large animals generally are
more wary than small ones, this may have resulted in a slight bias against the
larger size classes. Sex ratio and a length-weight relationship were
determined from captured individuals. Large crocodiles (> 1.8 m) were
caught at night from a boat. Smaller individuals usually were captured when


wading through shallow water habitats. Crocodiles were caught by hand, with
pilstrom tongs, or by using breakaway locking cable snares mounted on the
end of a pole (Jones 1965). Crocodiles were weighed on Homs spring scales
(100 g, 2 kg, or 10 kg capacity) or Hansen spring scales (136 kg capacity). All
captured crocodiles were marked in two ways; by placing self-piercing monel
tags in the webbing of the hind foot, and cutting numerical sequence of dorsal
caudal scutes. Due to uncertainties in the sexing procedure of juveniles (> 1
m) during 1983, sex data from these animals were not used. Because of the
difficulty of sexing small animals based on morphological differences in the
penis/clitoris (Joanen and McNease 1979), data on the sex of animals less
than 40 cm long were not taken. Growth rates were obtained using successive
lengths from recaptured animals. Hatchling growth rate also was estimated
by assuming a mean hatching date and length, based on hatchlings found in
recently opened nests. In this manner the age and growth of first-year
animals could be estimated.
Biomass was determined from the length-weight relationship of captured
animals and the size-class distribution of the population. The mass of a
crocodile at the midpoint of each size class was used as an estimate of the
average mass of a crocodile in that size class. These values then were
multiplied by the total number of crocodiles for each class and summed for all
four size classes. For the > 2.7 m size class, mean size was assumed to be 2.9

Reproductive Ecology

The location of the crocodile nesting beaches and the number of 1983
nests were determined by extensively searching lakeshore habitats during May
1983. Active nests were identified by the presence of an open hole
surrounded by eggshells and egg membrane fragments.
In 1984, nesting beaches were monitored beginning in early January for
signs of activity. Nests were located by following the tracks left by females
and probing by hand under the substrate in areas where obvious digging had
occurred. Once located, nests were carefully excavated to determine clutch
size and egg fertility rate (by egg banding, Ferguson and Joanen 1983) and to
measure nest hole dimensions. Measurements of egg dimensions and egg
mass were made on a sample (n = 5) of eggs from each clutch. A 100-200 g
soil sample was taken for later analysis of water content (by drying over a
butane stove) and soil particle size distribution (by passing through a series of
sieves). All weights were measured on a 200 g Pesola spring scale (0.5%
accuracy). A variety of other parameters were recorded at each nest site.
Height of vegetation was estimated to the nearest 0.5 m, height above the


lake to the nearest 0.3 m. Percent of shrub, grass, and leaf litter cover was
estimated to the nearest 10%.
In six nests copper-constantan thermocouples were implanted at the top
and the bottom of the clutch. Nest temperatures were recorded over a 30-
hour period using an Omega 871 digital thermometer.
To determine the environmental parameters important in the selection
of nest sites, 15 null sites were randomly chosen along the major nesting
shore. The same environmental parameters measured at the nest sites were
recorded at each of the null sites (except distance to lake which was
standardized at 25 m) and a stepwise discriminant analysis performed on the
data set.

Dietary Analysis

Stomach contents from crocodiles under 1 m total length were obtained
using the stomach flushing technique described in Taylor et al. (1978). For
crocodiles longer than 1 m a modified scooping technique was used.
Crocodiles were strapped to a wood plank with their taped jaws immobilized
in an open position around a 7.6 cm diameter section of PVC pipe. Stomach
contents were extracted using natural latex (Paramold, Imperial Adhesives
and Chemicals, Inc.) scoops moulded from small funnels (opening diameter
6.5 cm, 7.0 cm long). The narrow end of the funnel-shaped scoop was pushed
down the esophagus using a 2.5 cm diameter rod until the scoop was felt to
reach the end of the stomach. The scoop and rod were generously lubricated
with vegetable oil to reduce the chance of trauma to the esophagus during
this procedure. Once in the stomach, the rod was extracted and the scoop
was slowly pulled out using two strings attached to opposite sides of the
funnel rim. The narrow, open end of the scoop was covered with cheesecloth
to allow fluids to pass through as it was drawn through the stomach. This
procedure was repeated at least three times and was used on animals up to
2.88 m total length. All stomach contents were preserved in alcohol for later
identification and analysis. Stomach contents were categorized into three
groups: fresh, partly digested, and fragments. Items from the first two
groups were individually weighed on an Ainsworth 21N analytical balance to
the nearest 0.1 g. The presence of gastroliths, vegetation, and nematodes was
noted. For purposes of comparison, invertebrate prey items generally were
classified to the ordinal level. Representative invertebrate prey items were
identified to family or genus to allow analysis of prey ecology and, by
inference, crocodile foraging modes. Vertebrate prey was identified to genus
or species in all cases.


Habitat Selection

The various lakeshore habitat types were categorized by physiognomy of
the vegetation or shoreline features. The extent of the habitat types was
mapped on 1:25,000 topographic maps of the lake during day surveys by boat.
The locations of all crocodiles seen during the population surveys were
marked on a map of the lake and later assigned to one of the habitat types.
Shorelines or the lake-vegetation interface also were assigned an exposure
index (protected, moderate, or exposed) based on the amount of wave action
they received from the predominant easternly winds.
Spatial distribution of crocodiles around the lake was examined by
dividing the lake into eight segments of varying length (4.3-16.0 km long) and
comparing the crocodile population in each of these segments.



The Republic of Haiti (Fig. 1) occupies 27,700 sq km of the western
third of the island of Hispaniola, the second largest of the Greater Antilles
(Woodring et al. 1924). A French colony until 1804, Haiti became the
world's first black republic following a bloody revolution that lasted nearly 15
years. The name Haiti is derived from an Arawak Indian word meaning
"mountainous land" and provides a very apt description of this country, which
has peaks up to 2680 m and more than 65% of its surface area sloped greater
than 20 degrees (AID 1982).
Within its diverse topography, Haiti supports a wide variety of ecological
life zones and associated plant communities ranging from dry thorn scrub to
mountain pine forests. In fact, the Holdridge life zone classification system
was first developed during work on the mountain vegetation of the La Selle
ridge of southeastern Haiti (Holdridge 1947). Today, however, very little of
the natural vegetation remains because of extensive deforestation. With an
estimated population of more than 5 million, Haiti has one of the world's
highest population densities. This, in combination with a paucity of arable
land, has resulted in a degree of environmental degradation that is perhaps
without equal in the world today. The chief problem is one of rampant
erosion, resulting from the nearly complete deforestaton of many hillsides








0 20 40 km

FIGURE 1. Map of Haiti including some major landmarks. Inset is a map of the West
Indies with the relative location of Haiti shown as a solid black area.

without the implementation of any soil conservation techniques. Today, the
effects of such past practices are being sorely felt by the Haitian people who
have the lowest per capital income in the western hemisphere. Recognition of
the problem has been slow, but currently the Haitian government, in
cooperation with several foreign aid agencies and volunteer organizations, is
beginning to implement reforestation projects.
Centuries of human depredation and the virtually complete loss of
lowland forested regions have had drastic effects on the local fauna. The
hardest hit have been the endemic non-volant mammals, as out of a pre-
Colombian total of 25, today only 2 species survive, and both of these are
quite rare, persisting in only a few relatively undisturbed areas of suitable
habitat (C. Woods pers. comm.). Similarly with reptiles, the giant rock
iguanas (Cyclura cornuta and C. ricordi) have become very rare and today are
found only in a few dry, rocky areas inhospitable to man.


The crocodile has managed to survive in Haiti principally because man
and American crocodiles are essentially allopatric in their distribution, as man
finds the coastal wetlands the crocodiles prefer marginal for agriculture or
habitation. In contrast to the near total destruction of the terrestrial forests,
the coastal forests, especially mangrove, have fared considerably better.
During the period between 1956 and 1977 only 7% of the existing mangrove
disappeared. The corresponding figure for loss of pine forest was 40-70%
(FAO 1978). While the mangroves are not cleared for agricultural use as are
the terrestrial forests, mangrove is used for firewood in bakeries, home
cooking, distilleries, and dry cleaners. Mangrove wood also is used as fuel for
burning coral rock to produce lime for cement, making charcoal, and for
construction purposes. Mangrove has been spared to a large degree in the
past, but as the human population continues to grow, more and more
pressure will come to bear on these forests. Already the pace of mangrove
destruction appears to have been accelerated (pers. observ.).
Although less apparent than the cutting of mangrove, diversion of
freshwater for agriculture has probably had more lasting, although as of yet
largely undetermined, effects upon some of these ecosystems. This is most
notable in the l'Ester region, which contains Haiti's largest mangrove swamp.
Mangrove forest still remains in many parts of Haiti, however, and these areas
serve as nuclei for the present coastal distribution of crocodiles (see
Appendix I).
This section will present the results of a country-wide survey to
determine the present status of crocodiles in Haiti. The findings will then be
examined in relation to the past distribution of crocodiles, as determined
from historical records, to document the retreat of the crocodiles into
isolated populations and to provide some useful insights into the ability of
crocodiles to survive in man-dominated ecosystems.


Past Distribution of Crocodiles in Haiti

Fourteen historical accounts and eight place names were found that
made reference to crocodiles (Fig. 2). These sources, plus information on the
distribution of suitable crocodile habitat, were used to reconstruct the
probable former distribution of crocodiles in Haiti (Fig. 3).


Present Distribution of Crocodiles in Haiti

Four regions containing extant coastal crocodile populations were
identified: (1) the southern coast of the Tiburon Peninsula from Cote-de-Fer
west to the Riviere l'Acul, including Ile-A-Vache, (2) Ile de La Gonave, (3)
the l'Ester-Artibonite mangrove swamp, and (4) the Riviere Massacre-Lagon
aux Boefs region bordering on the Dominican Republic. In addition, the
largest remaining crocodile population is found in Etang Saumatre, an inland
lake not far from the capital of Port-au-Prince. The present range of
crocodiles in Haiti is summarized in Figure 4. A comparison of the present
and past distributions of crocodiles reveals that crocodiles have been

0 20 40
SL ------ i...j km

FIGURE 2. Locations of historical records of crocodiles and place names referring to
"caiman" in Haiti. (Historical Accounts: 1 Las Casas 1561, 2 Lescallierer 1764, 3 -
Moreau de St. Mery 1796, 4 Moreau de St. Mery 1797-8, 5 Descourtilz 1809, 6 Hearne
1834, 7 Ritter 1836, 8 Gosse 1851, 9 Fortunat 1889, 10 Hazard 1873, 11 Rodriguez
1915, 12 Wetmore Perrygo 1931, 13 Loederer 1935, 14 Steedman 1939. Place Names:
A Isleta de los Caimanes, B Bassin Caiman, C Caiman, D Bassin Caiman, E Caiman,
F Trou Caiman, G Riviere Caiman, H Trou Caiman.)


0 20 40



FIGURE 3. Reconstructed historical range of crocodiles in Haiti, based on Figure 2, the
present crocodile distribution, and the availability of suitable habitat.

extirpated from approximately 70% of their former coastal range, and two of
the three inland lake systems where they were once found (Etang Laborde,
Etang MiragoAne).
Southern Coast of the Tiburon Peninsula., A diffuse crocodile
population exists in this region from immediately west of Cotes-de-Fer, west
to the vicinity of the Riviere l'Acul (Fig. 5). Crocodiles are regularly seen in a
number of the more isolated coastal wetlands, specifically: the vicinity of
Laborieux-L'Osiendieu, the Aquin-Riviere Capolo region, the Riviere
Cavaillon, and the Rivi6re Bondonne. Crocodiles are sporadically seen in
pockets of suitable habitat between these areas, primarily associated with
mangrove swamps or the dense vegetative cover at river mouths.
Nesting reportedly occurs in vegetated beach strand habitats along the
lower reaches of the Rivieres Cavaillon and Bondonne. During surveys,
crocodiles were only seen in the Laborieux region (5 subadults seen, 17 April
1983), but according to local residents the largest population remains in a


0 20 40

FIGURE 4. Present range of crocodiles in Haiti.



0 20 40KM



FIGURE 5. South-central Tiburon Peninsula; marked locations indicate the position of
extant or former crocodile populations (1 Laborieux, 2 Osiendieu, 3 Riviere Capolo, 4 -
Rivi6re Millionaire, 5 Riviere Cavaillon, 6 Rivi6re Torbeck, 7 Riviere Bondonne, 8 -
Riviere l'Acul, 9 l'Etang, 10 Etang Laborde).


mangrove swamp at the mouth of the Riviere Cavaillon. A recently killed
specimen (1.2 m total length) was found in the Riviere Capolo (25 June 1983,
UF 54208).
Crocodiles were also reported from a small freshwater lake (called
L'Etang) on the northwestern end of Ile d Vache, located approximately 10
km off the southern coast of Haiti.
Ile de La Gonave., La Gonfve is the largest of Hispaniola's satellite
islands (658 sq km), or about 2.3% of Haiti's land surface. Much of the coast
is protected from wave action by a barrier reef, permitting the growth of a
mangrove fringe even though freshwater runoff is almost non-existent.
Crocodiles were reported from several of the coastal lagoons on the western
end of the island. During a night survey of Lagon Blanch (11-12 June 1983),
a shallow water lagoon along the north coast near the town of Richard, a
total of five subadult crocodiles (to 1.5 m total length) were observed.
l'Ester-Artibonite., Hispaniola's largest mangrove swamp (8490 ha) is
found in the l'Ester region just south of the town of Gonaives. Immediately
to the south of the l'Ester region is the mouth of the Riviere Artibonite,
Hispaniola's longest river (240 km). Crocodiles were well documented
historically from this area by Descourtilz (1809) in his treatise on the
"crocodile du St. Domingue." Today, crocodiles are well known to local
fishermen, although they are not seen with any frequency. During a daytime
survey by sailboat (4 June 1983) and a night survey of mangroves near
GonaYves (5 June 1983), no crocodiles were seen.
Crocodiles were also sporadically observed by local residents of Grande
Saline, at the mouth of the Riviere Artibonite, which lacks any protective
mangrove forests.
Riviere Massacre-Lagon aux Boefs., Lagon aux Boefs is a 4-sq-km,
mangrove-lined, freshwater lagoon connected at its northern end to the
Riviere Massacre, which forms the northeastern boundary between Haiti and
the Dominican Republic. The estuarine section of the Riviere Massacre has a
mixed riverine-fringe type mangrove swamp (after Lugo and Snedaker 1974)
of approximately 1030 ha, most of which is in the neighboring Dominican
Republic. Local Haitians were very familiar with crocodiles, which they
would catch and eat whenever possible. This is in stark contrast to the rest of
Haiti where crocodiles are not eaten. A daytime survey of Lagon aux Boefs
(16 June 1983) revealed no crocodiles. During a previous night survey of the
lower Riviere Massacre in December 1981 one 3 m crocodile was seen
approximately 2 km upstream from the river's mouth.
Etang Saumfitre and Trou Caiman., Haiti's largest remaining crocodile
population, approximately 450 individuals of all sizes, is found in Etang
Saumftre, located in the Cul-de-Sac valley 30 km northeast of Port-au-Prince
(see Ecological Study: Etang Saumfitre). A large lake (113 sq km), Etang
Saumatre is surrounded by a relatively sparsely inhabited region of the


country. The uninhabited eastern lakeshore, bordering the Dominican
Republic, contains a significant amount of juvenile crocodile habitat and
virtually all the nesting sites.
Trou Caiman is a marshy freshwater lake (6.9 sq km) located 6 km west
of Etang Saumatre. The two are connected by a small canal. The sporadic
accounts of crocodiles in this lake suggest that it does not contain a breeding
population but probably serves as a dispersal area for crocodiles from Etang

Extirpated Populations

North Coast West of Ft. Liberty., Crocodiles were known historically as
far west as the mouth of the Riviere Limb6 (Bassin Cayman). It is not known
exactly when the last crocodiles in this region were extirpated, but none has
been seen for many years. It is likely that at one time crocodiles ranged as far
west as Port-de-Paix, as pockets of suitable habitat exist at regular intervals
along the coast. West of Port-de-Paix, a rocky, high-energy coast
predominates, providing little in the way of crocodile habitat. Crocodiles also
were reported historically in the vicinity of Cap Haitien (Rodriguez 1915)
where a moderate-sized (760 ha) mangrove forest still exists along the lower
reaches of the Riviere Haut-du-Cap.
Crocodiles were also found in the Caracol region between Cap Haitien
and Fort Libert6. The only published account is that of Ritter (1836), who
mentions seeing crocodiles at Ft. Real, which may have been the old site of
Puerto Real, a Spanish colonial settlement in the Caracol region. The
presence of a small lagoon (the old river bed of the Grand Riviere du Nord)
called Bassin Cayman, and the finding of crocodile mandibles in Indian
middens from the area (W. Hodges pers. comm.), however, attest to the fact
that crocodiles were indeed in the area at one time.
North and West Coasts of the Tiburon Peninsula., Historically
crocodiles were found in the vicinity of Petit Goave (Riviere Caiman), the
Riviere Grande Anse near J6r6mie (Moreau de St. Mery 1797), and the
Tiburon region at the tip of the peninsula (Las Casas 1552). They also were
formerly found in several inland lakes in the area (see following section).
Currently there are no verified populations anywhere in this part of
Haiti. Crocodiles may still be found in small numbers in the Baraddres
region, although this is doubtful. The small individuals reported from Petit
Goave and J6r6mie (all in the 1.2-1.5 m range) probably represent vagrant
Inland Lakes: Etang Laborde., Etang Laborde is the largest of four
lakes located on the coastal plain 12 km north of Cayes (1978 size estimate


0.9 sq km). The region is heavily populated and extensive agriculture occurs
around the lake. The lake itself is very shallow and reportedly dried up in
1975 after an extended drought. Moreau de St. Mery (1797) stated that
crocodiles were found in this lake (then called Etang Vert) but had long since
disappeared, making this the earliest known extirpation of crocodiles in Haiti.
No crocodiles are currently found in Etang Laborde or any of the other lakes
in the region.
Inland Lakes: Etang Miragoine., Etang Miragoane presently consists
of two lakes (8.3 and 1.3 sq km) near the north coast of the Tiburon
peninsula, adjacent to the town of Miragoane. This region also is densely
populated, and there is currently much fishing activity in the lake. The lake is
fresh water with extensive grass fringes. Other vegetation includes Nuphar,
Nelumbo, Typha, and Potamogeton. Moreau de St. Mery (1797) mentioned
that the lake had many crocodiles 2.5-3.5 m long which nested in sandy areas
surrounding the lake during the summer. Etang Miragoane has no
crocodiles, and no one interviewed could remember there ever being
crocodiles in the area.


Analysis of the Present Distribution of Crocodiles

Coastal Crocodile Movements., Crocodylus acutus is one of two primarily
coastal dwelling crocodiles, the other being C. porosus from northern
Australia, the Indo-Malayan Archipelago, and Southeast Asia. The wide
coastal distribution and probable recent evolutionary derivation of both these
species (Densmore 1981) suggests that they are adept at moving along coasts
and possibly even making transoceanic journeys. This is best documented in
the case of C. porosus (Bustard and Choudhury 1980) where specimens have
been spotted at sea nearly 500 km north of New Zealand (Robb 1980), on
Cocos-Keeling Island in the Indian Ocean nearly 1000 km from the closest
known population in Indonesia, and on Ponape in the Western Caroline
Islands some 1360 km from the nearest population (Allen 1974).
Messel et al. (1982) developed a model of C. porosus population
dynamics for tidal rivers in northern Australia which proposes that a large
fraction of the subadult crocodiles leave the productive nesting rivers when
they reach a size (0.9-1.8 m) that brings them into conflict with larger
territorial adults. Such individuals, if not killed outright, are forced to leave
the river and find other, usually marginal, habitats. Some perhaps move
along the coast and manage to find another river where territorial adults are
less common (rivers less suitable for nesting) and take up residence there.


The majority, however, probably never survive. As adults it is possible the
crocodiles will move back into more suitable rivers for reproduction. The
model proposes, then, that movement and mortality are quite high for these
intermediate-sized crocodiles.
Logically, a similar pattern may hold for C. acutus, which is ecologically
similar but poorer known from a biological standpoint. Both Alvarez del
Toro (1974) and Medem (1981) reported C. acutus moving from river to river
using overland routes. Alvarez del Toro (1974) stated that such movements
are in response to territorial fighting and the drying up of temporary lagoons.
Mazzotti (1983) found C. acutus moved considerable distances in the coastal
regions of southern Florida. The presence of C. acutus on several mid-
oceanic islands (Cuba, Jamaica, Hispaniola, and formerly the Cayman
Islands) as well as a number of near-shore islands (Isla Margarita, Venezuela;
Islas del Rosario, Islas de Sn. Bernardo, Isla Fuerte, Isla Tortuguilla,
Colombia; and the Archipelago de los Canarreos, Cuba; as well as Ile A Vache
and Ile de La Gonave off Haiti) strongly suggests the species is adept at
moving long distances along the coast or across open water.
Fishermen in Haiti reported that on occasion crocodiles could be seen in
the ocean. Crocodile movement along the coast would explain many of the
unusual reports of local residents along the southern coast of the Tiburon
peninsula. In this region, crocodiles were said to be found in several areas
with little or no suitable habitat, and their presence in many of these areas
was reported to be of irregular occurrence.
Similarly, reports of crocodiles on the northern coast of the Tiburon
peninsula are most likely transient individuals, as are the ones reported from
Anse-a-Galets on eastern La Gonave. A pertinent point concerning these
last reports was that all the animals were 1.2-1.5 m individuals, the size class
that would be dispersing the most according to the Messel model.
Adult crocodiles will also move along the coast, resulting in large
individuals being reported in small coastal wetlands. Most of the areas where
crocodiles have been reported along the Tiburon peninsula contain more
than 60 ha of habitat. Only a fraction of this area, however, is available to the
crocodiles because of extensive fishing, rice cultivation, and other human
activities. The habitat at the mouth of the Riviere Capolo is much smaller,
however; so small it is impossible to make a size estimate from 1:50,000
topographic maps. A similar situation is found on the southern coast of
Jamaica where crocodiles may be found in almost any coastal wetland one
hectare or larger in size (Plotkin and Faibairn MS, referenced in
Groombridge 1982). This frequent usage of small coastal habitats suggests
considerable movement by crocodiles along the coast.
Human-related Mortality., Five direct causes of human-related
crocodile mortality can be identified in Haiti (other than habitat destruction):
(1) incidental capture in fishing nets or traps, (2) malicious killing, (3)


hunting for sport, (4) hunting for food, and (5) nest raiding. By far the most
important of these is being trapped in fishing nets and traps. When caught,
crocodiles either drown or are killed by the fishermen when pulled to the
surface. In most cases the body is simply discarded in the water. Occasionally
crocodiles may be eaten (see below) or the body may be disposed of by burial
or by dumping it at sea (see Folk Beliefs section below). In Etang Saumatre,
where gill netting is not commonplace, one 1.5 m crocodile was drowned in a
net during the 10-month period of time I spent there. As most bodies of
shallow water in Haiti are heavily fished, this source of mortality probably is
Malicious killings often occur in response to crocodiles taking livestock
or, in one reported case, killing humans. A large crocodile, approximately 3
m long, was killed at Tete Source in Etang Saumatre after it had taken
livestock on several occasions (goats and sheep). This crocodile was also
considered a nuisance because it would take fish from gill nets, leaving gaping
holes. The crocodile was caught using a baited hook and then beaten to
death with a long stick. Large crocodiles also are killed occasionally when
they accidentally wander into populated areas. Likewise, hunting for sport
claims adult crocodiles in certain areas, although the incidence of this appears
to have declined in the recent past. Throughout Haiti, the people are so poor
that the number of firearms is very limited, being restricted in rural areas to
certain local leaders and the military. Hunting excursions from Port-au-
Prince were popular in the past, especially during the 1917-1934 United
States Marine occupation (Steedman 1939, Cave 1952). Crocodile hunting
was also a popular pasttime of the colonial French prior to the independence
of Haiti (Descourtilz 1809).
Use of crocodiles for food is limited to only two areas in Haiti, the
Riviere Massacre and, to a much smaller extent, in Etang Saumatre. Both
these regions border on the Dominican Republic, and the usage of crocodiles
is undoubtedly due to a Dominican cultural influence (where crocodiles are
eaten and their by-products used). Although the better educated people in
Haiti will occasionally eat crocodiles, the vast majority of Haitians will not.
Active hunting of crocodiles only occurs near the Riviere Massacre, where
they are caught with harpoons, set nets, cast nets, and baited hooks. Most of
the hunting in this region centers on Lagon aux Boefs, with a smaller number
caught in the river itself. The meat is eaten and the fat is used to render an
oil to treat pneumonia and rheumatism.
The only other account of crocodile by-products being used comes from
the Cayes region. Although unconfirmed, three separate sources claimed that
crocodile teeth are sometimes used for false teeth in people, the work being
done in a hospital in Cayes.
Nest robbing probably is not a major source of mortality, although nests
may be dug up and the eggs left to die. In most areas, residents reported


nests as being very difficult to find and stated that like crocodile meat, they
did not eat the eggs. The only area where eggs were reported eaten (other
than the Riviere Massacre region) was Etang Saumatre. Residents of the
town of Fonds Parisien, on the southern shore of the lake, will eat them on
occasion (F. Conway pers. comm.). One nest near Tete Source was excavated
in 1983 and the eggs sold in the local market of Thomazeau (I. Lange pers.
There is no present market for crocodile skins in Haiti, and hide hunting
is non-existent. Interest was shown by an Italian firm during the 1950's when
it approached Mr. E. Lempke of Port-au-Prince about obtaining crocodile
hides. Nothing came of this, however, and little interest in commercial hide
production has surfaced since. There is a tannery in Port-au-Prince that deals
with reptile leathers (mostly lizard and snake skins from South America [J.
Wilson pers. comm.]). The skin of the crocodile that was killed for taking
livestock in Etang Saumatre was reportedly taken to this tannery. Until
recently there also was a small export trade in live juvenile crocodiles for pets.
This apparently has stopped in the last few years.
Folk Beliefs., The fact that crocodile meat generally is considered
inedible is undoubtedly one of the major reasons why there are still crocodiles
in Haiti today. Such folk beliefs evolved with the culture of the Haitian
people and are deeply tied to their religious beliefs. The indigenous Indians
ate crocodiles, as is evidenced by the presence of crocodile bones in middens
near the Caracol mangrove swamp (W. Hodges pers. comm.). Personal
observation, however, has shown that today there is a widespread cultural
taboo against eating crocodiles or their eggs. In most areas crocodiles are
considered inedible and simply thrown away when killed; however, there is
local variation in the method of disposal. In some areas (e.g. Gonaives), dead
crocodiles are buried in a grave, often in coffin-like boxes with a grave
marker. Around Etang Saumatre crocodiles are beheaded, with only the
head being buried, usually away from the rest of the body. This represents an
attempt to keep the spirit of the dead crocodile (which resides in the head)
separate from the body so that it can create no "mischief' after death (pers.
obs.). On the island of La GonAve crocodiles actually are considered
poisonous. When crocodiles are killed in this region, they are disposed of by
being weighed down with rocks and towed out to sea.
Crocodiles are eaten only in areas where there is cross-cultural exchange
with Dominicans. Around the Riviere Massacre crocodiles are accepted as
being edible. Near Etang Saumatre some Haitians also will eat crocodile, but
it is considered poor repast, equivalent to the Cyclura iguanas in the area. An
interesting example of cultural differences occurred at Las Lajas, a border
military post in the Dominican Republic. A Dominican guard had shot a 2.7
m crocodile in Etang Saumatre, dragged it ashore and cut out the tail meat to
eat and the penis (which is widely believed to be an aphrodisiac in the


Dominican Republic). Afterward, Haitians chopped off the head and buried
it several meters from the carcass to prevent the crocodile's spirit (called its
loa) from doing any harm.
Crocodile Distribution in Relation to Habitat., Crocodiles are found
only where there is suitable habitat. The habitat provides two important
functions: an environment that meets the biological needs of the animal and,
if it is to sustain a crocodile population, sufficient cover to protect the
crocodiles from man. Because of the extremely dense human population in
Haiti, the only significant coastal habitat type that satisfies both these criteria
is mangrove swamp. In areas where human densities are considerably less,
the second criterion obviously becomes less important. In historical times,
crocodiles probably were commonly associated with virtually all coastal
wetland habitats. The pattern of disappearance from these habitats is
inversely correlated with the degree of human activity in the area. Mangrove
swamps provide good habitat because they are relatively impenetrable to
humans and offer a wealth of hiding places. Mangroves also are a very
common form of tropical coastal wetlands, growing under a variety of
physiognomic conditions and, as such, have been well documented as a
preferred habitat of the American crocodile throughout its range (Alvarez del
Toro 1974; Ogden 1978, Medem 1981).
In Haiti, there is a correlation between the amount of mangrove habitat
and crocodile presence in each of the coastal D6partements (a political
subdivision) and the major satellite islands (Table 1). Coastal regions with
crocodiles contain, on average, significantly more mangrove (0.390 sq km/km
shoreline, as measured from 1:50,000 topographic maps) than areas without
(0.05 sq km/km shoreline) (t-test,p < 0.05).
The limited occurrence of crocodiles in coastal non-mangrove habitats
emphasizes the need for sufficient cover in which crocodiles can hide.
Although much of Haiti's coastal wetlands are dominated by mangroves,
there are a number of other small estuarine environments that could support
crocodiles. Most of these are on the north coast between Cap Haitien and
Port-de-Paix, or on the southern peninsula (e.g. Cayes Plain rivers, Riviere
Grande Anse near JMr6mie). Of the non-mangrove habitats, only two still
have crocodiles, both of which offer sufficient cover for the crocodiles in
them: the Riviere Artibonite (deep, murky water) and the Riviere Bondonne
(extensive herbaceous vegetation). Even with cover, however, the presence of
crocodiles in these areas probably is related strongly to the nearby occurrence
of mangrove habitat.
When considering the suitability of mangrove habitat for crocodiles,
however, there are considerations other than total area that need to be
addressed. Perhaps the most important are freshwater input and the
availability of nesting habitat. As Dunson (1982) demonstrated, hatchling C.
acutus can osmoregulate properly in water up to approximately 20 parts per


thousand (ppt), but cannot tolerate full strength sea water (35 ppt) for
extended periods of time. Periodic access to areas of fresh or brackish water
therefore is essential for hatchling recruitment (Mazzotti 1983). The
apparent lack of crocodiles in the extensive mangrove swamp at Caracol may,
in fact, be due to a lack of freshwater input into the region. One river, the
Riviere Trou du Nord, does empty into the mangrove adjacent to the town of
Caracol (population 3982). The heavy human use of the area and a possible
lack of suitable nesting habitat provide unsuitable conditions for crocodile
reproduction and recruitment. The xeric nature of the surrounding area
suggests also that periodic access to freshwater lenses formed by rainfall also
is unlikely.
In fact, in most of the mangrove areas in Haiti, freshwater influx is very
low. The majority of mangrove habitat is located in the subtropical dry forest
life zone, areas receiving less than 100 cm of rain annually. The lack of
freshwater runoff also is related to the high coastline to total country area
ratio. The amount of freshwater runoff is proportional to the amount of land
that receives rain, but mangrove habitat is a function of the length of the
coastline. Hence, Haiti, with a long irregular coast and a small surface area,
provides little freshwater runoff for its coastal mangrove forests. This
situation is further aggravated by the fact that much of Haiti is arid, and in
several areas (such as the l'Ester region) freshwater runoff is diverted for
The fringe forest of the l'Ester historically had a much larger freshwater
influx than at present, because of irrigation and channelization, and this
region once supported a very large crocodile population (Descourtilz 1809).
Diversion of freshwater probably had a significant effect on the habitat which,
in combination with intense fishing activity and past crocodile hunting, has
resulted in a drastic decline in the crocodile population.
The situation on the island of La Gonave also is worth mentioning in
regard to freshwater availability. No surface streams exist on the island;
instead, rainfall percolates down through the limestone bedrock, emerging in
springs, some below sea level. In this respect, suitable hatchling habitat may
be severely limiting, being restricted to the vicinity of freshwater springs that
feed into coastal lagoons. The area visited on the north coast of La Gonave
did, in fact, have at least one small spring adjacent to a mangrove swamp in
which juvenile recruitment was occurring.
Crocodile Distribution in Relation to Human Population Density., Most
human-related crocodile mortality in Haiti is accidental, therefore it can be
assumed to be directly proportional to the frequency of human-crocodile
encounters. This, in turn, is related to the prevalence of activities that bring
people into crocodile habitat or to accidentally kill crocodiles; these activities
include fishing, cutting mangrove, or collecting mangrove oysters. Although
it is virtually impossible to quantify such activities, they can be assumed to be


more or less directly proportional to human population density in the area.
In Haiti, population densities are, in fact, higher in areas where crocodiles
have been extirpated than in those regions which have extant crocodile
populations (Tables 2, 3). Because of the large variances involved, the
differences are not significant for the coastal areas (Table 2, t-test p > 0.05).
Inland lakes with crocodiles, however, are in areas of significantly lower
human population density (Table 3, t-testp < 0.05).
A noteworthy relationship exists between the status of crocodile
populations and the ecological life zone in which they are found (Table 4).
All historical crocodile populations were located in the two life zones that
predominate in the lowland regions: the subtropical moist and the
subtropical dry life zones (OAS 1972). The majority of the crocodile
populations in the moist zone (100-200 cm rain annually) have been
extirpated, only remaining today on the south coast of the Tiburon peninsula
and Ile a Vache. On the other hand, only two populations in the dry forest
zone have disappeared (Caracol region, L'Etang near Gonaives). In the latter
cases the crocodile populations were probably vulnerable because of a lack of
freshwater habitat, and small population size and ephemeral habitat
respectively. As adult crocodiles are often found in freshwater and hatchlings
require at least some freshwater, this relationship is not due to the availability
of freshwater per se. Apparently the presence or absence of crocodiles in
these areas is moderated indirectly through human population density, which
is higher in the greater rainfall moist zone, leading to the unexpected result of
finding crocodiles primarily in areas surrounded by semi-arid habitat.
In the previous discussion, crocodile distribution in Haiti has been
examined in relation to habitat availability and human population density. It
is reasonable to assume, however, that crocodile distribution is affected
simultaneously by both factors. Ranking coastal regions by population
density and the amount of mangrove habitat, neither parameter alone is
significantly correlated with the presence or absence of crocodiles (Wilcoxon
Rank test, p > 0.05). A composite rank combining both parameters (Table 5),
however, is significant (p < 0.05), indicating that the combination of mangrove
habitat and population density is a better indicator of an area's suitability for
crocodiles than either parameter alone. The extirpation of crocodile
populations then appears to be synergistically related to human population
density and the amount of suitable habitat. As crocodiles are rather long-
lived, prolific, and secretive animals, given sufficient habitat offering retreats
(mostly mangrove in Haiti), they can survive even in areas of dense human
populations (as along the south coast of the Tiburon peninsula). This is due
in no small part to their ability to move along coasts between pockets of
suitable habitat. Human-related mortality is, however, quite high and can
result in extirpation, especially where crocodiles are not afforded sufficient
cover (non-mangrove habitats) or where they are vulnerable (e.g. lack of


freshwater). These generalizations, however, only apply to areas where
mortality is mostly incidental, that is where there is no economic motivation
for killing crocodiles. Where active hunting occurs for food, or more
importantly for hides, crocodilian populations are much more likely to be



General Features of the Region

Etang Saumatre is Haiti's largest lake (113 sq km) and is located in the
Cul-de-Sac Valley approximately 30 km northeast of Port-au-Prince (Fig. 6).
The Cul-de-Sac graben, which has been referred to as perhaps the most






U 10 LU 3UR k.

FIGURE 6. Map of the Cul-de-Sac/Valle de Neiba region.


striking surface feature in Haiti (Woodring et al. 1924), is a low-lying valley
extending east-southeast from Port-au-Prince Bay completely across the
island to the Caribbean coast of the Dominican Republic, where it is referred
to as the Valle de Neiba. Mountains border the valley to the north and the
south, with Morne La Selle, Haiti's highest point (2680 m) lying directly south
of Etang Saumatre. The abrupt changes in elevation provide a great diversity
of ecological life zones within a relatively small area (Holdridge 1947).
The Cul-de-Sac/Valle de Neiba depression contains a series of lakes,
from east to west: Laguna del Rincon, Lago Enriquillo, Etang Saumatre,
and Trou Caiman. Lago Enriquillo, in the Dominican Republic, is the largest
(180 sq km) and most unusual of the four, as it is one of the lowest lakes in
the world (35 m below sea level) and is hypersaline (50 ppt in 1981). Because
of hypersaline lake water, the distribution of flora and fauna of the lake are
restricted principally to the fringing freshwater habitats.
Etang Saumatre (elevation 15 m) is located along the Haitian-
Dominican Republic border approximately 10 km west of Lago Enriquillo;
the two lakes are separated by a ridge of Pleistocene limestone and alluvial





0 1 2 3 4 km GANTHIER



FIGURE 7. Map of Etang Saumitre.


deposits. Although the vast majority of the lake lies in Haiti, two small
sections (at Malpasse and south of Las Lajas) extend into the Dominican
Republic (Fig. 7). Like Lago Enriquillo, Etang Saumatre has no surface
outlets, although the possibility of subsurface drainage into Lago Enriquillo
cannot be ruled out. Etang Saumatre is only slightly saline, and because of
this its ecology is quite different from that of Lago Enriquillo, in general
supporting a much more diverse flora and fauna.

Geology and Shoreline Features

Within the last several million years the Cul-de-Sac valley was a shallow
water marine strait that separated the Sierra de Neiba/Montagnes de Trou
d'Eau to the north from the Sierra de Bahoruco/Morne La Selle ridge to the
south (Woodring et al. 1924). This prior separation of Hispaniola into
"north" and "south" islands still is reflected in the biogeographical relations
of many taxa, as has been perhaps best documented for reptiles and
amphibians (Schwartz 1980).


Saumatre ,"

0 1 2 3 4k~~

FIGURE 8. Geology of the Etang Saumatre region.


The abundance of Quaternary limestones composed of extant coral
species is evidence of the recent marine inundation of the valley floor
(Woodring et al. 1924). In many areas throughout the region coraliferous
deposits are still recognizable, and in a few areas, such as Isla Cabritos in
Lago Enriquillo, virtually intact exposed coral reefs can be observed.
The placement of the lakes within the valley has been attributed by
Woodring et al. (1924) to uneven alluvial deposition from streams draining
the mountain watersheds to the north and the south. Areas that did not
accumulate sediments are now depressions that have filled with water and
remain as a series of lakes. The maximum known depth of the Etang
Saumatre depression is 30 m below the lake's surface, or about 15 m below
sea level.
The shoreline features of the lake reflect the geology of the area (Fig. 8).
The western lake margin, from Tete Source south to the vicinity of Ganthier,
is composed of Quaternary alluvial deposits, creating a shallow lakeshore
gradient. Continuing east along the south shore, Quaternary alluvials are
mixed with similar-aged limestones creating a mosaic of shallow gradient and
rocky, medium gradient shorelines. Just east of Fonds Parisien, older
limestones (Miocene and Oligocene) form the northern flanks of the Morne
La Selle ridge, and descend abruptly to the lake creating a rocky, steep
gradient shoreline. A similar rocky coast is found along the north shore from
Glore east to the vicinity of Las Lajas. However, along the north coast a
number of prominent valleys, filled with recent alluvial deposits, extend down
to the lake and create shallow gradient, non-rocky shoreline (coves). The
eastern shore, northwest of Malpasse, is a medium gradient shoreline
dominated by Quaternary limestone, containing several areas of shallow
gradient mudflats at the openings of arroyos.


Etang Saumatre is a brackish lake, with a salinity range of 8-10 ppt. In
the shallow northwestern lake region where much of the freshwater input
occurs, salinity is at the lower end of this range. The lake level fluctuates
periodically, apparently as a function of rainfall. During the period 1979-
1983, following a series of hurricanes, the lake rose approximately 2 m. At
the turn of the century, the lake level apparently was even higher than at
present. Tippenhauer (1901) reported its elevation as 20 m above sea level (5
m above present), and Wells (1893) stated that the water was potable, being
only slightly brackish. Similar fluctuations in lake level and salinity are known
from adjacent Lago Enriquillo (La Fuente 1976).


A number of freshwater springs (conductivity 500-600 mohmos/cm)
empty into the lake, primarily in the northwestern section of the lake, the
largest being at Tete Source. Several small springs are found in the
southeastern section of the lake near Malpasse, located directly along a fault,
giving them a high hydrogen sulfide content. Although much of the
freshwater input into the lake comes from these solution channel springs, a
significant amount of water enters the lake in seepage areas and, to a lesser
extent, through freshwater irrigation canals.
Various chemical analyses have been done on Etang Saumatre lakewater
since 1921 (Table 6). The fluctuations in salinity probably reflect changes in
lake volume associated with variable rainfall. The high phosphate content of
the water indicates the lake is eutrophic (M. Binford and M. Brenner pers.
comm.). Bond (1935) termed Etang Saumatre eutrophic and
"thalassohaline," meaning its ion concentrations are in the same relative
proportion as seawater. Bond (1935) argued that this was evidence of the
lake's marine origin.


The area surrounding the lake receives an annual average of 70-90 cm of
rain. With a mean monthly temperature of 26C, the region is classified in
the subtropical dry zone, as defined by Holdridge (1967). Rainfall follows a
predictable annual pattern (Fig. 9), peaking in May and October with a long
winter (November-March) and a short summer dry season (June-July). Mean
monthly temperature varies from 27.9C in August to a low of 23.7 *C in
Winds are predominantly from the east, and steady 18-36 kph winds
were not unusual. Under these conditions whitecaps cover the lake, with
wave amplitudes in excess of 1 m. The less common westerly winds were
usually associated with rainfall.


Terrestrial Vegetation., The riparian vegetation is a virtual monoculture
of buttonwood mangrove (Conocarpus erectus) growing in fringe 5-20 m wide
around the lake where there is sufficient soil. Because of the recent rise in
lake level, the Conocarpus frequently extended out into shallow water to a
depth of approximately 1 m. The most prolific Conocarpus stands are found
along the shallow gradient alluvial shorelines on the western shore between


50 100
(C) 30- \ 60 (MM)

10- -20


FIGURE 9. Walter diagram of rainfall and temperature variation in Thomazeau, adjacent
Etang SaumAtre. Shaded areas represent the dry season (after Walter 1973).

Tete Source and Ganthier, and on the western shore between Las Lajas and
Malpasse. Most of the Conocarpus is of low stature, rarely exceeding 4 m in
height. The upland areas immediately surrounding the lake are vegetated
with a xeric Acacia, Prosopis, and cactus association (Appendix II).
Aquatic Vegetation., The freshwater flora is restricted to a few springs,
canals, and freshwater seeps around the lake. In these areas the dominant
vegetation consisted of grasses (Echinochloa crusgalli, Paspalidium
geminatum), sedges (Eleocharis cellulosa, Scirpus pungens), floating vines
(Ludwigia leptocarpa, L. repens, Enhydra sessilis, Commelina geniculata),
submerged plants (Najas marina, Nitella sp., Saggitaria sp.), and cattails
(Typha domingensis).
The flora of the lake itself is rather limited, being restricted to several
halophytic algae and a few vascular plants. Shallow water sublittoral areas
usually supported dense bottom mats of algae (Chara homemannii and
Batophora oersteadi). These were the most productive areas of the lake and
supported large numbers of fish (mostly Tilapia). Another alga (Cladophora


sp.) frequently was found growing attached to Conocarpus roots. Ruppia
maritima forms dense mats in shallow water in several parts of the lake,
usually adjacent to freshwater seeps. The grass Halodule beaudettei was often
encountered along shores or in shallow water areas on mud or marl, usually
under Conocarpus. In the southeastern section of the lake near Malpasse,
Salicomia perennis grows along the lakeshore and out into shallow water.

Vertebrate Fauna

Fish., West Indian freshwater fish communities generally are lacking in
diversity (Myers 1937). Etang Saumatre only supports eight native species
(Appendix II), three of which (Strongylura notata, Gobionellus sp., and
Dormitator maculatus) typically are marine-coastal dwellers, reflecting the
marine origin of the lake. In terms of biomass the dominant native species
are Cichlasoma hatiensis (in the lake and springs) and Cyprinodon bondi (lake
only). The other native fishes all are poeciliids, the two genera (Limia and
Gambusia) being characteristic members of Hispaniolan freshwater fish
Two species of introduced fish also are found in Etang Saumatre:
Tilapia mossambica and carp (Cyprinus carpio). Both were first introduced
into the lake during the early 1950s as part of an FAO fisheries project. The
Tilapia have become quite abundant and probably are the dominant fish
overall in the lake in terms of biomass. The carp, on the other hand, are
rarely seen and almost never caught by fishermen. As carp are long-lived fish
and generally require cool water conditions for spawning, it is possible that no
reproduction has occurred in the lake, and the few seen are remnants of the
introduced stock.
Reptiles and Amphibians., Aside from crocodiles, the only aquatic
reptile found in Etang Saumatre is Trachemys decorate, a little-known
freshwater turtle restricted to the Cul-de-Sac/Valle de Neiba region. Very
secretive in their habits, the turtles were rarely seen, with most observations
being restricted to shallow water areas in or around Conocarpus. No
amphibians were found in the lake itself although several anurans (Bufo
guntheri, B. marinus, and Osteopilus dominicensis) bred in freshwater areas
adjacent to the lake.
Avifauna., Aquatic and semi-aquatic birds are quite common in the lake,
especially during the winter when there is an influx of migrants from North
America. The aquatic and semi-aquatic avifauna of the lake is listed in
Appendix II.
Mammals., No native mammals are found in the Etang Saumatre area.
The only local mammals (besides domestic stock) were rats (Rattus rattus, R.


noivegicus), mice (Mus musculus), feral cats (Felis domesticus), and mongoose
(Heipestes auropunctatus).


Population Size, Sex Ratio, and Size-class Distribution

Based on the corrected survey data the total population size in Etang
SaumAtre was estimated to be approximately 450, including crocodiles of all
size classes (Fig. 10).
Because sexing juvenile crocodiles is difficult, much of the juvenile sex
data was not used, so sample sizes are small (Table 7). The predominance of
males in the two smaller size classes is noticeable; however, it is not
significantly different from 50% (chi square, 0.25 < p < 0.10). All captured
crocodiles over 2.4 m were males; the largest female caught was 2.39 m long.
In the 1.8-2.7 m size-class the sex ratio of captured crocodiles probably was
biased in favor of males. This occurred because most adults were captured in
January on shallow-water feeding grounds at a time when many of the
females were near the nesting beaches. Nevertheless, the sex ratio of the
captured animals in this size-class was predominantly female (58.3%).
The size-class distribution was heavily skewed to the smallest class (0.3-
0.9 m), two-thirds of which were concentrated along 16 km of the
uninhabited eastern lakeshore (22.5% of the lake perimeter) adjacent to the
nesting beaches (see Habitat Selection). Breeding-sized animals composed
approximately 15.7% of the total population (1.8-2.7 m, > 2.7 m). This may be
a slight overestimate as sexual maturity is not attained until 2.2-2.3 m total
length (see Reproductive Ecology). Nevertheless, the great majority of the
animals seen in the 1.8-2.7 m size-class were 2.3-2.5 m long, and the
overestimate of reproductive animals is probably quite small. Only 10% of
the population was in the subadult (0.9-1.8 m) size-class.
The small number of subadult crocodiles appears to be a general
characteristic of most crocodilian populations. Cott (1961) commented on
this mysterious "disappearance" of small- and intermediate-sized crocodiles
in Africa, quoting Pitman as it being "a conspicuous feature of African inland
waters." Messel et al. (1981) noted a similar lack of subadult C. porosus in
northern Australia, as did Mazzotti (1983) for C. acutus in Everglades
National Park. This apparent lack of subadults may be a result of: (1) rapid
growth of young crocodiles, (2) extremely secretive behavior or occupancy of
marginal habitats, or (3) high juvenile mortality. In most populations these
factors are not mutually exclusive and may all play a role. Indeed, the last two




'm 300-

O N=413
U 100
u- 11.6
0 7.0

Z 300


100 -
10.0 1 .01

0.3-0.9 0.9-1.8 1.8-2.7 2.7


FIGURE 10. Size-class distribution and the total population size estimated from the
August 1983, January 1984, and combined survey data.


are major components of the population dynamics model proposed by Messel
et al. (1981) for C. porosus.
In Etang Saumatre, rapid growth does not appear to be a factor (see
following section). Subadults, however, do have a tendency to be found in
more "marginal" habitats (see Habitat Selection), and this may have resulted
in a slight underrepresentation of these crocodiles in the population surveys.
The possibility of movement of subadults out of Etang Saumatre also cannot
be ruled out. Local residents have reported crocodiles moving between Trou
CaYman and Etang Saumatre, especially during periods of heavy rain.
Crocodiles also have been reported crossing the arid strip between Lago
Enriquillo and Etang Saumatre (J. Ottenwalder pers. comm.). In both cases,
however, the animals seen were most often adults; the incidence of migration
of subadults remains unknown.
If we assume that the population in Etang Saumatre has a stable age
distribution, we then would be left with high juvenile mortality as the only
explanation for the small number of subadults. While this mortality probably
plays an important role, recent past events in the lake also must be
Prior to 1979 the lake was approximately 2 m below its present level. In
many areas one can still see Conocarpus snags standing in water of this depth.
Subsequently, three hurricanes hit Haiti in 1979 and 1980, causing the lake to
rise to its present level and flood out into Conocarpus habitat over 41% of the
lakeshore (Conocarpus fringe and Conocarpus flats habitats; see Habitat
Selection). Unless exposed to considerable wave action, these areas were
ideal habitat for young crocodiles, hiding by day in the Conocarpus root mats
and emerging at night to feed on the abundant fiddler crabs and other
invertebrates (see Diet). Although the amount of suitable juvenile habitat
before the hurricanes is unknown, it almost certainly was considerably less
than it is today. Aerial photographs of the lake when it was at a similarly low
level (Bond 1935) show considerable stretches of barren shoreline.
Furthermore, prior to 5-6 years ago, the major nesting areas on the
eastern shore were the sites of temporary human settlements. People lived
on the eastern lakeshore, cutting Conocarpus, making charcoal, and fishing,
bringing freshwater across the lake from Fonds Parisien by boat. Remains of
old thatch "ajoupas" were found in the middle of several of the nesting
beaches. Nests were robbed and the eggs eaten (F. Conway pers. comm.) by
residents of Fond Parisien. Undoubtedly, juvenile crocodiles also were killed.
Since that time movement across the lake by boat has been outlawed by the
Haitian government because of smuggling across the Dominican border, so
no one lives near the nesting beaches.
Consequently, because of reduced habitat availability and increased
human disturbance for a period of time prior to 1977-1980, hatchling
production and survivorship of juvenile crocodiles may have been


considerably lower than today. Based on growth rates of recaptured
crocodiles (see Growth Rates), the ones in the 0.9-1.8 m size class would have
been born during the period 1977-1980, and recruitment into this size-class
would undoubtedly have been adversely affected by these factors. Thus it
seems that both natural mortality and past changes in the level of human-
related mortality and juvenile habitat availability may be factors contributing
to the low observed proportion of subadults.

Density and biomass

Few data exist on any aspect of crocodilian population dynamics. This is
especially true for C. acutus where the lack of previous studies is due, at least
in part, to the difficulty of accurately censusing these animals in their typical
habitat (i.e. coastal wetlands). For comparative purposes, however, some
information is available for several other crocodilians species, most notably
Crocodylus niloticus, C. porosus, and Alligator mississippiensis. Density of
crocodiles in Etang Saumatre was calculated on a linear basis (per km
shoreline), as crocodiles are primarily littoral animals and generally do not
move far from shore. Therefore, in lacustrine or riverine habitats, density is
best described in this fashion. Based on the corrected survey data, the mean
density of crocodiles in Etang Saumatre was 6.3/km (crude density, 71.2 km
shore). Eliminating habitats unsuitable for crocodiles (rocky or high wave
energy shores), the ecological density was 9.6/km (46.7 km shore).
Density estimates for various crocodilians are presented in Table 8. The
high degree of variability among these values undoubtedly results from a
variety of factors such as: physical habitat structure, vegetation, water depth,
degree of wave exposure, aquatic productivity and the availability of food,
population structure, and even terrestrial habitat (inasmuch as it determines
the suitability of the area for nesting). Little is known quantitatively about
the roles these various factors play in determining population density.
Crocodile density in Etang Saumatre is variable depending on habitat type
and the degree of exposure to wave action (see Habitat Selection). Wood
and Humphrey (1983) found that density in Alligator mississippiensis was
correlated to lake productivity (nitrogen concentration). Anecdotal accounts
relate food availability to crocodile density (Montague 1983, Watson et al.
1971) or vice versa (Cott 1961, Fittkau 1970, 1975, Whitaker 1978, Glastra
1983), suggesting that in some instances crocodilians play a beneficial role in
maintaining healthy fish populations.
Although the factors mentioned above determine the attainable density,
or carrying capacity of a particular habitat, in reality actual densities are
usually held well below this value by human predation. Several hunted and


y =3.22x- 2.94


FIGURE 11. Log-log plot of the length-mass relationship of crocodiles captured in Etang
Saumitre. A maximum of 5 randomly chosen values are plotted for each 20 cm size class



non-hunted populations are included in Table 8. At the time of censusing,
the non-hunted Crocodylus niloticus populations probably existed in a more
or less undisturbed state, and densities in these areas are quite high (13.1-
21/km). Furthermore, within each of these areas densities were considerably
higher in favorable habitats. In parts of Lake Turkana, for example, densities
reached 55.8/km (Graham 1968). The highest reported value for A.
mississippiensis from 40 lakes in Florida was 29.06/km (Wood and Humphrey
1983). The corresponding figure reported for C. porosus in the tidal
waterways of northern Australia (excluding hatchling crocodiles) was 8.75-
10.1/km (95% confidence intervals, Messel et al. 1982). In Etang Saumatre,
the highest density for any section of shoreline was 16.05/km (Habitat
Selection, Table 23).
The length-weight relationship of 119 captured crocodiles (0.35-2.88 m
total length) is given in Figure 11. Five randomly chosen values are plotted
for each 20 cm size class (for size classes with more than 5 data points). From
the length-mass relationship (y=3.220x-2.994, where y=log mass [g] and x=log
total length [cm]), and the corrected survey data, the total biomass of
crocodiles in Etang Saumatre is estimated as 4741.8 kg. This represents a
crude density biomass of 66.6 kg/km shore, or 101.7 kg/km ecological density
(excluding rocky and high wave energy shores that crocodiles avoid). The
specific breakdown of biomass by size class is shown in Table 9.
Reported biomass figures of C. niloticus populations (Lake Turkana, 350
kg/km; Victoria Nile, 397.5 kg/km; Graham 1968; Parker and Watson 1970)
are considerably higher than those found for C. acutus in Etang Saumatre.
The greater difference in the biomass values between Etang Saumatre
(corrected census data) and Lake Turkana (66.6 vs 350 kg/km) as compared
to the density figures (6.3 vs 13.4 crocodiles/km) reflects differences in the
population's size-class distributions and the fact that crocodiles reach larger
sizes in Lake Turkana (to 4.7 m), and that the majority of the population
biomass is concentrated in the larger size classes (Table 9).
Whether or not the crocodile population in Etang Saumatre is near an
undisturbed state can best be addressed by a comparison with adjacent Lago
Enriquillo. A rough estimate of population size in Lago Enriquillo can be
made based on the number of nests in that lake and the demographic data
gathered in Etang Saumatre. A maximum of approximately 150 nests has
been found in Lago Enriquillo (J. Ottenwalder pers. comm.). Taking a high
and low range of 150 and 100 nests and assuming the same population
structure in both lakes, the most conservative estimate of adult population in
Lago Enriquillo is 336-504. Considering only adult crocodiles, the crude
population density in Lago Enriquillo (130 km shoreline) is 2.58-3.88
adults/km. The corresponding value for Etang Saumatre is 0.98, or 3.2 times
lower than in Lago Enriquillo. These data suggest that the crocodiles in Lago
Enriquillo may be in a nearly undisturbed state, and indicate that past


hunting and human disturbance has had a significant effect in reducing the
crocodile population in Etang Saumatre.


Mortality of young crocodiles always has been assumed to be quite high.
Owing to the difficulties of obtaining such data, however, few quantitative
estimates of juvenile crocodile mortality are available. What little
information is available does, however, indicate that mortality over the first
two years is substantial.
Although no quantitative estimates are available for Etang Saumatre, an
approximation of mortality can be obtained based on some of the data from
this study. Production of hatchling crocodiles in 1983 can be estimated from
nesting data. Twenty nests were located with a mean clutch size of 22.5
(SD=2.7) and a fertility rate of 90.1% (SD=10.5). This resulted in the total
1983 production of approximately 405 viable eggs. To estimate the number of
hatchlings egg mortality must be known. Egg mortality results from three
primary factors: predation, nest flooding, and egg dessication (Mazzotti
1983). No nest predation was observed in 1983, but one nest (5.8%) was lost
to flooding from heavy rainfall. In Florida Bay, egg loss from dessication
accounted for 0% and 15% egg mortality during a normal rainfall and very
dry year respectively (Mazzotti 1983). Using these as high and low estimates
for Etang Saumatre, we obtain a range of 5.8-20.8% egg loss due to
embryonic mortality. This results in an estimated production of 321-381
hatchlings in 1983.
The population censuses in both August 1983 and January 1984 show
that there are only approximately 320-340 crocodiles in the smallest size class
(0.3-0.9 m) which, based on the known rate of growth (see Growth Rate),
includes 3-year cohorts. If the 1981 and 1982 production of hatchlings was
comparable to the estimate for 1983, then clearly a significant fraction of each
year class has disappeared. As it is very unlikely these small crocodiles
dispersed from the lake, this loss must be assumed to be mortality.
Two population surveys revealed nearly identical estimates of 0.3-0.9 m
crocodiles over a 6-month interval (August-January). The first survey was
done 3-4 months after the 1983 hatch. If indeed there was little mortality in
this size class during the interval between surveys, it suggests that much of the
mortality takes place in the first 3-4 months after hatching. This hypothesis is
consistent with the predation that is presumed to account for a large part of
this mortality (i.e. from wading birds). Observation in Lago Enriquillo
suggests that yellow-crowned night herons (Nyctanassa violacea) take a large
number of freshly emerged hatchlings (J. Ottenwalder pers. comm.).


Undoubtedly, other wading birds such as great blue herons (Ardea herodias)
or great egrets (Casmerodius albus) also take hatchlings. After growing to 40-
50 cm, crocodiles are probably immune to this predation, with the exception
of the great blue heron (however, Gorzula [1978] reported that a white-
necked heron, Ardea cocoi, took an 80 cm long Caiman crocodilus).
Messel et al. (1982) suggested that mortality of 0.9-1.8 m crocodiles
associated with intraspecific aggression may be quite high. They found that
up to 80% of the crocodiles in this size class may be excluded from river
systems, presumably by adult aggression. The juveniles and subadults either
are lost through direct mortality or by being forced to move into marginal
habitats where many may perish. This hypothesis is supported by
independent observations of crocodilian behavior. Agonistic interactions
between adult and subadult crocodiles have been noted in captivity with
Crocodylus moreletii (Hunt 1977) and Alligator mississippiensis (Hunt and
Watanabe 1982). Juvenile C. porosus apparently first begin demonstrating
territorial and aggressive behavior in the 0.9-1.8 m size range (Bustard and
Kar 1980). Negative interactions between adult and subadult C. acutus also
have been inferred from data on size-class specific habitat selection in Florida
(Gaby et al. 1981).
Cannibalism has been implicated in a number of crocodilians, and in
most cases adults are eating subadults (as opposed to juveniles) (Caiman
crocodiles, Staton and Dixon 1975; Alligator mississippiensis, C. Abercrombie
and A. Woodward pers. comm.; Crocodylus niloticus, Cott 1961; and C.
acutus, Schmidt 1924).
Adult crocodile mortality is primarily human-related. During the 14-
month interval of this study at least three adults and one subadult were killed.
Fishermen occasionally will try to kill juveniles and subadults they encounter.
This was evidenced by a machete wound found on a 90-cm crocodile in an
area frequented by fishermen.
The frequency of injury of crocodiles in Etang Saumatre is quite low
(2.6% of the captured crocodiles had injuries). The lowest reported
frequency of injury among four populations reviewed in Webb and Manolis
(1983) was 6.5% for C. porosus in Australia (from Webb and Messel 1977).
A Jamaican population of C. acutus had an injury frequency of 14.1% (from
Garrick unpubl.). In the past, frequency of injury sometimes was assumed to
reflect predation pressure (Webb and Messel 1977, Dietz 1979). Most
evidence, however, indicates that while predation may lead to some injuries,
the majority are sustained during intraspecific social encounters (Cott 1961,
Staton and Dixon 1975, Gorzula 1978, Webb and Manolis 1983).


Growth Rate

The growth rates of crocodiles to 1.6 m total length were estimated from
the recapture of 12 individuals, one of which was recaptured three times.
Mean growth rate of the 0.3-0.9 m crocodiles was 0.058 cm/day (10
recaptures; SD=0.043). Due to the small sample size, no statistical analyses
could be done to test the effects of season, habitat type, or sex on the rate of
With a mean hatching date of 1 May, and a mean hatchling length of
24.4 cm (from six hatchlings found in a nest just prior to emerging), the
average hatchling growth rate over the first 65-86 days of life was 0.135
cm/day (SD=0.043, n=13), with a low estimate of 0.111 cm/day (mean hatching
date 15 April, SD=0.035, n=13). Both these values are substantially higher
than the growth rates of the recaptured 0.3-0.9 m crocodiles, all of whom
were at least 9 months old.
Based on the two 0.9-1.8 m crocodiles recaptured, there does not appear
to be any slowing of growth in males of this size class (mean growth rate 0.090
cm/day). As no females in this size class were recaptured, no data exist for
0.9-1.8 m females. Females do not grow as large as the males; consequently,
it is apparent that female growth slows sooner than that of the males. Messel
and Vorlicek (in press) have noted consistent differences in male and female
growth in C. porosus less than 1 m total length; however, these differences
were not significant. In animals over 1 m total length, sexual differences in
growth rates have been found to be significant (Webb et al. 1978, Chabreck
and Joanen 1979, Webb et al. 1983)
Although the sample size is small, several conclusions can be drawn
concerning the growth rates of crocodiles in Etang Saumatre. Hatchlings
appear to grow rapidly (0.111-0.135 cm/day) over at least the first three
months of life, thereafter slowing to 0.05-0.06 cm/day in the 1-2 year age
classes. Although growth among hatchlings was consistently high (range
0.059-0.204 cm/day), growth in larger animals was more unpredictable. Two
1-2 year old animals exhibited almost no growth (0.000 and 0.008 cm/day)
over a period of 168 days.
Seasonal differences in growth rate have been noted in a number of
crocodilians: Alligator mississippiensis (Chabreck and Joanen 1979),
Crocodylus porosus (Webb et al. 1978, Magnusson 1981, Messel and Vorlicek
in press), C. acutus (P. Moler pers. comm.), C. johnsoni (Webb et al. 1983), C.
niloticus (Pooley 1962), and Caiman crocodilus (Gorzula 1978). These
seasonal changes have been variously attributed to temperature and/or food
availability. Little information exists concerning seasonal differences in
growth rates in Etang Saumatre as the great majority of the recaptures (10 of




0 1 2 3 4 km t

FIGURE 12. Location of nesting areas and "harem" groups in Etang Saumatre. (A-M are
nesting beaches. X marks the location of a human-predated nest in 1983. Harem locations
are marked h.)

12) included both wet and dry season growth periods. One animal recaptured
3 times did grow at a slower rate over the winter dry season (0.088 cm/day,
interval 118 days) than during the summer wet season (0.155 cm/day, interval
58 days). Seasonal variation in growth rate, if it does occur, would most likely
be related to temperature. Mean monthly air temperature varies 4.1 C
annually, and reptiles, being ectotherms, are sensitive to changes in
temperature because metabolic rate is temperature dependent. Although
rainfall does increase in the wet season, it has little effect on lake level or
food abundance (the primary food item of juveniles, Uca, being abundant at
all times of the year).
A comparison of the growth rates of C. acutus from Etang Saumatre
with rates reported from other C. acutus populations and those reported
from C. porosus (Table 10) indicates the Haitian crocodiles are growing at a
slow rate. This occurs despite the fact that in the other populations the
crocodiles are not growing during significant portions of the year because of
low temperatures (Florida, P. Moler pers. comm.) or possibly food availability


(Australia, Webb et al. 1978). The Etang Saumatre crocodiles apparently are
growing throughout the year but at reduced rates.
The slow growth of the Etang Saumatre crocodiles is manifested in the
small size of adults. Males and females only reach lengths of 3.5 m and 2.4 m
respectively, whereas in other parts of its range C. acutus is reported to grow
considerably larger (Alvarez del Toro 1974, Ogden 1978, Medem 1980,
Mazzotti 1983). The maximum reported size of C. acutus is 6.25 m (Alvarez
del Toro 1974). A similar situation appears to hold in the large Lago
Enriquillo population, where crocodiles may grow slightly larger (males 4.0 m,
females 2.6-2.7 m). Jamaican crocodiles are also reported to reach similar
lengths (Garrick in litt.), so relatively small size may be characteristic of the C.
acutus in these Greater Antillian islands. The reasons for the slow growth in
Etang Saumatre, whether environmental or genetic, are unknown.

Reproductive Ecology

Courtship and Mating

Courtship and mating activity was not observed in Etang Saumatre, but
based on the timing in relation to nesting (Garrick and Lang 1977) was
assumed to take place during late December and early January. The
courtship of crocodiles in Lago Enriquillo was observed in 1979 by S.
Inchaustegui, J. A. Ottenwalder, and D. Robinson (pers. comm.). Three
males were observed to establish adjacent territories. The largest male was
dominant, excluding the other males from his territory. Females would move
freely through the territories of the males. One copulation was observed by
the dominant male (0900 h, 27 January 1979) during 15.5 hr of observation.
During this period the same male was observed courting several females and
interrupting the courtship of a neighboring male. The pattern and behavioral
inventory of courtship and mating was similar to that described in Garrick
and Lang (1977), with the exception of the "sub-audible vibration" which
never was observed at Lago Enriquillo.
In Etang Saumatre during early January 1984, 27 adult crocodiles were
observed in four distinct groups (mean intergroup distance 4.7 km, SD=2.9)
along the eastern lakeshore adjacent to the nesting beaches (Fig. 12). These
groups were quite distinct during the day, but at night the adults would
disperse along the lakeshore. These aggregations were inferred to be
courtship groups or "harems," as they contained one large male and several
smaller adults (presumably females, although possibly smaller males). The
sex ratio of males to females captured near the nesting beaches shortly after
the nesting period was 1:3. During roughly the same period of time, five


adults were captured in the northwestern section of the lake, away from any
known nesting areas, and these all proved to be males. This suggests that a
certain fraction of the adult males were excluded from breeding, a hypothesis
consistent with a polygynous mating system. This argument is strengthened
further by the fact that the "excluded" males were smaller (mean length=2.63
m, SD=0.16 m, n=5) than the males caught adjacent to the nesting areas
(mean=2.86 m, SD=0.04 m, n=2).

Minimum Size for Reproduction and Percentage of Population Breeding

The smallest female captured near the nesting beaches, and presumed
reproductively active, was 2.30 m, the largest was 2.39 m. The minimum size
for reproduction in either sex of C. acutus is not well known, but the length at
sexual maturity undoubtedly varies between populations. Alvarez del Toro
(1974), for instance, never found a reproductive female less than 2.8 m, in
Chiapas, Mexico, which is longer than the longest female in Etang Saumitre.
In Florida, Ogden (1978) estimated the sizes of nesting females to range from
2.5 m to 3.9 m. Also in Florida, Mazzotti (1983) estimated minimum female
breeding size at 2.25 m and found six females at nests ranging from 2.28 m to
3.08 m. Similar variation in the minimum breeding size of females has been
noted in Crocodylus niloticus (Cott 1961, Graham 1968). Assuming a
minimum breeding size of 2.25 m, age at sexual maturity is probably at least 8
years for females in Etang Saumatre (assuming no slowing of growth with age
up to 2.25 m).
The minimum breeding size of males is even more difficult to ascertain,
as the reproductive state of a male can be determined only by killing the
animal. Evidence from Lake Turkana indicates that male C. niloticus may be
sexually mature at lengths of 2.12 m (Graham 1968), although in other parts
of Africa 2.30 m may be the minimum (Cott 1961). Medem (1981) reported
that a 2.19 m captive C. acutus mated with a 2.36 m female, but produced an
infertile clutch. In all probability, however, males in the wild may be sexually
mature, but excluded from breeding by larger males, so minimum size at
reproduction needs to be considered from a behavioral, as well as a
physiological standpoint.
The percentage of adult females breeding in 1983 was estimated based
on demographic and nesting data, using the formula of Chabreck (1966):
E=N/(P*A*F); where E = percent of adult females nesting, N = total number
of nests, P = total population size, A = percent of population sexually mature,
and F = percent of females among mature crocodiles. In 1983, 20 nests were
located and another was reported, but not seen, making a total of 21 nests.
Based on the data in the preceding section, P=450, A=15.7%, and F=46.6%,


suggesting that 63.8% of the mature females nested that year. This figure is
comparable with values reported for other crocodilian populations (Table 11).
Reasons why an individual female may not breed in any particular year are
not well understood, but probably are related to energetic constraints or
reproductive sensecence (Graham 1968).

Timing of Nesting

In 1984, all 13 known nesting attempts occurred between 22 January and
12 Feburary. Hatching takes place in late April and early May after an
incubation period of approximately 90 days. This timing is similar to that
found in other soil-hole nesting crocodiles in that egg laying takes place
during the dry season and eggs hatch at the beginning of the rainy season
(Fig. 13). Oviposition during the dry season means incubation will take place
when water levels are dropping, thereby reducing the chance that the nests



FIGURE 13. Timing of nesting and hatching in relation to rainfall (Thomazeau rainfall


will be flooded. It also allows the newly emerged hatchlings to take
advantage of the increased invertebrate food and habitat availability
associated with the rainy season (Cott 1961). Similar timing of nesting in C.
acutus has been noted in Mexico (Alvarez del Toro 1974).
Although this pattern of reproduction is fairly typical of soil-hole nesting
crocodiles (as opposed to crocodiles that build vegetation mound nests), a
degree of asynchrony in breeding has been noted in some populations of
Crocodylus niloticus in Lake Turkana (Graham 1968) and Lakes Victoria and
Kioga (Cott 1961). Graham (1968) found evidence of reproductive activity at
all times of the year, although a definite peak occurred during the dry season
(late fall-early winter) when Modha (1967) noted courtship and mating. Cott
(1961) reported two nesting seasons in Lakes Victoria and Kioga, each
associated with one of the two annual rainy seasons. Interestingly, 15.1% of
the females examined by Graham (1968) that were ovulating or had just
ovulated contained another clutch of developing eggs, suggesting that females
may produce more than one clutch of eggs a year. Double clutching has been
noted in Crocodylus palustris in India (R. Whitaker pers. comm.), although all
evidence indicates that C. acutus nests only once a year.
A comparison of the timing of nesting with adjacent Lago Enriquillo
produces some unexpected results. Both lakes experience the same
temperature and rainfall regimes, and being located only 5-10 km apart, the
annual photoperiod is identical. Yet, crocodile courtship/mating and nesting
in Etang Saumatre appears to be 2 weeks to one month ahead of Lago
Enriquillo. The reasons for this asynchrony are unclear. The role of
environmental cues in determining the onset of reproduction has yet to be
examined in crocodilians and would merit future investigation.

Nest Site Characteristics

Physical Characteristics., Crocodile nests can be divided into two basic
types, eggs being deposited either in holes dug into the substrate or in
vegetation or soil mounds built up above the level of the surrounding terrain.
Under natural conditions, this dichotomy usually is consistent within species;
however, C. acutus will use hole nests or mounds constructed from soil
(Campbell 1972, Ogden 1978) or, rarely, from vegetation (Alvarez del Toro
1974, Medem 1981). All nests at Etang Saumatre were hole nests (Table 12).
The purpose of constructing mound nests presumably is to raise the
elevation of the egg clutch, thereby minimizing the possibility of nest flooding
(Mazzotti 1983). Some mound nests on Key Largo, Florida, however, are
constructed on spoil banks where the possibility of flooding is minimal (P.
Moler pers. comm.).


The mean height of nests in Etang Saumatre was 1.2 m (SD=0.5 m,
n=25) above lake level (Table 13) at the beginning of the incubation period.
The bottom of the average clutch is approximately 80 cm above lake level, as
the mean hole depth is 37.9 cm (Table 12). Because the lake only fluctuates
0.3-0.4 m annually (excluding years with hurricanes), egg mortality from rising
lake water would be minimal. The only flooding found to occur was
associated with surface inundation from heavy rainfall (one nest, 1983).
Along the eastern lakeshore, nests were located on coralliferous
limestone outcrops that extend down to the lakeshore. These outcrops often
were separated from one another by low-lying salt pans that supported little
vegetation other than frequently dense Conocarpus stands along the
lakeshore. Old beaches, formed when the lake level was higher, frequently
would create deep sand areas on these outcroppings, providing suitable
nesting habitat. Besides furnishing sand beaches close to the lakeshore, these
outcroppings provided deep-water approaches to the nesting area. Although
apparently suitable nesting areas were located behind the salt pans, these
were farther away from the lake (usually more than 50 m), and water
approaches were frequently through shallow water or over mudflats. These
two parameters, well-drained soil and deep water approaches, also were noted
by Ogden (1978) as being important in determining the suitability of habitats
for C. acutus nesting in Florida.
Besides using the deep sand of old beaches, crocodiles frequently would
nest in old charcoal mounds, usually located on the same raised, well-drained
banks where sand nests were found. The term "mound" refers only to the
fact that when the charcoal is being made, the slowly burning wood is covered
with a layer of soil, creating a mound. Upon finishing, the charcoal makers
scatter the remains of the mound more or less evenly with the surrounding
terrain. Out of 26 nest sites active in 1983 and 1984, 15 (57.7%) were either
in or adjacent to these old charcoal mounds.
To more closely examine the factors that are important in determining
nest site selection, a stepwise discriminant analysis (Barr et al. 1976) was
performed comparing the 1984 nest sites with 15 null sites randomly selected
within the range of the nesting beaches along the eastern lakeshore. Of the
eight nest parameters examined (Table 13), distance to lake was not used, as
this was standardized at 25 m for all null sites. The discrimnant analysis
revealed only soil moisture content to be important in separating nest sites
(dryer) from null sites (wetter) (p < 0.01). Percent shrub coverage was
significantly higher at null sites (p < 0.05) but was correlated with soil
moisture content so did not account for much of the difference between nests
and null sites once the variation due to soil moisture was removed (p > 0.38).
The importance of soil moisture content in selecting nesting areas is
obvious as eggs depend on oxygen diffusion for respiration (Ackerman 1980),
and gas diffusion rates are negatively correlated with the amount of water in


the soil. The mean water content of the nest soil (6.62%, SD=3.13, n=12) was
significantly lower than for null sites (20.33%, SD=5.01, n=15) and reflected
the fact that the areas selected for nesting were the well-drained old beach or
charcoal mound sites. The mean water content for three sand nests
measured in Florida was 10.3% (calculated from Lutz and Dunbar-Cooper
1982) and ranged from 4.89% to 19.25%, these extremes being recorded from
a single nest over the period of incubation.
As the soil parameter data were taken shortly after oviposition, the
moisture values reflect what the females were encountering as they excavated
the nests. On examining the nests, however, it was noted that the soil matrix
near the eggs appeared to be more moist than the surrounding soil. This was
tested by excavating holes of equal depth adjacent to four nests and
measuring soil water content. The nest soil was found to be significantly
wetter (Table 14, paired t-test, p < 0.05). The source of this moisture could be
from cloacal fluids released by the female during oviposition and/or the
mucous covering of the eggs. As during periods of low rainfall dessication
can cause egg mortality in C. acutus eggs (Mazzotti 1983), this extra moisture
may be important in preventing dessication mortality. Bustard (1971),
however, found that Crocodylus novaeguineae eggs hatched normally in soil
with only 2% water content.
Vegetation., Nests generally were located near the ecotone between the
Conocarpus-dominated riparian strip and the xeric upland flora, the species
assemblage being a mixture of both communities (Table 15). The percent of
shrub coverage at the nest sites (30.1%) was significantly lower than the null
sites (40.6%) (Table 13). The canopy of these trees and shrubs was quite
sparse and only provided partial shading. Nests were usually located near to,
but not directly under, trees or shrubs. The mean distance from nests to the
nearest tree/shrub over 1 m high was 2.1 m (SD=1.05 m). This, however, was
not significantly different from the null sites (2.7 m, SD=2.7 m). Herbaceous
cover was also sparse on the nesting beaches. The dominant grass, Uniola
virgata, usually was not found growing on the sand beaches or charcoal
mounds used for nesting.

Location of Nesting Beaches

The majority of the nesting occurred over 6.6 km of shoreline on the
eastern lakeshore (Fig. 12, containing 18 of the 21 nests in 1983 [2.7 nests/km
shore]). At least 13 nests occurred over the same area in 1984. Because of
the difficulty of locating nests before hatching, this 1984 figure represents a
minimum number and is probably an underestimate.


Colonial nesting in the sense of Cott (1961), or in Lago Enriquillo where
one may find 20-30 nests on a single nesting beach, was not in evidence.
Nevertheless, several nesting beaches had more than one nest (Table 16).
Single nests also were located on a small island near Malpasse (nesting
beach L), and on Osprey Island along the north shore 2 km west of Las Lajas
(nesting beach M, Fig. 12).
Location of nesting beaches on the lake was primarily determined by
three factors: (1) suitability of the terrestrial habitat for nesting (as discussed
above), (2) human population density, and (3) the presence of nearby aquatic
habitats protected from wave action.
The effects of human population density can be seen in the case of a
1983 nest reported from the northwestern section of the lake near Tete
Source (I. Lange pers. comm.). The nest was discovered by local residents,
excavated, and the eggs were brought to a local market for sale. The area
where the nest was located provides suitable nesting habitat and in the past
may have been an important nesting site. High population density and heavy
grazing/browsing by domestic stock today make this area marginal for nesting.
Extensive searching failed to reveal any sign of nesting in 1984. All other
known nesting areas are located away from areas of high human activity. The
two island nest sites are relatively isolated with only occasional use by
fishermen or charcoal makers. The nesting beaches along the eastern
lakeshore are likewise removed from any significant human activity.
Although the characteristics of the terrestrial environment are
important for choosing nesting areas in that they are selected to minimize egg
viability, the nature of the adjacent aquatic environment also is important. As
mentioned above, deep water approaches are favored as they allow the
crocodile easier access to the nest site. Nesting beaches also were located
adjacent to areas protected from wave action. With the predominant winds
from the east, the eastern lakeshore provides many such areas. In several
locations along the western lakeshore suitable terrestrial environments exist
for nesting, but these areas invariably are exposed to a high degree of wave
action (the nesting area near Tete Source mentioned above is located
adjacent to a protected water area).
The relationship between calm water habitat and nesting is closely tied
to the habitat preference of adult crocodiles, which tend to avoid areas with
any wave action and concentrate in calm water habitats (see Habitat
Selection). Calm water may be especially important for courtship and mating,
as many of the associated behaviors are visually oriented and take place when
the animals are floating at the surface of the water, thus requiring low wave
amplitude. Once courtship and mating are finished, the females may select
the closest available nesting area. I observed a similar pattern of nesting
beaches located adjacent to calm water habitat in Lago Enriquillo.


At the opposite extreme is the situation in Florida Bay, where crocodiles
spend most of the year in protected mangrove habitat but the females venture
out into the more exposed regions of Florida Bay to nest (Ogden 1978;
Mazzotti 1983). Reasons for this behavior are not well understood but may
be related to a lack of suitable nesting habitat in the protected regions of the

Clutch Size and Fertility

The average clutch size at Etang Saumatre was 22.5 (SD=2.7) (Table 17),
which is at the lower end of reported values for C. acutus (Table 18). Overall
egg fertility was 90.1% and ranged from 70.6 to 100% within clutches. Mean
clutch mass was 2.18 kg, or approximately 4.4% of female body mass (mean
female mass=49.7 kg, based on an average length of 236 cm). Clutch size has
been demonstrated to be positively correlated with female size in C. niloticus
(Cott 1961, Graham 1968), and it is reasonable to assume that the same holds
true for other crocodiles. Because the crocodiles in Etang Saumatre and
Lago Enriquillo do not reach large sizes, this could explain the small clutch
sizes in these lakes. Using data from Graham (1968) relating female length to
clutch size (y=0.2909x-43.34, r=0.86, n=10; where y=clutch size and x=total
female length in cm), the predicted clutch size for the average length female
in Etang Saumatre (236 cm) is 25.3, which is in good agreement with the
observed mean clutch size (22.5).
Using this same relationship together with the mean egg mass (97 g)
data and the length-weight relationship from this study, the predicted clutch
size and mass can be calculated for females of different lengths. These
relationships predict that clutch size remains a fairly constant 3-5% of body
mass over a wide range of female lengths, but trending slightly downward
with increasing female size (assuming that egg mass is independent of female
size). Ferguson and Joanen (1983), however, found that larger female
alligators laid larger eggs than smaller females. If this is true for crocodiles,
clutch mass as a percentage of body mass may remain remarkably constant
throughout life. Webb (1983) also found that clutch mass was approximately
5% of body mass in Crocodylusjohnsoni.
It should be noted that this relationship is for the average clutch size,
and actual clutch size may vary considerably from year to year. Yadav (1979)
reported nesting data from a captive pair of Crocodylus palustris where the
female (2.80 m total length) oviposited annually for 15 consecutive years.
Data for 12 years demonstrated that clutch size varied from 22 to 41
(mean=31.2, SD=5.2) with the high and low values being laid in consecutive


Nest Temperature

Temperature of incubation determines the sex of Alligator
mississippiensis (Ferguson and Joanen 1982, 1983), Crocodylus niloticus
(Hutton 1984), C. porosus, C. johnsoni (Webb and Smith 1984), and a
number of turtles (review in Bull 1980). As all crocodilians lack
heteromorphic sex chromosomes (Cohen and Gans 1970), it is reasonable to
assume that temperature dependent sex determination is a common feature
shared by all crocodilians. As such, information on the temperature regimes
of nests is an important aspect of nesting ecology.
Thirteen temperature recordings were made for the top and the bottom
of six egg clutches over a 30-hour period on 13-14 February 1984 (Table 19).
Overall mean temperature for the egg clutches was 29.3 C (SD=0.41).
Temperature at the top of the clutch varied slightly more (mean temperature
amplitude=0.9*C) than the bottom (0.6 C). Nevertheless, on average,
temperature remained remarkably constant, the largest temperature variation
in any one nest being 1.8 C (nest 84-4, top) while air temperature over this
period varied 8.9 C. This is even less variation than found by Lutz and
Dunbar-Cooper (1982, 1984) for C. acutus nests in Florida Bay (mean diel
variation=1.4'C), and also less than values reported for vegetation mound
nesting species (Chabreck 1973, Webb et al. 1977, Goodwin and Marion
1978). The diel temperature variation for a typical nest (84-8) is shown in
Figure 14. The high thermal inertia of the soil results in the nest reaching its
highest temperature during the night.
Little can be said about the differences in temperature regimes between
sand and charcoal nests. Of the six nests monitored, two were in charcoal
mounds (84-2 and 84-8); these nests were the hottest and coolest nests
measured, respectively.

Nesting Behavior

Crocodiles began visiting potential nest sites up to 28 days prior to
nesting. Similar early visits were noted in C. acutus in Florida (Ogden 1978,
Mazzotti 1983; P. Moler pers. comm.). During these early visits, females walk
along the nesting beach and make periodic shallow digs in the substrate. As
the time for nesting approached, deeper test holes were dug, often several in
a very small area, or scattered around the nesting beach. These test holes
either were left open or were filled in by the female before departing. Nest
digging or egg laying were never observed in Etang Saumatre; however,
observations in nearby Lago Enriquillo indicated that females begin nesting


soon after dark. One female was discovered in the final stages of egg laying at
2315 h on 12 February 1982. After oviposition the female, using her tail and
body, smoothed out the area surrounding the nest, making it difficult to find
the exact location of the hole.
During the incubation period females will remain in the vicinity of the
nesting beaches, although they never were observed on land near the nest as
has been reported for C. niloticus (Cott 1961, Modha 1967). No nest
predation was observed in Etang Saumatre during 1983 or 1984. In Lago
Enriquillo dogs, and possibly mongoose (Herpestes auropunctatus), were
reported to rob crocodile nests (J. Ottenwalder pers. comm.). The incidence
of nest predation in Etang Saumatre, however, is very low.
Crocodiles were not observed to be territorial around nest sites as has
been reported for C. acutus in Mexico (Alvarez del Toro 1974). In fact,
several nests were found within a few meters of one another, and two nests in
1984 (84-8 and 84-12) were laid (approximately 2 weeks apart) with their
clutches almost contiguous.
Crocodiles appear to nest on the same beaches year after year. The
actual reuse of 1983 nest sites in 1984, however, was only 46%. This figure is
similar to the values obtained for C. niloticus in the Okavango delta (44.3%,
Graham et al. 1976; 44.1%, Blomberg in Graham et al. 1976). Of the 1984
nests, 15% were in areas used as nests prior to 1983 (based on egg shell
fragments), and 31% were apparently in new sites.


- --- ------------------ -------

S 26.0 -


0800 1200 1600 2000 2400 0400 0800 1200 1600
FIGURE 14. Diel nest temperature variation (nest 84-8) over a 30-hour period, 13-14
February 1984.


Tracks of female on nesting beaches in Etang Saumatre revealed an
apparent random search component. Females could locate old nest sites
without difficulty, but often would wander considerably during their
nocturnal visits, or even come ashore in areas where no suitable nesting
habitat occurred. This type of searching behavior may be important because
of changes in the characteristics of the previously used nesting sites. In Etang
Saumatre (and in Lago Enriquillo) many old nest sites have been inundated
by the rising lake waters since the hurricanes of 1979 and 1980; others are
unsuitable because the egg cavities would now be below the water table. This
has required females to select entirely new nest sites in the last 5-6 years.
This random searching by the female no doubt familiarizes her with potential
nest sites in the area and facilitates switching to new nesting areas.
The reuse of nest sites by individual females has been speculated on
(Alvarez del Toro 1974, Ogden 1978) but is difficult to document. The only
data concerning individual nest reuse for hole nesting crocodiles concerns C.
niloticus in Botswana (Graham et al. 1976), where aerial photographs of
females on nests reveals that in two instances different females were
photographed at the same nest site in consecutive years. Obviously, different
females may use the same nest site in different years, and annual use of nest
sites should not be construed as the work of one female unless other
supporting data exists.
Based on tracks, females returned to open the nest at the end of
incubation. Some females were visiting the nest sites 2 weeks prior to
hatching and probably visited the nest frequently before it finally opened. In
several instances, eggshell membranes were found along the shoreline,
indicating that females carry their young to the lake, picking up egg fragments
in the process. In two of the 1983 nests, females left eggs covered in the nest
after opening it. In both nests, two eggs contained pipped young, and the
third egg held a dead embryo. Asynchrony in hatching also has been noted in
C. acutus in Lago Enriquillo (J. Ottenwalder pers. comm.) and Florida
(Mazzotti 1983).


Juvenile Crocodiles

For the purposes of analyzing the differences in diet among crocodiles of
varying lengths, four size-classes were defined (Table 20). The largest sample
was obtained for juvenile crocodiles (the smallest two size-classes), and for
these animals invertebrates composed the vast majority of prey items. No
vertebrate remains were found in any crocodile of the smallest size class (< 0.5


m). In the 0.5-0.9 m class, the occurrence of vertebrates increased
dramatically. Many of these, however, were samples with a few scattered
mammal hairs (Mus or Rattus) or bird feathers. Prey mass represents a more
unbiased estimate of diet because it considers only recently ingested food
items (fresh and partly digested categories) so there is less potential for bias
due to differential digestibility of prey (Jackson et al. 1974, Garnett 1985).
Based on prey biomass (Table 21), invertebrates comprised the great majority
(87.2%) of the food for 0.5-0.9 m crocodiles.
The dominant prey item in terms of frequency of occurrence and mass
was the fiddler crab, Uca bergersii. These crabs were very abundant (23.1-
121.8/m2) in all the protected shallow water habitats which juvenile crocodiles
preferred. Juvenile crocodiles also ate considerable numbers of beetles
(Coleoptera) and odonate larvae (Tables 20, 21). The occurrence of these
prey items indicates two separate foraging strategies. The majority of beetles
found in crocodile stomachs was of terrestrial origin (Table 22). Crocodiles
never were seen foraging on land, but frequently were observed sitting in
shallow water making sideswipes at surface disturbances. This method of
prey capture probably results in the ingestion of terrestral insects
(Coleoptera, Lepidoptera, and Hymenoptera) that accidentally fall into the
The high occurrence of odonate larvae in the diet of these crocodiles
suggests that they also actively forage underwater amongst the submerged
vegetation and/or bottom sediments. In this manner crocodiles also may
acquire gastroliths and accidentally ingest aquatic vegetation (Table 20).
Very few juveniles were found with fish in their stomachs. Of the three
juveniles (9.3%) that had recently eaten fish, two were captured in shallow
water muddy lagoons where catching fish was perhaps more easily
accomplished. All the fish eaten were small poeciliids (Limia sp. and
Gambusia hispaniolae). Predation on mammals by juveniles was restricted to
Conocarpus swamps or in the thick marshy vegetation surrounding canal

Subadult and Adult Crocodiles

Only a limited sample (n=9) of stomach contents from crocodiles over
0.9 m total length was obtained (Table 20). Of these, four were over 1.1 m
total length (1.20 m, 1.38 m, 1.95 m, and 2.43 m). Scooping was attempted on
seven other crocodiles over 2.0 m total length, but extracted no stomach
contents. Although this may indicate a high incidence of empty stomachs
(Graham 1968), it is equally likely that the scoop simply failed to bring up
large food particles.


As has been pointed out by other authors (see Cott 1961) there is a
dietary shift with age in crocodilians, from the predominantly invertebrate
food of juveniles, to primarily vertebrate prey for adults. The incidence of
both birds and fishes increased in the subadult and adult crocodiles in Etang
Saumatre (Table 20). Large crocodiles also were known to take domestic
stock (goats or sheep) and sometimes dogs. During January-February 1984,
at least three goats were known to be killed and eated by crocodiles along the
nesting beaches on the eastern lakeshore (pers. obs.). One adult (2.82 m
male), when captured, had the remains of a goat in his mouth. At least two
dogs were killed by a large male (3.5 m) in the spring at Tete Source over a
14-month period.
Nevertheless, the primary food item of adults appears to be fish. Adult
crocodiles frequently were seen in water 1-2 m deep where large fish (Tilapia
and Cichlasoma) were abundant. In these areas crocodiles were observed
sitting on the bottom making rapid sideways sweeps of the jaws to catch fish.
Crocodiles also would take fish trapped in gill nets set by fishermen near Tete
Source, and were not infrequently seen at night sitting on the bottom next to
these nets.

Habitat Selection

Spatial Crocodile Distribution

The distribution of crocodiles by lakeshore segment and size-class is
summarized in Figures 15 (August 1983) and 16 (January 1984). These data
are corrected for differences in the lengths of shoreline segments and
expressed as density per km shore in Table 23. The highest concentration of
hatchling and juvenile crocodiles (0.3-0.9 m) were found in section H, which
contains the majority of the nesting beaches. Mazzotti (1983) found that
hatchling C. acutus would disperse rapidly from nest sites in areas exposed to
wave action, moving to more protected waters. Hatchlings from the more
protected creek nesting sites were less likely to move and generally remained
in the vicinity of the nest. Rodda (1984) noted a high degree of philopatry
among 10 first year C. acutus in Panama. These animals had average home
range sizes of 330 m of shoreline and spent 80% of their time in core areas of
only 200 m.
In Etang Saumatre, of the 10 crocodiles (0.3-0.9 m) that were
recaptured, eight were found in the same location where they were originally
caught (mean recapture interval 143 days). Of the two that moved, one
apparently did so in response to the rising lake waters that exposed a
previously protected lagoon to considerable wave action. This juvenile moved


1 km into a temporarily flooded Conocarpus zone. The other juvenile moved
1.8 km along the eastern lakeshore over a period of 339 days.
Subadults (0.9-1.8 m) also were found frequently in section H; they were
also concentrated in the northwestern region of the lake (section E). The
concentration of subadults in this area is interesting, as it also contained
several apparently non-breeding males during the 1984 nesting season.
Subadults had a greater tendency to move than did juveniles. Of the
two subadults that were recaptured, one had moved (over 306 days) entirely
across the lake, a straight-line distance of 10 km. As this individual probably
moved along the shore, the actual distance travelled is closer to 22 km. The
other subadult moved 0.3-0.4 km over a period of 84 days.
The 1.8-2.7 m crocodiles, composed primarily of adult females, had a
high density during the August survey in section G. During January the

A-10 A-3 N
B- 8 B-1
C- 5 C-3
D- 2 D-0

B- 4
C- 10
A- 217
S\B- 14
C- 23
D- 3

0 1 2 3 4km N=14 SECTION B
A- 9 N.18
B- 1-15
JANUARY 984 2 AB- 0
JANUARY 1984 B- 0

C- 3
D- 0

A-3 C-0
B-0 0-0

FIGURE 15. Crocodile distribution by size class and lakeshore segments, August 1983.
(Crocodile size classes (in m) are: A = 0.3-0.9, B = 0.9-1.8, C = 1.8-2.7, D = > 2.7; all values
given represent total length.)

D- 2


majority of these animals was found in section H. In August, the 1.8-2.7 m
crocodiles in section G were concentrated in 2 areas: (1) in shallow water
"feeding grounds" that contained abundant Tilapia, and (2) under an active
heronry. Crocodilians have been reported to congregate under bird or bat
colonies (Hopkins 1968, Guggisberg 1972, Messel et al. 1981), presumably to
eat young or adults that fall into the water. January marks the beginning of
the nesting season and therefore the concentration of 1.8-2.7 m crocodiles in
section H (adjacent the nest sites) is not unexpected. Furthermore, the
heronry in section G is not active during this time of year. The shift in the
maximal abundance of these animals then appears to reflect the
concentration of crocodiles in productive feeding grounds during the non-
breeding season, and movement to the vicinity of nesting beaches sometime
prior to January.
Adult males (> 2.7 m) were distributed throughout the lake (excepting
section A), but were found in the highest densities in section E during both
the August and the January surveys. Section E contains a productive,

A- 8 A-6
6-13 B-1
C- I C-
D- 4 D-3

8- 6

0o I 2 3 4~ ,. N. ,8 S E C TIo N 2

D--0 D-
FIGURE 16. Crocodile distribution by- 16

(Size classes as in SECTION CFig. 15).
0 1 2 3 4km N=18 SECTION 8
A-13 N.18

A-4 C-0
I B-0 D-0

FIGURE 16. Crocodile distribution by size class and lakeshore segments, January 1984.
(Size classes as in Fig. 15).


shallow-water (1-2 m) "feeding ground" and an abundance of Conocarpus for
hiding in during the day, or during periods of rough weather. This area
appears to be where the majority of crocodiles on the western lakeshore

Distribution By Habitat Type

The lakeshore was divided into 11 habitat types, which are listed along
with their relative abundance in Table 24. Following is a brief description of

Sand-grass-mud. Shallow gradient dropoff, sandy beaches,
often ephemeral or constantly changing in conformation, or
mudflats. Usually exposed to wave action, often
accumulating Batophora wrack.
Salicornia flats. Restricted to the extreme southeastern end of
the lake. Shallow gradient mud shores covered with
Salicomia perennis.
Conocarpus flats. Shallow water areas supporting dense or
sparse growths of low stature Conocarpus erectus.
Seepage marsh. Shoreline marsh areas, identified by the
presence of freshwater vegetation, in areas where
underground seepage of freshwater occurs.
Canal marsh. Freshwater marsh around the mouth of
irrigation runoff canals feeding into the lake.
Conocarpus fringe. Moderate gradient shoreline fringed with
Conocarpus that may grow out into shallow water, often on
partially submerged sandbars, creating small protected
Acacia scrub. Moderate gradient sandy or somewhat rocky
shores where the xeric upland floral association extends
down to the lakeshore.
Rocky shore, medium gradient. Medium dropoff rocky shores
usually backed by xeric vegetation.
Submerged forest. Found only on the eastern shore south of
Las Lajas. High stature (to 10 m) Conocarpus forest
extending 20-50 m into the lake.
Cove. Moderate gradient dropoff, gravel beaches located
between rocky promentories along the north coast.


Rocky shore, steep gradient. Steep gradient dropoff rocky
shores, usually little or no vegetation, usually a high degree
of wave exposure.

The density of crocodiles varied greatly in the different habitat types
(Table 25). A chi-square goodness of fit test indicated the crocodiles were
not randomly distributed throughout the various habitat types. Using a Z
test of the form:
s- o(i)-e(i)

(where s = test statistic, o(i) = observed proportion of crocodiles in habitat i =
oi, e(i) = proportion of the total lake shoreline in habitat i = ei, n = number of
crocodiles observed), the distribution of all crocodiles > 0.9 m was tested on a
habitat by habitat basis against the null hypothesis of random distribution
around the lake. Crocodiles < 0.9 m were not included in this analysis
because they tended to remain in the vicinity of the nesting beaches and
would bias the results towards the Conocarpus fringe habitat that contained
the great majority of the nests. The results of this 2-tailed test show the
habitats where the crocodiles are significantly more abundant than would be
expected according to the null hypothesis (preferred habitats), and the
habitats where they are significantly less abundant (avoided habitats) (Table
26). Preferred habitats included Conocarpus fringe, Conocarpus flats,
Salicomia flats, submerged forest, and canal marsh. Both the medium and
steep gradient rocky shores were avoided.
Three factors determine why crocodiles are more abundant in the
preferred habitats: (1) protection from wave action, (2) food availability, and
(3) nesting habitat. Of these, the single most important factor was the degree
of wave action. Crocodile density in exposed habitats (0.73/km) was much
lower than along moderate exposure shorelines (8.55/km), which in turn had
fewer crocodiles than protected habitats (10.93/km). A similar avoidance of
wave action has been noted for C. acutus (Ogden 1978, Mazzotti 1983) and
other crocodilians (Cott 1961, Graham 1968, Woodward and Marion 1978,
Messel et al. 1981). Because of the proximity of the eyes and nostrils to the
surface of the water in a floating crocodile, any appreciable wave amplitude
would interfere significantly with respiration and visibility. Wave action also
makes movement more difficult and probably interferes significantly with
feeding activity.
The preference for Salicornia flats (100% protected) and Conocarpus
flats (83% moderate exposure, 17% protected) to some degree reflects this
avoidance of wave action. However, these areas also were adjacent to
productive shallow water areas that appeared to be favored feeding grounds
for adults.


The submerged forest habitat was considered to be 100% moderately
exposed to wave action, although areas well protected from wave action were
located back within the vegetation. The major attraction of this habitat was,
however, the presence of the active rookery with an estimated 300-400 pairs
of egrets, herons, and ibises. Throughout the 3.2 km of this habitat type,
crocodiles were seen only under or adjacent to the rookery. The rookery was
not active during the January survey, consequently the submerged forest was
not a preferred habitat during this time.
In January, the preferred habitats switched to canal marsh and
Conocarpus fringe. Crocodiles apparently were attracted by the cover offered
by the freshwater vegetation around the canals and always were found in high
densities in or around these marshes. One of the two areas of canal marsh
habitat type provided the only suitable crocodile habitat over 5 km of
shoreline near Fonds Parisien, and so tended to concentrate crocodiles.
Although crocodiles were found in high densities in these areas, the small
amount of canal marsh did not make this an important habitat for the
The preference for Conocarpus fringe in January reflects the
congregation of adult crocodiles around the nesting beaches during this time
of year. The majority of the crocodiles seen in this habitat during January
were 1.8-2.7 m individuals, composed primarily of adult females. Of these,
85% were seen adjacent to nesting beaches.
Habitats avoided by the crocodiles typically were those exposed to wave
action and offering no suitable cover. Crocodiles were rarely seen along steep
or medium gradient rocky shores. Crocodiles also typically shunned the
exposed sand-grass-mud habitats, although this did not show up as significant
because of the tendency of some crocodiles, especially subadults (0.9-1.8 m)
to use isolated patches along these shorelines (spring mouths and Conocarpus
clumps). In fact, using the combined August and January surveys, the sand-
grass-mud habitat is actually one of the "preferred" subadult habitats (Table
27). The relatively large number of 0.9-1.8 m crocodiles in this marginal
habitat supports the suggestion of possible exclusion of some of the subadult
population from more favored habitats.



Currently, there are few laws pertaining to wildlife in Haiti, and none
concerning crocodiles. Although laws should be enacted affording protection
to species currently endangered with extinction, the mere presence of laws


protecting wildlife would have little effect (besides symbolic) as the arm of the
government that deals with wildlife (Bureau des Ressources Forestieres et de
la Production de la Faune, D6partement de L'Agriculture des Ressources
Naturelles et de D6veloppment Rural) currently is so understaffed that
effective protection could not be achieved. Furthermore, the nature of most
of the human-related crocodile mortality (accidental drownings in nets or fish
traps) is such that little can be done without making unrealistic attempts to
change fishing techniques and/or fishermen's attitudes towards crocodiles.
Even more troublesome for the crocodiles is the present rate of habitat
destruction. Loss of coastal wetlands and high human population densities
around those that remain have resulted in a sizeable reduction of the range of
the crocodile in Haiti. The continued survival of those few, small crocodile
populations that do remain, as well as that of other coastal wildlife species
will depend on how these wetlands fare in the future. In this respect, perhaps
the most positive step that can be taken would be to initiate a plan for the
management of coastal resources. Because a significant proportion of the
commercially utilized marine species of fish and invertebrates depend, at one
point or another during their lifecycle, on mangrove ecosystems, the plan
should, at the very least, include fisheries and mangrove harvest. The primary
objectives of such a plan would be to insure the viability of these valuable
coastal ecosystems which provide a livelihood and food for a significant
portion of the Haitian human population. Within the framework of such a
program could be included plans to protect wildlife and some of the critical
habitat on which they depend. The most important region from this
standpoint is the l'Ester area, containing Hispaniola's largest mangrove
swamp. The l'Ester and its environs are the site of considerable fishing
activity and unmanaged mangrove harvest. This area also contains a
significant amount of wildlife including crocodiles, sea turtles, manatees,
flamingos, and wading birds. A trial program of coastal resource
management in the l'Ester region, if successful, could be expanded to include
other coastal areas. Effective protection of the wildlife in coastal Haiti will
depend on obtaining detailed information concerning critical habitats. With
respect to crocodiles, this especially includes nesting beaches and nursery
habitat for the hatchlings. Currently there has been interest shown by two
international development organizations (U.S. Agency for International
Development and the World Bank) in helping to develop programs fostering
coastal resource management in Haiti. It is hoped that if such programs are
developed in Haiti, plans will be made to include a wildlife component.
The creation of wildlife preserves also could be done in conjunction with
the newly established national parks program, currently being coordinated by
the Institute National Haitien de la Culture et des Arts and the D6partement
de L'Agriculture, des Ressources Naturelles et du D6veloppement Rural.
Two areas which should be considered for protection in this regard are the


eastern shore of Etang Saumatre and the Riviere Massacre-Lagon aux Boefs
The eastern shore of Etang Saumatre is uninhabited, and contains
virtually all of the lake's crocodile nesting areas. Additionally, this region
supports a diversity of other wildlife including wading birds, ospreys, and a
significant number of migratory waterfowl and shorebirds. Protection of this
area easily could be accomplished as the vast majority of the land is owned by
the Haitian government. Because this land parcel borders on the Dominican
Republic, a degree of international cooperation will be necessary if this plan is
to prove effective. As the land is isolated from the rest of Haiti by water, and
boats are prohibited from the lake (because of past smuggling), the area is
inaccessible to Haitians. Aside from this, the lack of freshwater prevents any
extensive human settlement. Currently, the only use of this land is by
Dominican ranchers who graze their cattle and goats seasonally along the
Another, more insidious, problem in Etang Saumatre is the shooting of
adult crocodiles by Dominican (and Haitian) border guards. As both the
border stations are adjacent to calm water areas regularly used by crocodiles,
the shooting has been a steady drain on the crocodile population. During a
10-month period, at least 2 adult male crocodiles were shot by Dominican
guards (the males are preferentially taken because the penis is used as an
aphrodisiac). Based on a high and low estimate of 2-4 crocodiles taken in this
manner every year, this represents a loss of 10-20% of the adult male
population each year. This action is clearly illegal as the government of the
Dominican Republic has officially declared the crocodile to be fully protected.
Efforts should be made to put a stop to this unnecessary killing by bringing it
to the attention of the superiors of the army personnel involved.
The Riviere Massacre, along the northeastern border with the
Dominican Republic, contains Haiti's only riverine mangrove ecosystem.
Crocodiles are found both in the river and in adjacent Lagon aux Boefs. The
region surrounding these habitats is sparsely inhabited, and recently the
Dominican Republic has declared the eastern bank of the river to be a
national park. A joint Haitian-Dominican Republic project would be most
effective in affording protection to the crocodile.


1. Enact legislation protecting the crocodile.


2. Establish a resource management area in the l'Ester region. Combine
managed harvest of mangrove with protection of the region's wildlife,
including crocodiles, sea turtles, manatees, flamingos, and wading birds.

3. Establish wildlife reserves on the eastern shore of Etang Saumatre and in
the Riviere Massacre/Lagon aux Boefs rea.

4. Stop the illegal shooting of crocodiles in Etang Saumatre by guards at
Dominican Republic border stations.


Prior to its colonization by Western man, probably all low elevation
wetland habitats of any size in Haiti were inhabited by crocodiles. Today, the
range of crocodiles in Haiti has been greatly reduced, with small populations
remaining only in relatively isolated areas, usually associated with mangrove
swamps. The largest remaining population (450 crocodiles of all sizes),
however, is in Etang Saumatre, a landlocked lake in a semi-arid region only
30 km from the capital.
The disappearance of crocodiles from their historical range has followed
a consistent pattern relative to human population density and the amount of
available mangrove habitat. Today, the few remaining populations are found
in areas of low human population density that contain sufficient amounts of
mangrove habitat for cover. An important modifying factor is the availability
of freshwater, which is needed by hatchling crocodiles to maintain an
adequate ion balance. Crocodiles are missing from Haiti's second largest
mangrove area (Caracol Bay) apparently due to a lack of fresh or brackish
water. Because of the tendency of crocodiles, especially subadults (0.9-1.8 m),
to move long distances along the coast, in some areas (such as the southern
coast of the Tiburon Peninsula and Ile de La Gonave) crocodiles are not
infrequently seen over a wide distribution. In these regions crocodiles are
often reported from areas not capable of supporting viable populations, but
appear to be transient individuals. Habitat destruction and incidental killing,
usually in fishermen's nets, represent the greatest threat to crocodiles in Haiti
today. Use of crocodiles for food or their by-products is limited to areas
bordering on the Dominican Republic.
The crude density of crocodiles in Etang Saumatre (6.3/km shoreline) is
relatively high compared to most other published values, although well below
the values estimated for nearby Lago Enriquillo and several other nearly
pristine African populations. This indicates that the population in Etang
Saumatre is below its carrying capacity. In terms of biomass, the mean for the


entire lake is 60.6 kg/km shore, or 92.3 kg/km shore when only considering
areas of suitable habitat (ecological biomass). The sex ratio of animals below
1.8 m total length appears to be skewed towards males, over 1.8 m TL it is 1:1.
Young crocodiles (> 0.9 m TL) grow at an average rate of 0.058 cm/day (21.2
cm/yr), considerably slower than reported values for C. acutus in Florida.
The reason for this slow growth rate is unknown. Compared to mainland
populations, adults do not appear to grow as large in Etang Saumatre. The
largest males seen were approximately 3.5 m TL, females 2.4 m TL.
Nesting in Etang Saumatre is almost entirely restricted to the
uninhabited eastern lakeshore. Nests are exclusively of the hole type,
generally dug in old beaches associated with moderate gradient shoreline
promentories. Soil moisture appears to be the most important factor
determining selection of nest sites. Egg-laying commences in late January, at
the height of the dry season, and lasts approximately three weeks. Hatching
begins in late April, coinciding with the start of the rainy season. Mean clutch
size is low for this species (mean=22.5) and appears to be related primarily to
the small size of the females. During 1983, 21 nests were located, suggesting
that only 63.8% of the adult females nested that year. Egg fertility rate was
90.1%. and natural nest predation was almost non-existent.
Crocodiles were found to be opportunistic feeders. The young subsisted
primarily on the abundant fiddler crabs (Uca bergersii), but also ate a
significant number of beetles and odonate larvae. Larger crocodiles consume
an increasing proportion of vertebrate prey, the adults feeding primarily on
The most important factor determining the distribution of crocodiles in
the lake was the degree of wave exposure. Crocodiles sought out areas that
were well protected from the often intense wave action associated with the
predominant easterly winds. Secondary factors important for adults were the
presence of shallow water feeding areas (both sexes) and the availability of
nesting areas (females during the breeding season).


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Table 1. Mangrove area and crocodile distribution in coastal departments (major islands considered

Department Mangrove area Shoreline Sq km mangrove
(sq km) (km) per km shore

I. Crocodiles present

Nord Est 44.6 60 0.74
Artibonite 93.3 140 0.66
Sud 16.9 230 0.07
La Gondve 11.5 140 0.08
Ile A Vache 16.1 40 0.40

Mean 0.39

II. Crocodiles absent

Nord 13.4 85 0.16
Nord Ouest 0.7 180 0.00
Ouest 7.5 155 0.05
Grande Anse 18.0 235 0.08
Sud-Est 0.0 145 0.00
Ile Tortue 1.1 85 0.01

Mean 0.05

'able 2. Human population density and crocodile distribution in coastal communes and major islands v
historically contained crocodiles.

Crocodiles present Crocodiles extirpated

Commune Population Commune Population
density density
(per sq km) (per sq km)

Ferrier 6 Caracol 10
Terrier Rouge 25 Terre Neuve 51
La GonAve 72 Baraderes 90
Aquin 116 Dame Marie 114
Gonaives 129 Bas Limb6 154
Ile A Vache 158 Petit Goave 229
Grande Saline 171 Limonade 235
Cavaillon 237 Jkr6mie 269
Torbeck 297 Cap Haitien 1079

Mean density = 134.6 Mean density = 247.9


Table 3. Human population density and crocodile distribution for inland communes which historically contained

Crocodiles present Crocodiles extirpated

Commune Population Commune Population
density density
(per sq km) (per sq km)

Ganthier 72 Miragoane 234
Thomazeau 112 Cayes 251

Mean density = 92 Mean density = 243

Table 4. Crocodile population status and ecological life zone.

Crocodiles present Crocodiles extirpated

Location Life Zone Location Life Zone

Tiburon Peninsula,
Laboreaux to Capolo dry Caracol moist

Tiburon Peninsula,
St. Louis du Sud- Tiburon Peninsula,
I'Acul moist north and west coasts moist

lie a Vache moist La GonAve (eastern) moist

La Gonave (western) dry Caracol dry

Artibonite dry Etang Laborde moist

I'Ester dry Etang Miragoane moist

Riviere Massacre-
Lagon aux Boefs dry

Etang Saumatre-
Trou Caiman dry


Table 5. Wilcoxon-rank analysis of coastal crocodile distribution in relation to human population density and
amount of mangrove habitat. Arrondissements and major islands which historically contained crocodiles.

Arrondissement Population Mangrove Combined Crocodiles
or island rank rank rank present

Gonaives 4 3 1 yes
La GonAve 3 8 2.5 yes
Trou-du-Nord 9 2 2.5 no
Ft. Liberty 1 12 4 yes
Nippes 7 6 5 no
Dessalines 13 1 6 yes
St. Marc 5 11 7 yes
Aquin 10 7 8.5 yes
lie A Vache 12 5 8.5 yes
Tiburon 2 16.5 10 no
Grande Anse 6 13 11 no
Limbe 11 10 12.5 no
Cap Haitien 17 4 12.5 no
Port-au-Prince 14 9 14.5 no
Port-de-Paix 8 15 14.5 no
LeogAne 15 14 16 no
Borgne 16 16.5 17 no

Note: Arrondissements (the next largest political subdivision above Communes) were used in this analysis as habitE
area data were not available for Communes.


Table 6. Chemical analyses of lake water. Etang Saumatre.



1. Total dissolved Solids (ppm) 7432 10296 12700 11606
2. Conductivity (mohm/cm) ---..... ----- 20000 18500
3. Dissolved oxygen ----- ----- 6.2 8.1-8.6
4. total phosphate ----- ----- 0.028 0.35
5. Nitrate trace ----- ----- 3.9
6. Ca 94 127 ----- 118.8
7. Mg 279 393 ----- 498.9
8. Na 2159 ----- 3180.0
9. K 3040 ----- 86.0
10. CI 3660 5154 ----- 6098.0
11. SO04 711 1001 ----- 500.0
12. C03 46 24 ----- 0.0
13. HCO3 161 223 ----- 348.7
14. Fe 0.48 trace ----- -----
15. PH ----- 8.5 7.6 8.1
16. Transparency (m) ----- 3.25 2.0-3.6 ---

* Sources:
A = Woodring et al. 1921
B = Bond 1935
C = DARNDR 1979
D = K. Lekkerkerker pers. comm.

Note: In 1921 and 1933 values for Na and K were combined

Table 7. Sex ratio by size class: Etang Saumitre.

Size class (m) Males Females Males/Females

0.3-0.9 16 10 1.60
0.9-1.8 8 5 1.60
1.8-2.7 5 7 0.71
>2.7 3 0 ----


Table 8. Crocodilian density estimates.

Species Density
Location (per km) Source

Crocodylus niloticus

Awash River

Lake Margherita
Blue Nile
Omo River



Lower Semiliki River
Lake Albert
Albert Nile
Victoria Nile

Lake Turkana
Upper Lorian Swamp

Grumeti River

Crocodylus porosus

Australia: Northern Territory

Western Australia

Kimberly System
Cape York



Crocodylus porosus-novaguineae

Papua New Guinea:


Alligator mississippiensi


Etang Saumdtre



crude density
ecological density


Sources: a = Cott and Pooley 1971
b = Parker and Watson 1970
c = Watson et al. 1971
d = Graham 1968

e = Messel et al. 1982a
f = Montague 1983
g = This study
h = Wood and Humphrey 1983

Note: Figures for Messel et al. 1982 are 95% confidence intervals for non-hatchling crocodiles.





Crocodylus acutus


Table 9. Size class contribution to total population biomass: Etang Saumitre.

Size class (m) Biomass (kg) Percent of total biomass

0.3-0.9 201.1 4.2
0.9-1.8 370.4 7.8
1.8-2.7 2,046.6 43.2
> 2.7 2,123.7 44.8

Total 4,741.8 100.0

Table 10. Summary of reported wild crocodile growth rates (cm/day).

Age class
Species Location Growth rate Source


Crocodylus acutus Florida 0.158 a
0.112 b
0.118 c

Crocodylus porosus Australia 0.188 d
0.100-0.120 e
1-2 Years

Crocodylus acutus Florida 0.107 a

Crocodylus porosus Australia 0.076 e

3-4 years

Crocodylus porosus Australia 0.063 e

Sources: a = Gaby et al. 1981 d = Magnusson 1978
b = Mazzotti 1983 e = Messel and Vorlicek in press
c = Moler pers. comm.

Table 11. Reported values of annual breeding effort for adult female crocodilians.

Species Location % breeding Source

Alligator mississippiensis Louisiana 68.1 Chabreck 1966
Crocodylus niloticus Zambia 80.0 Cott 1961
Botswana 67.0 Blomberg 1982
Kenya 87.6 Graham 1968
Crocodylus acutus Florida 72.0 Mazzotti 1983
Haiti 63.8 This study
Crocodylusjohnsoni Australia 90.0 Webb et al. 1983


Table 12. Nest hole dimensions (cm): Etang Saumitre.

Dimension Mean deviation Range N

Depth to top of clutch 24.1 4.7 16-33 13
Depth to bottom of clutch 37.9 4.3 30-45 13
Egg chamber width 32.4 4.3 28-42 12

Table 13. Summary of nest site and null site parameters for Etang Saumftre.

Parameter Nest/Null Mean deviation Range N

Distance from lake (m) nest 27.5 11.8 7-47 31
null ----- ----- ----- --
Height above lake (m) nest 1.2 0.5 0.6-2.1 31
null 0.6 0.4 0.3-1.5 15
Soil pH nest 6.2 1.6 5.2-7.1 15
null ... --- ---- --
Soil moisture (% water) nest 6.62 3.13 3.4-14.3 12
null 20.33 5.01 6.25-28.57 15
Percent shrub/tree coverage nest 30.1 14.5 10-60 29
null 40.6 34.3 0-90 15
Percent grass cover nest 5.9 5.8 0-20 29
null 40.0 35.1 0-100 15
Percent leaf litter cover nest 18.4 8.6 10-30 29
null 8.0 9.4 0-30 15
Height of vegetation (m) nest 3.4 0.6 2.0-4.5 27
null 3.0 1.1 0.0-4.5 15
Distance to nearest tree nest 2.1 1.1 0.5-5.0 27
null 2.7 2.7 1.0-8.0 15

Table 14. Soil water content: nests vs adjacent holes.

Soil moisture (percent water)

Nest Nest Adjacent hole Difference

84-1 9.67 3.92 -5.75
84-2 4.55 3.50 -1.05
84-8 6.32 3.17 -3.15
84-11 4.29 1.45 -2.84


Table 15. Incidence of vegetation over 1 m tall within a 5 m radius of 25 nest sites.

Species % Species %

Acacia famesiana 88 Prosopis juliflora 28
Conocarpus erectus 72 Lemaireocereus hystrix 8
Pithecellobium circinale 32 Consolea moniliformis 4
Guaicum officinale 28 Neoabbottia paniculata 4

Table 16. Number of nests at nesting beaches Etang Saumitre 1983-1984.

Nesting 1983 1984 Nesting 1983 1984
Beach Nests Nests Beach Nests Nests

A 3 2 H 1 0
B 2 3 I 1 0
C 2 2 J 1 0
D 3 2 K 0 1
E 2 1 L 1 0
F 1 1 M 1 0
G 2 0

Table 17. Egg clutch data: Etang Saumitre.

Parameter Mean deviation Range N

Clutch size 22.5 2.7 17-28 14
Egg mass (g) 97.0 8.1 80-116 68
Egg dimensions (mm)
width 45.4 1.00 42.4-48.8 83
length 76.5 3.28 70.7-82.4 83
Clutch fertility (%) 90.1 10.5 70.6-100.0 7


Table 18. Reported clutch sizes for Crocodylus acutus.

Location size N Source

Florida 39.3 8 Mazzotti 1983
39.1 8 Lutz and Dunbar-Cooper 1982
44 20 Ogden 1978
Colombia 40-60 -- Medem 1981
Panama 46 1 Breder 1946
Honduras 22 1 Schmidt 1924
Dominican Republic 23.8 80 Inchaustegui et al. 1980
Haiti 22.5 14 This study
Mexico 30-60 -- Alvarez del Toro 1974

Table 19. Nest temperature data from six nests at Etang Saumitre.

Average clutch temperature Temperature range

Nest Top Bottom Mean Top Bottom

84-1 29.1 29.3 29.2 28.8-29.4 29.1-30.1
84-2 30.1 30.2 30.1 29.9-30.5 30.0-30.5
84-4 29.5 29.2 29.3 28.8-30.6 29.0-29.6
84-7 28.9 29.2 29.0 28.5-29.4 29.0-29.5
84-8 28.9 29.1 29.0 28.7-29.5 28.9-29.3
84-11 29.1 29.3 29.2 28.8-29.5 29.1-29.6


Table 20. Crocodile diet by frequency in stomach samples.

Crocodile size class

<0.5 m 0.5-0.9 m 0.9-1.8 m >1.8 m
Prey item (N=14) (N=43) (N=7) (N=2)

Crustacea 85.7 90.7 71.4 0.0
Coleoptera 78.6 72.1 14.3 0.0
Odonata 64.3 46.5 42.9 0.0
Arachnida 28.6 30.2 42.9 0.0
Scolopendera 21.4 2.3 0.0 0.0
Hymenoptera 14.3 4.6 0.0 0.0
Lepidoptera 21.4 0.0 0.0 0.0
Amphipoda 14.3 0.0 0.0 0.0
Gerridae 7.1 0.0 0.0 0.0
Mantidae 0.0 2.3 0.0 0.0
Osteichthyes 0.0 11.6 0.0 100.0
Reptilia 0.0 2.3 0.0 0.0
Aves 0.0 2.3 28.6 50.0
Mammalia 0.0 11.6 14.3 0.0
Nematodes 35.7 39.5 57.1 50.0
Gastroliths 0.0 13.9 28.6 50.0
Vegetation 87.5 67.4 57.1 50.0

Table 21. Diet based on percent of mass of fresh and partly digested food items.

Crocodile size class

< 0.5 m 0.5-0.9 m 0.9-1.8 m
Food item (N=8) (N=28) (N=5)

Crustacea 33.5 62.3 32.6
Odonata 0.0 10.3 35.3
Coleoptera 0.0 8.9 0.0
Arachnida 4.0 4.9 14.5
Hymenoptera 25.0 0.5 0.0
Gerridae 12.5 0.0 0.0
Amphipoda 25.0 0.0 0.0
Osteichthyes 0.0 9.3 0.0
Aves 0.0 0.0 17.7
Reptilia 0.0 3.5 0.0

Table 22. Prey items identified from the stomach contents or observed ingestion by crocodiles from Etang Saumatre

Terrestrial prey

I. Class Insecta


Bothynus sp. (Scarabeidae)
Cyclocephala sp. (Scarabeidae)
Phyllophaga sp. (Scarabeidae)
Conerus sp. (Elateridae)
Pyrophorus sp. (Elateridae)
Lagocheirus sp. (Cerambycidae)
Chrysobothris sp. (Buprestidae)
Selenophorus sp. (Carabidae)
Calosoma sp. (Carabidae)
Cicmdela sp. (Cicindelidae)
Acalles sp. (Curculionidae)
Artipus sp. (Tenebrionidae)


II. Class Crustacea


Tethorchestia sp. (Talitroidae)

III. Class Chilopoda

Scolopenera alternans

IV. Class Arachnida

Tetragnatha sp. (Araneidae)

VII. Class Aves

Dulus dominicus (Dulidae)
Gallus gallus (Gallidae)

IIX. Class Mammalia

Mus musculus (Muridae)
Rattus sp. (Muridae)
Capra hircus (Capridae)
Canis familiaris (Canidae)

Aquatic prey

I. Class Insecta

Tropisternus sp. (Hydrophilidae)



Macrodiplax sp. (Libellulidae)
Brachymesia sp. (Libelullidae)

II. Class Crustacea

Uca bergersii (Ocypodidae)

III. Class Arachnida


IV. Class Osteichthyes

Limia sp. (Poeciliidae)
Gambusia hispaniole (Poeciliidae)

V. Class Reptilia

Trachemys decorate


Table 23. Crocodile density (per km) in Etang Saumfitre by shoreline section and size class.

Size class (m)

Shore section 0.3-0.9 0.9-1.8 1.8-2.7 >2.7 Total

August survey

0.49 0.00
2.00 0.29
1.26 0.10
1.07 0.13
1.86 3.02*
0.56 0.09
5.28 0.83
13.36* 1.00


25.88 5.46 2.78 2.17

0.37 0.00 0.00 0.00
2.14 0.00 0.43 0.00
0.87 0.10 0.19 0.19
0.80 0.00 0.00 0.13
2.33 1.86* 1.16 0.46*
0.28 0.09 0.28 0.00
7.36 0.56 1.39 0.14
13.56* 0.87 1.43* 0.19

27.71 3.38

4.88 1.11

* denotes highest density for that size class


January survey



Table 24. Shoreline habitat categories and amount of each habitat type.

Shoreline occupied Percent lake
Habitat type (km) shoreline

Sand-grass-mud 3.5 4.92
Salicornia flats 2.9 4.07
Conocarpus flats 8.9 11.94
Seepage marsh 3.6 5.10
Canal marsh 0.4 0.56
Conocarpus fringe 17.2 24.72
Acacia scrub 9.5 13.34
Rocky shore, medium gradient 5.6 7.87
Submerged forest 3.2 4.49
Cove 0.6 0.84
Rocky shore, steep gradient 15.8 22.19

Total 71.2 100.00

Table 25. Crocodile density by habitat type.

Survey Density Mean density
Habitat date (per km) (per km)

Sand-grass-mud August 3.14
January 1.14 2.14
Salicomia flats August 6.21
January 9.65 7.93
Conocarpus flats August 8.54
January 8.54 8.54
Seepage Marsh August 4.44
January 3.61 4.03
Canal marsh August 17.50
January 25.00 21.25
Conocarpus fringe August 14.77
January 14.24 14.51
Acacia scrub August 2.63
January 1.89 2.26
Rocky shore medium gradient August 0.36
January 1.07 0.72
Submerged forest August 3.44
January 2.19 2.82
Cove August 8.33
January 0.00 4.17
Rocky shore steep gradient August 0.13
January 0.19 0.16


Table 26. Preferred and avoided habitat types, subadult and adult crocodiles (> 0.9 meters).

Preferred habitats Avoided habitats

Salicomia flats Rocky shore, medium gradient
August Conocarpus flats Rocky shore, steep gradient
Submerged forest

Canal marsh Rocky shore, steep gradient
January Conocarpus fringe

Table 27. Preferred and avoided habitats of subadult crocodiles (0.9-1.8 m):
combined survey data.

Preferred habitats Avoided habitats

Sand-grass-mud Rocky shore, steep gradient
Salicornia flats
Conocarpus flats



Distribution of Mangrove in Haiti

Haiti, with a shoreline of 1525 km, has approximately 22,300 ha of mangrove forest.
While composing only 0.8% of the country's area, mangroves constitute what is probably the
least disturbed natural forested ecosystem type in Haiti today. Although mangroves are
scattered around the coast in association with sheltered bays, estuaries, and coastal lagoons,
approximately 40% (9000 ha) of the mangrove habitat is concentrated in the l'Ester-
Artibonite region. Taken together, the four largest mangrove forests contain 70.6% of the
mangrove habitat (see below).
Lugo and Snedaker (1974) have developed a classification of mangrove forest types
based on physiognomic characteristics. Using this system, the majority of the mangroves in
Haiti fall into the fringe mangrove category, growing in relatively protected areas and
receiving little freshwater influx. A similar situation has been described by Lugo and Cintron
(1975) in Puerto Rico, where fringe mangroves dominate in protected areas that are located
in the subtropical dry forest live zone. Lugo and Cintron (1975) noted that in areas with
greater rainfall and wave exposure basin and riverine mangroves tended to dominate.
Similarly, in Haiti, the four largest fringe forests (l'Ester, Baie de Caracol, Port-au-
Prince, and Aquin) are located in relatively low wave-energy areas which receive less than 100
cm of rain annually (subtropical) dry life zone of the Holdridge system). Basin forests are
typically located in the subtropical moist zone (100-200 cm rain annually) and generally along
high energy shorelines.


Appendix I continued. List of major mangrove swamps in Haiti.

Area Country Forest
Location (ha) total type

I. North coast
A. Ft. Liberty area
1. Riviere Massacre 60 0.27 R,B
2. Coastal 70 0.31 B,F
2. Baie de Ft. Liberty 340 1.52 F,B
B. Baie de Caracol 3,990 17.84 F
C. Cap Haitien 760 3.40 B,F
D. Limb6
1. Baie de l'Acul 480 2.15 F,B
2. Riviere Limb6 100 0.45 B
E. Port-de-Paix 70 0.31 B
II. West Coast
A. Anse Rouge 350 1.57 F
B. I'Ester 8,490 37.97 F
C. Artibonite 490 2.19 F,B
D. Port-au-Prince 670 3.00 F
III. Tiburon Peninsula
A. Petit GoAve 50 0.22 F
B. Trouin 70 0.31 B
C. Miragoane 350 1.57 F
D. Baraderes 1,200 5.37 F,B
E. St. Jean du Sud 180 0.81 F
F. Cayes area
1. Marsay 140 0.63 F,B
2. Cavaillion 350 1.57 B
3. Mombin 60 0.27 B
4. Riviere Millionaire 80 0.36 B
5. Scattered coastal 400 1.79 F,B
G. Aquin 490 2.19 F
IV. Satellite islands
A. Ile Tortue 110 0.49 F
B. Ile la GonAve 1,150 5.14 F
C. Grand Caymite 250 1.12 F
D. Ile a Vache 1,610 7.20 B

Total area 22,360

* Mangrove forest types: F = fringe; B = basin; R = riverine.



Aquatic and Semiaquatic Avifauna, Native Fish Fauna, and the Dry Forest Vegetative Association of
Etang Saumatre

Common name Scientific name Family


Pied-billed grebe
Great blue heron
Green heron
Little blue heron
Great egret
Snowy egret
Tricolored heron
Yellow-crowned night heron
Black-crowned night heron
Least bittern
Glossy ibis
West Indian tree duck
Northern pintail
Bahama pintail
Blue winged teal
American widgeon
Lesser scaup
Ruddy duck
Masked duck
Purple gallinule
Common gallinule
Caribbean coot
Northern jacana
Semipalmated plover
Thick-billed plover
Black-bellied plover
Ruddy turnstone
Black-necked stilt
Spotted sandpiper
Greater yellowlegs
Lesser yellowlegs
Least sandpiper
Western sandpiper
Laughing gull
Least tern
Royal tern
Caspian tern
Belted kingfisher

Podilymbus podiceps
Ardea herodias
Butorides viridescens
Florida caerulea
Casmerodius albus
Egretta thula
Hydranassa tricolor
Nyctanassa violaceae
Nycticorax nycticorax
Ixobrychus exilis
Plegadis falcinellus
Phoenicopterus ruber
Dendrocygna arborea
Anas acta
Anas bahamensis
Anas discors
Anas americana
Aythya affinis
Oxyura jamaicensis
Oxyura dominica
Pandion haliaetus
Porphyrula martinica
Gallinula chloropus
Fulica caribeae
Jacana spinosa
Charadrius semipalmatus
Charadrius wilsonia
Charadrius vociferous
Pluvialis squatarola
Arenaria interpres
Himantopus mexicanus
Actitis macularia
Tringa melanoleuca
Tringa flavipes
Calidris minutilla
Calidris mauri
Larus atricilla
Sterna albifrons
Thalasseus maximus
Hydroprogne caspia
Ceryle alcyon




Scientific name



Cichlasoma hatiensis
Cyprinodon bondi
Gobionellus sp.
Dormitator maculatus
Strongylura notata
Limia tridens
Limia melanonotata
Gambusia hispaniolae

Cichl id ae


Prosopis juliflora
Acacia famesiana
Bursera simaruba
Guaicum officinale
Phyllostylon brasiliensis
Zizyphus rignoni
Pithecellobium circinale
Haematoxylum campechianum
Calotropis procera
Comocladia dodonaea
Consolea moniliformis
Neoabbotia paniculata
Lemaireocereus hystrix
Harrisia divaricata




Survey Correction Procedure

1. Base estimate produced from the number of crocodiles observed during night-time
boat surveys.
2. Known animals (0.3-0.9 m, 0.9-1.8 m) not seen during the surveys were added.
3. Correction for reduced sightability:
A. Mean of three test boat surveys along densely vegetated shore, where the
actual number of crocodiles was determined by surveying the area on foot
with a spotlight, revealed that only 50% of the 0.3-0.9 m and 0.9-1.8 m
crocodiles in these areas were observed from the boat at night. As larger
crocodiles tended to avoid these densely vegetated, shallow water areas, it
was assumed that reduced sightability from dense vegetation had no effect
on the sightability of crocodiles over 1.8 m.
B. The amount of densely vegetated shoreline was estimated from aerial
photographs of the lake.
C. Counts of 0.3-0.9 m and 0.9-1.8 m crocodiles were increased 50%,
proportionately between the two size classes, along all densely vegetated
4. Line transects were conducted through two especially dense habitats during January
1984 (Trou Caiman Canal swamp, East Bay Swamp). These data were used, rather
than reduced sightability estimates, to determine the number of 0.3-0.9 m and 0.9-1.8 m
crocodiles in these habitats.
A. Line transects were conducted by walking slowly through the area at night,
following a single compass direction as closely as possible. Crocodiles were
spotted using a headlamp (4v, Mine spot) and their perpendicular distance
to the transect line was estimated. In this manner the transect width was
estimated to be 50 m.
B. Calculation of total transect area was done by multiplying transect width
(50 m) by the length (number of strides x 0.6 m). Transect width, divided
by the total area being surveyed (determined from 1:25,000 topographic
maps) provided an estimate of the fraction of the total area that was

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