• TABLE OF CONTENTS
HIDE
 Front Cover
 Title Page
 Table of Contents
 Acknowledgement
 List of Tables
 List of Figures
 Executive summary
 Introduction
 Distribution and abundance
 Reproductive ecology
 Habitat associations within Caracara...
 Movements and habitat associations...
 Foraging ecology
 Other
 Discussion and conclusions
 Management implications and...
 Literature cited
 Appendices/news-clippings






Group Title: Florida Cooperative Fish and Wildlife Research Unit Research Work Order 114
Title: Habitat associations, reproduction, and foraging ecology of Audubon's Crested Caracara in South-central Florida
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Permanent Link: http://ufdc.ufl.edu/UF00073777/00001
 Material Information
Title: Habitat associations, reproduction, and foraging ecology of Audubon's Crested Caracara in South-central Florida
Physical Description: vii., 138 p. : ill. ; 28 cm.
Language: English
Creator: Humphrey, Stephen R
Morrision, Joan L
Publisher: Florida Fish and Wildlife Conservation Commission
Place of Publication: Tallahassee FL
Publication Date: <2000>
 Subjects
Subject: Crested caracara -- Ecology -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references (p. 118-129).
Statement of Responsibility: Stephen R. Humphrey, Joan L. Morrison.
General Note: "Submitted as Final Report for Project E-1 III-1-4, report submitted August 1997."
General Note: "June 2000."
Funding: This collection includes items related to Florida’s environments, ecosystems, and species. It includes the subcollections of Florida Cooperative Fish and Wildlife Research Unit project documents, the Sea Grant technical series, the Florida Geological Survey series, the Coastal Engineering Department series, the Howard T. Odum Center for Wetland technical reports, and other entities devoted to the study and preservation of Florida's natural resources.
 Record Information
Bibliographic ID: UF00073777
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved, Board of Trustees of the University of Florida
Resource Identifier: aleph - 002755634
oclc - 48086076
notis - ANN3577

Table of Contents
    Front Cover
        Front cover
    Title Page
        Title page
    Table of Contents
        Table of contents
        Table of contents
    Acknowledgement
        i
    List of Tables
        ii
    List of Figures
        iii
        iv
    Executive summary
        v
        vi
    Introduction
        Page 1
        Page 2
        Objectives
            Page 3
        Study area
            Page 4
            Page 5
            Page 6
            Page 7
    Distribution and abundance
        Page 8
        Objectives
            Page 8
        Methods
            Page 8
        Results
            Page 8
            APAFR
                Page 9
                Page 10
                Page 11
                Page 12
    Reproductive ecology
        Page 13
        Objectives
            Page 13
        Methods
            Page 13
        Results
            Page 13
            Page 14
            Territorial occupancy and breeding rates
                Page 15
            Breeding chronology
                Page 16
            Reproduction parameters
                Page 16
            Reproductive success and productivity
                Page 17
            Nest failure
                Page 18
            Site fidelity of adults
                Page 19
                Page 20
                Page 21
                Page 22
                Page 23
                Page 24
                Page 25
                Page 26
                Page 27
                Page 28
    Habitat associations within Caracara territories
        Page 29
        Objectives
            Page 29
        Methods
            Page 29
            Page 30
            Page 31
            Page 32
            Page 33
            Page 34
        Results
            Page 35
            Characterization of habitat at the nest site
                Page 35
                Page 36
            Adult home ranges
                Page 37
            Habitat use vs. availability in APAFR territory
                Page 38
            Habitat composition in areas surrounding caracara sightings at APAFR
                Page 39
            Territory dispersion
                Page 40
            Nesting success, habitat associations, and patterns of land use
                Page 40
                Page 41
                Page 42
                Page 43
                Page 44
                Page 45
                Page 46
                Page 47
                Page 48
                Page 49
                Page 50
                Page 51
                Page 52
                Page 53
                Page 54
                Page 55
                Page 56
                Page 57
                Page 58
                Page 59
                Page 60
                Page 61
                Page 62
                Page 63
    Movements and habitat associations of juvenile caracaras
        Page 64
        Objectives
            Page 64
        Methods
            Page 64
            Page 65
        Results
            Page 66
            length of the post-fledging dependency period
                Page 66
            Time to independence
                Page 67
            Exploratory movements
                Page 67
            Sociality among siblings
                Page 68
            Congregations of immatures
                Page 68
                Page 69
                Page 70
                Page 71
                Page 72
                Page 73
                Page 74
                Page 75
                Page 76
                Page 77
                Page 78
    Foraging ecology
        Page 79
        Objectives
            Page 79
        Methods
            Page 79
        Results
            Page 79
            Identification of prey remains and pellet contents
                Page 80
            Roadkill surveys
                Page 81
                Page 82
                Page 83
                Page 84
                Page 85
    Other
        Page 86
        Sexing test using DNA
            Page 86
        Mercury analyses
            Page 86
        Education and public relations
            Page 86
        Papers presented at professional meetings
            Page 87
        Referred publications
            Page 88
    Discussion and conclusions
        Page 89
        Reproduction
            Page 89
        Habitat associations
            Page 90
        Diet and feeding associations
            Page 91
        Tolerance of human activity
            Page 91
        Population status
            Page 92
            Page 93
    Management implications and recommendations
        Page 94
        Page 95
        Page 96
        Page 97
    Literature cited
        Page 98
        Page 99
        Page 100
        Page 101
    Appendices/news-clippings
        Page 102
        Page 103
        Page 104
        Page 105
        Page 106
        Page 107
        Page 108
        Page 109
        Page 110
        Page 111
        Page 112
        Page 113
        Page 114
        Page 115
        Page 116
        Page 117
        Page 118
        Page 119
        Page 120
        Page 121
Full Text





HABITAT ASSOCIATIONS, REPRODUCTION, AND FORAGING

ECOLOGY OF AUDUBON'S CRESTED CARACARA (Caracaraplancus

audubonii) IN SOUTH CENTRAL FLORIDA


Final Report, Research Work Order 114


Principal Investigator:
Graduate Student:


Dr. Stephen R. Humphrey
Joan L. Morrison
Department of Wildlife Ecology and Conservation
University of Florida. Gainesville, FL 32611


Cooperators:
U.S. Fish and Wildlife Service Cooperative
Research Unit
National Biological Service
University of Florida
Gainesville, FL 32611


Environmental Flight
Avon Park Air Force Range
56 SS/CEN
236 South Blvd.
Avon Park, FL 33825














HABITAT ASSOCIATIONS, REPRODUCTION, AND FORAGING ECOLOGY OF
AUDUBON'S CRESTED CARACARA (Caracaraplancus audubonii) IN SOUTH
CENTRAL FLORIDA




Final Report, Research Work Order 114


Principal Investigator:
Graduate Student:


Dr. Stephen R. Humphrey
Joan L. Morrison
Department of Wildlife Ecology and Conservation
P.O. Box 110430
University of Florida, Gainesville, FL 32611


Cooperators:
U.S. Fish and Wildlife Service
Research Unit
National Biological Service
University of Florida
Gainesville, FL 32611


Cooperative


Environmental Flight
Avon Park Air Force Range
56 SS/CEN
236 South Blvd.
Avon Park, FL 33825










TABLE OF CONTENTS


ACKNOWLEDGMENTS i
LIST OF TABLES ii
LIST OF FIGURES iii
EXECUTIVE SUMMARY v
INTRODUCTION 1
Objectives 3
Study area 4
DISTRIBUTION AND ABUNDANCE 8
Objectives 8
Methods 8
Results 8
Study Area 9
APAFR 9
REPRODUCTIVE ECOLOGY 13
Objectives 13
Methods 13
Results 15
Territorial occupancy and breeding rates 15
Breeding chronology 16
Reproductive parameters 16
Reproductive success and productivity 17
Nest failures 18
Site fidelity of adults 19
HABITAT ASSOCIATIONS WITHIN CARACARA TERRITORIES 29
Objectives 29
Methods 29
Results 35
Characterization of habitat at the nest site 35
Adult home ranges 37
Habitat use vs. availability in APAFR territory 38
Habitat composition in areas surrounding caracara sightings at APAFR 39
Habitat composition in adult home ranges throughout the study area 39
Territory dispersion 40
Nesting success, habitat associations, and patterns of land use 40










TABLE OF CONTENTS (cont.)
Page
MOVEMENTS AND HABITAT ASSOCIATIONS OF JUVENILE CARACARAS 64
Objectives 64
Methods 64
Results 66
Length of the post-fledging dependency period 66
Time to independence 67
Exploratory movements 67
Sociality among siblings 68
Congregations of immatures 68
FORAGING ECOLOGY 79
Objectives 79
Methods 79
Results 79
Observations of food deliveries at nests 79
Identification of prey remains and pellet contents 80
Roadkill surveys 81
OTHER 86
Sexing test using DNA 86
Mercury Analyses 86
Education and public relations 86
Papers presented at professional meetings 87
Refereed publications 88
DISCUSSION AND CONCLUSIONS 89
Reproduction 89
Habitat associations 90
Diet and feeding associations 91
Tolerance of human activity 91
Population status 92
MANAGEMENT IMPLICATIONS AND RECOMMENDATIONS 94
LITERATURE CITED 98


APPENDICES









ACKNOWLEDGMENTS


We thank the Avon Park Air Force Range (APAFR) (DOI) for recognizing the
need for research on this little known species and for subsequently funding this study.
We wish to acknowledge the help and support of all personnel of the Environmental
Flight at APAFR. We particularly wish to thank P. Ebersbach, B. Progulske, and P.
Walsh for their continued interest and support. P. Margosian provided many hours of
assistance with the GIS analyses and mapping. S. Penfield, K. Olsen, S. Hanley, S. Van
Hook, and H. Blackburn provided sightings and information about caracaras on the
Range.
We also wish to thank the Nongame Wildlife Program of the Florida Game and
Fresh Water Fish Commission for providing additional funding. B. Millsap, N. Douglas,
and V. Echavez, in particular, provided logistic support, encouragement, and assistance in
the field. We wish to acknowledge the help provided by personnel and staff at the
MacArthur Agro-Ecology Research Center (MAERC) and Archbold Biological Station,
particularly J. Fitzpatrick, H. Swain, T. Bancroft, D. Childs, and G. Lollis. We
particularly appreciated the opportunity live at and to operate this project based out of
MAERC.
We thank V. Dreitz, D. Todd, C. Pages, J. Sanderson, J. Arnett, M. McMillian, M.
Parker, and J. Solomon for field assistance. Special thanks to S. McGehee for his
enthusiasm and untiring field assistance, particularly for finding nests and radiotracking.
We thank the staff at the Department of Wildlife Ecology and Conservation, Institute of
Food and Agricultural Sciences, University of Florida for their efforts to keep our
paperwork processed and bills paid. We thank B. Mealey for loan of Clyde, our research
caracara; C. Facemire for mercury analyses; M. Maltbie and R. Baker for sexing the
caracaras using the blood samples; D. Forrester, M. Spalding, and G. Foster for
processing parasite data; and R. Bowman for providing the Mayfield program. Thanks
also to Jim Wyatt and the pilots of Wyatt Aviation who kept us flying safely during all
the long hours of aerial radiotracking, and to the personnel at Wrenchmasters, who kept
our vehicles running.
Most importantly we thank landowners throughout south-central Florida, who so
generously provided access to their lands. Without their cooperation and support, this
study could not have been accomplished at all.









LIST OF TABLES


Table Title Page
1 Reproductive parameters for study population of Crested Caracaras in 20
south-central Florida, 1993 1996. ND = no data.
2 Mayfield and traditional estimates of nest success for Crested Caracara 21
nests in south central Florida, 1994.
3 Mayfield and traditional estimates of nest success for Crested Caracara 22
nests in south central Florida, 1995.
4 Mayfield and traditional estimates of nest success for Crested Caracara 23
nests in south central Florida, 1996.
5 Evidence of nest failure for Crested Caracara nests in south-central 24
Florida, 1993 1996. N = 38 failures.
6 Banding records for Crested Caracaras captured in south-central Florida, 43
August 1993 July 1996.
7 Home range statistics for 17 (10M, 7F) Crested Caracaras in south-central 49
Florida, 1994 1996.
8 Utilization-availability data and simultaneous Bonferroni confidence 50
intervals for habitat types within the caracara territory along the
Kissimmee River, APAFR.
9 Test of null hypothesis that distribution of exploratory movements by 71
juvenile Crested Caracaras by age in months post fledging, does not
differ from a random distribution.
10 Test of null hypothesis that distribution of exploratory movements by 72
individual juvenile Crested Caracaras by age in months post fledging,
does not differ from a random distribution.
11 Utilization-availability data and simultaneous Bonferroni confidence 73
intervals for habitat types at locations of 38 radiotagged juvenile Crested
Caracaras, 1994 1996.
12 Results of observations of food deliveries at nests. 82
13 A summary of the caracara's diet from preliminary analysis of a 83
subsample of prey remains collected at roost sites in active caracara
territories, 1994- 1995.
14 Comparison of reproductive success estimates among large raptors, 93
particularly some Florida species.










LIST OF FIGURES


Fig. Title Page
1 Geographic distribution of the Crested Caracara (Caracaraplancus). 5
(from Brown and Amadon 1968).
2 The historic range of Audubon's Crested Caracara (C.p. audubonii) 6
in Florida. (from Howell 1932).
3 Study area, including parts of 7 counties in south-central Florida. 7
4 Locations of 4 currently occupied Crested Caracara territories 11
encompassing parts of APAFR, and areas where caracaras were
formerly known to occur on the Range.
5 Sightings of Crested Caracaras at APAFR, 1993 1996. 12
6 Timing of egglaying and reproductive success for Crested Caracara 25
nests in study area in south-central Florida, 1994-1996.
7 Variation in clutch size with laying period. 26
8 Relationship between month of first nest initiation and occurrence 27
of renesting by Crested Caracaras following either an early failure
or a successful first brood, south-central Florida, 1994 1996.
9 Nest failure rate by nest stage for Crested Caracara nests in south- 28
central Florida, 1994 1996
10 Frequency distribution of number of trees in the nest tree group for 51
Crested Caracara nests, south-central Florida, 1994 1996.
11 Relationship between DBH and height of cabbage palms (Sabal 52
palmetto) at Crested Caracara nest sites, south-central Florida,
1994- 1995.
12 Average groundcover height within 100 m of Crested Caracara nests 53
in south-central Florida, 1994 1996.
13 Frequency distribution of distances to cover from the nest tree, averaged 54
for all quadrants.
14 Relationship between number of fixes and 95% MCP estimate of home 55
range area for 19 adult Crested Caracaras in south-central Florida.
15 Relationship between number of radiolocations and maximum range 56
width for Crested Caracaras in south-central Florida, 1994 1996.
16 Home ranges of adult and 2 juvenile Crested Caracaras at APAFR, 57
derived using the 95% MCP method.
17 Radio locations for adult and 2 juvenile Crested Caracaras at APAFR. 58
18 The proportion of habitat types throughout APAFR and within 59
combined areas around each caracara sighting on the Range.










LIST OF FIGURES (cont.)


Fig. Title Page

19 The proportion of habitat types throughout the entire study area 60
and within Crested Caracara home ranges (N = 17).
20 Overlap among 9 Crested Caracara home ranges on Buck Island 61
Ranch, Highlands Co. Home ranges shown as 95% MCP.
21 Relationship between landownership and major land use for Crested 62
Caracara territories in south-central Florida, 1994 1996.
22 Relationships between occupancy, breeding attempt, successful 63
nesting and landownership for 39 Crested Caracara territories,
1994- 1996.
23 Distances from the nest by age in months post fledging for juvenile 74
Crested Caracaras, south-central Florida, 1994 1996.
24 Age at dispersal of juvenile Crested Caracaras, south-central 75
Florida, 1994 1996.
25 Movement pattern of 2 juvenile Crested Caracaras from APAFR by 76
age in weeks post fledging, showing step pattern.
26 Sociality of sibling caracaras. Frequency of locations in which chicks 77
are closer to each other than to the radiotagged adult, on the same day.
27 Dispersal movements of APAFRjuveniles 0.848 and 0.659. Also 78
shown are areas along the Kissimmee River and in large dairies in
southern Glades County where juvenile caracaras congregate.
28 200 mile route for roadkill surveys, throughout the study area. 84
29 Abundance of roadkill and caracaras seen along the regular route 85
within the study area, 1993 1996.
30 Probability of observing a Crested Caracara in a known occupied 97
territory by month, time of day, and nesting stage.
Appendix I Study area as delineated by the land use/land cover data
obtained from the SFWMD. Shown are 81 Crested Caracara
territories and home ranges of 17 adults (10 M, 7 F).
Appendix II Examples of media coverage distributed during the study.











EXECUTIVE SUMMARY


We studied the reproductive ecology, habitat associations, and foraging ecology of
Crested Caracaras (Caracaraplancus audubonii) in south-central Florida, from August 1993
to June 1996. This population is believed to be declining, and is listed as Threatened, both
federally and by the state. Until recently, little empirical data were available to evaluate
population trends or viability within the currently available habitat. This research constitutes
the first in-depth study of this population. The purpose of this study was to elucidate the
caracara's biology and to evaluate its potential for long-term persistence given the rapidly
changing habitat matrix in this part of Florida. Although we collected data at a region-wide
scale, we emphasized the caracaras and habitats at the Avon Park Air Force Range within the
context of the regional population.

We located 81 occupied territories throughout the 7-county study area. We found
only one pair of caracaras nesting on the Avon Park Air Force Range, although we
occasionally saw caracaras in other areas throughout the Range. These areas were along the
Kissimmee River and in Arbuckle Marsh. During 1994, 1995, and 1996, we followed
reproductive success in 29, 49, and 55 territories, respectively, throughout the study area.
Unlike many raptors, year-to-year occupancy and breeding rates for a preselected subsample
of these territories were high, at 100% and 98% respectively. Nesting success, estimated
using the Mayfield method, was also high and averaged 70% among the three years.
Productivity averaged 1.78 young per successful pair. Florida's caracaras have an extended
breeding season, from September through June, although the peak in egglaying occurred in
late January during all years. Pairs can make several nesting attempts per year. Renesting
occurred predictably following a failure early in the season. Double brooding was confirmed
in approximately 10% f the sample population during all 3 years. Although nest failure rates
were generally low, collisions with vehicles were a major cause of mortality for fledglings
and immatures.

Caracaras nested primarily in open habitats, which were characterized by clusters of
palms and oak trees separated by large expanses of open grassland. Groundcover was short
and nest stands contained little shrub or other tall vegetation. Cabbage palms were the
preferred nesting substrate, and nests were strongly oriented towards the southeast. Land
where caracaras were found differed primarily in management regime. On privately-owned
lands, the primary focus was on forage production for cattle. The focus of management on
most publicly-owned lands was to retain natural areas. Differences in management practices
on these lands translate into differences in vegetation structure. Our results suggest that these
differences may translate further into differences in occupancy rates and nesting success
within caracara territories.

We banded 238 Crested Caracaras during this study and radiotagged 39 adults and
116 juveniles. Estimates of home range size made using the 95% harmonic mean contour
averaged around 10 km2, for 17 adults. These contours did not differ between males and
females. Though we documented movements by breeding adults of up to 11 km from the









nest, most activity occurred within 3 km of the nest. Analyses of habitats used showed
preference for pastures, wetlands, palm/oak hammocks, agricultural habitats such as citrus
and dairies, and recently plowed and burned areas. Caracaras take a wide variety of prey as
well as carrion, from a wide variety of habitats.

After fledging from the nest, juvenile caracaras remain within the natal territory and
are dependent on their parents for at least 2 months. If the adults do not have another brood,
the family may stay together for as long as 10 months. After leaving their natal territory,
juveniles may wander widely, but tend to stay in a particular location for some time before
moving on. Eventually, many return to an area not far from their natal territory. Immatures
congregate in groups. We identified certain areas throughout the study area where groups of
up to 30 mixed-age-class individuals are regularly found.

Caracaras are generally tolerant of some human activity and moderate habitat changes
within their territory, as long as the nest site is left intact. Routine levels of activities such as
burning, clearing, and removal of sod are well-tolerated. Caracaras are most sensitive to any
kind of disturbance near the nests during the nestbuilding, incubation, and early nestling
stages. Results of this study suggest that this population may be stable at present. The
greatest threat continues to be loss and degradation of nesting habitat. A conservation
strategy for this population should be based on protecting known nest sites and areas where
immatures congregate. Such a strategy should focus at a regional scale. Management plans
must address effects of habitat loss and degradation, particularly rapid conversion of pastures
to citrus. Because most suitable habitat is in private ownership, habitat protection must
incorporate cooperative efforts between land managers and landowners and include creative
alternatives to direct land purchase. Management efforts should also incorporate a strong
education component to reduce the negative impressions of scavengers and stress the value of
the Crested Caracara as an example of the potential for coexistence of sustainable economic
activities and native wildlife.










INTRODUCTION

In Florida, where widespread habitat fragmentation and loss continue at a rapid rate,
conservation of native biodiversity is of urgent concern. Because of their role as top
predators, birds of prey may serve as indicators of ecosystem health (Hickey 1969). The
Crested Caracara (Caracara plancus), a unique raptor/scavenger, is easily recognizable with
its bold black and white plumage pattern and bright yellow-orange face and legs. Known
locally as "Mexican buzzard", this raptor is most easily observed perched high on a tree or
utility pole within its territory or scavenging alongside vultures on roads and in pastures.
Although often aligned with vultures, the Crested Caracara is actually a member of the falcon
family, Falconidae.

Strictly a bird of the western hemisphere, the Crested Caracara has a fragmented
geographic range. Isolated populations occur in Cuba, the Isle of Youth, and peninsular
Florida. Its continuous distribution extends from southern Texas and Arizona, south
throughout Baja California Sur, parts of Mexico, Central America except Belize, South
America to Tierra del Fuego and various offshore islands (Fig. 1). This species was first
described in the United States in 1831 by John James Audubon, who collected a specimen
near St. Augustine, Florida (Audubon 1840). Named for its founder, Audubon's Crested
Caracara (C p. audubonii; hereafter, caracara) is one of 4 currently recognized subspecies
(American Ornithologists' Union 1983, del Hoyo et al. 1994) and is found in the southern
United States, parts of Mexico and Central America, and Cuba.

In south-central peninsular Florida, the core of the caracara's range conforms closely
to the original distribution of the major prairie ecosystems (Davis 1967, Abrahamson and
Hartnett 1990). Prior to the early 1900s, the caracara's range in Florida may have been larger
than at present, mostly north of its current range (Bryant 1859, Bailey 1925, Howell 1932)
(Fig. 2). Records that suggest a wider earlier distribution include the St. John's River
marshes where they were reportedly common (Maynard 1889, Nicholson 1929), Volusia and
St. Lucie Co. (Howell 1932, Kuerzi 1938), along the Caloosahatchie River (Scott 1892,
Phelps 1912), Enterprise (Allen 1871), West Palm Beach, Indian River City, Orlando,










Manatee River, Duval, Co., Myakka River State Park, Melbourne, and Lake Helen Blazes
(Nicholson 1930, Carbury 1938, Grimes 1944, Sprunt 1954).

In recent decades, native grassland and prairie habitats in south-central Florida have
undergone extensive conversion to urban and agricultural development. Concomitant with
this habitat loss has been the apparent contraction of the caracara's historic range
(Funderberg and Heinzmann 1967, Heinzman 1970, Layne 1978). Results of surveys of
historic territories conducted during the late 1980s and early 1990s indicated as much as a
26% reduction in the number of occupied territories throughout the historic range since the
1970s (Millsap 1989), suggesting that the population may be in a long-term decline.
Conversion or loss of suitable habitat is of concern because habitat structure is known to be
an important factor influencing population dynamics, reproductive effort, and foraging
behavior of raptors (Smallwood 1988).

Based on these findings, in 1987, Florida's population of caracaras was federally
listed as threatened (U.S. Fish and Wildlife Service 1987), followed by a similar state listing
(Wood 1990). In ranking Florida's vertebrate taxa according to biological vulnerability,
Millsap et al. (1989) suggested that the caracara's small population size, restricted range, and
history of population decline may contribute to its vulnerability to extirpation and targeted
the species for future work. Recommendations made by Millsap et al. (1989) highlighted
research into the species' basic life history and habitat requirements as major priorities.

Although a Species Recovery Plan was prepared (U.S. Fish and Wildlife Service
1989), none of its research priorities have been acted upon. The paucity of ecological and
demographic information on this population has precluded accurate assessment of its status,
viability within the extant habitat matrix, or potential for long-term persistence. The caracara
is now believed to be restricted to remnant areas of open grassland habitat on private
ranchlands or within protected areas such as Kicco and Three Lakes Wildlife Management
Areas, the National Audubon Society's Kissimmee Prairie Reserve, and the Avon Park Air
Force Range (APAFR). Erlich et al. (1992) reported that APAFR contains a "primary
portion of the Caracara's range." Because relationships among this raptor and the available
habitat were not well understood, however, research focusing on these issues was urgently










needed. This information is critical for development of management guidelines that address
long-term persistence of this population.

The overall purpose of this study was to elucidate the ecology of Florida's Crested
Caracara population. Although we collected data across much of the population's current
range, we emphasized APAFR's caracaras and habitats within the context of the regional
population. A primary goal was to supply information to resources managers at APAFR in
their efforts towards compliance with the Endangered Species Act and support of the Species
Recovery Plan. An additional goal was to provide management recommendations for
caracara habitat on APAFR. Resource managers can use this information to develop
management guidelines and monitoring methods for caracaras on the Range.

Objectives
Overall study objectives were:

1) to determine the distribution and abundance of caracaras on APAFR and throughout the
study area;
2) to document reproductive activity and evaluate reproductive success;
3) to characterize habitat associations within nesting territories;
4) to evaluate movement patterns and habitat associations of immatures;
5) to determine diet and characterize habitat associations for foraging;
6) to address implications of activities at APAFR as they relate to management and
persistence of caracaras on the Range;
7) to provide management recommendations to the Air Force in support of compliance
with the Endangered Species Act and the Species Recovery Plan.

An additional goal of this project was to provide education regarding the caracara, its
habitats, and the conservation implications of this research. Because many caracaras nest on
private land, the opportunity existed to work closely with regional landowners. Throughout
the project's duration, we maintained regular contact with numerous landowners, prepared
several newspaper and popular magazine articles, and spoke to a variety of public and private
groups. The caracara has become a symbol representing the potential for cooperation
between conservationists and landowners. Such cooperation may enhance opportunities for











both parties to work toward mutually acceptable goals. The outcome of these educational
efforts should be a better understanding of the caracara's ecology and, perhaps, improvement
of its chances for long-term persistence in Florida.

Study Area
The study area encompassed parts or all of 7 counties in the center of the caracara's
historic Florida range: Highlands, Okeechobee, Glades, Osceola, DeSoto, Polk, and Indian
River (Fig. 3). We accessed private lands if permission was obtained. We accessed public
lands where feasible. In this report, we present information on distribution, abundance,
reproduction, and foraging ecology for territories monitored during 1994 1996 in all 7
counties. Land use/land cover data were available only for Highlands, Glades, Okeechobee,
and parts of Polk and Osceola Counties. Therefore, we report data on habitat associations
and results of habitat analyses only for these areas.



























































Fig. 1. Geographic distribution of the Crested Caracara (Caracaraplancus). (from Brown
and Amadon 1968).




























































Fig. 2. The historic range of Audubon's Crested Caracara (C.p. audubonii) in Florida. (from
Howell 1932).









































,3N A


Fig. 3. Study area, including parts of 7 counties in south-central Florida.










DISTRIBUTION AND ABUNDANCE

Objectives
1) to determine distribution ofcaracara territories within the study area;
2) to determine distribution of caracara territories and sightings on APAFR.

Methods
We located occupied caracara territories by visiting sites of known mapped historic
territories (B. Millsap pers. comm., J. Layne pers. comm.) and other areas of potentially
suitable habitat that we found by driving throughout the study area. Systematic sampling of
habitats throughout the population's range was not possible because of access difficulties.
Therefore, the main objective for assessing distribution of caracara territories throughout the
study area was to obtain information on as large and widespread a sample as possible. We
visited each territory beginning in the fall of 1993, 1994, and 1995 and conducted
observations to determine occupancy and locate nests.

On APAFR, beginning in the fall of each year, we searched for nests in areas where
caracaras had been observed within the past 5 years and in other areas of potentially suitable
habitat. We used the same searching methodology as for other sites throughout the study
area. We conducted observations near potential nest sites and covered entire areas on foot to
look into individual cabbage palms (Sabal palmetto). We set out bait in certain areas.
Generally, if caracaras were nesting nearby they approached the bait and carried food to the
nest, which helped us to find it. To elicit assistance in compiling caracara observations on
APAFR, we distributed observation forms to APAFR personnel requesting information on
sightings. All caracara nest locations and sightings were entered into the APAFR GIS
database.

Results
Study Area
Throughout the duration of the study, we identified 81 occupied territories within the
study area (see Appendix I). We obtained data on reproductive ecology and habitat use for
caracaras occupying a subset of these territories each year. These territories only represent a
sample of territories in this region. Due to access limitations; we did not do a complete










DISTRIBUTION AND ABUNDANCE

Objectives
1) to determine distribution ofcaracara territories within the study area;
2) to determine distribution of caracara territories and sightings on APAFR.

Methods
We located occupied caracara territories by visiting sites of known mapped historic
territories (B. Millsap pers. comm., J. Layne pers. comm.) and other areas of potentially
suitable habitat that we found by driving throughout the study area. Systematic sampling of
habitats throughout the population's range was not possible because of access difficulties.
Therefore, the main objective for assessing distribution of caracara territories throughout the
study area was to obtain information on as large and widespread a sample as possible. We
visited each territory beginning in the fall of 1993, 1994, and 1995 and conducted
observations to determine occupancy and locate nests.

On APAFR, beginning in the fall of each year, we searched for nests in areas where
caracaras had been observed within the past 5 years and in other areas of potentially suitable
habitat. We used the same searching methodology as for other sites throughout the study
area. We conducted observations near potential nest sites and covered entire areas on foot to
look into individual cabbage palms (Sabal palmetto). We set out bait in certain areas.
Generally, if caracaras were nesting nearby they approached the bait and carried food to the
nest, which helped us to find it. To elicit assistance in compiling caracara observations on
APAFR, we distributed observation forms to APAFR personnel requesting information on
sightings. All caracara nest locations and sightings were entered into the APAFR GIS
database.

Results
Study Area
Throughout the duration of the study, we identified 81 occupied territories within the
study area (see Appendix I). We obtained data on reproductive ecology and habitat use for
caracaras occupying a subset of these territories each year. These territories only represent a
sample of territories in this region. Due to access limitations; we did not do a complete










DISTRIBUTION AND ABUNDANCE

Objectives
1) to determine distribution ofcaracara territories within the study area;
2) to determine distribution of caracara territories and sightings on APAFR.

Methods
We located occupied caracara territories by visiting sites of known mapped historic
territories (B. Millsap pers. comm., J. Layne pers. comm.) and other areas of potentially
suitable habitat that we found by driving throughout the study area. Systematic sampling of
habitats throughout the population's range was not possible because of access difficulties.
Therefore, the main objective for assessing distribution of caracara territories throughout the
study area was to obtain information on as large and widespread a sample as possible. We
visited each territory beginning in the fall of 1993, 1994, and 1995 and conducted
observations to determine occupancy and locate nests.

On APAFR, beginning in the fall of each year, we searched for nests in areas where
caracaras had been observed within the past 5 years and in other areas of potentially suitable
habitat. We used the same searching methodology as for other sites throughout the study
area. We conducted observations near potential nest sites and covered entire areas on foot to
look into individual cabbage palms (Sabal palmetto). We set out bait in certain areas.
Generally, if caracaras were nesting nearby they approached the bait and carried food to the
nest, which helped us to find it. To elicit assistance in compiling caracara observations on
APAFR, we distributed observation forms to APAFR personnel requesting information on
sightings. All caracara nest locations and sightings were entered into the APAFR GIS
database.

Results
Study Area
Throughout the duration of the study, we identified 81 occupied territories within the
study area (see Appendix I). We obtained data on reproductive ecology and habitat use for
caracaras occupying a subset of these territories each year. These territories only represent a
sample of territories in this region. Due to access limitations; we did not do a complete










DISTRIBUTION AND ABUNDANCE

Objectives
1) to determine distribution ofcaracara territories within the study area;
2) to determine distribution of caracara territories and sightings on APAFR.

Methods
We located occupied caracara territories by visiting sites of known mapped historic
territories (B. Millsap pers. comm., J. Layne pers. comm.) and other areas of potentially
suitable habitat that we found by driving throughout the study area. Systematic sampling of
habitats throughout the population's range was not possible because of access difficulties.
Therefore, the main objective for assessing distribution of caracara territories throughout the
study area was to obtain information on as large and widespread a sample as possible. We
visited each territory beginning in the fall of 1993, 1994, and 1995 and conducted
observations to determine occupancy and locate nests.

On APAFR, beginning in the fall of each year, we searched for nests in areas where
caracaras had been observed within the past 5 years and in other areas of potentially suitable
habitat. We used the same searching methodology as for other sites throughout the study
area. We conducted observations near potential nest sites and covered entire areas on foot to
look into individual cabbage palms (Sabal palmetto). We set out bait in certain areas.
Generally, if caracaras were nesting nearby they approached the bait and carried food to the
nest, which helped us to find it. To elicit assistance in compiling caracara observations on
APAFR, we distributed observation forms to APAFR personnel requesting information on
sightings. All caracara nest locations and sightings were entered into the APAFR GIS
database.

Results
Study Area
Throughout the duration of the study, we identified 81 occupied territories within the
study area (see Appendix I). We obtained data on reproductive ecology and habitat use for
caracaras occupying a subset of these territories each year. These territories only represent a
sample of territories in this region. Due to access limitations; we did not do a complete










census. We believe the population is well-represented by this sample, however, because we
covered such a wide geographic area. The fact that many of these territories and nests were
within 2 km of a major road undoubtedly introduced an element of bias into the study. This
was unavoidable, again due to access limitations.

APAFR
Observations indicated that there are 4 currently occupied caracara territories that
include parts of APAFR. Three territories are along the Kissimmee River on the eastern
Range boundary and one encompasses part of Arbuckle marsh (Fig. 4). We believe that for 3
of these territories, the nests are not on Range lands but are outside the Range boundaries, on
lands we could not access.

1) The nest in the territory in the southeastern corer of the Range (APAFR) was
found in May 1994. It failed during that year. In 1995, the pair successfully fledged 2
chicks from a nest in a different tree. In 1996 they built their nest in the 1994 tree and
successfully fledged 1 chick.

2) In both 1994 and 1995 we observed 2 adult and up to 3 fledgling caracaras along
the river spoil road just south of the Kissimmee campground. When approached, these
individuals always flew across the river to the east, where there is open pasture, palms, and
cattle. We believe the nest in this territory is east of the river. We attempted to trap caracaras
in this territory but were unsuccessful, probably because we were not near the nest.

3) During several days in both 1994 and 1995 we set out bait along the river at the
northern boundary of APAFR (Highlands/Polk Co. boundary). We observed 2 adult
caracaras flying to the bait from the east and returning to that area with food. This again
suggests that the nest is on the east side of the river. We also saw immature caracaras in this
area during both years. We thoroughly searched all palms on the Range side of the river in
this area but did not find a caracara nest.

4) We set out bait and attempted trapping in Arbuckle marsh where APAFR
personnel had seen adult and immature caracaras. When we saw caracaras, they flew in from
and away to the west. We also searched all palms in this area but did not find a nest. We
believe these caracaras are nesting on private ranchlands west of Arbuckle Creek.











There are two additional areas on the Range where caracaras had been observed
nesting or with young during the past 5 years (Fig. 4). Two adults and a juvenile were seen
in the Tick Island Marsh area in 1992 (R. Bowman, pers. comm.). We thoroughly searched
this area and set out bait at least once each year, but never found a nest and did not see any
caracaras. Although a pair attempted nesting in cabbage palms at the south end of the main
runway as recently as 1993 (B. Progulske, pers. comm.), we did not see any adult caracaras in
this area. Despite searching all palms in the area, we did not find a nest. Occupancy of these
2 areas by caracaras seems to be inconsistent and unpredictable, unlike many other territories
throughout the study area.

We found other nests in areas surrounding APAFR. Juveniles from these nests might
use the Range after dispersal. In 1995, we found a nesting pair on Kicco Wildlife
Management Area (WMA) along the Kissimmee River (Fig. 4). This pair may have
reproduced successfully in 1994. In January 1995, we found the pair building a nest in a
palm approximately 0.5 km from the river spoil. In March we found eggshells at the base of
the tree, suggesting that the nest had been depredated. In 1996, the pair was observed
building a new nest in the same tree. Repeated visits to the area in 1995 and 1996 failed to
provide evidence that the pair nested successfully during either of these years. We also found
two nests along SR 60, both within 2 km of the Kissimmee River (see Appendix I). In 1996,
we attached a radiotransmitter to one juvenile from each of these nests. To date, neither has
left their natal territory.

Using GIS, we created a database and maps that incorporated all recorded sightings of
caracaras made on the Range during the period from 1993 through December 1995. We
obtained this information from Bob Progulske, who kept a database of sightings. We
obtained other records from Natural Resources employees and research cooperators who
reported their sightings to us via the sightings report datasheet. Areas of concentrated use are
along the Kissimmee River, along Kissimmee Road at the southern end of Management Unit
4, and in Tick Island Marsh (Fig. 5). Most sightings occurred only once or during a few days
in any particular area. In addition, most of the individuals seen in areas outside known
territories were immatures, suggesting that these individuals were not resident birds.










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REPRODUCTIVE ECOLOGY

Objectives
Low territorial occupancy and annual breeding rates, small clutch sizes, and low
productivity are often attributed to birds of prey (Newton 1979, Steenhofand Kochert 1982),
including caracaras (Runde and Millsap 1990). Particularly for an isolated population, there
is a concern that its long-term persistence and potential for expansion might be limited by
reproduction. The main objective of this part of the study was to evaluate the caracara's
reproductive ecology. We wished to assess whether the reproductive performance of this
population might be a limiting factor to its long-term persistence. Specific objectives were:

1) to evaluate year-to-year territorial occupancy and breeding rates;
2) to document breeding chronology and define various reproductive parameters;
3) to estimate reproductive success and productivity;
4) to determine site fidelity of adults.

Methods
Territory occupancy and breeding rates
Estimates of reproductive rates and nesting success for a population vary according to
data collection methods. Biases can result from the timing of nesting surveys and from
additive inclusion of new pairs found each season. Pairs found late in the season inflate
productivity estimates because proportionately more conspicuous successful breeders are
found during late surveys (Steenhof and Kochert 1982). Along with nest success, territorial
occupancy and breeding rates are often used as indicators of the stability and productivity of
a population (Steenhof 1987). The territorial occupancy rate is the percentage of known
territories that remains occupied from year to year. Breeding rate defines the percentage of
pairs in occupied territories that initiate a breeding attempt.

Estimating territorial occupancy and breeding rates for a set of preselected territories
during several years provides less biased estimates of these parameters for a population
(Steenhofand Kochert 1982, Fraser 1978). This may be particularly true for caracaras
because they are resident and faithful to traditional nesting sites. In 1994, we identified 33
territories for which we collected data on occupancy and breeding rates. We defined











REPRODUCTIVE ECOLOGY

Objectives
Low territorial occupancy and annual breeding rates, small clutch sizes, and low
productivity are often attributed to birds of prey (Newton 1979, Steenhofand Kochert 1982),
including caracaras (Runde and Millsap 1990). Particularly for an isolated population, there
is a concern that its long-term persistence and potential for expansion might be limited by
reproduction. The main objective of this part of the study was to evaluate the caracara's
reproductive ecology. We wished to assess whether the reproductive performance of this
population might be a limiting factor to its long-term persistence. Specific objectives were:

1) to evaluate year-to-year territorial occupancy and breeding rates;
2) to document breeding chronology and define various reproductive parameters;
3) to estimate reproductive success and productivity;
4) to determine site fidelity of adults.

Methods
Territory occupancy and breeding rates
Estimates of reproductive rates and nesting success for a population vary according to
data collection methods. Biases can result from the timing of nesting surveys and from
additive inclusion of new pairs found each season. Pairs found late in the season inflate
productivity estimates because proportionately more conspicuous successful breeders are
found during late surveys (Steenhof and Kochert 1982). Along with nest success, territorial
occupancy and breeding rates are often used as indicators of the stability and productivity of
a population (Steenhof 1987). The territorial occupancy rate is the percentage of known
territories that remains occupied from year to year. Breeding rate defines the percentage of
pairs in occupied territories that initiate a breeding attempt.

Estimating territorial occupancy and breeding rates for a set of preselected territories
during several years provides less biased estimates of these parameters for a population
(Steenhofand Kochert 1982, Fraser 1978). This may be particularly true for caracaras
because they are resident and faithful to traditional nesting sites. In 1994, we identified 33
territories for which we collected data on occupancy and breeding rates. We defined











REPRODUCTIVE ECOLOGY

Objectives
Low territorial occupancy and annual breeding rates, small clutch sizes, and low
productivity are often attributed to birds of prey (Newton 1979, Steenhofand Kochert 1982),
including caracaras (Runde and Millsap 1990). Particularly for an isolated population, there
is a concern that its long-term persistence and potential for expansion might be limited by
reproduction. The main objective of this part of the study was to evaluate the caracara's
reproductive ecology. We wished to assess whether the reproductive performance of this
population might be a limiting factor to its long-term persistence. Specific objectives were:

1) to evaluate year-to-year territorial occupancy and breeding rates;
2) to document breeding chronology and define various reproductive parameters;
3) to estimate reproductive success and productivity;
4) to determine site fidelity of adults.

Methods
Territory occupancy and breeding rates
Estimates of reproductive rates and nesting success for a population vary according to
data collection methods. Biases can result from the timing of nesting surveys and from
additive inclusion of new pairs found each season. Pairs found late in the season inflate
productivity estimates because proportionately more conspicuous successful breeders are
found during late surveys (Steenhof and Kochert 1982). Along with nest success, territorial
occupancy and breeding rates are often used as indicators of the stability and productivity of
a population (Steenhof 1987). The territorial occupancy rate is the percentage of known
territories that remains occupied from year to year. Breeding rate defines the percentage of
pairs in occupied territories that initiate a breeding attempt.

Estimating territorial occupancy and breeding rates for a set of preselected territories
during several years provides less biased estimates of these parameters for a population
(Steenhofand Kochert 1982, Fraser 1978). This may be particularly true for caracaras
because they are resident and faithful to traditional nesting sites. In 1994, we identified 33
territories for which we collected data on occupancy and breeding rates. We defined











REPRODUCTIVE ECOLOGY

Objectives
Low territorial occupancy and annual breeding rates, small clutch sizes, and low
productivity are often attributed to birds of prey (Newton 1979, Steenhofand Kochert 1982),
including caracaras (Runde and Millsap 1990). Particularly for an isolated population, there
is a concern that its long-term persistence and potential for expansion might be limited by
reproduction. The main objective of this part of the study was to evaluate the caracara's
reproductive ecology. We wished to assess whether the reproductive performance of this
population might be a limiting factor to its long-term persistence. Specific objectives were:

1) to evaluate year-to-year territorial occupancy and breeding rates;
2) to document breeding chronology and define various reproductive parameters;
3) to estimate reproductive success and productivity;
4) to determine site fidelity of adults.

Methods
Territory occupancy and breeding rates
Estimates of reproductive rates and nesting success for a population vary according to
data collection methods. Biases can result from the timing of nesting surveys and from
additive inclusion of new pairs found each season. Pairs found late in the season inflate
productivity estimates because proportionately more conspicuous successful breeders are
found during late surveys (Steenhof and Kochert 1982). Along with nest success, territorial
occupancy and breeding rates are often used as indicators of the stability and productivity of
a population (Steenhof 1987). The territorial occupancy rate is the percentage of known
territories that remains occupied from year to year. Breeding rate defines the percentage of
pairs in occupied territories that initiate a breeding attempt.

Estimating territorial occupancy and breeding rates for a set of preselected territories
during several years provides less biased estimates of these parameters for a population
(Steenhofand Kochert 1982, Fraser 1978). This may be particularly true for caracaras
because they are resident and faithful to traditional nesting sites. In 1994, we identified 33
territories for which we collected data on occupancy and breeding rates. We defined










occupancy as observations of adult caracaras on 3 or more visits to a particular site. We
considered a "breeding attempt" to be actual egg laying, not just nest construction. During
1995 and 1996, we began regular observations in these preselected territories in October, to
determine occupancy and occurrence of breeding attempts. We conducted observations in
each territory at least monthly or until breeding was confirmed. We used the nonparametric
Cochran's Q-test (Sokal and Rohlf 1995) to evaluate whether there was a'significant change
in occupancy and breeding rates among the 3 years.

Breeding chronology and reproductive parameters
Each year beginning in October we conducted observations in each territory to find
nests. We made observations from a vehicle beginning at sunrise. Once we observed a pair
of caracaras, we contacted the landowner for permission to access the land and search for the
nest. Subsequent to finding a nest, we checked it approximately weekly to monitor status.
We used an extendible pole with a mirror attached to ascertain clutch and brood size and
chick age, which we determined by assessing the size of chicks and their feather
development.

To evaluate breeding chronology, we divided each month into two periods, early and
late (1-15 and 15 to end, respectively). Each year we assigned initiation of egglaying for
each of our sample nests to one of these periods.

Reproductive success and productivity
We estimated nesting success using Mayfield's method (Mayfield 1961, 1975;
Johnson 1979). Rather than simply calculating nest success as the number of successful nests
divided by total nests, this method more appropriately calculates nest success by correcting
for time during which each nest is actually under observation. To compute and compare
Mayfield probabilities of nest success for our sample population of caracara nests, we
modified an existing BASIC program (R. Bowman, pers. comm.). Because of the length of
the caracara's breeding season (at least 5 months) and because we visited nests approximately
weekly, we estimated probabilities of nest success and mortality rates for each week rather
than each day, which is usually done with this method (Mayfield 1961).










We estimated probabilities of nest success for 3 periods during the nesting season:
incubation, nestling, and post-fledging, using lengths of 4, 8, and 8 weeks for these 3 periods,
respectively. Because the chicks remain with their parents in the natal territory for several
months after fledging, it is possible to determine survival after the first 8 weeks post-
fledging. We set a carcass in the nest stand area just before dark, and the following morning,
observations of surviving family members can be made. For many raptors, estimates of nest
success have been based only on two visits to the nests (Steenhof 1987). The fact that we
obtained weekly information regarding egg, nestling, and fledgling survival for the caracaras
provides better estimates of nest success than are available for most raptors.

We defined a successful nest as one in which at least one fledgling survived until the
end of the 8 week post-fledging period. We defined productivity as the number of young per
successful pair. For comparisons of nest success between habitats or time periods, we used a
Z-test (Hensler and Nichols 1981). We used two-sample t-tests and one way analysis of
variance for comparisons of reproductive parameters among habitats and years. All statistics
were evaluated at the t= 0.05 level.

Site fidelity of adults
During successive years, we conducted observations to determine whether known
banded and radiotagged adults remained within the same territory and whether they nested in
the same or different trees within the territory. To calculate distances between alternate nest
trees within the same territory, we obtained GPS locations (latitude/longitude) at each nest
tree.

Results
Territorial occupancy and breeding rate
Territorial occupancy rates for the 33 preselected territories were high overall during
the 3 years (Table 1), but we rejected the null hypothesis that these rates remained similar
among all years (Q = 6.0 > (o0.05)2df = 5.991). We were unable to confirm occupancy and
breeding at the traditional nesting site in 2 of these territories in 1996. This conclusion
probably resulted in an underestimate of the true breeding and occupancy rates, however. At
both of these sites, we saw adults carrying food in nearby areas that could have been within










the same territory, suggesting that the territories were occupied. These pairs may only have
moved their nest site a considerable distance. None of the adults in these 2 territories were
banded. Among occupied territories during all 3 years, the percentage of pairs that initiated a
breeding attempt did not change and remained high, at 99% (Q = 1.55 < (0.oos)2df = 5.991).

Breeding chronology
During 1994, 1995, and 1996 we monitored reproductive activity at 32, 63, and 61
nests in 29, 49, and 54 territories, respectively. Double brooding and renesting after early
failure account for the differences. Apparently, caracaras in Florida may attempt to breed
during almost every month of the year. We found nests containing eggs in every month
except August, and chicks fledged from successful nests as early as December and as late as
July. The median period of egg-laying for the sample population was late January in all 3
years (Fig. 6). During a 6-week period from about mid December through mid-February,
45% to 75% of the population initiated egglaying each year. Secondary peaks of egglaying
in March and April (Fig. 6) represent territories where double brooding occurred.

Reproductive parameters *
Clutch size differed somewhat among the three years (F = 3.62, P = 0.03) but did not
differ between 1995 and 1996 (t = 0.04, P = 0.97). The larger mean clutch size in 1994
(Table 1) was probably due to the small sample size of nests that year. We examined the
relationship between mean clutch size and laying period throughout the breeding season. We
wished to determine whether there were differences in mean clutch size among the laying
periods and whether clutch size decreased as the breeding season progressed. Because the
number of clutches sampled varied among the laying periods, we used a weighted regression
technique (Sokal and Rohlf 1995). Although clutch size decreased slightly as the breeding
season progressed, deviations from regression did not differ from 0. Variation among
clutches could not be explained by laying period and the regression was not significant (F =
1.48 < F.05, 1/16 = 4.49) ) (Fig. 7). This relatively constant clutch size throughout the
breeding season suggests that there may be little cost associated with producing a clutch.
This could be true particularly if resources are in high abundance throughout the breeding


season.










the same territory, suggesting that the territories were occupied. These pairs may only have
moved their nest site a considerable distance. None of the adults in these 2 territories were
banded. Among occupied territories during all 3 years, the percentage of pairs that initiated a
breeding attempt did not change and remained high, at 99% (Q = 1.55 < (0.oos)2df = 5.991).

Breeding chronology
During 1994, 1995, and 1996 we monitored reproductive activity at 32, 63, and 61
nests in 29, 49, and 54 territories, respectively. Double brooding and renesting after early
failure account for the differences. Apparently, caracaras in Florida may attempt to breed
during almost every month of the year. We found nests containing eggs in every month
except August, and chicks fledged from successful nests as early as December and as late as
July. The median period of egg-laying for the sample population was late January in all 3
years (Fig. 6). During a 6-week period from about mid December through mid-February,
45% to 75% of the population initiated egglaying each year. Secondary peaks of egglaying
in March and April (Fig. 6) represent territories where double brooding occurred.

Reproductive parameters *
Clutch size differed somewhat among the three years (F = 3.62, P = 0.03) but did not
differ between 1995 and 1996 (t = 0.04, P = 0.97). The larger mean clutch size in 1994
(Table 1) was probably due to the small sample size of nests that year. We examined the
relationship between mean clutch size and laying period throughout the breeding season. We
wished to determine whether there were differences in mean clutch size among the laying
periods and whether clutch size decreased as the breeding season progressed. Because the
number of clutches sampled varied among the laying periods, we used a weighted regression
technique (Sokal and Rohlf 1995). Although clutch size decreased slightly as the breeding
season progressed, deviations from regression did not differ from 0. Variation among
clutches could not be explained by laying period and the regression was not significant (F =
1.48 < F.05, 1/16 = 4.49) ) (Fig. 7). This relatively constant clutch size throughout the
breeding season suggests that there may be little cost associated with producing a clutch.
This could be true particularly if resources are in high abundance throughout the breeding


season.










Mean brood size did not differ among the 3 years (F = 2.41, P = 0.12), and averaged
70% of mean clutch size. We saw no evidence of infanticide or siblicide. Brood reduction is
likely due to eggs or chicks falling out of nests (Morrison pers. obs.) or starvation of the
smallest or youngest chick. In all years, less than 50% of nests that contained 3 eggs raised
all 3 chicks to fledging (Table 1).

The ability to make multinesting attempts seems to be a widespread and consistent
pattern for this population. If a pair's first nesting attempt occurs in October, November, or
December, the chance of that pair renesting either following failure of the first attempt or by
producing a second brood can be as high as 90% (Fig. 8). We confirmed double brooding in
all years, predictably in those territories that fledged the first brood before March 1 (Table 1).
We defined double brooding as production of a second clutch after successfully fledging one
brood. Renesting after failure during the incubation or nestling stages was not considered
double brooding. Thirty-three percent of the pairs that double brooded used the same nest
tree for the second nest. The other pairs built a new nest in a different tree. Second clutches
were laid from late March through early May, in most cases when fledglings from the first
brood were still dependent and resident in the territory. Shortly after the second clutch
hatched, however, the fledglings from the first brood left the territory (from telemetry).
Observations of banded individuals and of adults' behavior led us to believe that the same
adults participated in both nesting efforts in all double-brooded territories during all years.

Reproductive success and productivity
We believe we did not miss early nest failures in 1995 and 1996 because we began
observations in all territories beginning in October of each year. We revisited territories
approximately every two weeks until nesting stage was determined. Mayfield estimates are
similar to traditional estimates, particularly for 1995 and 1996 (Tables 2-4). During those
years, we found most nests in the nestbuilding stage, due to site fidelity of pairs.

The caracaras have an extended breeding season and timing of activity varied greatly
among pairs throughout the study area. Overall nesting success of all sample nests remained
high among all years, however. Mayfield estimates of nest success did not differ between
1994 and 1995 (Z = -0.18, P = 0.24) but success in 1996 was higher (Z = 3.80, P < 0.05,










I'able 1). We tested the hypothesis that early breeders are more successful than late breeders,
which is typical of many avian species, including raptors (Newton 1979). We found that nest
success was higher for pairs that initiated egglaying before Feb. 1. Approximately 55% 75
% of all sample pairs initiated egglaying before Feb. 1 during the 3 years. Mayfield estimates
of nest success were higher (Z = 3.41, P < 0.0001) for these early pairs (0.80 + 0.03 SD), than
for pairs that did not begin egg laying until after Feb. 1 (0.60 + 0.05 SD). For pairs that
double-brooded, nest success was lower (Z = 3.34, P < 0.0001) for second (0.32 + 0.16 SD)
than for first broods (0.87 + 0.04 SD).

Productivity was consistent and did not differ (F = 2.47, P = 0.09) among the three
years (Table 1). Of the nests that successfully produced young, most fledged 2 chicks (Table
1). Most nests initiated after early April failed (Fig. 6). Some of these late nests apparently
were abandoned during the incubation stage. In 1995, this may have been due to excessively
hot ambient temperatures in May and June. Late fledging chicks also grow more slowly and
are smaller and lighter in mass at fledging than those that fledge early in the season. Some
did not survive the fledgling-dependency period.

Nest failure
One of the assumptions of the Mayfield method is that weekly survival probabilities
are constant throughout the nesting period (Mayfield 1961, Johnson 1979). We tested this
assumption by evaluating whether nest failure rates were higher during any particular nest-
stage. Nest failure rates were low overall, but were slightly higher during the latter part of
incubation and early nestling stages in all years (Fig. 9). With weekly nest checks it was
difficult to determine whether the eggs disappeared near the end of incubation or whether
they actually hatched and the nestlings were lost during the first week. In any case, nests
may be particularly vulnerable to loss right around hatching. Changes in the adults' behavior
could make nests more vulnerable to predation. Small chicks may succumb in inclement
weather.

We were unable to determine the cause of failure for most nests that failed during the
incubation and early nestling stages (Table 5). We did determine that nests occasionally
blow out of trees or become dislodged by growing fruiting stalks or fronds of palms causing










eggs or young to fall out. What appears to be brood reduction (Table 1) may reflect this
mortality. Starvation of the youngest, smallest sibling is also assumed, particularly in broods
of 3. Predation of eggs and chicks by American Crows (Corvus corax) and raccoons
(Procyon lotor) has been recorded (Layne 1996). We found raccoons sleeping in caracara
nests both during and outside the breeding season. They were found in 3 nests in which there
had been eggs or chicks. We do not know whether the raccoons preyed upon nest contents,
however. Dickinson (1995) reported failure of second broods in Texas due to predation by
fire ants. In our study area, death of fledglings due to collisions with vehicles was the most
common cause of nest failure during the fledgling-dependency period (Table 5).

Site fidelity of adults
Adult caracaras are apparently very site faithful. Seven of 10 adults banded in 1994
were still present in the same territory and reproduced there in 1995 and 1996. Of 26 adults
banded in 1995, 22 remained in the territory and reproduced successfully in 1996. These
figures represent an overall annual turnover rate of approximately 20%. We do not know the
fate of 6 (3M, 3F) of the banded adults that disappeared. The 7th individual (F) was killed by
a car. For nests that we followed for 2 or more years, 55% were either in the same tree or in
a nearby tree within the same stand during all years. In 32 territories, distance between
alternate nest trees averaged 0.71 km + 0.06 (SE) (range 0.02 1.62 km).












Table 1. Reproductive parameters for study population of Crested Caracaras in south central Florida, 1993-1996.
ND = no data.


Total number of territories studied
Territorial occupancy rate
Breeding rate of occupied territories
Total number of nests followed
Mean clutch size
Mean brood size
Nests with 1 egg
Nests with 2 eggs
Nests with 3 eggs
Productivity (number of
young per successful pair)
Nests that fledged 1 chick
Nests that fledged 2 chicks
Nests that fledged 3 chicks
Nests containing 3 eggs
that fledged all 3 chicks
Overall probability of nest success
Double brooding territories
Successful double broods
Number of double-brooding
territories that successfully fledged
first brood before March 1
Failures
During incubation/hatching
During nestling period
After fledging
Attempted renesting after early failure
(incubation or nestling period)
Approximate time between attempts
Study territories we believe failed
to produce any young during
period despite nesting attempt


1993-1994
29
100%
100%
32
2.56 (n = 16)
1.78 (n = 32)
1 (6%)
5 (31%)
10 (63%)

1.96 (n = 28)
21%
61%
18%


5(50%)
0.66
3 (10%)
3 (100%)



2 (66%)
7 (22%)
2
1
3
'ND

'ND
7 (24%)


1994-1995
49
100%
98%
63
2.17 (n = 41)
1.44 (n = 63)
3 (7%)
28 (68%)
10 (24%)

1.72 (n = 46)
37%
54%
9%


4 (40%)
0.64
7(15%)
4 (57%)



6 (86%)
21(33%)
9
7
5
6/8 (75%)



9(18%)


1995-1996
54
94%
99%
61
2.17 (n = 42)
1.63 (n = 62)
2 (5%)
31(74%)
9 (21%)

1.66 (n = 53)
38%
58%
4%


2 (22%)
0.83
5 (9%)
3 (60%)



3 (60%)
10 (19%)
4
5
1
2/3 (66%)

4-6 wk 3-14 wk
6(11%)











Table 2. Mayfield and traditional estimates of nest success for Crested Caracara nests in
south-central Florida, 1994.


Total Nests Observed = 32
Hatched = 29
Fledged = 28
Survived to week 8 after fledging = 26


Incul


Expected number of weeks in period

Total nests observed in period

Number of successful nests

Traditional success estimates

Total observed weekly exposure

Mayfield estimated weekly survival probabilities

Standard deviation

Total probability of successor entire period (Mayfield)
Standard deviation

Total P of nesting success over entire nesting period
Standard deviation


nation
4

13

10

0.77

43.50

0.93

0.04

0.75
0.06

0.66
0.09


Nestling
8

29

28

0.97

155.00

0.99

0.01

0.95
0.02


Fledgling
8

28

26

0.93

215.00

0.99

0.01

0.93
0.02











Table 3. Mayfield and traditional estimates of nest success for Crested Caracara nests in
south-central Florida, 1995.


Total Nests Observed = 63
Hatched = 57
Fledged = 47
Survived to week 8 after fledging = 42


Incubation
Expected number of weeks in period 4

Total nests observed in period 49

Number of successful nests 43

Traditional success estimates 0.88

Total observed weekly exposure 182.00

Mayfield estimated weekly, survival probabilities 0.97

Standard deviation 0.01

Total probability of successor entire period (Mayfield) 0.87
Standard deviation 0.02

Total P of nesting success over entire nesting period 0.64
Standard deviation 0.04


Nestling
8

53

44

0.83

361.50

0.98

0.01

0.82
0.02


Fledgling
8

47

42

0.89

359.00

0.99

0.01

0.89
0.02











Table 4. Mayfield and traditional estimates of nest success for Crested Caracara nests in
south-central Florida, 1996.


Total Nests Observed = 61
Hatched = 58
Fledged = 52
Survived to week 8 after fledging = 50


Incul


Expected number of weeks in period

Total nests observed in period

Number of successful nests

Traditional success estimates

Total observed weekly exposure 1

Mayfield estimated weekly survival probabilities

Standard deviation

Total probability of successor entire period (Mayfield)
Standard deviation

Total P of nesting success over entire nesting period
Standard deviation


nation
4

48

45

0.94

86.00

0.98

0.01

0.94
0.02

0.83
0.03


Nestling
8

55

51

0.93

394.00

0.99

0.01

0.92
0.01


Fledgling
8

52

50

0.96

410.00

0.99

0.01

0.96
0.01












Table 5. Evidence of nest failure for Crested Caracara nests in south-central Florida, 1993-1995.
N = 38 failures.

NEST STAGE
CAUSE INCUBATION NESTLING FLEDGLING
Suspected predation 11% 8%
Abandonment 11% 3%
Accident or illness 5% 3%
Vehicle 11%
Fell out of tree 5%
Unknown 11% 26% 8%































































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HABITAT ASSOCIATIONS WITHIN CARACARA TERRITORIES

Objectives
The overall objective of this part of the study was to examine habitat associations of
caracaras at nest sites and within adult home ranges. We also wished to evaluate
relationships between the habitat composition and dispersion of caracara territories and
patterns of land use and land ownership throughout the study area. Specific objectives were:

1) to characterize specific habitat features at nest sites;
2) to define adult home ranges, evaluate range size, and maximum range width;
3) to evaluate use vs. availability of habitats within the APAFR territory;
4) to evaluate habitat composition in the areas immediately surrounding caracara sightings
on the Range;
5) to evaluate habitat composition in adult home ranges throughout the study area;
6) to evaluate territory dispersion throughout the study area; specifically, distances
between adjacent nests and territory overlap;
7) to examine land ownership and patterns of land use within territories;
8) to examine relationships between particular habitat features of the nest site and nest
success or failure.

Methods
Characterization of habitat at the nest site
Objectives were twofold: 1) to evaluate the nest location itself- i.e., orientation and
relationship of the nest tree to other trees in the stand, and 2) to characterize the types and
structure of vegetation within the vicinity of the nest tree. During the first 2 months after
fledging, chicks spend much time on the ground near the nest, hiding under vegetation,
presumably from predators. Therefore, habitat analysis at the nest site focused on
characterizing the vegetation within the general nest stand area. We wished to evaluate the
amount of cover where the fledglings can hide and open pasture where they can feed on
insects and watch for adult birds returning with food. Plant species composition was not
recorded because we assumed that vegetation structure is probably more important in
caracara nest site selection than types or distributions of individual plant species.










HABITAT ASSOCIATIONS WITHIN CARACARA TERRITORIES

Objectives
The overall objective of this part of the study was to examine habitat associations of
caracaras at nest sites and within adult home ranges. We also wished to evaluate
relationships between the habitat composition and dispersion of caracara territories and
patterns of land use and land ownership throughout the study area. Specific objectives were:

1) to characterize specific habitat features at nest sites;
2) to define adult home ranges, evaluate range size, and maximum range width;
3) to evaluate use vs. availability of habitats within the APAFR territory;
4) to evaluate habitat composition in the areas immediately surrounding caracara sightings
on the Range;
5) to evaluate habitat composition in adult home ranges throughout the study area;
6) to evaluate territory dispersion throughout the study area; specifically, distances
between adjacent nests and territory overlap;
7) to examine land ownership and patterns of land use within territories;
8) to examine relationships between particular habitat features of the nest site and nest
success or failure.

Methods
Characterization of habitat at the nest site
Objectives were twofold: 1) to evaluate the nest location itself- i.e., orientation and
relationship of the nest tree to other trees in the stand, and 2) to characterize the types and
structure of vegetation within the vicinity of the nest tree. During the first 2 months after
fledging, chicks spend much time on the ground near the nest, hiding under vegetation,
presumably from predators. Therefore, habitat analysis at the nest site focused on
characterizing the vegetation within the general nest stand area. We wished to evaluate the
amount of cover where the fledglings can hide and open pasture where they can feed on
insects and watch for adult birds returning with food. Plant species composition was not
recorded because we assumed that vegetation structure is probably more important in
caracara nest site selection than types or distributions of individual plant species.










HABITAT ASSOCIATIONS WITHIN CARACARA TERRITORIES

Objectives
The overall objective of this part of the study was to examine habitat associations of
caracaras at nest sites and within adult home ranges. We also wished to evaluate
relationships between the habitat composition and dispersion of caracara territories and
patterns of land use and land ownership throughout the study area. Specific objectives were:

1) to characterize specific habitat features at nest sites;
2) to define adult home ranges, evaluate range size, and maximum range width;
3) to evaluate use vs. availability of habitats within the APAFR territory;
4) to evaluate habitat composition in the areas immediately surrounding caracara sightings
on the Range;
5) to evaluate habitat composition in adult home ranges throughout the study area;
6) to evaluate territory dispersion throughout the study area; specifically, distances
between adjacent nests and territory overlap;
7) to examine land ownership and patterns of land use within territories;
8) to examine relationships between particular habitat features of the nest site and nest
success or failure.

Methods
Characterization of habitat at the nest site
Objectives were twofold: 1) to evaluate the nest location itself- i.e., orientation and
relationship of the nest tree to other trees in the stand, and 2) to characterize the types and
structure of vegetation within the vicinity of the nest tree. During the first 2 months after
fledging, chicks spend much time on the ground near the nest, hiding under vegetation,
presumably from predators. Therefore, habitat analysis at the nest site focused on
characterizing the vegetation within the general nest stand area. We wished to evaluate the
amount of cover where the fledglings can hide and open pasture where they can feed on
insects and watch for adult birds returning with food. Plant species composition was not
recorded because we assumed that vegetation structure is probably more important in
caracara nest site selection than types or distributions of individual plant species.










We established a 3.14 ha (100 m-radius) plot centered on the nest tree, then
established 2 transects, one aligned N-S and the other E-W that bisected the plot into 4
quadrants. To characterize the nest tree with respect to other trees in the plot, we measured
dbh and height of the nest tree, distance to and height of the nearest 3 trees within each
quadrant. We also ranked the 4 quadrants from the most to the least number of trees within
30 m of the nest tree. Nest orientation in the nest tree was estimated using a compass.

We evaluated the structure of vegetation in the plot by recording the height and type
of vegetation (grass/forb, shrub, or tree) at a point 2 m from the nest tree, then at each point
every 10 m along the 100 m transect in each cardinal direction. We measured vegetation
height with a meter stick. We defined cover in each quadrant as vegetation taller than the
average height of the ground cover that appeared to be sufficient to conceal a caracara
fledgling from a predator. We evaluated dispersion of cover throughout the plot by
measuring the distance to the nearest such vegetation in each quadrant. When possible, we
directly measured distances to major landscape features such as primary and secondary roads
and human activity. Otherwise, we measured these distances from maps or aerial photos.
We also measured the distance to the nearest tree, snag, or pole in or near the nest stand that
we recognized as a perch frequently used by the adults.

Adult Home Ranges
Because Crested Caracaras range widely across the landscape, radiotelemetry is the
method of choice for obtaining data on home range and habitat associations. The need to
obtain these data necessitated capture of adult caracaras in selected territories.

Trapping and radiotagging. We trapped adult caracaras at selected nest sites using a
Q-net (large bow net) and a tethered live, captive caracara as a lure (Morrison and McGehee
in press). We found this to be the only effective method for capturing adult caracaras. It also
worked well for capturing selected individuals. Success of this method averaged 67% for all
3 years

We handled all captured individuals in the field. We banded each individual with a
standard (size 7A) USFWS aluminum leg band and a unique color leg band that permits
identification of individuals. We took standard morphometric measurements and blood










samples for a sexing test using DNA, serum chemistry analysis, and mercury analysis. We
noted each individual's general health, and prior to release, we administered approximately 5
cc of lactated Ringer's solution to reduce stress and replace fluids lost as a result of the blood
sampling. After handling, we released all caracaras in the nest stand.

Radiotransmitters used during 1994 and 1995 were manufactured by Holohil, Inc. In
1994, transmitters contained 12 month batteries and in 1995 they contained 24-month
batteries. We attached the transmitters using a standard backpack harness constructed of
Teflon ribbon and secured at the bird's chest. Total weight of the transmitter and harness did
not exceed 25 g, or < 2.5% of the caracara's adult weight (approximately 1100 g).

Telemetry. Because the majority of land in the study area is privately owned, ground
access to many of the areas used by caracaras is limited. Therefore, we conducted
radiotracking primarily by way of weekly aerial surveys from a fixed-wing Cessna 172
aircraft. During flights, we located all adults and obtained GPS coordinates
(latitude/longitude) of their locations. We took the following notes at each location:

1) the bird's activity (perched or moving),
2) the habitat where it was found. We defined habitats as follows: natal area (within 2 km
of nest), improved pasture (contains wetlands or ditches), native pasture (contains
wetlands or ditches), palm or oak hammock, urban pasture, river floodplain or marsh,
plowed field, shrub or scrubby vegetation, citrus, dairy, sod, pine flatwoods, canefield,
and urban landfill.
3) whether or not cows were present at the location,
4) whether other caracaras were associated with each individual, either by obtaining visual
observations or by checking for signals of other radiotagged birds.

Data collection for radiotagged adults focused on evaluating site fidelity and
estimating home range size and territorial overlap. The accuracy of home range estimation
for each individual is strongly dependent of the number of radiolocations. To ensure
adequate numbers of locations for use in the home range models, we obtained ground
locations for some radiotagged adults using triangulation (White and Garrott 1990). We used
a FORTRAN program to determine UTM coordinates of the birds' actual locations using










known positions of ground tracking sites and the bearings obtained at those sites (Kennedy et
al. 1995).

Determining accuracy of telemetry locations is important when evaluating habitat use
and home range size, particularly when attempting to place an individual within a small
habitat patch. To estimate error of aerial locations, we routinely calculated differences
between known and estimated locations of transmitters that were placed at random locations
by an independent assistant.

Home Range analyses. An adult caracara's home range is defined as the area over
which it moves while conducting its regular activities such as foraging and territorial patrol.
Range width is the maximum distance between two locations, for each individual. We used
the program RANGESV (Kenward and Hodder 1995) to estimate size, shape, and amount of
overlap for adults' home ranges. To identify outlier locations, we used the cluster analysis
method within RANGESV tempered by a biological evaluation based upon our knowledge of
each bird's behavior. These outliers were not used in estimations of home range size. We
used the harmonic mean (HM) method in RANGESV to delineate size and shape of each
caracara's home range. We chose this estimator because it (1) is non-parametric, (2) is not as
sensitive to number of locations as are other estimators, and (3) is commonly used to estimate
home range sizes of raptors (White and Garrott 1990, Kennedy et al. 1995).

We identified the boundaries of the home range of each bird with the 50% and 95%
isopleths. These contours define the area in which we expect to find a caracara 50% and 95%
of the time, respectively. Home ranges included locations obtained for each bird all year
round, as caracaras do not migrate. Thus, home ranges reported here represent estimates of
the maximum area that an individual might use inclusive of the breeding and the non-
breeding seasons. We used a Kruskal-Wallis test (Sokal and Rohlf 1995) to analyze the areas
defined by the 50% and 95% contours for gender differences.

We assumed independence of aerial radiolocations for all individuals (cf. Swihart
and. Slade 1985) because they were obtained at least 5 days apart. Therefore, all aerial
locations obtained for adults were used in home range analyses. We assumed independence
of ground locations that were obtained a minimum of 24 hours apart, so only those locations










were included in these analyses. Telemetry studies of other raptors have determined that
independence of locations can occur in as little as 4 hours (Bloom et al. 1993). Visual
observations accounted for approximately 20% of all ground locations for adults. When a
radiotagged adult was observed in the field, we noted its location on an aerial photo, and we
returned later to obtain GPS coordinates at that spot. We included in the analyses only those
visual locations that were obtained a minimum of 24 hours apart.

Habitat use vs. availability in APAFR territory
We used the chi-square goodness of fit test (Neu et al. 1974) to test for significant
differences between habitat availability and habitat use by caracaras on APAFR. This test
uses the observed number of locations in each habitat type and the "expected" number of
locations based on the known proportional availability of these habitat types. Results were
investigated further by calculating Bonferroni confidence intervals to determine which
vegetation types were preferred (Byers et al. 1984).

For this analysis we used the GIS coverage containing data on APAFR plant
communities. We combined similar plant communities, particularly those that are rarely
used by caracaras (as indicated by observations and telemetry), assuming that the differences
between them were not significant to caracaras. This resulted in a coverage containing 15
habitat types defined for the entire Range. We defined habitat availability throughout the
Range as the relative proportions of each of these 15 types.

To examine habitat use vs. availability for the adult and two juvenile caracaras from
the APAFR territory, we used each bird's home range as defined by the 95% minimum
convex polygon (MCP). We used the MCP method rather than the HM method for this
analysis because the MCP describes the known maximum area that could be used by the
caracara. The MCP method makes no assumptions about the utilization distributions for
different habitats within the home range but includes all habitats within the area defined by
the 95% contour. We overlaid the 95% contour polygons for these 3 birds on the coverage of
15 habitat types for the entire Range. We determined habitat availability by calculating the
proportion of each habitat type within these home ranges. We assessed habitat use by
determining the numbers of radiolocations within each habitat type for each bird.










Habitat composition in areas surrounding caracara sightings at APAFR
We evaluated habitat use by caracaras across the entire Range as defined by the
sightings database (Fig. 5). Using GIS, we generated a 0.5 km buffer around each sighting
point and overlaid these areas on the coverage of 15 habitat types. Caracaras readily travel
distances of 0.5 to 1 km within their ranges, so we assumed that a caracaras could use any
location equally within this 0.785 km2 area. We evaluated habitat use within all these areas
by assessing the relative proportion of each habitat type within them. We determined habitat
availability by calculating the relative amount of each habitat type throughout the Range as
described above. We used a log-likelihood ratio test or G-test (Sokal and Rohlf 1995) to
evaluate differences in the distributions describing the proportions of each habitat type within
these sighting areas and throughout the Range.

Habitat composition in adult home ranges throughout the study area
We used the same method as above for examining habitat composition in adult home
ranges throughout the study area. We exported 95% MCP boundaries from RANGESV for
all radiotagged adults into PC-ArcView Geographic Information System (GIS). We overlaid
these polygons on a GIS coverage of land use/land cover data obtained from the South
Florida Water Management District (SFWMD). Using these land use data, we combined
similar habitats based on our knowledge of use of these habitats. This resulted in 20 habitat
types defined for the entire study area. We again used the G-test to evaluate differences in
the distributions describing the proportions of each habitat type within the home ranges and
throughout the study area.

Territory Dispersion
Using GPS coordinates for each nest site, we calculated between-nest distances for
known adjacent pairs. We used RANGES V to calculate the amount of overlap among
adjacent territories.

Nesting success. habitat associations, and patterns of land use
To evaluate whether patterns of land use and land ownership were related to territorial
occupancy, breeding rates, or nest success, we used the preselected set of 33 territories as
described in Reproductive Ecology, above.










We examined habitat features at a sample of nest sites throughout the study area to
determine differences associated with failed and successful nests. This sample consisted of a
subsample of nests from 1994 and 1995 for which we collected data on habitat variables at
the nest site (see Characterization of habitat at the nest site, above). Caracaras are very site
faithful and use of alternate nests would result in lack of independence among sites within a
given territory between years. To avoid pseudoreplication, we used only one nest per
territory. We also only used first nests in each territory, not double brood nests. Success or
failure of these second nests is likely influenced by the timing and fate of the first nest.
Nesting success was similar among 1994 and 1995 and sample sizes were small, so we
pooled data for both years. Sample size for this analysis was 42 nests. Twelve nests failed
and 30 were successful.

Habitat characteristics measured at nest sites as described in Characterization of
habitat at the nest site, above, were used in this analysis. Features included landownership
(LANDOWN) and major land use (LAND USE); nest tree height (NTRHGT); number of
trees in nest tree group (NUMTRGRP); height of vegetation at the nest tree (HTVEGNTR); a
combined variable comprised of several variables that measured the amount and height of
shrub vegetation (SHRUBVEG); nearest primary road (NRROAD); and nearest human
activity (NRHUMAN). We used a step-wise logistic regression procedure to identify
whether any of these variables were good predictors of nest success and discriminated
between successful and failed nests. We chose stepwise logistic regression over discriminate
function analysis because the former does not assume multivariate normality (Press and
Wilson 1979). We used Rayleigh's test and the Watson-Williams test (Zar 1974) to examine
relationships among nest orientation (NANGLE) and nest success.

Results
Characterization of habitat at the nest site
We collected data on an array of habitat variables at a total of 73 nest sites. These
included all sites from 1994, new sites added in 1995, and alternate nest sites used in 1995
that were within territories found in 1994.










We examined habitat features at a sample of nest sites throughout the study area to
determine differences associated with failed and successful nests. This sample consisted of a
subsample of nests from 1994 and 1995 for which we collected data on habitat variables at
the nest site (see Characterization of habitat at the nest site, above). Caracaras are very site
faithful and use of alternate nests would result in lack of independence among sites within a
given territory between years. To avoid pseudoreplication, we used only one nest per
territory. We also only used first nests in each territory, not double brood nests. Success or
failure of these second nests is likely influenced by the timing and fate of the first nest.
Nesting success was similar among 1994 and 1995 and sample sizes were small, so we
pooled data for both years. Sample size for this analysis was 42 nests. Twelve nests failed
and 30 were successful.

Habitat characteristics measured at nest sites as described in Characterization of
habitat at the nest site, above, were used in this analysis. Features included landownership
(LANDOWN) and major land use (LAND USE); nest tree height (NTRHGT); number of
trees in nest tree group (NUMTRGRP); height of vegetation at the nest tree (HTVEGNTR); a
combined variable comprised of several variables that measured the amount and height of
shrub vegetation (SHRUBVEG); nearest primary road (NRROAD); and nearest human
activity (NRHUMAN). We used a step-wise logistic regression procedure to identify
whether any of these variables were good predictors of nest success and discriminated
between successful and failed nests. We chose stepwise logistic regression over discriminate
function analysis because the former does not assume multivariate normality (Press and
Wilson 1979). We used Rayleigh's test and the Watson-Williams test (Zar 1974) to examine
relationships among nest orientation (NANGLE) and nest success.

Results
Characterization of habitat at the nest site
We collected data on an array of habitat variables at a total of 73 nest sites. These
included all sites from 1994, new sites added in 1995, and alternate nest sites used in 1995
that were within territories found in 1994.










Most caracara nests were in cabbage palms, although in 1996, a pair successfully
fledged 2 chicks from a nest in a cypress (Taxodium distichum) along the edge of Lake
Istokpoga (Morrison et al. in press). Nest tree height averaged 7.3 m (range 3.5 16 m).
Average nest tree height was slightly taller (1.13 times) than the average height of trees in the
nest stand, perhaps allowing ease of aerial access. Most nests were in single trees or in
clumps with > 10 trees (Fig. 10). Analysis of the circular distribution of nest orientation in
the nest tree (Batschelet 1981, Fisher and Lewis 1983) indicated strong selection for a S-SE
direction (mean angle 170.470, Rayleigh's r = 0.71, P<0.0001). If the nest tree was located
within a stand of 3 or more trees, it was generally located on the southern or eastern edge of
the stand. Using a chi-square analysis, we evaluated whether the distribution of ranks among
the four quadrants in the plot differed from an equal distribution of ranks, with respect to the
number of trees within 30m of the nest tree. For all sites, the northwest quadrant ranked first
most often (had the most trees within 30m) (X = 21.00, P < 0.005). Such orientation of nest
and nest tree may provide optimum microclimate conditions within the nest by facing toward
the early morning sun and away from the prevailing northwesterly winter winds (Chen and
Gerber 1990).

Relationships between tree height and basal area within a stand of trees are often
reported as important factors characterizing suitable nesting habitat for many raptors (Mosher
et al. 1987). For caracara nesting habitat the dispersion and orientation of trees may be more
important. Cabbage palms within the prairie ecosystem generally grow in clusters separated
by large expanses of open grassland. Consequently, we believe that reporting basal area or
density of cabbage palms is not appropriate when describing these habitats. Furthermore, a
strong negative relationship exists between height and dbh of cabbage palms (R sq = 0.195, F
= 21.10, P < 0.001) (Fig. 11). This and the fact that caracara nests were not particularly
associated with any particular size or height of cabbage palm suggests that caracaras are not
necessarily selecting for size or height of the nest tree. They may instead select for structure
that would provide adequate nest support and orientation that would provide adequate
microclimate.










Habitat at the nest site is quite open, in general. Analysis of transect data within the
100 m-radius plots indicated that groundcover (grasses and forbs) in all directions out to
100m was generally less than 0.5 m in height (Fig. 12). Tall trees close to the nest occurred
mostly on the north and west transects, again as might be expected if a southern and eastern
nest orientation offers the most protection from prevailing winds. Twenty-one percent of
nests had no cover within 100m of the nest tree. When present, cover was mostly within 15
m of the nest tree (Fig. 13). Most of our sample of nests were within 2 km of a road and
human activity; this lends some bias to our evaluations of habitat selection. On some ranches
we had permission to access areas farther than 2 km from a main road. In areas on these
ranches where management practices were the same as along roads, we also found caracaras
nesting, in similar densities and with similar nesting success, as caracaras nesting within 2
km of main roads and human activity.

Adult Home Ranges
We trapped and banded 49 adult caracaras during the study (Table 6). Of these, we
radiotagged 39 (17 M, 12 F, 10 sex unknown). No injuries or mortality were incurred during
trapping or handling. Due to the unexpected occurrence that adult caracaras were able to
remove and disable the radiotransmitters, transmitter loss in 1994 and 1995 was higher than
expected.

A strong relationship generally exists between the number of locations for each
individual and the estimate of its home range size. Analyses of adult location data using
RANGESV indicated that at least 30 fixes are required to obtain an adequate representation
of a caracara's home range (Fig 14). We also determined that a slightly positive relationship
existed between the number of locations and maximum range width (Fig. 15). This
regression was not significant, however (F = 3.82, P = 0.07). For the analyses of home range
size and habitat use, we only used individuals for which we had 30 or more fixes (N = 17; 10
M, 7 F).

Average distance between estimated and actual locations of randomly placed
radiotransmitters for aerial locations was approximately 365 m. The standard deviation of
these differences was approximately 170 m. Because of this error, we did not attempt to










assign individuals to small habitat patches when determining habitat associations during
aerial surveys. For analysis purposes, we assumed that a distance of 1 500 m is of little
significance to a caracara. They regularly travel distances of 2 3 km when foraging
throughout their home ranges. We assumed visual observations had an error of 0.

Adult caracaras ranged as far as 11 km from the nest, although the actual defended
nesting territory and area regularly used for foraging and territorial patrol during the nesting
season are probably much smaller. Female home ranges (n = 7) as defined by the 95% HM
contour varied in size from 3.8 24.9 km2 (mean = 10.7 + 2.42 km2) (Table 7). Maximum
range width for females ranged from 4.9 to 9.8 km (mean = 6.6 + 0.74 km). Female home
ranges did not differ (H = 31, df = 1, P = 0.70) in size from male home ranges (95% HM) (n
= 10) which ranged from 3.9 22.5 km2 (mean = 10.1 + 1.7 km2). Maximum range widths
for males varied from 4.2 to 8.4 km (mean = 5.7 + 0.45 km) and did not differ (H = 22, df=
1, P = 0.21) from those of females. The 50% HM contours did not differ between females
and males (H = 40, df = 1, P = 0.63), and averaged 1.62 + 0.36 km2 and 2.08 + 0.39 km2,
respectively.

Home range size as defined by the 95% MCP for the adult male caracara (0.479) on
the APAFR territory was approximately 15.74 km2. The 95% MCP areas of the two
juveniles (0.659 and 0.848) mirrored the area of the adult (Fig. 16 and 17) and were 12.49
and 15.21 km2 in size, respectively. Range width for the adult was 6.2 km and for the 2
juveniles was 5.9 and 5.8 km, respectively.

Habitat use vs. Availability in APAFR territory
Analysis of radiolocation data for the adult and 2 juvenile caracaras within the
APAFR territory indicated a difference between the "expected" utilization of habitat types
(based on their availability) and the observed frequency of their usage by the caracaras (X =
35.61, df= 5, P < 0.05). The Bonferroni confidence intervals (Table 8) indicate preference or
avoidance of habitat types. If the expected proportion of usage does not lie within the
confidence interval for the observed proportion of usage, we conclude the expected and
actual utilization are significantly different (Byers et al. 1984). The data for the 3 caracaras
combined suggest higher than expected use of oak hammocks and of road, levee, and sand










habitats. Use offlatwoods and marsh habitats was less than expected, based on their
availability (Table 8). We often saw these caracaras along the river spoil in the area of short
vegetation, where cattle occasionally graze. Because of their terrestrial habits, the caracaras
probably can forage easily in these habitats. Caracaras also forage regularly along the edges
of marsh habitats. The apparent lack of preference for marsh habitats may be due to the fact
that much of this habitat in this area is deepwater marsh with tall vegetation. These habitats
are not used by caracaras. The apparent preference for the oak hammocks may reflect the
tendency for the juveniles to hide in this habitat during the first few months after fledging
(Morrison, pers. obs.).

Habitat composition in areas surrounding caracara sightings at APAFR
We examined the proportions of habitat types throughout the range and within the
0.785 km2 areas around all caracara sightings. These 2 distributions differed significantly (G
= 28.62, P < 0.025) (Fig. 18). The relative amounts of bahaia, marsh, road or levee, and
cabbage palm/oak hammock habitats are greater in areas immediately surrounding caracara
sightings than would be expected from the relative proportions of these habitats throughout
the Range, suggesting selection for these habitats. The relative amounts of forested
flatwoods and planted pine habitats in these areas are less than would be expected from their
relative proportions throughout the Range.

Habitat composition in adult home ranges throughout the study area
We also examined the proportions of habitat types within the caracara home ranges
and throughout the study area. These 2 distributions differed (G = 60.1, P < 0.001) (Fig. 19).
The proportions of pasture, palm/oak forest, and some agricultural habitats are higher within
home ranges than would be expected. The proportion of wetlands in home ranges appears to
be less than expected. This finding was unanticipated, since caracaras forage regularly in
wetlands. We concluded that many wetlands throughout the study area as outlined in this
land use/land cover database, such as large, deepwater wetlands and ponds, are not of the
types used by caracaras. Small wetlands of the types used by caracaras were not identifiable
on the land use data at this resolution.










Although these distributions differed, these analyses do not provide information on
selection of certain habitats by caracaras, because of the scale of the analyses and the broad
categories of the available land use data. The MCP method makes no assumptions regarding
utilization distributions of habitats within a home range. Telemetry data indicate that
caracaras do occasionally forage in open agricultural areas including cane fields, citrus
groves, sod farms, and recently plowed or burned areas. These habitats may be included in a
caracara's 95% MCP range, but from these analyses, we cannot determine their importance
relative to other habitats.

Territory dispersion
Based on telemetry, we assumed that the center of activity for a caracara's territory
was the nest site. In areas where we knew nest locations for adjacent pairs of caracaras,
distances between these territory centers averaged 3.4 km + 0.2 (SE) (range 1.5 6.1 km, N =
29 pairs). The maximum local density recorded was 9 successfully breeding pairs within
4850 ha or approximately 1 pair/540 ha, on Buck Island Ranch in Highlands County (Fig.
20). Based on these findings, we believe there is a high probability that additional pairs of
caracaras occupy suitable habitats and in similar densities, in areas farther than 2 km from
roads where we could not search for them.

RANGESV analysis of home range overlap among 3 sets of adjacent pairs of
caracaras indicated that home ranges as defined by the 95% MCP overlapped an average of
approximately 23%. Among one set of 3 adjacent territories, the 95% MCP home ranges did
not overlap at all. Overlap among the other 2 sets of territories (3 pairs and 4 pairs,
respectively) ranged from 4.4% to 45.9% (Fig. 20). The 50% MCP core home ranges of
adjacent pairs did not overlap. These results support our belief that caracaras are highly
territorial, particularly around the nest site, although adjacent pairs may forage in areas that
are common to both home ranges.

Nesting success. habitat associations, and patterns of landuse
In our sample of territories, only 7 (11%) were on public lands. Where territories
were identified on private lands, the land use was overwhelmingly cattle ranching. Lands
under public ownership where we found caracara territories were primarily managed as










Although these distributions differed, these analyses do not provide information on
selection of certain habitats by caracaras, because of the scale of the analyses and the broad
categories of the available land use data. The MCP method makes no assumptions regarding
utilization distributions of habitats within a home range. Telemetry data indicate that
caracaras do occasionally forage in open agricultural areas including cane fields, citrus
groves, sod farms, and recently plowed or burned areas. These habitats may be included in a
caracara's 95% MCP range, but from these analyses, we cannot determine their importance
relative to other habitats.

Territory dispersion
Based on telemetry, we assumed that the center of activity for a caracara's territory
was the nest site. In areas where we knew nest locations for adjacent pairs of caracaras,
distances between these territory centers averaged 3.4 km + 0.2 (SE) (range 1.5 6.1 km, N =
29 pairs). The maximum local density recorded was 9 successfully breeding pairs within
4850 ha or approximately 1 pair/540 ha, on Buck Island Ranch in Highlands County (Fig.
20). Based on these findings, we believe there is a high probability that additional pairs of
caracaras occupy suitable habitats and in similar densities, in areas farther than 2 km from
roads where we could not search for them.

RANGESV analysis of home range overlap among 3 sets of adjacent pairs of
caracaras indicated that home ranges as defined by the 95% MCP overlapped an average of
approximately 23%. Among one set of 3 adjacent territories, the 95% MCP home ranges did
not overlap at all. Overlap among the other 2 sets of territories (3 pairs and 4 pairs,
respectively) ranged from 4.4% to 45.9% (Fig. 20). The 50% MCP core home ranges of
adjacent pairs did not overlap. These results support our belief that caracaras are highly
territorial, particularly around the nest site, although adjacent pairs may forage in areas that
are common to both home ranges.

Nesting success. habitat associations, and patterns of landuse
In our sample of territories, only 7 (11%) were on public lands. Where territories
were identified on private lands, the land use was overwhelmingly cattle ranching. Lands
under public ownership where we found caracara territories were primarily managed as









natural areas, with moderate grazing and farming in some areas (Fig. 21). During all 3 years
of the study, occupancy rates, breeding rates, and nesting success were higher for territories
on privately-owned lands (Fig. 22).

Management activities such as grazing, burning, mowing, and plowing influence
vegetation structure. This structure probably affects the presence/absence of caracaras and
their nesting success more closely than does the actual composition of vegetation species.
Variables that characterized vegetation structure in the nest stand area indicated that nest sites
on public and private lands differed primarily with respect to the amount and variability in
height of vegetative types. These differences are most likely related to the types of
management activities conducted on these lands. Grass/forb vegetation on private lands was
generally shorter and less variable in height whereas nest sites on public lands generally had
more and taller shrubs and more trees along the transects, in all directions.

Results of stepwise logistic regression indicated that the variable SHRUBVEG, which
describes the amount and height of shrub vegetation in the nest stand area, was the best
predictor of nest success (R = 0.34, df= 1, P = 0.006). The overall model predicted nest
success 87% of the time. In other words, nests were more likely to succeed if there was little
or no shrub vegetation within the nest stand area. Results of these analyses also indicated
that successful nests were also associated with taller nest trees, more than one tree in the nest
tree group, and closer (within 1 km) proximity to a major road and human activity. None of
these relationships were significant at the a = 0.05 level, however, probably due to the
sample size of nests. There were few nest failures overall; the sample for these analyses
included only 12 failed nests. Watson-Williams' test (Zar 1974) did not indicate any effect
of nest orientation on nest success (F = 3.21, P > 0.05).

These data on vegetation structure at nest sites perhaps are beginning to create a
picture of habitat "gestalt" for the Crested Caracara in Florida. Habitats on cattle ranches
where we found caracaras most predictably are characterized by open expanses of short
grasslands with scattered groups of cabbage palms and oaks and little diversity of other types
of vegetation such as shrubs. Most nest trees in this habitat have little vegetation around
them. In contrast, habitats on public lands where we found caracaras were characterized by







42

greater variability in types and heights of vegetation in the nest stand. Nest sites at on these
lands generally contain taller grasses, more and taller shrubs interspersed throughout the
trees, and taller vegetation closer to the nest tree.










Table 6. Banding records for Crested Caracaras captured in south-central Florida, August 1993 -
July 1996.


TpOr Cnlnr


T~pO AaP Fripniipncv


Thatp Th211dr CA1ltn v


98799361 R
98799362 L
98799363 R
98799364 R
98799365 L
98799366 R
98799367 R
98799368 R
98799369 R
98799370 L
98799371 R
98799372 L
98799373 L
98799374 L
98799375 L
98799376 L
98799377 R
98799378 L
98799379 L
98799380 R
98731217 L
98731218 R
98731219 L
98731220 R
98731221 L
98731222 R
98731223 L
98731224 R
98731225 L
98731226 L
98731227, blue L
98731228 R
98731229 L
98731230 black L
98731231 R
98731232 blue L
98731233 R
98731234 L
98731235 R
98731236 blue L
98731237 R


Blue D L HY 151.519
Black R HY -
Green L HY -
Black L HY 151.280
Green R HY -
Blue L HY -
Blue/silver L HY 151.501
Blue L A/F 151.260
Black L A/M -
Silver R A/F 151.379
Green L A/M -
Blue R A/M 151.440


Black R HY
Blue/silver R HY
Black/green R HY
Blue/black R HY
Blue/green L HY
Silver/black R HY
Blue/green R HY
Black/silver L HY
Black/silver R HY
Blue/black L A/F
Black/blue R HY
Black/blue L HY
Silver/green R HY
Black/green L HY
Silver/blue R HY
silver/blue L HY
green/black R HY
green/blue R HY
blue R HY
silver/black L HY
green/silver R HY
blue R HY
silver/green L HY
black R HY
green/blue L HY
orange R HY
green/black L HY
green R HY
orange L HY


151.300
151.799



151.321
151.977
151.938
151.358
151.780
151.839

151.338

151.859

151.639
151.620
151.896

151.957


151.670

151.877


8/31/93
1/9/94
1/9/94
2/14/94
2/15/94
2/15/94
2/15/94
2/20/94
2/20/94
3/5/94
3/5/94
3/7/94
3/7/94
3/9/94
3/9/94
3/10/94
3/10/94
3/10/94
3/10/94
3/10/94
3/14/94
3/12/94
3/17/94
3/23/94
3/23/94
3/23/94
3/23/94
4/7/94
4/7/94
4/7/94
4/8/94
4/8/94
4/8/94
4/8/94
4/10/94
4/10/94
4/10/94
4/10/94
4/10/94
4/10/94
4/10/94


Highlands
Highlands
Highlands
Okeechobee
Okeechobee
Okeechobee
Okeechobee
Glades
Glades
Okeechobee
Okeechobee
Okeechobee
Okeechobee
Glades
Glades
Okeechobee
Okeechobee
Okeechobee
Highlands
Highlands
Okeechobee
Okeechobee
Highlands
Okeechobee
Okeechobee
Highlands
Highlands
Highlands
Highlands
Glades
DeSoto
Highlands
Highlands
Highlands
Okeechobee
Okeechobee
Glades
Glades
Glades
Glades
Glades


TISFWS #


TU 1 P..1 n rt .A Fri-n,.v,.v nnti- T.nn.ipvi n,,,.e









Table 6 (cont.).


T .PO Cnlnr


T~pc AaiP Fpreniipncv


98731238 L Blue 9
98731239 R BlueE
98721240 green R green
98731241 L Blue 8
98731242 R Black 4
98731243 L Green 2
98731244 R Blue 2
98731245 L Black H
98731246 R Green C
98731247 L Black E
98731248 R Green W
98731249 R Black U
98731250 R Green O
180736805 L Black T
180736806 R Green M
180736807 L Green 8
180736808 R Green A
180736809 L Brown 2
180736810 R Purple 8
180736811 L Green 7
180736812 L Brown E
180736813 L Black R
180736814 R BlueR
180736815 L Black V
180736816 L Brown N
180736817 R Purple K
180736818 L Brown A
180736819 L Blue H
180736820 R Purple E
180736821 L Black O
180736822 L Blue 5
180736823 R Purple 3
180736824 L Green 3
180736825 R Blue P
180756701 L Brown T
180756702 L Black I
180756703 R Purple V
180756704 L Black G
180756705 R Green V
180756706 L Brown M
180756707 R Purple 2
180756708 L Brown O
180756709 R Green 1


R A/M 151.558
L A/F 151.600
L HY 151.540
R HY -
L HY 151.687
R HY -
L HY -
R HY -
L HY 151.738
R HY 151.321
L HY -
L A/M 151.759
L A/F 151.718
R HY(2) -
L HY(2) -
R HY(2) 151.670
L HY(2) -
R HY 151.817
L HY 151.260
R HY 151.799
R HY 151.440
R HY 151.877
L A/M 150.010
R A/M 150.810
R HY 150.050
L HY 150.140
R A/F 150.120
R HY 150.160
L HY 150.300
R HY 151.759
R A/F 150.260
L HY 150.030
R A/F -
L A/M 150.280
R HY 150.439
R A/F -
L A/M 150.200
R HY -
L HY -
R A/M 150.458
L A/M 150.418
R HY 150.320
L HY 150.360


4/12/94
4/17/94
4/20/94
4/27/94
4/27/94
4/27/94
4/27/94
4/30/94
4/30/94
5/2/94
5/2/94
5/3/94
5/3/94
6/16/94
6/16/94
6/16/94
6/16/94
1/23/95
1/29/95
1/29/95
2/1/95
2/2/95
2/7/95
2/8/95
2/12/95
2/12/95
2/13/95
2/20/95
2/20/95
2/20/95
2/24/95
2/25/95
2/26/95
2/26/95
2/26/95
2/28/95
2/28/95
3/5/95
3/5/95
3/7/95
3/17/95
3/19/95
3/19/95


Highlands
Highlands
Highlands
Okeechobee
Okeechobee
Okeechobee
Okeechobee
Highlands
Highlands
Glades
Glades
Highlands
Glades
Okeechobee
Okeechobee
Okeechobee
Okeechobee
Okeechobee
DeSoto
DeSoto
Highlands
Highlands
Okeechobee
DeSoto
Glades
Glades
Highlands
Highlands
Highlands
Highlands
Glades
Osceola
Glades
Glades
Glades
Highlands
Highlands
Highlands
Highlands
Okeechobee
Highlands
Glades
Glades


T TFWS #


I TVFW v # ('nlnr Tr cy A cyi Rri Un"IV f v TCntp Rnntlprl int
,vd -


natPRanrlPrl rnllntrr









Table 6 (cont.).


T Pro nlnr


T. o A o


Frp.mlnnr.v


Vkrt~ Rind~F' Cnuntv


180756710
180756711
180756712
180756713
180756714
180756715
180756716
180756717
180756718
180756719
180756720
180756721
180756722
180756723
180756724
180756725
180756726
180756727
180756728
180756729
180756730
180756731
180756732
180756733
180756734
180756735
180756736
180756737
180756738
180756739
180756740
180756741
180756742
180756743
180756744
180756745
180756746
180756747
180756748
180756749
180756750
180756751
180756752


Black S
Purple H
Orange
Blue V
Purple W
Black 7
Blue W
Purple S
Green P
Black 9
Brown B
Brown 9
Blue K
Brown V
Purple 4
Green U
Black M
Brown 1
Green 5
Green Z
Purple Y
Purple A
Brown X
Blue M
Purple X
Green 9
Green N
Black P
Blue N
Purple R
Brown K
Black A
Green B
Purple M
Blue U
Brown H
Brown C
Black M
Green T
Brown 5
Blue X
Grn/blk
Black C


HY
HY
HY
HY
HY
HY
5wk
5 wk
A/M
HY
HY
HY
HY
6wk
6wk
5 wk
5 wk
HY
HY
A/F
A/M
HY
A/M
HY
HY
HY
A/M
A/F
HY
HY
HY
HY
HY
6wk
5 wk
5wk
A/F
A/M
A/F
7wk
7wk
7 wk
A/M


150.498
150.398
150.560
150.770

150.343
150.659
150.848
150.479
150.380

150.889

150.689


150.709
150.518
150.729

150.627
150.828
151.110
150.588
151.007
151.209

150.609
150.748
150.788
150.948
151.088

150.988



151.159
151.919
151.192
150.588

150.969


3/20/95
3/20/95
3/20/95
3/20/95
3/21/95
3/21/95
3/22/95
3/22/95
3/24/95
3/24/95
3/26/95
3/29/95
3/29/95
3/29/95
3/29/95
3/29/95
3/29/95
4/2/95
4/2/95
4/3/95
4/3/95
4/6/95
4/10/95
4/11/95
4/11/95
4/11/95
4/17/95
4/17/95
4/17/95
4/17/95
4/18/95
4/18/95
4/18/95
4/18/95
4/18/95
4/18/95
4/19/95
4/19/95
4/23/95
4/25/95
4/28/95
4/28/95
5/3/95


Okeechobee
Okeechobee
Glades
Glades
Okeechobee
Okeechobee
Highlands
Highlands
Highlands
Highlands
Highlands
Okeechobee
Okeechobee
Okeechobee
Okeechobee
Okeechobee
Okeechobee
Glades
Okeechobee
Glades
Glades
Glades
Glades
Okeechobee
Highlands
Highlands
Okeechobee
Okeechobee
Highlands
Highlands
Glades
Glades
Glades
Glades
Highlands
Highlands
Highlands
Highlands
Glades
Highlands
Glades
Glades
Highlands


T TRFW :U


uvr v Ir u- vvrv u-- r--- nr qi r. Rrq ujrulrr nrmlv









Table 6 (cont.).


TTSFWS #


180756753
180756754
180756755
180756756
180756757
180756758
180756759
180756760
180756761
180756762
180756763
180756764
180756765
180756766
180756767
180756768
180756769
180756770
180756771
180756772
180756773
180756774
180756775
180756776
180756777
180756778
180756779
180756780
180756781
180756782
180756783
180756784
180756785
180756786
180756787
180756788
180756789
180756790
180756791
180756792
180756793
180756794
180756795


inllntyr


Purple 9
Purple 1
Brown 8
Green X
Green K
Green 4
Brown Y
Purple T
Purple D
Purple 2
Blue T
Purple 6
Black 8
Green D
Green R
Purple 6
Blue Z
Green G
Brown Z
Brown U
Black X
Green Y
Black N
Blue Y
Yellow N
Brown D
Green S
Brown 6
Purple C
Black K
Blue G
Purple 5
Yellow G
Green 3
Black D
Brown S
Purple B
Yellow A
Green G
Yellow V
Yellow O
Green H
Yellow D


T.po A(TP


TL.eg Fnlnr


6wk
A/F
7wk
7wk
A/M
7wk
7wk
6wk
5 wk
7wk
7 wk
A/M
7wk
HY
4 wk
A/F
A/F
A/M
6wk
HY
HY
HY
HY
A
HY
HY
7wk
A
4wk
4wk
A
7wk
7wk
7 wk
7 wk
31 d
A
A
HY
HY
HY
HY
HY


151.969
151.398

151.469
151.540
151.489
151.710



150.498
151.509
150.908
150.518
150.360
151.728
151.589
151.989


150.928
151.568
151.989
151.053
151.272
151.234
150.538
151.163
151.523

151.693
151.552
151.503
151.420
151.243
151.608
151.710
151.073
151.314
150.832
151.183
151.344


5/3/95
5/5/95
5/7/95
5/7/95
5/12/95
5/13/95
5/13/95
5/14/95
5/15/95
5/16/95
5/16/95
5/23/95
5/25/95
5/26/95
5/27/95
5/27/95
5/28/95
5/30/95
5/31/95
6/7/95
6/7/95
6/9/95
6/12/95
1/17/96
1/29/96
1/29/96
1/30/96
2/7/96
2/10/96
2/10/96
2/13/96
2/14/96
2/14/96
2/14/96
2/20/96
2/20/96
2/22/96
2/28/96
3/1/96
3/1/96
3/6/96
3/12/96
3/12/96


Glades
Glades
Highlands
Highlands
Highlands
Highlands
Highlands
Glades
Highlands
Highlands
Highlands
Highlands
Okeechobee
Okeechobee
Highlands
Highlands
Highlands
Highlands
DeSoto
Okeechobee
Okeechobee
Okeechobee
Highlands
DeSoto
DeSoto
DeSoto
Glades
Glades
Glades
Glades
Okeechobee
Okeechobee
Okeechobee
Okeechobee
Highlands
Highlands
Highlands
Highlands
Okeechobee
Okeechobee
Okeechobee
Highlands
Okeechobee


T~ ~ ~ ~ ~ ~~~~~~. j-1RQ # .-rC~r T-- y r-"n- lt nA it,


Freauency


Date Banded









Table 6 (cont.).


TTTCTWSO #


T o nlorf


T (p Aoi


Frpn pnr v


MMLI 4 Urp m Ukq MU rm.b. &.mm&XX


180756796
180756797
180756798
180756799
180756800
180761501
180761502
180761503
180761504
180761505
180761506
180761507
180761508
180761509
180761510
180761511
180761512
180761513
180761514
180761515
180761516
180761517
987-49289
180761518
180761519
180761520
180761521
180761522
180761523
180761524
180761525
180761526
180761527
180761528
180761529
180761530
180761531
180761532
180761533
180761534
180761535
180761536
180761537


Yellow 2
Yellow C
Purple 7
Yellow 8
Black Y
Blue 2/2
Brown 7
Blue 0/5
Yellow P
Purple U
Blue 0/6
Brown P
Blue 2/7
Purple N
Yellow 1
Purple O
Blue 1/9
Yellow 3
Yellow T
Brown G
Brown 3
Blue 2/4
Black B
Yellow K
Black Z
Blue 2/2
Yellow M
Black 3
Blue 0/9
Blue 3/4
Yellow 5
Blue 1/1
Yellow U
Brown R
Yellow Y
Blue 0/7
Purple P
Blue 2/6
Blue 1/4
Brown 4
Blue 3/0
Yellow B
Brown W


HY
6wk
6wk
HY
HY
HY
HY
HY
HY
A
HY
HY
HY
HY
HY
A
HY
HY
HY
HY
7wk
7wk
A
HY
HY
A
HY
HY
6wk
HY
A
HY
HY
5 wk
6wk
6wk
7wk
HY
7wk
7wk
HY
HY
HY


150.673
151.143
151.603

151.642
151.614
151.453
150.518
151.382
151.544

150.814

150.120
151.432

151.582
151.334

151.412
150.689
151.263


150.398
151.633

151.033
151.568

150.870
151.373

151.922
151.122
150.543

150.574


3/13/96
3/13/96
3/13/96
3/13/96
3/13/96
3/13/96
3/19/96
3/19/96
3/19/96
3/20/96
3/21/96
3/21/96
3/23/96
3/23/96
3/23/96
3/26/96
3/27/96
3/27/96
3/28/96
3/28/96
3/29/96
3/29/96
4/1/96
4/1/96
4/1/96
4/2/96
4/2/96
4/2/96
4/4/96
4/8/96
4/9/96
4/10/96
4/10/96
4/10/96
4/15/96
4/15/96
4/17/96
4/19/96
4/19/96
4/19/96
4/23/96
4/23/96
4/23/96


Highlands
Glades
Glades
Highlands
Highlands
Highlands
Highlands
Highlands
Highlands
Highlands
Osceola
Okeechobee
Okeechobee
Highlands
Highlands
Highlands
Indian River
Indian River
Highlands
Highlands
Highlands
Highlands
Highlands
Highlands
Highlands
Hendry
Hendry
Hendry
Highlands
Glades
Highlands
Highlands
Highlands
Highlands
Highlands
Highlands
Polk
Glades
Highlands
Highlands
Glades
Glades
Glades


Date 13anded









Table 6 (cont.).


1 A e Feuecy


Thte RnardPd


ku m M&7 kr r ro k 6W k m e &X


HY -
HY -
HY 151.663
7.5 wk -


180761538
180761539
180761540
180761541
180761542
180761543
180761544
180761545
180761546
180761547
180761548
180761549
180761550
180761551
180761552
180761553
180761554
180761555
180761556
180761557
180761558
180761559
180761560
180761561


Blue 1/3
Blue 3/7
Black 2
Blue 2/3
Yellow 5
Yellow 7
Black 5
Blue 3/9
Yellow Z
Blue 0/4
Yellow R
Black 9
Yellow H
Blue 1/5
Yellow E
Blue 4/5
Yellow X
Blue 3/3
Blue 4/1
Blue 4/0
Blue 4/3
Yellow 6
Yellow W
Blue 3/6


4/23/96
4/24/96
4/24/96
4/25/96
4/26/96
4/27/96
4/30/96
4/30/96
5/2/96
5/2/96
5/2/96
5/2/96
5/5/96
5/5/96
5/6/96
5/6/96
5/8/96
5/8/96
5/8/96
6/24/96
7/10/96
7/10/96
7/17/96
7/17/96


Glades
DeSoto
DeSoto
Highlands
Glades
Hendry
Highlands
Highlands
Highlands
Glades
Glades
Highlands
Okeechobee
Okeechobee
Highlands
Highlands
Highlands
Highlands
Highlands
Okeechobee
Okeechobee
Okeechobee
Highlands
Highlands


T Tabe t


T C ln r


7wk
HY
HY
HY
A
6wk
6wk
HY
HY
HY
A
A
7wk
7wk
7wk
HY
HY
HY
7wk
7wk


150.643
150.560


151.489


150.993

151.672
151.088


1.613

0.623
0.398
1.923
1.552
1.540


r" 1 +r










Table 7. Home range statistics for 17 (10M, 7F) adult breeding Crested Caracaras in south
central Florida, 1994 1996. HM = harmonic mean contours. MCP = minimum
convex polygon contours. Area is expressed as km2


Bird ID Sex # points 50% HM 95% HM 95% MCP Range width (km)
0609 F 41 1.84 17.17 9.95 5.78
1969 F 35 1.08 4.89 3.79 4.88
0360 F 36 2.94 20.84 11.39 9.79
0120 F 33 0.65 9.23 6.25 5.63
1379 F 31 0.94 4.36 8.96 5.01
1600 F 32 1.63 12.40 10.73 5.93
1728 F 34 3.27 24.86 23.89 8.88
0280 M 32 0.70 3.89 3.61 4.16
0458 M 46 3.91 21.71 19.29 7.73
0479 M 40 3.02 16.58 15.74 6.19
1110 M 37 1.03 6.91 5.59 4.79
0969 M 32 2.34 11.07 9.39 4.82
1469 M 39 2.12 11.05 8.28 6.69
0498 M 36 1.33 9.24 8.48 4.88
1589 M 37 4.09 22.47 17.98 8.35
0200 M 35 0.71 7.62 6.34 5.17
1558 M 37 1.42 8.72 6.41 4.64

























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55



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45-


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40-
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35



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S-
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15 I I
2 4 6 8 10 12

Height (m)

Fig. 11. Relationship between DBH and height of cabbage palms (Sabalpalmetto)
at Crested Caracara nest sites, south-central Florida, 1994-1995.
Equation for the regression line is DBH = 48.811 (1.948*height).


















O




0)

a U

C)

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o -
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h-?^~~ -st|




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ii'ii~ iiiii;i~i i~ i!,...... ,iiii .....


........... ...... N : : .:::: ; :: ::::

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11
S Regression
10-
*

9-


8 8

4 7


c 6-




4-


3- *



15 20 25 30 35 40 45 50

Number of radiolocations

Fig. 15. Relationship between number of radiolocations and maximum range width
for Crested Caracaras in south-central Florida, 1994 1996.






(0
CT-



0
m

00
qo





co( (D
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1 I I I I I _I I j I I











































CARACARAS


MALE 1600
FEMALE 0360
MALE 0969
FEMALE 1469
MALE 1558
UNK 1608
UNK 1710
UNK 0689
UNK 1489


LAND USE CLASSIFICATIONS
1 PASTURE
S CITRUS
SOD FARM
MIXED FOREST
PALM/OAK HAMMOCK
WATER
NON-FORESTED WETLANDS
S SCRUB
rM CYPRESS
E13 RESIDENTIAL


Fig.2Q Overlap among 9 Crested Caracara home ranges
on Buck Island Ranch, Highlands Co. Home ranges shown as 95% MCP.







































I,
"o



0









L
'E
0
*Y







Cb









ia
Cs



















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ch
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cu









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ue


0o 0 0 0 0 0 0
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MOVEMENTS AND HABITAT ASSOCIATIONS OF JUVENILE CARACARAS

Objectives
The overall objectives of this part of the study were to define the fledgling-
dependency period and to characterize the movement patterns and habitat associations of
juvenile caracaras. Specific objectives included:

1) describe movements around the nest stand area;
2) determine age at dispersal from the natal territory;
3) describe patterns of movement (direction and distance) away from the natal territory;
4) examine social interactions among siblings and adults;
5) evaluate philopatry of immatures to particular regions of the study area;
6) evaluate habitat associations within immature congregation areas.

Methods
We banded 189 juvenile caracaras during 1993 1996 (Table 6) and radiotagged 116
of these individuals. We handled juvenile caracaras when they were between 7 and 8 weeks
of age while still in the nest, or during the first 24 hours after fledging when they can be
captured easily on the ground because they do not yet fly well. Transmitters were of the
same type as those used for adults and were attached in the same manner as described in
Adult home ranges, above. If a fledgling died, we retrieved the radio when possible and
affixed it to another juvenile or adult caracara.

To obtain locations on radiotagged juvenile caracaras, we conducted radiotracking
surveys from a fixed-wing Cessna 172 aircraft as described in Telemetry, above. During
flights, we attempted to find all juveniles. We took GPS coordinates (latitude/longitude) of
the location of each individual found. We also took notes on habitat associations and activity
of these individuals, as described in Telemetry, above. Difficulties with access to many areas
used by juvenile caracaras precluded our ability to obtain ground locations efficiently, or
even to find certain individuals on the ground. Therefore, triangulation was not used to
obtain radiolocations for juvenile caracaras.

To examine exploratory movements by juveniles, we measured the linear distance
from the nest to each location and examined the mean distance to the nest for all juveniles by









MOVEMENTS AND HABITAT ASSOCIATIONS OF JUVENILE CARACARAS

Objectives
The overall objectives of this part of the study were to define the fledgling-
dependency period and to characterize the movement patterns and habitat associations of
juvenile caracaras. Specific objectives included:

1) describe movements around the nest stand area;
2) determine age at dispersal from the natal territory;
3) describe patterns of movement (direction and distance) away from the natal territory;
4) examine social interactions among siblings and adults;
5) evaluate philopatry of immatures to particular regions of the study area;
6) evaluate habitat associations within immature congregation areas.

Methods
We banded 189 juvenile caracaras during 1993 1996 (Table 6) and radiotagged 116
of these individuals. We handled juvenile caracaras when they were between 7 and 8 weeks
of age while still in the nest, or during the first 24 hours after fledging when they can be
captured easily on the ground because they do not yet fly well. Transmitters were of the
same type as those used for adults and were attached in the same manner as described in
Adult home ranges, above. If a fledgling died, we retrieved the radio when possible and
affixed it to another juvenile or adult caracara.

To obtain locations on radiotagged juvenile caracaras, we conducted radiotracking
surveys from a fixed-wing Cessna 172 aircraft as described in Telemetry, above. During
flights, we attempted to find all juveniles. We took GPS coordinates (latitude/longitude) of
the location of each individual found. We also took notes on habitat associations and activity
of these individuals, as described in Telemetry, above. Difficulties with access to many areas
used by juvenile caracaras precluded our ability to obtain ground locations efficiently, or
even to find certain individuals on the ground. Therefore, triangulation was not used to
obtain radiolocations for juvenile caracaras.

To examine exploratory movements by juveniles, we measured the linear distance
from the nest to each location and examined the mean distance to the nest for all juveniles by









MOVEMENTS AND HABITAT ASSOCIATIONS OF JUVENILE CARACARAS

Objectives
The overall objectives of this part of the study were to define the fledgling-
dependency period and to characterize the movement patterns and habitat associations of
juvenile caracaras. Specific objectives included:

1) describe movements around the nest stand area;
2) determine age at dispersal from the natal territory;
3) describe patterns of movement (direction and distance) away from the natal territory;
4) examine social interactions among siblings and adults;
5) evaluate philopatry of immatures to particular regions of the study area;
6) evaluate habitat associations within immature congregation areas.

Methods
We banded 189 juvenile caracaras during 1993 1996 (Table 6) and radiotagged 116
of these individuals. We handled juvenile caracaras when they were between 7 and 8 weeks
of age while still in the nest, or during the first 24 hours after fledging when they can be
captured easily on the ground because they do not yet fly well. Transmitters were of the
same type as those used for adults and were attached in the same manner as described in
Adult home ranges, above. If a fledgling died, we retrieved the radio when possible and
affixed it to another juvenile or adult caracara.

To obtain locations on radiotagged juvenile caracaras, we conducted radiotracking
surveys from a fixed-wing Cessna 172 aircraft as described in Telemetry, above. During
flights, we attempted to find all juveniles. We took GPS coordinates (latitude/longitude) of
the location of each individual found. We also took notes on habitat associations and activity
of these individuals, as described in Telemetry, above. Difficulties with access to many areas
used by juvenile caracaras precluded our ability to obtain ground locations efficiently, or
even to find certain individuals on the ground. Therefore, triangulation was not used to
obtain radiolocations for juvenile caracaras.

To examine exploratory movements by juveniles, we measured the linear distance
from the nest to each location and examined the mean distance to the nest for all juveniles by









age in months post fledging. We determined bearings from the nest for each location > 3 km
from the nest for each individual, then calculated the mean bearing. Rayleigh's test (Zar
1974) was used to test the hypothesis that the distribution of locations of juveniles away from
their nests at independence does not differ from a random distribution.

We again used the method of Neu et al. (1974). to evaluate use of different habitats by
immatures after they left their natal territory. We assessed habitat use by determining the
numbers of radiolocations within each habitat type for each bird. We assessed habitat
availability using the GIS coverage of the 20 habitat types created from the land
use/landcover database of the SFWMD. For this analysis we only used radiolocations
obtained on juveniles after they left their natal territory. We assumed that while juveniles
were still within their natal territory, their selection of habitats was probably influenced by
their proximity to the nest and also by the adults.

To examine sociality among siblings, we investigated whether they stayed together
while still in the natal territory and when they began to make exploratory movements away
from the territory. At 6 nests, we radiotagged one adult and 2 siblings. We obtained
locations for these adults and chicks on 96 days, then calculated the linear distance between
each chick and the adult and between the two chicks on all those days.

When analyzing movement data for radiotagged juvenile caracaras, we considered the
sample size to be the number of birds, not the number of individual locations. For each
analysis, we combined all locations for each bird in each age or analysis class then used one
value (the mean) as the datapoint. All statistics were evaluated at the a = 0.05 level. For
analysis of circular distributions (distances and bearings to habitat features and to
radiolocations), we used circular statistics (Batschelet 1981). We conducted statistical
analyses using SYSTAT and Microsoft EXCEL statistical packages. We conducted
additional analyses using FORTRAN programs written specifically for this research.

For juveniles radiotagged in 1996, we used transmitters manufactured by Advanced
Telemetry Systems, Inc. These transmitters contain a programmable computer chip and are
set to transmit a signal 12 hours per day for 5 days per week. Expected life is between 3 and
4 years. By 1996, we had collected considerable data on movement patterns for 45 juveniles









from 1994 and 1995, thus we wished to expand the scope of the questions that could be
answered using telemetry on these immature caracaras. We used these longer-lived
programmable transmitters because we hope to obtain information on longer-term survival of
immatures and ultimately, on recruitment rates of young into the breeding population.
Movement data for the 1996 juvenile cohort are not included in this report because most had
not yet left their natal territories.

Results
It is believed that Crested Caracaras, like Bald Eagles (Haliaetus leucocephalus), do
not breed until they are 3 4 years of age. They do not attain the Definitive Basic adult
plumage until this time, although few data exist and are mostly on captives (Layne 1986).
Before this study, no information was available on activities and habitat associations of these
immature age classes. Telemetry data obtained during this study on juvenile caracaras are
beginning to provide knowledge of this time period in the caracara's life history. As yet, no
information currently exists on recruitment rates. This information is critical to development
of demographic models that predict long-term population persistence.

Length of the post-fledging dependency period
The post-fledging dependency period can be defined as approximately the first two
months after fledging. During this time fledglings remain close to the nest site and are
dependent on the parents for food, although they begin walking about searching for insects
soon after leaving the nest. At fledging, the young average 88% of adult mass. Wing chord
is 83% and tarsus 100% of mean adult lengths, respectively. Newly fledged chicks are not
capable of sustained flight. They can fly short distances and usually make awkward landings
on the ground. If disturbed during the first 24 hours after leaving the nest, they run rather
than fly away, but within 2 days they can fly up into trees. During the first few weeks they
spend most of their time perched low in vegetation and lying on the ground. If a predator is
nearby they flatten the body, pull in the head, and remain motionless. Their brown and tan
camouflage coloring makes them extremely difficult to see. Juvenile caracaras do not appear
on visible high perches until about 3 months after fledging; then only rarely.









from 1994 and 1995, thus we wished to expand the scope of the questions that could be
answered using telemetry on these immature caracaras. We used these longer-lived
programmable transmitters because we hope to obtain information on longer-term survival of
immatures and ultimately, on recruitment rates of young into the breeding population.
Movement data for the 1996 juvenile cohort are not included in this report because most had
not yet left their natal territories.

Results
It is believed that Crested Caracaras, like Bald Eagles (Haliaetus leucocephalus), do
not breed until they are 3 4 years of age. They do not attain the Definitive Basic adult
plumage until this time, although few data exist and are mostly on captives (Layne 1986).
Before this study, no information was available on activities and habitat associations of these
immature age classes. Telemetry data obtained during this study on juvenile caracaras are
beginning to provide knowledge of this time period in the caracara's life history. As yet, no
information currently exists on recruitment rates. This information is critical to development
of demographic models that predict long-term population persistence.

Length of the post-fledging dependency period
The post-fledging dependency period can be defined as approximately the first two
months after fledging. During this time fledglings remain close to the nest site and are
dependent on the parents for food, although they begin walking about searching for insects
soon after leaving the nest. At fledging, the young average 88% of adult mass. Wing chord
is 83% and tarsus 100% of mean adult lengths, respectively. Newly fledged chicks are not
capable of sustained flight. They can fly short distances and usually make awkward landings
on the ground. If disturbed during the first 24 hours after leaving the nest, they run rather
than fly away, but within 2 days they can fly up into trees. During the first few weeks they
spend most of their time perched low in vegetation and lying on the ground. If a predator is
nearby they flatten the body, pull in the head, and remain motionless. Their brown and tan
camouflage coloring makes them extremely difficult to see. Juvenile caracaras do not appear
on visible high perches until about 3 months after fledging; then only rarely.









Time to independence
After about 3 months post fledging, juveniles begin to explore areas farther away (up
to 6 km) from the nest but regularly return to roost at night in the nest stand or the nest tree
itself. We defined independence as permanent movement greater than 3 km away from the
nest. Most permanent departure from the natal territory occurred 4-6 mo post fledging (40%,
n = 38), although some young remained until adults began breeding the following year (25%
during 2 yr); sex differences unknown. For 38 caracaras that have been tracked past
independence, the average distance of locations from the nest increased with age (X2 = 105,
P < 0.001) (Fig. 23). There were definite periods of abrupt movement, which represented
dispersal away from natal territories.

To evaluate time to independence, we examined single broods and the first of double
broods separately because we assumed that dispersal of juveniles from nests in which double
brooding occurred was influenced by the second brood, not necessarily by normal dispersal
mechanisms. Average time to independence was significantly earlier (11 weeks vs. 29
weeks, t = 4.79, P < 0.001) for juveniles whose parents had a second brood compared to
those whose parents did not (Fig. 23). Bimodality in the distribution of ages at independence
(Fig. 24) may be related to sex. To date, these data are not available.

Exploratory movements
After leaving their natal territory, individuals wander widely throughout but rarely
travel outside the population's range. They may remain at a location for several weeks
between large movements and may return after several months to a familiar area near their
natal territory. Rayleigh's test indicated that at most ages post fledging, the distribution of
locations of juveniles away from their nests does not differ from a random distribution (Table
9). In other words, as an entire sample, there appears to be no directionality to their
movements. This is expected for a resident population, reflecting absence of a need to
establish a navigational target (cf. Baker 1993).

If the distributions of locations are examined for individual caracaras, however, some
directionality is evident (Table 10). For most individuals, movements were not random.
This is because movements by individuals show somewhat of a step pattern. A juvenile









Time to independence
After about 3 months post fledging, juveniles begin to explore areas farther away (up
to 6 km) from the nest but regularly return to roost at night in the nest stand or the nest tree
itself. We defined independence as permanent movement greater than 3 km away from the
nest. Most permanent departure from the natal territory occurred 4-6 mo post fledging (40%,
n = 38), although some young remained until adults began breeding the following year (25%
during 2 yr); sex differences unknown. For 38 caracaras that have been tracked past
independence, the average distance of locations from the nest increased with age (X2 = 105,
P < 0.001) (Fig. 23). There were definite periods of abrupt movement, which represented
dispersal away from natal territories.

To evaluate time to independence, we examined single broods and the first of double
broods separately because we assumed that dispersal of juveniles from nests in which double
brooding occurred was influenced by the second brood, not necessarily by normal dispersal
mechanisms. Average time to independence was significantly earlier (11 weeks vs. 29
weeks, t = 4.79, P < 0.001) for juveniles whose parents had a second brood compared to
those whose parents did not (Fig. 23). Bimodality in the distribution of ages at independence
(Fig. 24) may be related to sex. To date, these data are not available.

Exploratory movements
After leaving their natal territory, individuals wander widely throughout but rarely
travel outside the population's range. They may remain at a location for several weeks
between large movements and may return after several months to a familiar area near their
natal territory. Rayleigh's test indicated that at most ages post fledging, the distribution of
locations of juveniles away from their nests does not differ from a random distribution (Table
9). In other words, as an entire sample, there appears to be no directionality to their
movements. This is expected for a resident population, reflecting absence of a need to
establish a navigational target (cf. Baker 1993).

If the distributions of locations are examined for individual caracaras, however, some
directionality is evident (Table 10). For most individuals, movements were not random.
This is because movements by individuals show somewhat of a step pattern. A juvenile









caracara most often went somewhere and stayed there for a period of time before making
another large movement. Distances moved between successive locations are generally short
(< 3 km) and if one examines the cumulative distance moved between successive locations
for these caracaras, the step pattern is evident (Fig. 25).

Telemetry data from 38 immatures indicated preference for pasture, dairy, and citrus
habitats, and less use than expected of scrub, urban, marsh, and pine forest habitats (Table
11). Immature caracaras were often found in burned and plowed fields, in canefields and in
other agricultural areas. For the purposes of this analysis, we lumped the burned and plowed
areas into the pasture category, because these areas were formerly pasture and this land use
state was only temporary. We lumped canefields and other agriculture together in the
"agriculture" category. Locations within the "urban" category were generally in what we
referred to as "urban pastures", which were generally small pastures or open areas surrounded
by developments and roads. At the resolution of the land use/landcover data used for these
analyses, many of the areas classified as marsh are probably large deepwater wetlands not
used by caracaras, hence the apparent lack of preference for this habitat.

Sociality among siblings
During the first 2 months after leaving the nest, siblings associate with each other
and remain mostly within 1 km of the nest. As they become nutritionally independent, they
do not necessarily remain together or with the adult (Fig. 26). They may forage alone or with
an adult, at farther distances from the nest. At the next breeding season, remaining young are
chased out of the territory by the adults. After leaving the natal territory, siblings do not
regularly associate with each other, although telemetry data indicate that occasionally they
are found together after several weeks apart.

Congregations of immatures
After leaving their natal territories, immature Crested Caracaras apparently form
groups. Members are from widely separated territories. Groups of 3 or more unrelated
immature and sub-adult caracaras were observed regularly, particularly during winter
months. These groups may be feeding associations. Mixed age-class groups of up to 30
individuals have been seen foraging in pastures, dairies, recently burned fields, and in citrus









caracara most often went somewhere and stayed there for a period of time before making
another large movement. Distances moved between successive locations are generally short
(< 3 km) and if one examines the cumulative distance moved between successive locations
for these caracaras, the step pattern is evident (Fig. 25).

Telemetry data from 38 immatures indicated preference for pasture, dairy, and citrus
habitats, and less use than expected of scrub, urban, marsh, and pine forest habitats (Table
11). Immature caracaras were often found in burned and plowed fields, in canefields and in
other agricultural areas. For the purposes of this analysis, we lumped the burned and plowed
areas into the pasture category, because these areas were formerly pasture and this land use
state was only temporary. We lumped canefields and other agriculture together in the
"agriculture" category. Locations within the "urban" category were generally in what we
referred to as "urban pastures", which were generally small pastures or open areas surrounded
by developments and roads. At the resolution of the land use/landcover data used for these
analyses, many of the areas classified as marsh are probably large deepwater wetlands not
used by caracaras, hence the apparent lack of preference for this habitat.

Sociality among siblings
During the first 2 months after leaving the nest, siblings associate with each other
and remain mostly within 1 km of the nest. As they become nutritionally independent, they
do not necessarily remain together or with the adult (Fig. 26). They may forage alone or with
an adult, at farther distances from the nest. At the next breeding season, remaining young are
chased out of the territory by the adults. After leaving the natal territory, siblings do not
regularly associate with each other, although telemetry data indicate that occasionally they
are found together after several weeks apart.

Congregations of immatures
After leaving their natal territories, immature Crested Caracaras apparently form
groups. Members are from widely separated territories. Groups of 3 or more unrelated
immature and sub-adult caracaras were observed regularly, particularly during winter
months. These groups may be feeding associations. Mixed age-class groups of up to 30
individuals have been seen foraging in pastures, dairies, recently burned fields, and in citrus









groves. These immatures are consistently gregarious, regularly chasing and flying together,
displacing one another from perches, and vocalizing. Immatures frequently roost together,
sometimes with vultures. Telemetry data indicate that groups are able to enter territories of
adult pairs.

We occasionally found juveniles from one territory within a 3 km radius of an
adjacent pair's nest. Telemetry data revealed that as they become older and begin to move
away from their natal territory, juveniles often make exploratory forays into other known
territories.

We identified what appear to be particularly important areas for these groups of
immature caracaras throughout the study region. One area is along the Kissimmee River in
Okeechobee County just north of SR 98 (Fig. 27), where we located approximately 48% of
the radiotagged immature caracaras at least once. Some of the immatures found here moved
to this area from distant territories. At the age of 11 months post-fledging, a radiotagged
juvenile from a nest on Lake Tohopekaliga traveled more than 40 km south to this area.
Before this time, we had located it repeatedly within 15 km of its nest, occasionally in 3
Lakes WMA. This individual remained along the river in the congregation area until we lost
its signal in April 1996. Other individuals remained in the area for several weeks then made
long excursions away to another location, only to return eventually to this area along the
river. Another area where immatures congregate is just north of US 27 in Glades County,
west of the town of Moore Haven (Fig. 27). Habitat in these areas is primarily large
expanses of pasture and dairy, but the particular resource values of these areas are unknown.
These areas may also be of some historic importance.

Identification of these congregation areas and the fact that we are finding so many of
our radiotagged juveniles there is particularly interesting, considering that the ratio of
radiotagged to unbanded juvenile caracaras is probably quite low. Routine observations of
immatures made throughout the study area reveal many more unbanded individuals than
banded ones. These findings further support recognition of these congregation areas as
particularly important to Florida's Crested Caracara population.









The two juveniles that fledged in the APAFR territory in March 1995 remained in the
territory until late January 1996. They both left the territory about the same time, within 2
weeks of egglaying by the adults in the new 1996 nest. One juvenile, 0.659, traveled north
first, where we obtained one location for it on Kicco WMA. Then both individuals traveled
south along the Kissimmee River to the congregation area (Fig. 27). Since February, they
have been found along the Kissimmee River and in improved pasture and dairy habitats in
northern Highlands and Okeechobee counties. Telemetry data suggest that neither individual
has returned to APAFR. None of the other radiotagged immature caracaras has been located
on APAFR, suggesting that the Range does not receive regular use by immatures. This
conclusion is also supported by reports of sightings on the Range. Most sightings occurred
only once or over a period of only a few days in any particular area. Most individuals seen
were immatures, suggesting that these individuals were not resident birds and probably
moved on.









Table 9. Test of null hypothesis that distribution of exploratory movements by juvenile Crested
Caracaras by age in months post fledging, does not differ from a random distribution.
indicates rejection of the null hypothesis.


N Months Rayleigh's Accept/
Birds post- r Reject
fledging
6 3 0.23 NS
10 4 0.2 NS
12 5 0.33 *
11 6 0.45 *
8 7 0.67 *
9 8 0.15 NS
8 9 0.22 NS
9 10 0.29 NS
9 11 0.44 *
8 12 0.16 NS
8 13 0.33 NS
6 14 0.51 *
6 15 0.17 NS










Table 10. Test of null hypothesis that distribution of exploratory movements by individual
juvenile Crested Caracaras does not differ from a random distribution, N = 15. *
indicates rejection of the null hypothesis, i.e., movements of individuals were not
random.


N Bird Rayleigh's Accept/
Locations r Reject
10 0.030 0.61 *
12 0.343 0.95 *
13 1.260 0.99 *
55 1.280 0.88 *
47 1.300 0.76 *
12 1.338 0.99 *
32 1.358 0.21 NS
19 1.440 0.80 *
17 1.639 0.60 *
26 1.670 0.40 *
19 1.817 0.30 NS
45 1.839 0.81 *
27 1.859 0.81 *
17 1.938 0.29 NS
19 1.957 0.29 NS












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