Conservation and Management of the Swallow-tailed Kite (Elanoides forficatus)

Conservation and Management of the Swallow-tailed Kite (Elanoides forficatus)

FINAL REPORT Kenneth D. Meyer

December 2004

Florida Fish and Wildlife Conservation Commission 620 South Meridian Street Tallahassee, FL 32399-1600

Conservation and Management of the Swallow-tailed Kite (Elanoides forficatus)

Kenneth D. Meyer

Avian Research and Conservation Institute 411 N.E. 7 Street Gainesville, FL 32601

Submitted as final report for Florida Fish and Wildlife Conservation Commission Project NG97-024 December 2004

This report is the result of a project supported by the Florida Fish and Wildlife Conservation Commission’s Nongame Wildlife Trust Fund. It has been reviewed for clarity, style, and typographical errors, but has not received peer review. Any opinions or recommendations in this report are those of the authors and do not represent policy of the Commission.

Suggested citation: Meyer, K. D. 2004. Conservation and management of the swallow-tailed kite (Elanoides forficatus). Final report. Florida Fish and Wildlife Conservation Commission, Tallahassee, Florida, USA.

Conservation and Management of the Swallow-tailed Kite (Elanoides forficatus)

Kenneth D. Meyer Avian Research and Conservation Institute, 411 N.E. 7 Street, Gainesville, FL 32601

Abstract: The northern subspecies of the swallow-tailed kite (Elanoides forficatus) once nested in 17 and perhaps as many as 21 states. This Neotropical migrant’s U.S. population suffered an abrupt decline at the turn of the century and has changed little since reaching its low point in the 1940s. Estimates are about 3,500–5,000 individuals, two-thirds of which are in Florida. Our objectives were to expand studies of nesting ecology and demography from southern to central and northern Florida, to locate pre-migration roosts, to develop a long-term monitoring plan, to describe the migration route and winter range, and to analyze the genetic relationships of swallow-tailed kite subpopulations in the U.S. Of 38 nests found in 1998, 26 were on industrial forests. Nest densities on national forest lands were low compared with industrial and private timberlands. Fifteen of the 38 attempts (61%) in 1998 failed and the remaining 23 fledged at least 1 young. Productivity was 0.84 young fledged per attempt and 1.39 young fledged per successful attempt. Success and productivity in northern Florida did not differ from our estimates for 9 years in southern Florida. Post-fledging movements varied among individuals, similar to the behavior of juveniles in southern Florida. We found 11 of 73 radio-tagged juveniles at 1 year old (15%), consistent with our detection rate (15–20%) for smaller samples of 1-year-olds in 6 of the previous years. We observed 45 pre-migration communal roosts ranging in size from 2 to 1,840 kites in 1998 and 1999. Most (38) had fewer than 40 birds at their peak. Any long-term monitoring plan should focus on roosts that consistently have >150 kites, which are the most predictable in location and timing. The 6 largest sites that we monitored contained >3,000 kites within an 8-day period in July 1999, or 60% of the largest estimate for the U.S. population. Satellite tracking of 12 southbound swallow-tailed kites provided the first description of migration behavior, route, and wintering destinations. During this flight, which took 2.5–3.5 months, the kites concentrated in Cuba, the Yucatan Peninsula, northern Belize, southwestern Colombia, and portions of the western border region of Brazil. The corridor was narrowest in the Andes of southwestern Colombia, where the kites passed through the mountains from west to east. Cuba, the Yucatan Peninsula, and Belize may be used as a stopover by north- and southbound kites before and after crossing the Gulf of Mexico. We learned of 9 roost sites in Brazil that were used by 6,000–8,000 wintering swallow-tailed kites. All were on privately owned ranches, which harbor the largest remaining patches of the habitats used by wintering and breeding kites. Genetic analyses indicated that kites from central and southern Florida are homogeneous.

This may result from founder effect or a low rate of mixing among sub-populations in the U.S. Based on what we have learned about breeding behavior, mixing probably is occurring at a sufficient rate to produce the observed homogeneity and founder effect is not a concern.

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ACKNOWLEDGMENTS I thank the following for their contributions to the project. John Arnett and Renata Leite for their enthusiastic field work in Florida and Audrey Washburn for her thorough job of coordinating the summer and winter field efforts, assisting with administrative tasks, and helping in the field. Audrey and John produced excellent data in Brazil under difficult conditions. Jennifer Coulson (Tulane University, Louisiana), John Cely (South Carolina Department of Natural Resources), and Jim Elliott (South Carolina Center for Birds of Prey) provided blood samples from swallow-tailed kites and deployed some of our satellite transmitters. Many people in state and federal agencies, conservation organizations, and land-management corporations provided sighting information, including some nest locations. I especially thank Steve Lowrimore of Georgia-Pacific Corporation; Mark Latch and Parks Small of the Florida Department of Environmental Protection; Jane Monaghan, Laura Lowery, and Susan Fitzgerald of the U.S. Forest Service; Anne Moore; and Henry Sansing of the U.S. Fish and Wildlife Service for their contributions. Many agencies, corporations, and private landowners granted us access to their lands, often assisting logistically. These included the U.S. Forest Service, Florida Fish and Wildlife Conservation Commission, Florida Department of Environmental Protection, Florida Division of Forestry, various state water management districts, Georgia-Pacific Corporation, St. Joe Paper Company, and Jefferson-Smurfitt Corporation.

Georgia Department of Natural Resources provided a plane and pilot for a kite survey. John Cely, Jennifer Coulson, and Mark Woodrey organized flights outside of Florida and assisted with the aerial surveys. Mark Woodrey arranged for funding from the Mississippi Museum of Natural Science for 10.3 hours of flying time. I thank David Cook, Michael Evans, and Stuart Cumberbatch, Florida Fish and Wildlife Conservation Commission, for their assistance in establishing and administering this contract; Brian Millsap for advice and helpful discussions on the project; and George Wallace and Cavell Kyser for their helpful reviews of an earlier draft.

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TABLE OF CONTENTS ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 OBJECTIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Nesting Ecology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Demography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Pre-migration Communal Roosts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Long-term Monitoring Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Migration Corridor and Winter Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Genetics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Nesting Ecology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Demography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Pre-migration Communal Roosts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Long-term Monitoring Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Migration Corridor and Winter Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Genetics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Other Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 DISCUSSION AND RECOMMENDATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Nesting Ecology and Demography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Roosts and a Long-term Monitoring Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Migration Corridor and Winter Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Genetics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 APPENDIX A. Proposed Population Monitoring Protocol . . . . . . . . . . . . . . . . . . 41

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INTRODUCTION The northern subspecies of the swallow-tailed kite (Elanoides forficatus), which breeds in the southeastern United States and spends the boreal winter in South America (Cely 1979, Robertson 1988), once nested in 17 and perhaps as many as 21 states (Meyer 1995). The U.S. population (herein synonymous with northern subspecies) suffered an abrupt decline at the turn of the century, perhaps due to shooting and habitat loss (Robertson 1988). The breeding distribution has changed little, if any, since the 1940s, when the population reached its low point. At present, nesting occurs only in Florida and small portions of 6 other southeastern states. Estimates place the U.S. breeding population at 800–1,200 pairs or, at the end of the breeding season, about 3,500–5,000 individuals counting nonbreeding adults and young of the year (Meyer 1995). Florida probably harbors about two-thirds of the remaining swallow-tailed kites, with sub-populations numbering no more than about 100–150 pairs in each of the other 6 southeastern states (Meyer 1995).

The Florida Fish and Wildlife Conservation Commission (FWC), in setting priorities for conservation efforts in the state, ranked the swallow-tailed kite as one of Florida’s most vulnerable and poorly understood species (Millsap et al. 1989). Partners in Flight considers the swallow-tailed kite an at-risk species of high priority for conservation action across the southeastern U.S. Swallow-tailed kites have been recommended for consideration for Endangered listing at state and federal levels (Meyer and Collopy 1996).

Our previous studies of swallow-tailed kites in southern Florida over the last 9 years, funded mainly by the FWC, have highlighted the most important needs for further work. These priorities include breeding biology (habitat selection, nesting success and productivity, correlates of nesting success, recruitment to the breeding population) in northern and central Florida, where nesting ecology apparently differs from that in southern Florida; communal roost locations in central and northern Florida; a long-term monitoring plan; breeding biology and critical areas for the sub-populations in other states (work by ourselves and others is underway in Georgia, Louisiana, and South Carolina); landscape-scale management recommendations for the Southeast, particularly for privately owned lands; a regional study of dispersal, including rates of movement and mixing among state sub-populations; a study of migration routes and behavior, wintering destinations, critical sites, and threats in Latin America; and development of a conservation plan that addresses needs on regional and international levels. We are addressing some of these priorities with grants from the National Fish and Wildlife Foundation, the Disney Wildlife Conservation Fund, and the Georgia Department of Natural

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Resources. These projects include deploying larger numbers of VHF transmitters to study regional movements, using additional satellite transmitters to identify risks related to migration; and helping to start an international conservation planning process that will examine the needs of the northern subspecies of the swallow-tailed kite in all seasons, throughout its geographic range.

CONSERVATION AND MANAGEMENT OF SWALLOW-TAILED KITES—Meyer

OBJECTIVES 1. Expand the studies of nesting ecology (habitat selection, nesting success and productivity) and demography (juvenile survival, philopatry, age at first breeding) from southern to central and northern Florida.

2. Locate pre-migration roost sites using radio tracking and direct observations.

3. Develop a long-term monitoring plan based on regular, systematic counts and productivity estimates at pre-migration roosts.

4. Describe areas of concentrated or extended use along the migration corridor, determine the extent of the wintering range in Brazil, and identify potential threats along the migration corridor and on the wintering range (with additional support from the National Fish and Wildlife Foundation and the Disney Wildlife Conservation Fund).

5. Begin analyzing the genetic relationships of swallow-tailed kite sub-populations in the U.S. to assess genetic distances among them. This work also will help address questions about the origin of the U.S. population and the degree of relatedness among geographically distant populations (with additional support from the National Fish and Wildlife Foundation and the Disney Wildlife Conservation Fund).

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METHODS Nesting Ecology Florida field work focused on areas known to be used by kites and for which physiography and nesting ecology differ most from previously studied areas in southern Florida (north of 27째N latitude, or from Highlands-DeSotoSarasota-Okeechobee counties northward). These areas include Green Swamp, Ocala National Forest, St. Johns River area, Osceola National Forest, Gulf Hammock, Apalachicola National Forest, and lowland forests of the Big Bend, northern peninsula, and eastern panhandle associated with rivers (e.g., Santa Fe, Withlacoochee, Suwannee, Waccasassa, Wacissa, Aucilla, St. Marks, Wakulla, Sopchoppy, and Apalachicola).

Our goal was to find and monitor 40 nests per year in Florida in 1997 and 1998 (the contract did not begin until April 1998, but we incorporate 1997 nest data and tracking results for birds radio tagged in 1997). The basic methods were the same as for our previous work in Florida (Meyer and Collopy 1995, Meyer 1993). Requests for sighting reports were distributed to likely cooperators (agency personnel, conservationists, birders) in February. We began searching for nests in early March, relying on existing knowledge of regularly used areas, new sighting reports, and our own direct observations.

Nest searching is most successful during the courtship and nest-building stages (March and April), when the kites are most conspicuous and their behavior is more likely to lead the observer to the nest. Considerably more effort is required to find nests once incubation begins (mid-April to mid-May).

Once located, nests were monitored at no greater than weekly intervals.

Causes of nest failures were determined whenever possible. We considered a nest successful if it fledged at least 1 young. Productivity was expressed as young fledged per attempt (nest with eggs) and young fledged per successful attempt. Regular nest visits also allowed us to estimate hatching dates and ages of the young so that nestlings could be radio tagged at the most suitable time.

We collected the following vegetation data at accessible active nest sites.

For the nest tree and 5 randomly selected overstory trees within a 0.4-ha circular plot centered on the nest tree, we recorded species, height (measured with a clinometer at a measured distance from the base of the tree), dbh, crown height, crown width (longest and shortest axes), and basal area (measured with a scaled viewing device from the base of each selected overstory tree). For the nest tree, we also measured height of the nest and adjacent crown closure with a densiometer. A global positioning system (GPS) receiver (GPS 12, Garmin, Olathe, Kansas) was used to determine the coordinates of each nest.

CONSERVATION AND MANAGEMENT OF SWALLOW-TAILED KITES—Meyer

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Demography In 1998 and 1999, we tracked juveniles radio tagged in 1997 and 1998.

The young were captured in the nest about 1 week prior to fledging (mid-May to late June) by a climber who used a rope and mechanical ascenders to reach the nest. They were fitted with 2.3-year VHF transmitters that weighed <3% of body weight and were attached with a backpack harness of a proven design made with 6-mm-wide teflon ribbon (Bali Ribbon Mills, Bali, Pennsylvania).

The ends of 4 separate strands were stitched together with cotton thread at a single point prior to capture and a 12-mm square of soft material was threaded onto the teflon to form a cushion at the junction. In the field, the junction was placed on the bird’s sternum and the free ends of the harness brought up onto the bird’s back (2 strands anterior to the wings, 2 strands posterior to the wings and anterior to the legs), passed through holes at the front and back of the transmitter, tied, and stitched through the knot with dental floss. This method has a number of advantages. Teflon, which is strong, nonabrasive, and nonphotosensitive, has been widely used with excellent results. The cotton thread at the closure will eventually rot, allowing both the front and back harness loops to open simultaneously, thus ensuring that the transmitter and harness will fall free of the bird. The harness is quickly attached in the field and can be accurately fitted and adjusted with little difficulty.

We banded each bird with a U.S. Fish and Wildlife Service aluminum band, took standard measurements, and drew a small blood sample (<1 cc) for sex determination and for genetic analyses.

By relocating and monitoring kites radio tagged as juveniles, we examined post-fledging mortality, first- and second-year survival, extent of site fidelity, age at first breeding (at least the percentage of birds that breed prior to their third year), and dispersal behavior. Because young of the year made wideranging movements from their natal areas, we did much of the radio tracking from the air. The equipment consisted of a programmable scanning VHF receiver (R-4000, Advanced Telemetry Systems, Isanti, Minnesota) with a 164.000–165.999 MHz range, wing-mounted 3-element yagi antennas connected to the receiver with coaxial cables, a switch-box for selecting either or both antennas (Advanced Telemetry Systems), headphones, and an intercom system to permit simultaneous monitoring of the receiver and communication with the pilot. We aerial tracked from Cessna 152, 172, and 182 single-engine high-wing aircraft (operated by 6 different flying services scattered throughout the study area) along transects 100 km apart at an altitude of 500–700 m above ground level and an airspeed of about 180 km/hour (previous experience has shown these altitudes and flight speeds to be optimal for signal detection and efficiency; combined with the specified VHF

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transmitters, detection ranges were consistently >50 km). The location and orientation of the transects varied depending on the last known position of the subjects of our search. We used a GPS receiver to identify and maintain flight along the specified transects and to determine the coordinates of kites as they were detected.

To estimate survivorship, we searched for 73 radio-tagged swallow-tailed kites in Florida and Brazil during 1998 and 1999 (the transmitters’ expected life was 2.3 years). In Florida, during the spring and summer, we searched from the ground at least weekly and from the air at 2- to 3-week intervals. All telemetry searches in Brazil were by air from mid-November to late December; any given area was checked 1–3 times during that period. Annual survival rates were derived using the product-limit estimator (Kaplan and Meier 1958, Lee 1980), modified to allow for the staggered entry of new radio-marked animals added to the sample population as the study progressed (Pollock et al. 1989). The product-limit estimator allows for the removal or “censoring” of animals over time when their radio transmitters fail.

Pre-migration Communal Roosts We monitored all detectable radio-tagged kites at least once a week from June through August to find communal roosts and to describe post-breeding movements, roost attendance, and timing of roost development. The goal was to find and monitor as many roosts as possible statewide. We also solicited observations via the same network used to gather information on nesting locations. Most roosts occupied by radio-tagged kites were found initially from the air. Monitoring from the air and ground continued after mid-August to detect changes in behavior near the onset of migration.

Long-term Monitoring Plan The goal was to develop a long-term monitoring plan based on standardized counts of pre-migration roosts, which offer the best opportunity for tracking population trends at the state or national level. We recognize that counts at large roosts in Florida will reflect the size of the U.S. population, not simply that of Florida, and that a trend at the national level may not necessarily be occurring in Florida. We suggest that, given the large proportion of the national population that nests in Florida, any information about the U.S. population’s trend will serve as a useful index of population change in Florida.

A monitoring method based on nest surveys would illuminate distinctions between state and national trends, but nest surveys are not a feasible monitoring method for swallow-tailed kites.

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Concurrent roost counts will be necessary to derive a statewide population estimate because individual large roosts vary considerably from year to year (Meyer 1993), perhaps because many of the kites move among roost sites within and between years. We incorporate as many large (>100 individuals) roost sites as possible into the monitoring protocol to minimize the effects of annual variations at individual sites. The monitoring plan also includes a protocol for making annual estimates of productivity based on counts of the relative numbers of young of the year and all older kites (Meyer 1993).

Migration Corridor and Winter Range Ten kites were fitted with satellite transmitters in Florida in 1996 and 1997 (4 in the north, 6 in the south). Jennifer Coulson tagged 2 adults with satellite transmitters for us in Louisiana during the 1997, 1 adult was tagged in South Carolina by John Cely and Jim Elliott in 1998, and we tagged 2 adults and 2 juveniles (young of the year) in northern Florida in 1998. Mortality or radio failure while still in the U.S. reduced the 17-bird sample to 12 for the migration analysis.

The trap consisted of 2 2-x-12-m mist nests tied together along their length (making 1 4-x-12-m net) and attached at each end to a pulleyed rope suspended from the top of an extendable pole. The net was placed within 30â&#x20AC;&#x201C;50 m of an active nest. A live disabled owl (usually a barn owl [Tyto alba] or barred owl [Strix varia] borrowed from a wildlife rehabilitation facility) was tethered to a 2-m perch placed below the center of the net. When a kite dove at the owl and was caught in the net, the net was quickly lowered and the kite removed. This arrangement has been used successfully many times in South Carolina and Florida without injury to kites or owls. Setting and running the trap is labor intensive and the response of individual kites varies considerably, but this remains the safest and most effective method for trapping free-flying swallow-tailed kites.

The satellite transmitters (Microwave Telemetry, Columbia, Maryland), which weighed 20 g, were attached with a backpack harness of the same design described for VHF transmitters. This transmitter was the most reliable model available and the only one small enough to be used on a swallow-tailed kite. Battery capacity was relatively small, which limited the transmittersâ&#x20AC;&#x2122; life to about 30 transmission periods (duty cycles). The transmitters were programmed to operate intermittently (e.g., 1 day on, 5 days off) to extend data collection over several months.

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Location and transmitter-status data were processed and distributed by Service Argos. The accuracy class of each location was specified and we chose the most reliable locations individually. This decision was based on acceptable levels of error and the availability of accurate prior and subsequent locations. Useful locations were obtained about 60% of the time during the period when the transmitters activated.

From early November to 11 January 1999, we conducted fieldwork in southwestern Brazil to search for VHF radio-tagged kites from U.S. study populations to locate and monitor large communal roosts occupied by wintering kites and to identify potential threats, such as rapid habitat degradation, drastic changes in land use, contaminants, human persecution, and competition from conspecifics and ecologically similar species (e.g., kites of the genus Ictinia).

The fieldwork in Brazil involved aerial telemetry searches (same methods used in the U.S.), road surveys, ground and aerial focal observations at roosts, and consulting with agency and academic biologists and private landowners.

Genetics We collaborated with Kim Norris-Caneda of the South Carolina Center for Birds of Prey and Allen Strand of the College of Charleston on analyses of genetic relatedness among swallow-tailed kites from different regions of Florida, sub-populations across the southeastern U.S., and breeding populations throughout the hemisphere (the last topic is being investigated as a M.S. graduate research project by ARCI staff biologist Audrey Washburn).

This study uses randomly amplified polymorphic DNA (RAPD), a DNA marker technology with potential for analyzing genetic relationships among and within closely related species (Welch and McClelland 1990). The technique employs the polymerase chain reaction (PCR) and amplification with primers of arbitrary nucleotide composition. The products are separated by gel electrophoresis. Polymorphisms are observed as the presence or absence of a given DNA product and result when differences in the DNA sequence change the primer binding site or change the distance between oppositely oriented binding sites.

The RAPD technique, requiring only small amounts of DNA and no prior knowledge of the genome, is useful for species from which only limited samples can be collected and where total sample size may be small. RAPD analysis is a relatively simple technique that can reveal a large number of polymorphic loci. A preliminary screening for polymorphic RAPD markers was conducted on samples from 8 swallow-tailed kites. These samples

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represented individuals from the most geographically dispersed nesting areas in Florida. A subset of primers was then chosen for RAPD analysis on all 85 individuals, consisting of 77 samples taken from northern Florida to the Everglades, 5 from southern Louisiana, and 3 from coastal South Carolina.

All individuals were scored for the presence or absence of the RAPD marker at each identified polymorphic locus. Only robust, reproducible markers were included in the analysis. For each of the 5 populations considered in this study, we estimated the proportion of individuals that lacked a band at each RAPD locus. These allele frequencies were then used to estimate FST, the ratio of among population to total genetic variance (Wright 1951) using the method described by Lynch and Milligan (1994). We used the FORTRAN program RAPD FST to estimate FST. DNA samples isolated from the radio-tagged kites also were used to determine the sex of each bird.

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RESULTS Nesting Ecology Through June 1998, we found 38 nesting attempts (eggs laid in completed structures) (Table 1). Our objective was to find 40 nesting attempts. It required 15% more person-hours of search time in 1998 to locate 17% fewer nests than in 1997, when we found 46 nesting attempts. In our previous studies in southern Florida, both high- and low-water levels were negatively correlated with nesting attempts. Floods in northern Florida early in 1998 were followed by extreme drought in April. Kite nesting probably was adversely affected by these extreme water conditions in 1998.

The contract did not call for locating and monitoring nests in 1999.

Fortunately, however, Steve Lowrimore of Georgia-Pacific located and monitored 8 nests that year on company lands, which provided data on nest fates and habitat selection on industrial forest land and opportunities for radio tagging additional birds. Georgia-Pacific also donated 4 hours of helicopter time for aerial searches (we found 1 site in addition to the 8 known sites) and to search for roosts.

A high proportion of the nests we monitored in northern Florida were on timber-managed lands, unlike in southern Florida where almost none of the nests monitored from 1988 to 1996 were on such lands. Of the 38 nesting attempts found in 1998, 26 were on industrial forests and were in or close to (within 300 m of) stands actively managed for timber production. Nine of the 26 attempts were on Georgia-Pacific lands, 8 were on other privately owned timber lands, and 9 were on publicly owned lands (Ocala, Osceola, and Apalachicola national forests). Of the remaining 12 nesting attempts, 4 were on state-owned recreation lands, 4 were on private lands not managed for timber production, 3 were on state wildlife management areas, and 1 was on a national wildlife refuge.

Thirty-five (92%) of the 38 nests in 1998 were in longleaf (Pinus palustris), loblolly (P. taeda), or sand pine (P. clausa); 2 (5%) were in oaks (Quercus spp); and 1 (3%) was in a sweet gum (Liquidambar styraciflua).

Fifteen of the 38 attempts in 1998 failed, and the remaining 23 nests fledged at least 1 young. Thus, nesting success was estimated at 61%, uncorrected for degree of exposure (i.e., not a Mayfield [Mayfield 1961] estimate). Productivity was 0.84 young fledged per attempt and 1.39 young fledged per successful attempt.

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Table 1. Coordinates of Florida swallow-tailed kite nests in 1998 and 1999 (latitude/longitude in decimal degrees).

Year

Nest

County

1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1998 1999 1999 1999 1999 1999 1999 1999 1999 1999 1999 1999 1999 1999 1999

Osceola pignic Smurfitt Suannee II Lake Disston (Anne) Goethe W II Gothe Sonny GP Buck Island Rd GP Road 1 Liquidamber McIntire HC (slough) McIntire Hunt Club Parker Rd Pine Beetle E Pine Beetle W Stop sign Rd #2 Swilley Rd Apalachicola II FR 109 (Apalachicola) Camp 43 #2 Fern Hammock Ft McCoy blackberry Ft McCoy Swamp Ft. McCoy seminario Gunters II Juniper Creek ICU Powerline #2 Prairie Creek Rainbow Springs SP Lower Wekiva SP Tosohatchee SR Wekiwa Spring Green Swamp Pao Richloam E #2 Richloam W #2 Parsley Haw E II Parsley Haw W Big N II Ochlockonee-owens 236/263 (Osceola) 236A (Osceola) Disston #1 ‘99 Disston #2 ‘99 115 173/#1 173/#2 Clearcut FR109-99 Long Mirkwood Truck Fern Hammock ‘99 Phil’s Nest (LWNWR)

Columbia Columbia Dixie Flagler Levy Levy Levy Levy Levy Levy Levy Levy Levy Levy Levy Levy Liberty Liberty Marion Marion Marion Marion Marion Marion Marion Marion Marion Marion Orange Orange Orange Sumter Sumter Sumter Taylor Taylor Wakulla Wakulla Columbia Columbia Flagler Flagler Liberty Liberty Liberty Liberty Liberty Liberty Liberty Liberty Marion Volusia

Longitude (°west) 82.465 82.419 83.123 81.369 82.575 82.573 82.751 82.713 82.868 82.925 82.926 82.866 82.769 82.771 83.013 82.793 85.020 85.014 81.710 81.709 81.942 81.941 81.993 82.334 81.655 81.706 81.347 82.441 81.402 80.966 81.473 81.992 82.036 82.039 83.937 83.939 84.158 84.547 82.550 82.580 81.350 81.360 85.107 85.044 85.085 85.105 85.021 85.034 85.085 85.040 81.710 81.360

Latitude (°north) 30.361 30.402 29.342 29.300 29.093 29.092 29.268 29.375 29.258 29.276 29.281 29.261 29.395 29.392 29.327 29.262 30.184 30.201 29.180 29.182 29.411 29.410 29.309 29.403 29.208 29.178 29.823 29.103 28.906 28.498 28.724 28.348 28.520 28.521 30.135 30.135 30.177 30.009 30.290 30.260 29.310 29.300 30.067 30.186 30.118 30.077 30.229 30.196 30.086 30.191 29.180 29.080

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FLORIDA FISH AND WILDLIFE CONSERVATION COMMISSION FINAL REPORT

Nest trees were significantly taller than adjacent randomly selected overstory trees at the 39 sites where we measured vegetation in 1998 (Table 2) (P < 0.01, t = 3.71, df = 202, 2-tailed) and 1999 (Table 3) (P < 0.01, t = 3.34, df = 46, 2-tailed). Mean nest-tree heights in northern Florida were 39% greater than in southern Florida, and mean overstory heights in northern Florida were 29–39% greater than in southern Florida (Meyer and Collopy 1995).

Table 2. Vegetation measurements within a 0.4-ha circular plot surrounding 31 swallow-tailed kite nest trees in Florida in 1998.

Variable Nest height (m) Tree height (m) Dbh (cm) Crown height (m) Crown area (m2)

Nest tree (n = 31) 24.8 ± 4.0 27.7 ± 4.8 42.0 ± 12.6 15.2 ± 5.0 37.5 ± 31.5

Random overstory tree (n = 155) n/a 24.3 ± 4.7 37.9 ± 13.3 13.7 ± 4.7 40.4 ± 42.7

Crown closure = 42.1% ± 21.1% Basal area = 15.03 ± 12.9 m2/ha

Table 3. Vegetation measurements within a 0.4-ha circular plot surrounding 8 swallow-tailed kite nest trees in Florida in 1999.

Variable Nest height (m) Tree height (m) Dbh (cm) Crown height (m) Crown area (m2) Crown closure = 81.1% ± 16.9% Basal area = 28.1 ± 11.9 m2/ha

Nest tree (n = 8) 27.7 ± 8.0 27.8 ± 5.4 42.0 ± 13.5 9.8 ± 4.8 30.4 ± 24.0

Random overstory tree (n = 40) n/a 22.5 ± 3.8 64.2 ± 51.4 9.8 ± 4.0 21.6 ± 80.6

CONSERVATION AND MANAGEMENT OF SWALLOW-TAILED KITES—Meyer

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Demography From 29 May to 23 June 1998, we captured 19 juveniles in their nests and fitted them with VHF transmitters. The objective was to radio tag 20 juveniles. We were unable to attempt radio-tagging at several nests, however, because an unusually large number of broods attained tagging age within a period of about a week. The interval in which we can safely climb nest trees and tag juveniles is only about 3–4 days (if attempted too early, the birds are too small to be fitted with the harness; if attempted too late, they are likely to jump or fly from the nest). Thus, along with 54 swallow-tailed kites captured as nestlings in 1996 and 1997, we had a sample of 73 radio-tagged birds with which to investigate first-year survival, philopatry, and dispersal during the present study (1998 and 1999) (Table 4).

From 27 May to 19 June 1998, we fitted 2 adults and 2 juveniles with satellite transmitters. Initially, location data were transmitted during a 4-hour period every 10 days to keep the transmitters functioning properly. The rate increased to an 8-hour period every 2 days on 11 August 1998.

Ground and aerial searches for telemetry signals from kites tagged as juveniles in the area in 1997 and 1998 continued until mid-September 1998.

Following is a summary of the locations of the 4 kites radio tagged (VHF) during the summer of 1997 and found as yearlings during the summer of 1998.

Table 4. Juvenile swallow-tailed kites (n = 75) VHF radio tagged in Florida from 1996 through 1998.

Frequency (ID#) 382 396 414 427 441 459 474 488 503 516 547 557 596 623 636 577 667 706 691 713

Nest location BFE (BI) Miller/110 (Blks) Miller/110 (Blks) Ready to Go (CREW) Ready to Go (CREW) More Ready’ Go(CREW) More Ready’ Go (CREW) Branch (CREW) 94 (Blks) DeSoto/122 DeSoto 120 SE Willow Marsh (CREW) PB 44 NW (Addtn) PB 50 S (Addtn) C-18-Lean SW (Rac pnt.)

C-18- North-4 (Rac pnt.)

Dwight’s N (CREW) Dwight’s N (CREW) Vincent S (S Flint Pen) Tony’s II (loop)

Date trapped 5/16/1996 5/20/1996 5/20/1996 5/22/1996 5/22/1996 5/22/1996 5/22/1996 5/22/1996 5/22/1996 5/23/1996 5/24/1996 5/25/1996 5/26/1996 5/26/1996 5/28/1996 5/28/1996 5/29/1996 5/29/1996 5/29/1996 5/30/1996

Sex F M F M M F F M F M F F M M M M M F F M

Band # 50002 50003 50004 50005 50006 50007 50008 50009 50010 60001 60002 60004 60006 60007 60008 60009 60010 70001 70003 70004

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FLORIDA FISH AND WILDLIFE CONSERVATION COMMISSION FINAL REPORT

Table 4. Continued.

Frequency (ID#) 727 733 744 753 760 790 770 779 801 805 807 824 655 831 100 759 906 750 927 916 896 861 89 881 873 855 839 813 706 781 656 322 356 476 441 669 758 881 747 775 243 334 352 364 289 261 276 300 320 378 396 544 529

Nest location Blown Out (APBR) Steve’s (Bar-D) Marker 24 (Rac pnt.)

Reservoir (Bar-D) Reservoir (Bar-D) Narrow Strip (ENP) Tony’s NW (loop) Willow Marsh (CREW) Pontedaria (Bar-D) Pontedaria (Bar-D) McMillian (Bar-D) North of Nates (ENP) Found Twice (S Flint Pen) Finger West (Addtn) Relief (Grn Swp) Relief (Grn Swp) Salt Springs North Osceola W Osceola W Watson Trail (GP) Watson Trail (GP) Osceola E Salt Springs South Salt Springs South Juniper Springs. Camp GP WMA, Putnam Co. Goethe Mud (Akin’s prop) Goethe Mud (Akin’s prop) GP WMA, Putnam Co. Osceola In Between Suwanee Suwanee Droopy (St. Joe/Marks) Salt Springs Rd. Pine Beetle W (GP) Pine Beetle W (GP) Parker Rd. (GP) Parker Rd. (GP) Lake Disston Lake Disston Swilley Rd. (GP) Pine Beetle E (GP) Rainbow Springs Rainbow Springs Camp 43- Ocala Buck Island Rd. (GP) Liquidambar (GP) Wekiwa Springs FR 109 (Apalachic.)

Goethe West-2 Ochlokonee Riv. Tosohatchee Gunter 2

Date trapped

Sex

Band #

5/31/1996 5/31/1996 6/2/1996 6/6/1996 6/6/1996 6/7/1996 6/7/1996 6/8/1996 6/8/1996 6/8/1996 6/9/1996 6/11/1996 6/13/1996 6/14/1996 5/23/1997 5/23/1997 5/29/1997 6/2/1997 6/2/1997 6/3/1997 6/3/1997 6/4/1997 6/5/1997 6/5/1997 6/7/1997 6/9/1997 6/9/1997 6/9/1997 6/15/1997 6/19/1997 6/22/1997 6/22/1997 6/26/1997 6/27/1997 5/29/1998 5/29/1998 5/31/1998 5/31/1998 6/1/1998 6/1/1998 6/6/1998 6/6/1998 6/7/1998 6/7/1998 6/8/1998 6/9/1998 6/11/1998 6/13/1998 6/15/1998 6/17/1998 6/18/1998 6/20/1998 6/23/1998

F F F F F F F M F M M M F F unk unk unk unk unk unk unk unk unk unk unk unk unk unk unk unk unk unk unk unk F M M M F M M F F F M F F M M M F F F

70005 70006 70008 70009 70010 56403 60003 60005 56404 56405 56406 56402 56407 56408 56414 56415 56417 56419 56420 56421 56422 56423 56424 56425 56426 56427 56428 56429 56430 56431 56433 56434 56436 56437 56466 56467 56468 56469 56470 56471 56473 56450 56451 56452 56475 56476 56477 56478 56479 56480 56481 56483 56484

CONSERVATION AND MANAGEMENT OF SWALLOW-TAILED KITESâ&#x20AC;&#x201D;Meyer

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#759, Green Swamp, unknown sex. This kite was detected from the air in its natal area on 16 April 1998, where it remained through the summer of 1998. We also located and observed this bird briefly from the ground. #813, Goethe, unknown sex. This kite was detected on 28 May 1998 during a flight over Goethe State Forest. Kite #813 was found and observed from the ground near Rainbow Springs 6 days later and was located north of Rainbow Springs during the 11 June 1998 flight. #857, Osceola National Forest, unknown sex. On 9 June 1998, this kite was found from the air west of Lake City. It was in the San Pedro Bay area of northeastern Taylor County, near the Taylor/Lafayette County line, on 18 June 1998. #870, Ocala National Forest, unknown sex. During the 18 June 1998 flight we detected this kite in the vicinity of the upper Aucilla or Wacissa rivers in southern Jefferson County.

In addition to the Florida survey flights, we flew a total of 4.5 hours in South Carolina (with John Cely) and 5.7 hours in Louisiana, Mississippi, and Alabama (with Jennifer Coulson and Mark Woodrey). We focused on the river floodplain systems in which we had obtained locations for other kites tracked by satellite during the post-breeding period in 1997. In South Carolina, we searched near the Savannah, Ashepoo, Combahee, Edisto, Salkehatchie, and Santee rivers on 25 June 1998; we also surveyed Francis Marion National Forest. In Louisiana, Mississippi, and Alabama, we searched the Pearl, Pascagoula, Tombigbee, and Alabama rivers and the Mobile Delta on 30 June 1998. Coulson and Woodrey also searched for radio-tagged Florida kites during 4.6 hours of flying in Mississippi along the Pearl, Pascagoula, and Chickasahay rivers on 29 June 1998. No kites from our radio-tagged Florida sample were detected during these 14.8 hours of aerial searches.

Our detection rate for 1- and 2-year-old kites radio tagged in Florida was low, about 15â&#x20AC;&#x201C;20% of the radio-tagged cohort, and consistent among years.

Our attempts at locating the undetected kites in the areas of the Atlantic and Gulf coastal plains with the highest densities of swallow-tailed kites failed to detect any radio-tagged birds from Florida.

Because kites usually have left their immediate nest areas by mid-July, most of our late-summer tracking in 1998 and 1999 was from the air. In 1998, we made 9 flights for a total of 24 hours during this pre-migration dispersal stage. The cumulative flying time for the 1999 nesting season was 58 hours

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FLORIDA FISH AND WILDLIFE CONSERVATION COMMISSION FINAL REPORT

in 20 flights. These surveys covered most of the state, including the area from 40 km west of the Apalachicola River east through the panhandle and south through the peninsula to the northern Florida Keys. We concentrated our surveys in the Apalachicola National Forest; northern Gulf coastal plain of the eastern panhandle; Osceola National Forest; Suwannee River drainage; St. Johns River drainage; Big Bend region; Ocala National Forest; Gulf Hammock; Withlacoochee River and State Forest; Goethe State Forest; eastern Gulf coastal plain north of Tampa; Green Swamp; lowlands east and west of the Central Ridge; St. Johns Marsh; the Peace, Myakka, and Kissimmee rivers; ranchlands of Highlands, Polk, DeSoto, Glades, Hardee, Okeechobee, Hardee, Hendry, Lee, and Collier counties; water management areas; Corkscrew Swamp and the Corkscrew Regional Ecosystem Watershed (CREW); Big Cypress Swamp; and Everglades.

Of the 19 juvenile kites tagged in May and June 1998, 16 (84%) survived into August and probably began their southward migration. In previous years, 75–80% (n = 92 radio-tagged juveniles) of the fledglings survived to departure on their first migration, with very little variance among the 5 annual samples.

The 16 juveniles that were assumed to survive to the onset of fall migration were last detected from 29 July to 26 August. Of these 16, 12 (75%) disappeared in the 12-day period from 9 to 21 August. We lost contact with 9 (56%) of these birds during the 5 days from 9 to 14 August.

The most significant result of our aerial surveys was that the only kites detected from among the samples marked in 1997 and 1998 were 3 yearlings that had already been found and monitored during the previous year. Thus, the detection rate for birds that were tagged the previous year was 15%. This is consistent with our results for the previous 8 years in which we searched for kites tagged as nestlings in the previous 2 years and detected 15–20% in each year (n = 109 tagged birds).

No 2-year-old radio-tagged kites were found. In previous years, we found 0–1 birds of this age per year.

No radio tagging was proposed for 1999. Ground and aerial searches for kites tagged as juveniles in 1997 and 1998, however, continued in 1999.

Following is a summary of the locations of the 3 kites radio-tagged (VHF) during the summer of 1998 and found as yearlings during the summer of 1999. #772, Lake Disston male. This bird, the sibling of #743, had been found on the winter range in Brazil as a 7-month-old bird in December 1998. It was detected in Florida on 26 May 1999 in the vicinity of its

CONSERVATION AND MANAGEMENT OF SWALLOW-TAILED KITES—Meyer

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natal territory and was consistently found among a group of 9–13 kites associated with 2 nests in that area. Number 772 roosted in the vicinity of the nests through the nesting cycle, then moved into the large pre-migration roost at Lake Woodruff, Volusia County, on 20 July. On 27 July, #772 was in the large roost at Fisheating Creek, near Lake Okeechobee. That was the last time it was detected in Florida.

Several close visual observations indicated that #772 was in very heavy molt, missing 3 of its longest rectrices, at least 3 primaries and secondaries, and so many upper wing coverts that the wing appeared to have translucent windows when viewed from below. This was consistent with past observations of tagged birds known to be 12–14 months old. It appeared that this bird’s first complete molt was progressing rapidly, leaving it in poor flight condition but probably assuring that at least the flight feathers would be replaced before fall migration. #743, Lake Disston female. This yearling was found from the air in Orange County on 14 April 1999. This bird subsequently moved north to the Lake Woodruff area. Number 743 occupied east-central Florida until late July 1999 and was seldom near its natal area at Lake Disston (although it often came within 30–40 km). This kite began using the large roost at Lake Woodruff soon after it began forming in late June and regularly roosted at or near that site until 20 July 1999.

On 27 July, #743 was east of Lake Istokpoga in Highlands County, perhaps headed toward the vicinity of the large roost at Fisheating Creek, where its sibling was found on this date. #876, Gulf Hammock male. This yearling kite remained in its natal area until early July, where it had been found consistently all summer, after which it was never detected.

These 3 kites, along with 7 yearlings found in previous seasons, displayed a pattern in which 1-year-old males appeared more likely that 1-year-old females to frequent their natal areas. When the 10 birds are ranked with regard to distance observed from their natal territory, the distances for the 4 females are all greater than the distances for any of the males (P = 0.028, MannWhitney U = 0). This is the first indication that one sex (females, in this case) may be more likely than the other to disperse from its natal area.

The 3 birds found in 1999 represented 16% of 19 kites tagged as nestlings in 1998. In 1998, we located 3 of 20 (15%) nestlings tagged in 1997. In the 4 preceding years, we located 15–20% of kites tagged as nestlings the previous year. When short-tailed kites (yearlings) were counted at the Fisheating Creek

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FLORIDA FISH AND WILDLIFE CONSERVATION COMMISSION FINAL REPORT

pre-migration roost in early April 1996, the ratio of yearlings to older birds was consistent with this estimate of a 15–20% return rate. The low frequency at which we had seen heavily molting birds such as #772 in June and July further supports the inference that relatively few kites return at 1 year old. The accumulating evidence suggests that first-year survival is very low, that some yearlings remain in South America after overwintering, or some combination of the 2 explanations.

Based on the genetic analyses, the sex ratio for 71 nestlings was 0.87:1.00 (33 males:38 females or 46% males). This does not differ significantly from 1.00:1.00. There was some tentative suggestion that nestling sex ratios may vary among areas (e.g., Everglades vs. Big Cypress vs. private ranchlands in central Florida), perhaps reflecting a relationship with habitat quality.

Tracking data for 1- and 2-year-old kites suggests that females may disperse farther from their natal areas than males.

To assess survival, we tried to locate each of the 73 VHF-radio–tagged swallow-tailed kites for over 2 years after they were marked as nestlings (transmitters were expected to last 2.3 years, but we searched for each bird into the third nesting season after tagging). These searches included the summer range in Florida and the (boreal) winter range in Brazil. The survival analysis, however, applies only to the first year (fledging to 1 year old) because the small number of detections at 1 year old did not provide an adequate sample for estimating second-year survival. Only 11 of 73 (15%) radio-tagged swallow-tailed kites were found alive in Florida at 1 year old.

The Kaplan-Meier estimate of survival rate for the first year was 0.12.

Pre-migration Communal Roosts A goal of this study was to recommend an effective and feasible long-term method for monitoring Florida’s population of swallow-tailed kites, based on systematic observations at pre-migration communal roosts, that would estimate absolute number and annual productivity. Because accuracy would increase with the number of sites monitored, we tried to locate as many communal roosts as possible. In 1998, we identified 41 sites in northern Florida with 2–360 swallow-tailed kites at the peak of roosting activity. In all, 992 kites were observed and, based on the locations of the roost sites and our counting methods, we concluded that this number closely represents the total number of individuals (i.e., few birds were recounted at a second or third site). The mean number of kites per roost was 24 ± 57 (n = 41). At their peak, 21 of the roosts had 2–10 kites, 17 contained 11–40 kites, 2 had 41–100, and 1 had > 100. Most of the roosts peaked from 27 July to 10 August (range: 25 July to 18 August).

CONSERVATION AND MANAGEMENT OF SWALLOW-TAILED KITES—Meyer

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During the same period in 1998, 1,410 kites roosted at the Fisheating Creek (Millsap 1987), CREW, and Corkscrew sites in southern Florida. Thus, the total number of kites in communal roosts in Florida in 1998 was 2,402, or about half the maximum estimate for the entire U.S. population at the end of the breeding season. The Fisheating Creek count, furthermore, was the lowest since these observations began in 1987 (1,150 versus an annual average of 1,700 for the previous 11 years). Corkscrew had 140 versus a previous average of 250, and CREW had 120 versus 190. Poor nesting conditions and hurricanes that approached Florida in July and August may have contributed to the early departures. The apparent trend at southern Florida roosts, however, has been downward for the last few years.

During the 1998 roost season, we were able to compare some of the features of northern Florida versus southern Florida roosts and large versus small roosts. In southern Florida, most of the roosts of 10 or more kites have been in the same location from year to year. All were in wetland mosaics of forested and unforested habitats and the kites’ foraging activity radiated outward from the roost site. The northern Florida roosts were small, and the smaller the roost, the less likely it was to form consistently in the same place.

The northern Florida sites were mainly along rivers, streams, lakes, or other linear features. The best example is the collection of 8 sites found along the Apalachicola River, where sightings of foraging flocks and our satellite and VHF data suggested there was a large roost. Concentrated search effort, however, revealed 8 roosts, with an average of 14 kites per roost (109 total, range 7–30), varying in location from night to night. We saw a similar pattern on other rivers in northern Florida. This arrangement of roosts may result from the kites’ linear foraging ranges along the river floodplains, unlike the activity ranges used around roosts in southern Florida, where the landscape is more heterogeneous. The largest northern Florida roost, at Lake Woodruff National Wildlife Refuge (Volusia County), which peaked at 360 kites in late July, was more similar in size, phenology, and landscape to the southern Florida roost sites.

Radio tracking kites with VHF transmitters during the pre-migration stage (late June through mid-September) was our best means of discovering communal roost sites. Satellite transmitters did not provide locations accurately or frequently enough to reveal roost locations. Because we did not plan to deploy additional VHF transmitters in 1999, we had only 3 marked birds to lead us to previously unknown sites. Two of these birds (#772 and #743) used roosts with which we were already familiar (Lake Disston, Lake Woodruff, Fisheating Creek). The third (#876) used a series of very small roosts near its nest despite the fact that a roost of 30 was found in the general area in 1998 (no such roost was found near that location in 1999).

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FLORIDA FISH AND WILDLIFE CONSERVATION COMMISSION FINAL REPORT

Through the 1999 nesting season, we observed 45 communal roosts ranging in size from 2 to 1,840. Most of these (38) had fewer than 40 birds at their peak; these were found mainly during 1997 and 1998 by tracking radiotagged kites. We checked the majority of these sites, and searched in their vicinity, during the 1999 roosting season but detected only 4 roosts with a maximum of 21 birds. One larger roost, in Seven Sisters Islands of the St. Johns River (Putnam County), had 74 when it was found in 1998 and 94 in 1999. In 1999, however, the kites did not remain in the same location for the duration of the roost season.

For monitoring absolute numbers of roosting kites in 1999 and to help us develop the monitoring plan, we focused on aerial surveys at the 5 largest known roosts. Their locations, peak numbers, and peak dates in 1999 were Fisheating Creek, 1,840, 22 July; Lake Woodruff National Wildlife Refuge, 576, 14 July; Corkscrew Swamp, 240, 20 July; Oklawaha River, 200, 19 July; and CREW, 170, 22 July.

A new large roost on the Withlacoochee River in Sumter County contained 144 kites when discovered on 9 August 1999 by a FWC wildlife officer.

About 150 were present when the site was checked on 12 August. It is likely that this roost was larger in mid- to late July, when the 5 roosts listed had maximum numbers.

Thus, these 6 pre-migration communal roost sites probably contained a total of over 3,000 swallow-tailed kites in mid- to late July 1999. It is unlikely that all of these roosts peaked at the same time, and we know from telemetry surveys that individual kites move among large roosts. It appears, however, that the largest of the communal roosts, all in central and southern Florida, peak in roughly the third week of July. This synchrony, plus the large number of birds at this collective set of roosts, provides a rare opportunity to monitor state and national populations of swallow-tailed kites.

Long-term Monitoring Plan Results of our roost-finding and monitoring efforts in 1998 and 1999 made it possible to assess factors that will influence the success of a monitoring plan.

These include the consistency with which individual sites are used (do the numbers vary drastically or do locations shift from night to night?), the total time period over which the set of roosts peak, regional patterns for the timing of the roostsâ&#x20AC;&#x2122; development, and the various logistic requirements associated with making peak counts at sites in a short time frame (e.g., scheduling flights, departure points, weather, how many counts must be made per site to specify when the peak occurs, variations among observers in aerial counts).

CONSERVATION AND MANAGEMENT OF SWALLOW-TAILED KITESâ&#x20AC;&#x201D;Meyer

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For several reasons, the best general strategy will be to focus on roosts that have consistently had at least 150 swallow-tailed kites at their peaks since monitoring began. First, such large sites are the most predictable in location and phenology from year to year. This means they can be found consistently from an airplane without the benefit of having radio-tagged birds present and surveys can be scheduled within a specified time span. Second, by limiting the number of observation sites, it will be logistically possible to check each site several times during the roosting season to detect accurately the point at which the roosts reach peak numbers. Finally, the 6 largest sites (Fisheating Creek, Woodruff, Oklawaha, Withlacoochee, Corkscrew, and CREW) contained a total of more than 3,000 kites within an 8-day period in July 1999, or 60% of the largest estimate for the total U.S. population. Adding the next 3 largest roosts (a total of 175 birds) to the monitoring protocol would complicate the survey logistics considerably while only increasing by <4% the portion of the national population included in counts.

Migration Corridor and Winter Range We placed 2 satellite transmitters on juveniles in 1998, one of which stopped producing data following a large wildfire near the kiteâ&#x20AC;&#x2122;s nest in Osceola National Forest a few days after the kite fledged. The other juvenile behaved normally until its final location was obtained, at 0310 hr off the coast of Andros Island, Bahamas. This bird was well east of the route taken by most of the tagged kites. Two adults (1 in 1997 and 1 in 1998) made similar departures from Florida, tracking well to the east of the other marked birds.

This route requires considerably longer water-crossings than the more typical path to western Cuba and then to the Yucatan Peninsula. In all 3 cases (the 2 adults and the 1998 juvenile), hurricanes were approaching from the eastsoutheast and were producing northwesterly winds in southern Florida. Both adults survived the long water-crossings and continued their migration; the juvenileâ&#x20AC;&#x2122;s transmitter did not provide any subsequent sign that it was operating and the young bird was presumed dead. Various confirmed (by our satellite data) and speculated routes that could be used by southbound migrating swallow-tailed kites to traverse the Gulf of Mexico and Caribbean Sea are shown in Fig. 1. The satellite-derived migration locations in this region for the 12 southbound kites tracked by satellite are shown in Fig. 2.

Apart from the variation for the initial water crossing described above, the routes of the 12 kites tracked by satellite from 1996 to 1999 were consistent: Cuba (mainly the western portion), eastern Yucatan Peninsula, coastal lowlands of eastern Central America, Pacific coastal plain of Columbia, a small portion of the Andes, southern margin of the Amazon basin through northern Peru, northern Bolivia and western Brazil, to southwestern Brazil for

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FLORIDA FISH AND WILDLIFE CONSERVATION COMMISSION FINAL REPORT

Fig. 1. Possible (dashed lines) and confirmed (solid lines) southbound migration routes for the northern (U.S.) breeding population of swallow-tailed kites.

the winter (Fig. 3). These 12 tagged birds (9 adults, 5 females and 4 males, and 3 juveniles, sex unknown) originated at breeding sites in southern Florida, northern Florida, Louisiana, and South Carolina.

The 1998 satellite transmitters stopped providing data in late October, at least 1 month earlier than expected. By that time, however, the adults had reached the northern portion of their winter range in southwestern Brazil.

No tagging with VHF transmitters was proposed for 1999, and we had no funding for satellite transmitters. We had 1 unused satellite transmitter, and Microwave Telemetry refitted it with a fresh battery and reprogrammed it for use in 1999. They also donated 5 additional transmitters ($2,900 each), in part because the 5 satellite transmitters deployed in 1998 stopped providing data 2 months earlier than expected. Nothing about the transmittersâ&#x20AC;&#x2122; performance indicated that Microwave Telemetry or Service Argos (which provided the tracking data) was at fault. A number of research projects tracking animals in

CONSERVATION AND MANAGEMENT OF SWALLOW-TAILED KITES—Meyer

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Fig. 2. Satellite-derived locations for southbound migrating swallow-tailed kites in the Caribbean region, Mexico, and Central America based on 1996–1999 tracking data for 12 individuals (9 adults [4 males, 5 females] and 3 juveniles of unknown sex).

South America lost data in 1998 due to radio interference of unknown origin (P. Howey, Microwave Telemetry, personal communication). Microwave Telemetry asked Service Argos to provide free tracking time in 1999 for the donated transmitters, and Service Argos agreed to do so.

Microwave Telemetry also made 2 modifications to the transmitters: changing the transmission frequency to the upper end of the available band, perhaps avoiding interference, and replacing the previously used battery with one more heat-tolerant (transmitter temperatures, which were provided along with tracking data, ran well above average for the kite radios, perhaps due to the bird’s black back and tendency to remain aloft all day).

Five adults and 1 juvenile (nestling) kite were captured and fitted with satellite transmitters from 18 May to 9 June 1999. Two adults, from separate territories, were tagged at nests in the Gulf Hammock region of Levy County, on Georgia-Pacific land. One adult was tagged at a nest on Osceola National

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FLORIDA FISH AND WILDLIFE CONSERVATION COMMISSION FINAL REPORT

Fig. 3. Satellite-derived locations for southbound migrating swallow-tailed kites in North, Central, and South America based on 1996â&#x20AC;&#x201C;1999 tracking data for 12 individuals (9 adults [4 males, 5 females] and 3 juveniles of unknown sex).

Forest. Two adults, a breeding pair, were tagged at the Lake Disston nest where we had fitted VHF transmitters on 2 1998 nestlings (#743 and #772) that returned to their nest area in 1999. The single juvenile fitted with a satellite transmitter in 1999 was 1 of 2 offspring of the tagged pair of adults at the Disston nest. This was the first time that we marked 3 members of a kite family with either VHF or satellite transmitters.

Through June 1999, all 6 tagged kites were alive and behaving normally, and the transmitters were performing as expected. By late August and early September 1999, however, it was apparent that the transmitters were once again not performing well and, once the birds reached Central America, very little data were received. Following is a brief summary of the movements of the 6 kites fitted with satellite transmitters in 1999. #16081, Gulf Hammock Georgia-Pacific adult male (breeding status not known). This kite was still in its nest area in early July and used

CONSERVATION AND MANAGEMENT OF SWALLOW-TAILED KITES—Meyer

Devil’s Hammock (headwaters of the Waccasassa River) to roost, perhaps at a site where we observed roosts of 12–20 kites in previous years. It was not detected for several reporting cycles, but was last located on 9 August 1999 in northeastern Nicaragua. #16082, Lake Disston adult male breeder. Kite #16082 was last detected on 17 July 1999 near its nest. It was not detected after 17 July 1999, for unknown reasons. Lack of any data (transmitters sometimes provide status information even when a location cannot be determined) suggested radio failure. #16083, Lake Disston adult female breeder. This kite was near its nest until early July 1999, then in or near the large communal roost at Lake Woodruff National Wildlife Refuge (about 25 km south of its nest) on 11 July 1999. On 31 July 1999 at 1900 hr local time, this kite was in Lee County, in or near the large communal roost on CREW land. Five hours later (just after midnight), however, #16083 was in or very near the large communal roost at Fisheating Creek, 80 km northeast of the CREW site. Even if this bird left for the Fisheating Creek roost immediately after the 1900-hr fix and traveled at a relatively high flight speed of 40 km/hour, it would have arrived after dark. We have noted many night flights in the past by satellitetransmittered kites as they are about to migrate and, especially, during migration. Kite #16083 was next detected on 11 August 1999 near Cardenas on the northern coast of Cuba, 120 km east of Havana. It was not detected after that time. #16084, Osceola National Forest adult male breeder. We obtained very little data for this bird. Several reports scattered over the reporting period contained status data and poor-quality location data that indicated that the transmitter was near the nest but not moving. It was not possible to determine if the radio had been shed by the bird or if the bird had died with the radio attached. The position information was not accurate enough to permit us to locate the transmitter. #16085, Gulf Hammock (Georgia-Pacific) adult male breeder. This kite remained in the general vicinity of its nest prior to 22 August 1999, when it was detected in central Florida near Reedy Creek Swamp and Lake Tohopekaliga. The next and final location was on 22 September 1999 in western Panama. #16086, Lake Disston juvenile female. This bird was the 1999 offspring of #16082 and #16083, which occupied the same nest that

25

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FLORIDA FISH AND WILDLIFE CONSERVATION COMMISSION FINAL REPORT

produced VHF-transmittered nestlings #772 and #743 in 1998. This young kite remained near its nest through most of July 1999, but on 28 July, it was in the Lake Woodruff roost area (25 km south of its nest) at 2000 hr. On 7 August and again on 16 August 1999, #16086 was near the Tensas River in northeastern Louisiana, an area that was important historically to swallow-tailed kites. On 29 August 1999, #16086 was in the Mexican state of Neuvo Leon, between Monterrey and Saltillo. This bird was not detected after that date. The last location for #16086 was the first time we detected a radio-tagged kite in Mexico north of the Yucatan Peninsula, indicating that some swallow-tailed kites from the U.S. migrate over land through Mexico as well as over water to the eastern Yucatan. Two juveniles tracked by satellite in previous years revealed a similar initial route northwestward from Florida (1 kiteâ&#x20AC;&#x2122;s transmitter failed or the bird died in southern Alabama; the other bird apparently died just west of the Mississippi River near Natchez, Mississippi). An adult from a Louisiana nest, on which Jennifer Coulson deployed one of our satellite transmitters in 1997, traveled west into eastern Texas before next being detected in Guatemala. An over-land route through Mexico might be particularly important to juveniles because they would avoid crossing large expanses of water when it would pose the greatest risks.

The main objective of all this work was to identify the migration corridor and wintering range of the northern subspecies of the swallow-tailed kite. The migration route is outlined above. The winter range consists of 2 relatively small areas at opposite ends of a 1,400-x-350-km crescent-shaped area curving around the eastern side of the Pantanal in southwestern Brazil. The constricted migration route and wintering area increases the speciesâ&#x20AC;&#x2122; vulnerability, but it also enhances our ability to focus conservation attention on specific, highpriority areas. One good example is the point in the Colombian Andes where the migrating kites cross the mountains from west to east.

We began conducting fieldwork in Brazil in 1996 to study northern swallow-tailed kites on their winter range, and to begin learning about the nesting ecology of southern swallow-tailed kites breeding at the same time.

Audrey Washburn and John Arnett worked together in southwestern Brazil from 21 October to late December 1998, and Arnett remained until midJanuary 1999. Meyer traveled to the study area for 10 days in early December.

Washburn and Meyer returned to Brazil in late 1999 to find radio-tagged kites and roost sites and to observed wintering habitats and behavior.

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Summary of Migration Study Through 1999.—Adults left the U.S. several weeks before the young of the year, but the latter traveled twice as fast and caught up with the older birds by November. In 1 case, a 5-month-old male carrying a satellite transmitter left Florida 5 weeks after its mother (also fitted with a satellite radio) and followed exactly the same route as the adult.

The 2 birds were eventually detected while wintering within 20 km of each other in southwestern Brazil. The southbound flight took 2.5–3.5 months, much longer than what was required for a bird this size. It is possible that the kites’ movements are keyed to the emergence of flying insects, on which they prey heavily in Brazil.

There were places on the migration route where the kites concentrated and/or slowed their rate of travel, including Cuba, the Yucatan Peninsula, northern Belize, southwestern Colombia, and portions of the western border region of Brazil. It is likely that these areas are traversed by concentrations of other migratory species, as well.

Radio locations of the migrating kites were associated with river systems.

Large expanses of continuous forest, and particularly the Amazon Basin, were avoided. The portions of Brazil occupied by wintering (northern) and breeding (southern) swallow-tailed kites during the boreal winter were dominated by relatively dry vegetation communities, primarily cerrado and patches of dry tropical forest. These drier, more “upland” habitats are at risk of conversion to agriculture. Gallery forests, the narrow strips of tall trees along riparian courses, also were focal points for kite nesting and foraging activity. These thin bands of vegetation were often the only forest left standing within vast stretches of agricultural lands.

Large communal roosts were found on the winter range in southwestern Brazil during November and December of each year. The largest roost contained over 1,300 and 1,400 swallow-tailed kites at its peak in 1996 and 1997, respectively. From mid-November 1998 through 12 January 1999, we continued to monitor this site, which is on a large ranch, Fazenda Campana, near Dourados, Mato Grosso do Sul. This roost peaked at 1,673 kites in midNovember 1998. By 1 January 1999, the number had decreased to about 600.

By 5 January, there were 450–500 kites, 300 by 11 January, and none on 12 January 1999. No radio-tagged kites were present during January 1999, although 1 was found in the roost in early December 1998.

The pattern and timing of the decrease of the large communal roost at Fazenda Campana reinforced our speculation that the large roosts in the Brazilian wintering range may serve as pre-migration staging areas prior to the northbound flight of northern kites.

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A second large roost was found in 1998, about 130 km from the previously discovered one, by radio tracking a VHF radio-tagged juvenile from Florida.

This roost contained over 1,000 swallow-tailed kites when found, which was well after the seasonal peak of other roosts in the region, and it almost certainly contained considerably more kites during peak occupancy. Although we do not know the exact origin of the roosting kites, their behavior suggests that they were wintering, rather than breeding, birds. The physical structure of these roosts and the behavior of the kites were essentially the same as what we have described for pre-migration roosts in Florida. These sites appear to be habitually used and should be considered important in planning swallowtailed kite conservation.

Satellite and VHF telemetry in 1998 and 1999 taught us that the winter range is even smaller than previously thought, and it coincides with the breeding range of the southern subspecies. All of the radio-tagged kites that we found in Brazil were associating with nesting groups of the southern subspecies. We soon learned that the easiest way to locate nests of breeding kites was to monitor the movements of our radio-tagged birds.

In addition to this strong association with their southern conspecifics, the northern kites also over-winter amidst Mississippi kites (Ictinia mississippiensis), which nest in the U.S. and winter in South America, and plumbeous kites (I. plumbea), separate populations of which nest and winter sympatrically in this region. Both species occur in very large numbers in southwestern Brazil. As with the swallow-tailed kite, Ictinia species forage in large flocks and prey on flying insects, particularly when they swarm.

Northern swallow-tailed kites wintering in southwestern Brazil appear to face strong competition, unlike any they encounter in the U.S., from breeding conspecifics with high food demands and from high densities of ecologically similar breeding and wintering species.

Genetics In collaboration with Kim Norris-Caneda (South Carolina Center for Birds of Prey) and Allen Strand (College of Charleston), we began a genetic analysis of DNA isolated from the blood of kites in Florida, Louisiana, and South Carolina. Our goal was to describe the genetic composition of the Florida population and, ultimately, to compare these results with analyses for populations in other states and in other parts of the hemisphere.

Fourteen polymorphic markers from 10 primers were used in the final analysis. No unique diagnostic bands were found in any of the 5 subpopulations. Although there was apparent variation in allele frequencies

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29

among the sub-populations (Table 5), much of this probably was due to sampling error. Two of the populations described here are represented by only 3 individuals each.

Estimates of FST for each locus are presented in Table 6. Given the means and standard deviations of FST for each locus (Table 6), we could not reject the null hypothesis that there is no genetic structure among the populations included in this study.

There was considerable variation in band frequencies when viewed as the proportions of individuals that lacked a band at each locus in each subpopulation (Table 5). The permutation test of heterogeneity (Table 6) shows that no loci were significantly heterogeneous across populations when using a Table 5. Proportions of individuals that lacked bands at 14 RAPD loci, and the gene frequencies inferred from these band frequencies.

Locus A1:1370 A1:600 A2:1070 A4:800 A5:1490 A7:2100 A7:830 A7:675 A8:1190 A8:550 A11:520 B1:1100 B19:1920 P2:1400 aCF

CF (n = 10)

LA (n = 3)

0.6 0.781 0.2 0.471 0.4 0.645 1 1 0.3 0.564 0.5 0.716 0.6 0.781 0.8 0.897 0.8 0.897 0.6 0.781 0.7 0.841 0 0 0.1 0.356 0.9 0.95

0.333 0.63 0 0 1 1 1 1 0 0 0.25 0.552 0.5 0.73 0.25 0.552 1 1 1 1 0.75 0.875 0.25 0.552 0 0 1 1

Populationa NF (n = 19) 0.889 0.944 0.278 0.527 0.444 0.673 0.778 0.884 0.278 0.537 0.278 0.537 0.278 0.527 0.667 0.819 0.944 0.972 0.889 0.944 0.889 0.944 0.056 0.267 0 0 0.889 0.944

SC (n = 3)

SF (n = 29)

1 1 0 0 0.667 0.834 1 1 0 0 0 0 0.333 0.63 0.333 0.63 0.667 0.834 0.667 0.834 1 1 0 0 0 0 1 1

0.69 0.832 0.276 0.531 0.448 0.673 0.793 0.892 0.276 0.531 0.586 0.768 0.414 0.647 0.379 0.62 0.759 0.872 0.655 0.811 0.724 0.852 0.103 0.334 0.069 0.279 0.931 0.965

= Central Florida, LA = Louisiana, NF = North Florida, SC = South Carolina, SF = south Florida.

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Table 6. Among-population heterogeneity and population structure for 14 RAPD loci is represented by FST. Locus designations are the same as in Table 5. Pr is the proportion of times that Ghet, calculated from the original data, was greater than the same statistic calculated from a randomly selected data set with the same overall proportions.

Locus

Ghet

Pr

A1:1370 A1:600 A2:1070 A4:800 A5:1490 A7:2100 A7:830 A7:675 A8:1190 A8:550 A11:520 B1:1100 B19:1920 P2:1400

5.426 0.669 3.884 1.704 0.807 5.841 3.028 8.923 3.227 4.396 2.128 2.241 1.819 0.768

0.157 0.903 0.354 0.645 0.88 0.143 0.487 0.031 0.329 0.229 0.553 0.502 0.512 0.862

FST 0.06 0.324 0.088 0.059 0.349 0.349 -0.088 -0.008 -0.035 0.005 -0.011 0.227 0.199 -0.008

multiple test correction. Even when the adjustment for multiple tests is ignored, only a single locus (A7:675) shows significant heterogeneity. A visual inspection of the phenogram based on UPGMA clustering of interindividual similarities revealed no clusters that corresponded to geographic location.

The results indicate that kites from central and southern Florida kites are relatively homogeneous. The distinct polymorphisms that have been identified, however, indicate that these characteristics probably could be used to identify the geographic origins of individuals on various scales, within and beyond Florida.

Other Activities In April 1998, we presented a paper entitled â&#x20AC;&#x153;Trans-equatorial migration of the swallow-tailed kite: Implications for conservationâ&#x20AC;? at the North American Ornithological Conference in St. Louis, Missouri. One of our Latin American collaborators, Cesar Marquez Reyes, presented the results of the migration study at Hawk Mountain (Pennsylvania) and at the annual meeting of the Alexander von Humbolt Institute in Bogota, Colombia. In an effort to help train Latin American biologists, we consulted with over 25 students and field technicians who wished to be involved with the project. We presented our results to biologists at the Brazilian migratory bird agency, CEMAVE, with whom we are collaborating. CEMAVE will serve as our Brazilian

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sponsor. As our future training, monitoring, and educational programs develop, CEMAVE will be our main contact and a repository for equipment, data, and educational materials. We submitted a report to the National Fish and Wildlife Foundation describing the formation of an international working group; minutes of our meetings; contact lists; committee memberships; and draft recommendations and planning guidelines, distributed for review, that identify goals and objectives, information needs, and potential cooperators.

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DISCUSSION AND RECOMMENDATIONS Nesting Ecology and Demography On a large scale, swallow-tailed kite nesting habitat in northern Florida differs from that in central and southern peninsular Florida. The northern landscape is characterized by coastal-plain features, with more expansive and heterogeneous hydric forests, although less so than nesting habitat on the Atlantic coastal plain of Georgia and South Carolina and the northern Gulf coastal plain of Alabama, Mississippi, and Louisiana, where river floodplain forests are a more prominent feature.

As in southern Florida, nests were placed near the top of the tree and nest trees were taller than adjacent overstory trees (Meyer and Collopy 1995).

Selecting a nest position high in an emergent tree suggests that these sites provide the kites better access, support for the structure (closely spaced adjacent limbs), visibility, and protection from fire (Meyer 1995). Tree heights in the nest stands were substantially taller in northern Florida (Meyer and Collopy 1995), but the physical structure of the stand is probably more important in site selection than absolute size of the trees (i.e., height of the nest tree relative to adjacent trees). This suggests that uneven-aged forests, or at least thinned stands on timber-managed lands, provide more suitable nest sites than even-aged/even-structured plantation forests. In southern Florida, where wind was a major cause of nest failures, trees with unsuccessful nests had ratios of dbh to tree height that were significantly smaller than those for trees with nests that were successful, suggesting that nests in spindlier, more flexible trees were more vulnerable to wind damage (Meyer and Collopy 1995). In northern Florida, where wind rarely appeared to cause failures, there was no such relationship between dbh:height and fate.

The biggest difference in kite habitat between northern Florida and the rest of the state is land ownership and management. Most of the nests in the present study were on public and private lands intensively managed for timber production. The nests were found mainly on 2 types of timberland: national forest (Apalachicola, Osceola, Ocala) and corporate industrial forest (principally that of Georgia-Pacific Corporation). The 2 types of timbermanaged forest presented different types of management issues for swallowtailed kites and also appeared to support different levels of kite nesting densities, with nests more numerous and closely spaced on the industrial forest of the Gulf Hammock region. Kite neighborhoods on national forest lands were within what appeared to be suitable nesting habitat, with relatively open (well-burned) stands of very large, mature trees. Such stands fit the profile of attractive kite nesting habitat in central and southern peninsular Florida, with

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33

uneven age, or at least uneven structure, and relatively open canopies and mature pine trees with open, laterally compressed crowns that provide easy access for kites and good support for their nests. Swallow-tailed kite nest densities on national forest lands, however, were not high overall. Some wellestablished neighborhoods had high densities, but these areas were scarce within extensive tracts of apparently suitable nesting habitat. For this comparison, our main reference for industrial forest was Gulf Hammock, which may have high kite densities for reasons other than current timber management practices. Given the level of kite nesting effort on timberlands outside of peninsular Florida, the relationship between nesting ecology and timber management is an important topic. This will become more of an issue even in Florida as privately owned ranchlands in the central and southern portions of the state, which support high numbers of nesting kites, are lost to more intensive, less compatible agricultural and residential development.

Our estimates for success and productivity for northern Florida in 1998 are essentially equal to those from 9 years of study in southern Florida. The proportion of adults that attempted to breed in northern Florida in 1998 was below average. Those that did nest, however, achieved average nesting success and productivity. A similar trend was noted in southern Florida during 3 years with unusually high water conditions in the spring and early summer.

Weather, particularly strong winds, did not seem to be as prominent a factor in nest failures in northern Florida as it was in southern Florida from 1988 to 1996. This may be due to fewer severe storms in 1998. Overall, egg-laying in northern Florida was later in 1998 than in 1997, when the earliest nests fledged young by the third week of May. Juvenile kites were highly variable in their post-fledging movements, similar to the behavior of juveniles in previous years. Some individuals remained within small areas near their nests (range of 10–30 km2), while others vacated their natal ranges within 2–3 weeks of leaving the nest and either established activity ranges 30–60 km away or periodically moved from one area to another. There was no indication that these differences in postfledging behavior were related to differences in nesting habitats, but our study was not designed to detect this. The differences in dispersal strategies may have been a function of sex, habitat quality, parental feeding rates, or chance.

Overall, kites of all ages left northern and southern Florida earlier than usual in 1998. This may have been due to the same poor environmental conditions that reduced nesting attempts. Weather also may explain the earlier departures. The 6-day period from 9 to 14 August 1998, when we lost contact with 9 of the 16 surviving juveniles, coincided with the departure of 2 of the 3 adults tracked by satellite and the approach of a hurricane that produced northerly winds in Florida. Such winds, associated with tropical low-pressure

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systems in the region during the late summer, may serve as a proximate stimulus for migration.

We expanded our sample of radio-tagged juveniles to 73 during the study and obtained enough data to estimate some key demographic variables. We learned that the return rate for 1-year-old kites is very low. Our observations and counts of 1-year-olds relative to older birds during the spring in Florida breeding areas, based on tail lengths (confirmed by observations of radiotagged individuals of known age), produced a very similar estimate of survival. Our ability to detect radio-tagged kites may have been poor, but we relocated the same tagged individuals in Florida many times over the course of the breeding season during wide-ranging telemetry flights, and the same was true for our winter surveys in Brazil. If our detection rate had been poor, repeated detections of tagged birds should have been much more variable.

The only likely explanations, which may occur simultaneously, are low survival and that some individuals remain south of the U.S. following their first winter. We were not able to search the Brazilian winter range for tagged birds remaining after January, but most of the kites in the study area vacated the region for the austral winter. It would not be feasible to track VHF signals to find wintering destinations for southern swallow-tailed kites, and satellite transmitters were deployed only on adults.

In Louisiana, Coulson (Tulane University, personal communication) has observed nearly twice the return rate of 1-year-old radio-tagged kites. She also sees higher nesting success and productivity than in Florida. One Louisiana adult was tracked migrating west into Texas and then south through Mexico. Perhaps this overland route, presumably safer than crossing the Gulf of Mexico (especially for a 4- to 5-month-old, inexperienced bird), is used by some Florida juveniles, but they may represent a small portion of the stateâ&#x20AC;&#x2122;s population relative to the kites in Alabama, Mississippi, and Louisiana that use this route. Our satellite results indicate that the first 1,000 km of the southbound fight from the southeastern U.S. varies most among tagged birds and is potentially the most life-threatening. Florida swallow-tailed kites, particularly juveniles from the peninsula, may be more likely to die as a result of their first southbound migration.

We found 11 of 73 radio-tagged juveniles at 1 year old, or about 15%.

This is consistent with our detection rate for smaller samples of 1-year-olds in 6 of the previous years (a total of 36 additional birds), when the detection rate was always between 15 and 20%. We believe it is likely that most of the missing birds are dead, not undetected in Florida, or occupying areas beyond our U.S. study area.

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35

The sexes were equally represented in our sample of radio-tagged juveniles. There was some suggestion that sex ratios varied among areas within Florida in relation to habitat quality. In Louisiana, Coulson (personal communication) found a slight male bias among juveniles. The male bias is stronger in South Carolina (J. Cely, South Carolina Department of Natural Resources, personal communication) and Georgia (K. Meyer, unpublished data). This may be an interesting question to revisit as sample sizes and data on the correlates of nestling sex ratios accumulate.

Roosts and a Long-term Monitoring Plan Observations at pre-migration communal roosts in Florida, which are used to some extent by birds breeding in other southeastern states, provides an excellent opportunity to monitor population trends. We acknowledge that national representation in Florida’s large roosts confounds the effort to track Florida’s breeding population of swallow-tailed kites. Roost observations, however, are the best available method for monitoring swallow-tailed kites at any population level, and we are confident that the results will serve as a meaningful index of trends within Florida’s breeding population.

We know of 45 pre-migration roosts of various sizes, from 2 to over 1,600 swallow-tailed kites. There was an apparent positive relationship between size of the roosts and site fidelity, and the largest roosts were in more heterogeneous landscapes with potential foraging habitat in various directions.

Roosts along rivers of the Atlantic and Gulf coastal plains were small and highly variable in location, between years and even over periods of days within years.

At least 60% of the estimated U.S. swallow-tailed kite population probably passes through the 6 largest pre-migration roosts during July and August each year. The concentration of such a large portion of the population makes them vulnerable to disturbance, habitat alteration, or severe weather.

This poses a challenge to swallow-tailed kite management and conservation.

It also provides a valuable opportunity for long-term monitoring. A proposed population monitoring plan (Appendix A) is a first step. It requires testing for several years to evaluate the variance in total counts. It also will help during this time to continue searching for large roosts using whatever radio-tagged birds are available to find any temporary or newly formed roost sites that might be reducing attendance at sites targeted for counting. The second part of the proposed monitoring plan, estimating annual productivity, also must be tested. We could assess the method’s accuracy by looking at the extent to which estimated proportions of young vary from year to year during peak roost attendance. The relative proportions of adults and young shift

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continuously as adults, which begin migration weeks before juveniles, gradually leave the roost. We suggested standardizing the time for counting young by monitoring changes in each roostâ&#x20AC;&#x2122;s numbers and, retrospectively, using the ratio of adults to young obtained on the date closest to the inferred peak date for the roost (Meyer 1993). There may be too much variation between years in the relative departure times of adults and young or in how accurately we can determine when the roost peaks. If the consistency of the productivity counts over several years is within acceptable limits, we can evaluate the productivity estimates in relation to predictions based on accumulated nest monitoring and radio-tracking data.

Migration Corridor and Winter Range The northern subspecies of the swallow-tailed kite fits the general model suggested for Neotropical migratory bird species that probably originated in the tropics (Hagan and Johnson 1992, Rappole 1995). Some individuals presumably found suitable breeding conditions in the temperate zone, beyond the northern limit of their migratory range, and were able to avoid competition from higher densities of conspecifics and ecologically similar species in the tropics. They continued to return, however, to their ancestral, tropical range during the boreal winter (not necessarily to avoid harsh conditions in the north, but because they originated in the south). Their winter range is often smaller than their breeding range, increasing competition. Conditions on the winter range of the northern subspecies of swallow-tailed kite have the potential to be limiting, relative to conditions on the northern breeding range.

The most striking feature of the migration route is its constricted nature from the Yucatan Peninsula southward. The initial portion of the southbound corridor, from the southeastern U.S. to the northern end of the Yucatan Peninsula, is variable. In this region, we have evidence of kites traveling from southern Florida to western Cuba (and then on to the Yucatan in nearly a straight line), which is probably the preferred route; directly from southern Florida to the northern Yucatan (by-passing Cuba and the opportunity to rest or feed); from southern Florida to eastern Cuba or farther east into the Antilles (such movements were associated with westerly winds produced by approaching hurricanes or tropical storms); and westward from Florida across the northern Gulf coastal plain through Texas and into Mexico, after which they probably continued overland to Central America. It is this initial portion of the migration route, from the U.S. to the Yucatan Peninsula, that probably poses the greatest risks to southbound swallow-tailed kites.

One of our objectives for the proposed migration study is to identify concentration points and potential stopover sites along the migration corridor.

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We spent time in 1997 exploring the region of the Andes in southwestern Colombia where the kites pass through the mountains from west to east. This is an austere environment that must pose risks to most migratory birds (Rappole 1995). The challenges have been exacerbated by large-scale clearing of forest and subsequent erosion. Another potentially critical region is Cuba and the western coast of the Caribbean (Yucatan Peninsula and Belize), which may be used for staging and stopover areas for both north- and southbound kites before and after they cross the largest expanses of water on their migration route.

By combining the advantages of VHF and satellite telemetry, we have already learned about the threats to swallow-tailed kites from rapidly changing conditions on the winter range in southwestern Brazil. The U.S. population of swallow-tailed kites concentrates in 2 very small areas about 1,200 km apart, north and south of Brazilâ&#x20AC;&#x2122;s Pantanal. We know that radio-tagged kites move between the 2 wintering concentrations but mainly reside for the season in one or the other. More important, though, is the management and conservation status of these areas. We know of 9 roost sites that are used by 6,000â&#x20AC;&#x201C;8,000 wintering swallow-tailed kites, including perhaps most of the U.S. population.

All of these 9 sites are on privately owned ranches, which harbor the last remaining stands of the habitats most strongly associated with wintering northern kites and breeding kites of the Brazilian population: native dry tropical forest, cerrado (dry, open shrub and scrub land), and gallery forest (very narrow riparian strands of tall trees) (Cochrane et al. 1985). As in Florida, intensive row-crop agriculture is more lucrative than cattle ranching (Alho et al. 1988). Most of the ranches where the roosts are located will be converted to such farming practices, many within the next few years.

We have established a collaborative relationship with CEMAVE, the Brazilian environmental agency responsible for bird conservation, and have begun documenting the conservation value of the kite roost sites. This is the first step toward bringing these parcels under the protection of a federal program that offers tax remission, lending priority, and technical support to landowners who agree to permanently protect portions of their land deemed critical to wildlife conservation.

Genetics We are in the early stages of investigating the genetic structure of the U.S. swallow-tailed kite population, particularly in Florida. The RAPD technique provided a preliminary, reasonably accurate assessment of overall genetic diversity in the population. It appears that at least the Florida population exhibits low genetic variation (i.e., high homogeneity). Although we analyzed

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few samples from beyond Florida, the results suggested that the U.S. population can be characterized in the same way. This is not surprising given the small size of the U.S. population and the swallow-tailed kiteâ&#x20AC;&#x2122;s ability to cover long distances easily. The species seems to be highly mobile while in the U.S., at least before and after the nesting season, and nonbreeding birds may be moving long distances while others are tied to nest territories.

Sightings are regularly reported throughout the eastern U.S. and Canada, particularly in the early spring and late summer. One might expect that genetic mixing would easily occur among swallow-tailed kites within the U.S. On the other hand, swallow-tailed kites seem to exhibit strong site fidelity to regularly reused nest sites. At this stage in our telemetry studies, we do not know whether these regularly used nest territories are being occupied from year to year by the same individuals. Strong site fidelity, however, suggests that reproductive mixing, at least among kites from geographically distant areas, is relatively limited. This conclusion would be supported by the very slow rate at which swallow-tailed kites colonize vacant, suitable habitat. We suspect that the speciesâ&#x20AC;&#x2122; strong social tendencies are a factor in this inertia, effectively handicapping single pairs trying to breed in relative isolation.

If additional work supports our conclusion regarding low genetic diversity, it remains to be determined whether this situation results from a low rate of mixing among nesting neighborhoods and sub-populations in the U.S., or if considerable mixing occurs but cannot override the influences of founder effect. In the latter case, the argument would be that the U.S. population originated from a small number of Latin American individuals and the genome of the U.S. population remains restricted. If this were so, even high rates of mixing within the U.S. might not produce a genetically heterogeneous population.

Based on what we know and can speculate, it seems more likely that mixing is occurring at a sufficient rate to cause the observed homogeneity and that founder effect is not a concern. Resolving this question may require additional genetic analyses using different approaches, including microsatellites or mitochondrial DNA. Ongoing research (A. Washburn, unpublished data) should provide some insight into this question. We have at least made good progress toward understanding the conservation genetics of swallow-tailed kites, particularly with regard to discovering primers to illuminate useful polymorphic markers.

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LITERATURE CITED Alho, C. J. R., T. E. Lacher Jr., and U. C. Goncalves. 1988. Environmental degradation in the Pantanal ecosystem. BioScience 38:164–171.

Cely, J. 1979. Status of the swallow-tailed kite and factors affecting its distribution. Pages 144–150 in D. M. Forsythe and W. B. Ezell Jr., editors.

Proceedings of the first South Carolina endangered species symposium.

South Carolina Wildlife and Marine Resources Department, Columbia, South Carolina, USA. Cochrane, T. T., L. G. Sanchez, L. G. de Azevedo, J. A. Porras, and C. L. Garver. 1985. Land in tropical America: a guide to climate, landscape, and soils for agronomists in Amazonia, the Andean Piedmont, Central Brazil, and Orinoco. Centro Internacional de Agricultura Tropical, Cali, Colombia, and Empresa Brasileira de esquisa Agropecuaria, Centro de Pesquisa Agropecuaria dos Cerrados, Planaltina, D. F. Brasil.

Hagan, J. M., III, and D. W. Johnston, editors. 1992. Ecology and conservation of Neotropical migrant landbirds. Smithsonian Institution Press, Washington, D.C., USA. Kaplan, E. L., and E. Meier. 1958. Nonparametric estimation from incomplete observations. Journal of the American Statistical Association 53:457–481.

Lee, E. T. 1980. Statistical methods for survival data analysis. Lifetime Learning Publications, Belmont, California, USA. Lynch, M., and B. G. Milligan. 1994. Analysis of population structure with RAPD markers. Ecology 3:91–99.

Mayfield, H. 1961. Nesting success calculated from exposure. Wilson Bulletin 73:255–261.

Meyer, K. D. 1993. Communal roosts of the American swallow-tailed kite in Florida: habitat associations, critical sites, and a technique for monitoring population status. Final report. Florida Game and Fresh Water Fish Commission, Tallahassee, Florida, USA.

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_____. 1995. Swallow-tailed kite (Elanoides forficatus). In A. Poole and F. Gill, editors. The birds of North America. Number 138. Academy of Natural Science, Philadelphia, Pennsylvania, and American Ornithologists Union, Washington, D.C., USA. _____, and M. W. Collopy. 1995. Status, distribution, and habitat requirements of the American swallow-tailed kite (Elanoides forficatus) in Florida. Final report. Florida Game and Fresh Water Fish Commission, Tallahassee, Florida, USA. _____, and _____. 1996. American swallow-tailed kite. Pages 188–196 in J. Rodgers, H. Kale II, and H. Smith, editors. Endangered biota of Florida.

Volume 5: Birds. University Press of Florida, Gainesville, Florida, USA. Millsap, B. 1987. Summer concentrations of American swallow-tailed kites at Lake Okeechobee, Florida, with comments on post-breeding movements. Florida Field Naturalist 15:85–92. _____, J. Gore, D. Runde, and S. Cerulean. 1989. Setting priorities for the conservation of fish and wildlife species in Florida. Florida Game and Fresh Water Fish Commission, Tallahassee, Florida, USA. Pollock, K. H., S. R. Winterstein, C. M. Bunck, and P. D. Curtis. 1989.

Survival analysis in telemetry studies: the staggered entry design. Journal of Wildlife Management 53:7–15.

Rappole, J. H. 1995. The ecology of migrant birds. Smithsonian Institution Press, Washington, D.C., USA. Robertson, W., Jr. 1988. American swallow-tailed kite. Pages 109–131 in R. S. Palmer, editor. Handbook of North American birds. Volume 4. Yale University Press, New Haven, Connecticut, USA. Welch, J., and M. McClelland. 1990. Fingerprinting genomes using PCR with arbitrary primers. Nucleic Acids Research 18:7213–7218.

Wright, S. 1951. The genetical structure of populations. Annual Eugenics 15:323–354.

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Appendix A. Proposed population-monitoring protocol for swallow-tailed kites (Elanoides forficatus) in Florida.

The goal of this proposed monitoring plan for Florida’s swallow-tailed kites is to produce an index of the species’ numbers and reproduction that will reveal population trends. The protocol consists of annual counts of individuals and relative numbers of juveniles and adults at large pre-migration communal roosts.

The latter would provide an estimate of within-year breeding productivity. Any monitoring plan for swallow-tailed kites must be economically feasible and sufficiently accurate to reveal meaningful population trends. The proposed plan takes advantage of the annual concentration of more than half the U.S. population of swallow-tailed kites at a few consistently used sites in Florida prior to its southward migration. This is a rare opportunity to monitor a vulnerable species. The proposed plan should be affordable, but we do not yet know if it can produce sufficiently accurate estimates to detect potentially harmful population declines.

Estimating Total Numbers of Roosting Kites Conduct aerial surveys at the 5 largest known roost sites: Fisheating Creek (Lake Okeechobee), Lake Woodruff, Corkscrew Swamp, CREW, and Oklawaha River. Each of these sites contained at least 150 kites at its peak during the years they were monitored in the 1990s.

The following dates are an approximate reference for the numeric peak at each roost.

Fisheating Creek 22 July Lake Woodruff 14 July Corkscrew Swamp 20 July CREW 19 July Oklawaha River 22 July Timing of the peak for any roost can vary by 5–10 days and the relative timing of the peaks among the 5 sites may change between years.

Make a series of 3 morning counts at each of the 5 sites, select the peak date, and determine the median date among the 5 peak-count dates. For each roost site, select the single count made closest to that median date. The total count for that year is the sum of the 5 selected counts. This method will help compensate for differences in peak dates among the 5 sites and for movement of individual kites among the roosts.

It would be better to count all 5 sites on the median peak date for the 5 roosts, but 1 observer could not accomplish this, and multiple observers might impose count biases. It might be acceptable for 2 or 3 observers to count the 5 roosts on the same mornings, as long the degree of observer bias was acceptable.

As with a single observer, this also would require making a series of daily counts, at 2-day intervals with 3 or 4 repetitions, to identify the day with the greatest overall numbers. It would be helpful to determine the relative accuracy of these 2 alternatives (i.e., single vs. multiple observers). One way to test for interobserver differences is for 2 observers, in different airplanes, to count the same roost on a given morning and compare counts. We have never done this.

If a single observer will make all 15 counts (3 at each of the 5 sites), schedule flights so that each roost is counted on its reference peak date (listed above) plus once 3 days before and once 3 days after the peak.

Some pairs of roosts can be counted on a single morning, but 3 counts per morning are not possible. For instance, Fisheating Creek and either CREW or Corkscrew can be counted on the same morning, as can Lake Woodruff and Oklawaha. To succeed, no time can be lost to bad weather en route or to any delays at the roost sites.

Making 3 counts per site with each site’s counts centered on its peak date will mean starting the flights on 11 July (3 days before the earliest peak, at Lake Woodruff) and finishing by 25 July (3 days after the latest peak, at Fisheating Creek and CREW). This allows 14 days to make 15 counts. Some days will be lost to bad weather (morning fog or low lying clouds are common at this time of year), inoperative aircraft, or other unpredictable delays. Even brief delays can prevent the observer from reaching a second site on

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Appendix A. Continued. time within a morning. Making 15 counts within a 14-day period will be challenging and will require practice. It will help to fly with the same pilots whenever possible (although different pilots will probably have to be used to cover the northern and southern regions). Pilots will learn the routine, the importance of a strict schedule, and how to safely fly the survey pattern at each roost without disturbing the birds, while meeting the observer’s needs. If multiple observers/aircraft are used to cover 2 or more sites per morning, scheduling will be easier and the probability of accomplishing all 15 counts in 14 days will increase.

During late July, counts can be made as early as 0700 hr EDT (sufficient light to count is the limiting factor) but no later than 0815–0830 hr EDT (kites usually begin leaving the roost at about this time). If you fly from an airport relatively close to the first site to be observed that morning, you can arrive by 0700 hr or soon thereafter. If you complete the count within 15–20 minutes, you will have at most about 1 hour remaining to fly to and count the second site. This would be adequate between Fisheating Creek and Corkscrew, Fisheating Creek and CREW, or Lake Woodruff and Oklawaha, if there are no delays.

See Meyer (1993) for instructions on counting the roosts from the air.

Estimating Annual Productivity Swallow-tailed kite young of the year can be distinguished by their shorter tails. Molting adults also have short tails (for a different reason), but they will show molt in the wing at this time. Young of the year will exhibit no molt, just a short tail. For plumage comparisons and suggestions for identifying young, see Meyer (1993).

Because of this distinction between adults and young, and because the total number of kites in the 5 largest pre-migration communal roosts represents at least half the U.S. population, it could be possible to derive an index of within-year productivity by making systematic counts of the ratios of adults to young in large roosts. The counting method is described in Meyer (1993). This technique, however, has not been attempted repeatedly, and we lack a sufficient series of annual counts to evaluate its potential accuracy.

As the roost season progresses, individual kites begin their southbound migration. Adults, however, leave before young of the year (Meyer 1993), resulting in a continuous change in the ratio of adults to young within a roost. For this reason, it is necessary to standardize the timing of the counts, possibly by performing the counts of adults:young as close as possible to the peak. This is more likely to reflect the timing of the nesting cycle within a year than simply using the calendar date.

Productivity estimates are made by analyzing sets of photographs taken from the ground as the kites leave the roost in the morning. Photographs are most useful if taken from directly below the flying kites as they gather in circling flocks before moving away from the immediate vicinity of the roost. Methods for photographing and counting the birds are described in Meyer (1993).

We lack sufficient trials and statistical evaluation of these protocols to judge their accuracy. The next step will be to collect count data for several years and evaluate effectiveness and feasibility.

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