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DRAFT FINAL REPORT PROJECT TITLE: Seasonal movements and habitat use of Snail Kites (Rostrhamus sociabilis) in Florida: A comparative study of satellite and VHF tracking methods. CONTRACT SOURCE:

United States Fish and Wildlife Service 1339 20th Street, Vero Beach, FL 32960 772-562-3909

GRANT AGREEMENT:

#401816G084

DUNS #:

010600208

EIN:

59-3455864

CONTRACTOR:

Avian Research and Conservation Institute (ARCI) 411 N.E. 7 Street, Gainesville, Florida 32601 352-514-5606, meyer@arcinst.org

PROJECT DIRECTOR:

Kenneth D. Meyer, PhD

REPORT AUTHORS:

Kenneth D. Meyer, PhD, ARCI Gina M. Kent, MS, ARCI

COLLABORATING WITH:

Kristen Hart, PhD, USGS Ikuko Fujisaki, PhD, USGS

PROJECT BIOLOGIST:

Peter Mahoney

DATE SUBMITTED:

12 April 2011


INTRODUCTION Understanding the seasonal movements, habitat use, and spatial needs of species of critical conservation concern is essential to identifying threats and planning effective management. Challenges abound, however, in designing effective but affordable research. Studying the conservation biology of Snail Kites (Rostrhamus sociabilis) epitomizes these challenges. This social raptor’s distribution extends from Cuba and southern Mexico through the lowlands of Central America and most of South America, but its occurrence in the United States is limited to Florida. The species is listed as Endangered federally and by the state of Florida. Anthropogenic changes to Florida’s wetlands over the last century threaten populations of numerous wetland-dependent species in complex ways. Observed changes in Snail Kite populations during this period have been tied to landscape-scale perturbations in wetlands, particularly changes in hydroperiod (Sykes 1984, Beissinger 1988, Bennetts et al. 1994, Sykes et al. 1995). Snail Kites feed almost entirely on a single species, the Apple Snail (Pomacea paludosa). This food supply is influenced by the timing and distribution of particular hydrologic conditions across the Snail Kite’s central and southern Florida range. The mechanisms by which environmental changes affect the behavioral ecology of Snail Kites and the best management approaches for mitigating these impacts remain poorly understood. The main goal of this project was to quantify the differences in cost and effectiveness between satellite and VHF radio telemetry for locating marked Snail Kites following dispersal, for describing habitat use and home ranges, and for estimating survival. In the course of determining which tracking technology best answers important management questions, we also will contribute to our knowledge of Snail Kite ecology and movements in response to changing environmental conditions at a time when concerns are growing about the sustainability of the U.S. population, which is faced with intensifying human pressures and management of critical wetlands. Movements of Snail Kites in relation to water conditions are poorly understood. Although changes in hydrology apparently are correlated with long-term changes in Snail Kite distribution, annual and seasonal shifts in distribution do not always coincide with changes in local hydrology (Bennetts et al. 1994). Disagreements surrounding Snail Kite movements, furthermore, have burdened the planning process for wetland restoration in central and southern Florida (Bennetts and Kitchens 1997). Most ambitious among these efforts is the Comprehensive Everglades Restoration Plan (CERP), in which proposed changes in hydrologic regimes appear to promote the management objectives for some listed species while compromising those of others. Sound inferences based on the best available data are the only means of reducing such conflicts and identifying the best course for critical species and the overall health of the ecosystem. In the case of Snail Kites, the most important questions can be identified, but the most cost-effective application of available technology is not readily apparent. The present study provides comparative results that will help to select the best methodology and to design productive field studies of the seasonal movements of Snail Kites in relation to impending changes in Florida’s water management regimes.


OBJECTIVES 1. Determine the relative effectiveness and costs of satellite and VHF telemetry for tracking yearround, long-distance movements of Snail Kites in Florida. 2. Compare the two methods in their ability to describe foraging habitat and to quantify the vegetation and physical landscape features represented in each bird’s home range. 3. Compare the two methods in their ability to estimate home-range size and to identify core areas, including expense per point and the degree to which each method approaches an asymptote for range area. 4. Determine the relative effectiveness of the two methods for finding dead radio-tagged birds or a shed transmitter, including the time required after death and the relative costs for retrieval. Although not proposed as objectives, we also are reporting on the following to help compare the utility of the two tracking technologies: 5. Long-distance movements and alternative core areas. 6. Adult survival based on satellite tracking.

METHODS Study area Snail Kites were trapped in Central Florida on Lake Tohopekaliga and Lake Kissimmee, part of the Kissimmee chain of lakes. Our study area consisted of all the places these birds were detected by at least one of our two tracking methods from February 2007 through December 2008. The radiotagged Snail Kites were tracked north to Marion County and south to Monroe County. General comparison of the two tracking methods Telemetry studies are costly whether the location data are collected by tracking VHF signals from the air and ground or remotely by satellite. However, the particular expenses vary substantially in type (e.g., flying versus digital data processing) and extent between the methods. For this study, we deployed a radio unit that incorporated both satellite and VHF capabilities in a single package that weighed less than 12 grams, thus complying with the weight restriction imposed by the U. S. Geological Surveyâ&#x20AC;&#x2122;s Bird Banding Laboratory (<3% of body weight). The satellite component was a 9-gram, solar-powered, basic transmitter (no GPS receiver; model PTT-100, Microwave Telemetry, Inc., Columbia, Maryland, USA). To the satellite transmitter, we attached at small, battery-powered VHF transmitter, which operated continuously and emitted one pulse every 1.8 seconds (~34 beats per minute). Thus, we gathered both satellite and VHF data from the same individuals, thereby reducing sampling error and the potential confounding effects that would result from comparing a small number of Snail Kites with satellite transmitters to a small number of different individuals with VHF transmitters. To ensure that the person searching for the VHF signals of dispersed kites was not aware of their location based on the satellite locations, one PI compiled the satellite data and the other PI managed


the VHF surveys. Trapping and radio tagging In order to radio tag Snail Kites, we collaborated with University of Florida (UF) researchers, directed by Dr. Wiley Kitchens, on their ongoing study of Snail Kites, for which they were already capturing and radio tagging kites in habitually used nesting areas. The exact trapping locations were determined with reference to the UF team’s VHF tracking results and in consultation with U. S. Fish and Wildlife Service staff. The tracking areas during the non-breeding study period were determined by the kites’ movements. The trap we used was an original design (Mahoney et al. 2010). We constructed 2’-by-2’ square frames from PVC and joined at the corners with 90-degree PVC unions. We then strung 17lb test fluorocarbon monofilament through eyelets, producing 16 parallel stringers. Nooses were tied to each stringer using a clinch knot for a total of 256 nooses per trap. A mesh basket was made using untreated nylon window screening and sized to allow for ~3” of depth when attached to the frame. Areas within each lake were chosen as trap locations based on densities of foraging kites. Airboats and kayaks were used to access the foraging locations and trapping sites. Before any trapping would take place, all birds were observed for a short period (i.e. 1-2 hours) in order to confirm they were not nesting and to identify a pattern of perch usage. When a trapping location was chosen, the trap was set once the perch was vacated. The best locations were upwind from the expected perch site and about 3 meters away (Mahoney et al. 2010). We ensured that the noose loops were open and protruding above the water, and then scattered 3-7 snails (frozen or live) in the mesh basket. Once a kite was captured, we approached the trap carefully and quickly to prevent injury to the bird. With the kite secured, we removed the trap from the water and loosened the nooses to free the bird, which was measured and fitted with a transmitter and released at the trap site within 45 minutes of capture. From 5 February to 3 March 2007, we captured 10 adult Snail Kites and fitted them with dual satellite/VHF radios (Table 1). We searched for the VHF radio signals of the 10 marked kites during 27 flights over a 31-week period, from 14 March to 19 October, 2007, and compiled satellite-derived locations continuously for all 10 birds for nearly 23 months, from when we tagged the first kite on 5 February 2007 through 31 December 2008, the end of the analysis period for this report.

Collecting location data The VHF locations for all our analyses were collected during aerial surveys in a Cessna 172 (singleengine high-wing) or AirCam (twin-engine high-wing) aircraft with Telonics two-element Hantennas attached to the wing struts. These flights were conducted at 500 to 700 meters above ground level and an airspeed of about 165 kilometers per hour. The search transects were positioned with regard to topography (the distribution of wetland systems likely to support Snail Kites), expected dispersal distances of missing birds from their last known VHF locations, and budget constraints. We did not see the marked Snail Kites, but we acquired latitude and longitude coordinates (in decimal degrees, with a GPS receiver) for our best approximation of each bird’s position (Table 2). The satellite data were processed by CLS America, Inc. We retrieved sets of coordinates weekly from a website and parsed the data into a cumulative database. Of the 6 Location Quality Classes


(LC), we used only the 3 of highest quality in our analyses (LC 1, 2, and 3, with maximum errors of 1,500 to 250 meters, respectively). We considered fixes of LC 0 only as needed to confirm survival during gaps in transmission of higher-quality locations. After selecting the highest-quality fixes, we reviewed the entire database to remove duplicate fixes (an anomaly of the data-processing and reporting system) and locations that fell within 1hour of another, thus increasing statistical independence of the data. When locations were close in time, the one with the poorest (smallest number) LC was removed. When they had the same LC, 1 location was randomly selected for removal. We used the VHF and satellite data for the period from 14 March to 19 October 2007 for all comparisons of habitat use and home-range estimates between the tracking methods. These dates marked the first and last day of our near-weekly aerial surveys in central Florida (n = 27). To align the time frames for the satellite and VHF data, we selected only day-time satellite fixes (from 08:30 to18:30 hours local time) of LC 1, 2, or 3. We then selected only the satellite fixes for a given bird that were within 24 hours of a VHF location for that bird. These satellite fixes and their matching VHF fixes from the 27 flights were then paired and mapped to measure the distances between the VHF and satellite locations per pair. Detection following dispersal This portion of the fieldwork was conducted mainly during the period immediately following dispersal from breeding areas. Thereafter, we referred to the satellite data to plan the VHF aerial surveys in order to remain within our proposed flight budget. During the post-breeding dispersal stage, the PI compiling and monitoring the satellite data was aware of the positions of all tagged kites. A field biologist who was unaware of the satellite-derived locations was responsible for the VHF surveys. This person planned the flights during the 30-week VHF-tracking period with reference to the last known locations of the study subjects, likely dispersal sites within an expected dispersal distance, known hydrologic conditions within this area (i.e., where we would expect Snail Kites to be based on current water levels), and budget constraints. Measuring home ranges We searched for VHF radio-tagged kites from the air to collect as many as 27 fixes per bird (some were not detected on each of the 27 flights) at a rate of one per week from March through October (Table 2). The VHF-derived home ranges were compared to those determined from the satellite data (LC 1, 2, and 3) that were day time fixes no less than 1hr apart and within the dates of the VHF flights (14 March to 19 October). We calculated both a Minimum Convex Polygon (MCP) (Samuel and Fuller1994) and Kernel Density Estimates (KDE) (Seaman and Powell 1996) to depict home ranges for each tracking method. The 100 % MCP analysis was run using ArcGIS (ESRI 1996) Hawths Tools extension (Beyer 2004). The KDEs at volumes of 99, 95, 75, and 50 % were run through the Home Range Extension (Rogers and Carr 1998) in ArcView 3.2a (ESRI 1996). Our standardization style was unit variance with a least-squares-cross-validation (LSCV) smoothing factor (Worton 1989) and a 50-cell raster resolution. MCP and KDE areas (square kilometers) also were compared between males and females and between 2 age classes: first- and second-year kites versus those in their third year or older. Quantifying foraging habitats The same set of VHF and satellite locations used in the home-range analysis was also used for quantifying foraging habitats. Using GIS software, all locations (VHF and satellite) were buffered with a 1500-m radius (an enclosed area of 7 sq km or 700 ha) to account for the magnitude of the


greatest error in satellite-location accuracy. Proportions of vegetation cover types were calculated within each buffer by overlaying the buffer circles on the habitat layer and using the Area Calculator in ArcView GIS. The VHF-derived vegetation proportions were compared to those determined from the satellite data using a) the entire set of all satellite locations; and b) 216 satellite locations randomly selected from the entire set (i.e., the same number as the VHF sample). In order to determine habitat use-versus-availability by the foraging kites for the two telemetry methods, we calculated the habitat proportions with an available area delineated by 100% MCPs based on the total distribution of VHF and satellite locations respectively (ArcView 3.2 Animal Movements extension, Hooge and Eichenlaub 1997). Snail Kite satellite locations were then compared to the MCP created by the total set of satellite locations. The same process was repeated for the VHF locations. The land-cover layer for this analysis was the 43-cover type classification scheme (30 m x 30 m resolution) created by the Florida Fish and Wildlife Conservation Commission in 2003. This spectral satellite data had an Albers HPGN projection in the NAD 1983 datum. Not all 43 cover types were represented within the buffer areas around the Snail Kite locations or the available area within the MCP. There were 33 classes within the largest available area polygon (satellite), which were consolidated into 11 classes (Table 3). All statistical tests were performed with JMP 4.0 software (SAS Institute, Inc.). First, we used Student t-tests (p<0.05) to compare the proportions of the occupied habitats derived from satellite versus VHF tracking. Next, we used Student t-tests to compare the proportions of habitats within buffered areas around each kite location to the parametric proportions of the corresponding habitats in the available area (comparing sample means to hypothesized values; Sokal and Rolf 1995: 169175), thus determining whether specific habitats were selected more or less than expected based on their availability. Core areas and long-distance movements We measured the total lengths of movements for each of the 10 Snail Kites based on the entire set of satellite locations (LC 1, 2, 3, >1 hour apart), from tagging dates through 31 December 2008. For each bird, the progression of movements was depicted by linking all locations with a polyline using the Hawths Tools (Beyer 2006) extension in ArcGIS (ESRI 1996). Lengths of lines were summed for each bird and compared between the two age groups (first and second year versus all older birds) and between the sexes. Detectability of downed transmitters Because none of the radio-tagged Snail Kites died during the two-year study, we were not able to evaluate the two tracking methods for their relative abilities to determine the timing, location, and potential causes of actual mortalities. Instead, as proposed, we made systematic comparisons by deliberately placing both types of transmitters in three locations simulating mortality of a radiotagged bird: in woody vegetation 3 to 5 meters above the waterâ&#x20AC;&#x2122;s surface; in emergent graminoid vegetation within 1 meter above the surface of water in an open marsh, and underwater at a depth of 20 to 30 centimeters. Adult survival Survivorship of adult and juvenile age classes has been well studied in Snail Kites (Bennetts and


Kitchens 1997. We did not propose a rigorous estimate of annual adult survival due to the small sample of radio-tagged birds and the relatively short duration of the study. Our objective was to compare coarse survival estimates qualitatively between the tracking methods.

RESULTS Collecting location data The 30-week tracking period for the last-deployed VHF transmitter ended on 28 September 2007, but 9 of the 10 radios did not begin failing (from expired batteries) until late October 2007 and some operated until late December. We continued our flights through most of this period, although on a reduced schedule (i.e., not weekly after mid-October). The exception was transmitter #164.218 (Satellite #67451), which began producing an unusual signal in mid-July 2007 that suggested impending, premature failure. We were unable to detect a VHF signal for this Snail Kite during the next flight and never heard it again. However, this birdâ&#x20AC;&#x2122;s satellite transmitter continued to produce location data that indicated the bird was alive and moving about normally. There were 64 pairs of satellite-VHF locations that fit the criteria (i.e., day time, within 24 hours, and highest-quality LC for satellite) for measuring the distances between corresponding satellite- and VHF-derived locations (Figure 1, Tables 4 and 5). The mean distance between the VHF and satellite locations for these VHF/satellite pairs was 4.1 (+ 5.3) km. Over the 30 week VHF tracking period, we were usually able to detect 6 to 10 of the radio-tagged Snail Kites on any flight. Seven of the 10 kites began making substantial moves in mid-June 2007 away from their capture locations (lakes Tohopekaliga and Kissimmee). These movements challenged our ability to maintain VHF contact with these individuals given the transmission range of the radios, the sudden and unpredictable timing of the departures, the rates at which the kites moved to their new locations, and, in many cases, their unpredictable destinations. Seven of the 10 radio-tagged kites made a total of 30 long-distance movements (mean: 4.3 movements per individual) ranging from 40 to 220 km based on the satellite-derived locations and measured point-to-point (i.e., not actual travel distance) (Figures 2 and 3). The mean distance for the 30 movements was 95.3 km. Five (71%) of the 7 kites that moved were females, similar to the proportion of females in our radio-tagged sample (70%). Three of the 7 kites (43%) were radio tagged on Lake Tohopekaliga; their mean distance per movement was 122 km. The four (57%) radio tagged on Lake Kissimmee traveled an average of 87 km per movement. Our understanding from concurrent projects was that Snail Kite abundance and nesting effort were greater on Lake Tohopekaliga than on Lake Kissimmee during the study period (C. Cattau, personal communication). The limited movement results from our small sample apparently do not reflect this reported asymmetry in feeding conditions. That is, the 5 kites that were tagged on Lake Kissimmee did not appear to be more likely to make long-distance movements and their movements were not longer than the 5 kites tagged on Lake Tohopekaliga. The data quality and quantity produced per satellite transmitter varied over the course of the study. At the time of deployment, the satellite transmitters were the smallest and lightest ever used on freeranging animals, weighing only 9 grams. We used this extremely light model so that we could mount a small VHF transmitter alongside without exceeding the permissible weight for this species,


thus allowing us to collect satellite and VHF data from the same individuals. The drawback, as we learned, was that the solar-charging circuitry of these very small satellite transmitters barely recharges the onboard storage battery enough to support effective transmission to orbiting satellites, even under good solar recharging conditions. Lengthy periods of cloudy weather did not allow sufficient recharging to keep the transmitters running on their programmed duty cycle of eight hours on (transmitting) and 48 hours off (to recharge). This probably was the cause of interruptions in data acquisition that lasted for one or two duty cycles (i.e., no fixes for 6 to 9 days). We also experienced some very long interruptions, far beyond what we expected from cloudy weather. We first encountered this problem with satellite transmitter #67451, deployed on 11 February 2007 (Table 1). When we recaptured this bird after 2 weeks without receiving any data, we saw that the surface of the clear epoxy covering the solar panel atop the transmitter was clouded by a fine, dusty film. We suspect that this was powder down from the bird because it had an oily texture that made it adhere to the radio. When we reviewed the record from another radio that had a long lapse in transmission, followed by a sudden resumption of good service, we realized that it had transmitted intermittently or not at all for over two months when no rain had fallen, but began performing normally after several days of rain, which may cleaned the clear coating over the solar panels. The combination of occluded solar panels and the marginal recharging capability of this very small transmitter probably caused the long lapses in transmission that we experienced with many of the satellite transmitters. Seven of the 10 Snail Kites had satellite data gaps of 30 days or more. There were 15 data gaps that were over 31 days from tag dates in February and March 2007 through 31 December 2008. Ten of the data gaps were about 30 days long. PTT# 36308 did not transmit for 57 days, #36316 had a gap of 65 days, 40565 had one of 68 days, and 40568 had the longest two gaps at 96 and 104 days. Detection following dispersal Except for recharging problems, satellite transmitters provided uninterrupted detections. This was not true for the VHF transmitters, which became increasingly more difficult to locate as dispersal distance increased (the search area expanded exponentially relative to the linear distance that the bird traveled). It gradually became impractical and unaffordable to fly until each signal was detected. Describing and measuring home ranges The mean areas of MCPs (Figure 4) for the 10 Snail Kites were 239.4 square km for VHF (range: 26.65 to 828.51) and 841.26 square km for satellite (range: 18.21 to 3656.77 square km) (Table 6). The paired t-test comparing the 100% MCP areas for satellite and VHF locations did not reveal any significant differences between the methods (t = 0.15, df = 9, P = 0.150), nor did comparing all MCP areas with an ANOVA (F = 2.493, P = 0.132). There also were no differences between males and females (VHF: t = 0.549, P = 0.549; Satellite: t = 0.980, P = 0.354). The VHF MCP area was greater for 1- and 2-year old kites (t = 2.26, df = 8, P = 0.05), but there were no significant age-related differences based on the satellite MCPs (t = 0.06, df = 8 P = 0.95). We calculated KDEs for all 10 Snail Kites at 99, 95, 75, and 50% volumes for the 7-month VHF and satellite datasets (Figures 5, 6, and 7) and for the 2-year satellite-only dataset (Table 7). There were no differences between home range area estimates based on satellite versus VHF locations (Table 8, paired t-test). The ANOVA analysis for each of the 4 volumes of kite locations (50%, 75%, 95%, 99%) also showed no differences (Table 8). The Kernel home-range estimates differed between tracking methods in a two-way ANOVA (f = 4.625, df = 1, P = 0.035) for both area and volume,


with satellite estimates being larger. There were no differences between males and females for any of the 4 volumes within both VHF and satellite Kernels. Quantifying foraging habitats Of the 11 possible habitat categories we created from 43 classes, one whole category (coastal forested and unforested) was not represented in the size of the largest MCP created by all satellite fixes (Table 3). This is not surprising given the Snail Kiteâ&#x20AC;&#x2122;s affinities for freshwater wetlands. In addition none of the following habitats were represented in the 1,500 m buffers: Sandhill, cabbage palm-life oak hammock, tropical hardwood hammock, cypress/pine/cabbage palm, hydric hammock, bottomland hardwood forest, Australian pine, melaleuca, Brazilian pepper, or extractive (Table 3). Within the 1,500 m buffers, proportional habitat representations among the VHF (n = 216), total satellite (n = 416), and equal satellite (n = 216) location sets (Table 9) differed for some cover types. There was more agriculture than forested wetlands and upland forest for the VHF data. Open water was most prevalent (46 to 52%) within the 1,500 m buffer for both methods and was significantly more common in the satellite analyses than for VHF (Table 9). Dry grassland and open habitat was the second most prevalent cover type around kite locations at 12-17%, with significantly greater areas resulting from the VHF analyses. Overall, the habitat proportions within the buffers around Snail Kite locations varied between the tracking methods. Of the 8 habitat types represented, only freshwater marsh and urban habitats were not significantly different (Table 9). Within the available area of the satellite MCP, dry grassland and open habitats represented 30% of the area, followed by open water, sugar cane and freshwater marsh (Table 10). For the VHF MCP, the top 2 habitats covered a similar area. Sugar cane and freshwater marsh (only 9%) were less prevalent (Table 10). The tagged Snail Kites selected for all 11 habitat types in the MCP-defined areas, except for urban habitat for the VHF MCP. All selections were consistent between satellite and VHF areas except freshwater marsh, which was selected for in the VHF area and against in the satellite area. The only other habitat significantly selected was open water (Table10). Core areas and long-distance movements Based on satellite tracking, the radio-tagged Snail Kites moved an average of 1,898 km (Table 11, Figures 2 and 3) from their tagging location through 31 December 2008 (range: 578 to 3242 km). Movements between locations averaged 6.7 kilometers (range 0.1 to 147.8 km). The longest single move was 266 km by kite PTT #67450 (Table 11). There were no significant differences in total movements from tag date through 31 December 2008 between the sexes or age groups (sex: F = 0.716, df = 8, P = 0.494; age: F = 0.695, df = 8, P = 0.429). Six of the radio-tagged Snail Kites, however, moved much farther, from 115 to 220 km (mean: 168 km) in straight-line distances from their capture point. Four of these birds also made substantial moves in roughly the opposite direction from their capture point, resulting in simplified MCPs with longest-axis lengths of 190 to 335 km (mean: 251 km). Note that the home ranges of all the radiotagged kites that made long-distance movements (at least 7 of the 10) were linear and oriented northnorthwest by south-southeast. This may have resulted from seasonal variations in water resources that correlate with latitude. That is, if a bird was seeking better foraging conditions, it may have been more likely to succeed by moving north or south rather than east or west.


The 7 kites that made long moves stayed at their destinations from 1 day to over 3 weeks. Regardless of time spent there, however, the transit time was brief in all cases with no apparent loitering at intermediate locations. Destinations other than Lake Tohopekaliga and Lake Kissimmee in Osceola County included the following (the number of individual kites in parentheses): East Lake Tohopekaliga (Osceola County, 2), Lake Istokpoga (Highlands County, 1), Lake Marian (Osceola County, 1), headwaters of the Oklawaha River (northern Lake County, 1), Oklawaha River north of Eureka Dam (northern Marion County, 1), Withlacoochee River/Tsala Apopka (Sumter County, 1), Loxahatchee Slough (Palm Beach County, 2), southeastern Osceola County (1), St. Johns River (northern Brevard County, 1), west of Lake Rosalie (Polk County, 1), wetlands south of Lake Harris/west of Lake Apopka (western Lake County, 1), upper Reedy Creek drainage (southwestern Orange County, 1), west of Rotenberger Wildlife Management Area/north of Big Cypress Indian Reservation (central Hendry County, 1), St. Johns Marsh (Indian River County, 1; Brevard County, 1), south-central St. Lucie County (east of Allapattah Flats, 1), and Holey Land Wildlife Management Area (Palm Beach County, 1). Sex differences in home range, habitat use, and movements There were no apparent or statistically significant differences between the sexes in our small sample (seven females, three males) for home-range size, habitat use, or movements. Detectability of downed transmitters Based on our simulated tracking of deliberately-placed transmitters, the two telemetry methods differed in their abilities to reveal the timing, location, and potential causes of mortality. The VHF transmitters offered an advantage over satellite transmitters in being at least slightly detectable when submerged when the tracking aircraft was nearly overhead. The time for which the pulsing signal was audible was very brief – less than 10 seconds in all cases and usually no more than 5 seconds, depending on the altitude and speed of the airplane. This meant the observer usually would hear no more than two to four pulses for the VHF transmitters used in our study. Thus, the probability of finding such a transmitter in a large search area was very small. However, no signals were detected from the satellite transmitters in the same setting. For the radios placed just above the water’s surface (within 1 meter, on emergent vegetation) and in shrubs (3 to 5 meters above the water), the satellite transmitters, which broadcast their signals to satellites well above the horizon, encountered less interference from intervening vegetation than the VHF transmitters, for which searching was conducted from aircraft flying closer to the horizon. The VHF transmitters placed in shrubs and on emergent vegetation could be heard well when the airplane’s antennas were within line-of-sight range of the transmitters, but this occurred for a short time period relative to the available detection time for the satellite transmitters. The VHF signals from three transmitters, tested in succession, were audible for 6 to 28 seconds, depending on the plane’s position relative to interfering vegetation, at lateral distances of about 1.8 to 9.6 km. The signals were most audible during the very brief period when the plane was roughly abeam the transmitter, rising and falling gradually (unlike the abrupt changes for the underwater transmitter) on either side of the point. Factors other than intervening vegetation appeared to impede the signals in several cases, perhaps including reflection or refraction of the radio waves due to nearby vegetation or topographic features.


The quantity and accuracy (i.e., LC 1, 2, and 3) of the locations for the satellite transmitters placed on emergent vegetation and shrubs was not distinguishable from that of satellite transmitters deployed on birds we have tracked in this and other studies. Adult survival The monthly survival rates determined by VHF aerial tracking produced a 67% estimate of annual adult survival during 2007 for our sample of 10 tagged Snail Kites. The satellite-telemetry data for the same for the same 10 kites indicated that all 20 were alive at the end of 2007. All 10 were still alive at the end of the study, 2 years after the satellite/VHF transmitter packages were deployed.

Relative cost effectiveness of the two tracking methods Over 2 years, the 10 satellite transmitters deployed on Snail Kites produced 7,227 locations of the 3 highest location-quality classes. The purchase price of the 10 transmitters was $29,500, and the data-processing costs totaled 26,000 over the 2-year period. The expected life of the satellite transmitters, a function of the size of the storage battery (which is repeatedly recharged by the solar panels) was 3 to 5 years (larger transmitters last 5 to 6 years). For an expected life of 4 years, the pro-rated purchase price of each satellite transmitter was $61.45 per month. The per-location cost in our 2-year study was $7.68. Because the initial cost of the transmitter does not recur, the per-location cost declines by about 50% after the first 2 years. During the 7 months that each VHF transmitter operated, we obtained 216 useable locations. The purchase price of the 10 VHF transmitters was $1,700. The 27 tracking flights cost a total of $32,400, including hourly airplane and pilot expenses, observer salary, and associated travel and equipment. With an expected life of 7 months, the pro-rated purchase price of the each VHF transmitter was $24.29 per month. The per-location cost in our study was $150.00. Because the initial cost of a VHF transmitter is relatively small, the per-location cost changes very little over time.

DISCUSSION Detection following dispersal Except for the apparent inconsistencies in recharging, the satellite transmitters provided uninterrupted detections of the 10 kites. This was not true for the VHF transmitters, which became increasingly more difficult to locate as dispersal distance increased (the search area expanded exponentially relative to the linear distance that the bird traveled). VHF telemetry for studies of survival and site fidelity may not yield sufficient detectability for studies that require estimates of survival, site fidelity, longevity, and emigration. The spatial comparison if the present study between VHF and satellite detections suggests that non-satellite tracking methods may not be effective enough to detect permanent emigration or to ensure homogeneous detections probabilities, important considerations for population monitoring (Figure 8). Obviously, much depends on the duration of the study, the size and accessibility of the survey area, and search effort. It is clear, however, that satellite telemetry, although expensive relative to visual detection methods, provides substantial benefits where detection probability would otherwise decline following long excursions to unpredictable areas.


Describing and measuring home ranges Satellite tracking appeared to produce larger MCP home-range estimates than VHF tracking 841 versus 240 square km), but the difference was not significant. The same was generally true for the KDEs, except that by 1 analysis, the satellite-derived range estimates were significantly larger than those produced with VHF data. In general, the satellite locations appeared to produce KDEs with a larger number of activity centers that were also more broadly dispersed. These outlying activity centers may represent destinations during declining prey conditions, which in turn may play an important role in Snail Kite foraging ecology. For this reason, KDE analyses of satellite-tracking data may offer advantages for planning Snail Kite habitat management. Reliable depictions of outlying feeding sites and refugia might also contribute to refinements of survey methods for monitoring protocols. Quantifying foraging habitats The 2 tracking methods appeared to favor different habitat types when characterizing the landscape surrounding the telemetry locations. The satellite data were more strongly associated with wet habitats, mainly open water, whereas the VHF data suggested that the kites were frequently occupying drier, more disturbed areas, including agricultural and urban environments. A lot of the variation between tracking methods can probably be explained by the number and wide distribution of satellite locations in south Florida, where there was greater habitat diversity (most of the VHF locations were within a much smaller area in central Florida). One possible explanation is that kites occupying relatively isolated wetlands within drier, more developed landscapes were erroneously mapped by the less-precise VHF tracking methodology as being in the adjacent, unsuitable habitat rather than the embedded wetland. Core areas and long-distance movements Multiple core activity areas were the most consistent feature illuminated by both tracking methods, suggesting that individual kites know and frequent specific wetlands within the broader landscape that may be dominated by unsuitable habitat. Based on the satellite-based depictions of the birdsâ&#x20AC;&#x2122; use of the landscape, they appear to move rapidly and directly among these scattered activity areas, some of which are quite small. This suggest prior knowledge along with the ability and willingness to cross unsuitable habitat to capitalize on resources that may be very restricted spatially and ephemeral in time. The satellite data frequently revealed quick flights, often over tens of kilometers, to a very small area and quickly followed by a return flight to their original location. Such flights may be useful for evaluating present foraging conditions at a previously-exploited site. Being relatively social, Snail Kites may gain knowledge of such recurring foraging opportunities by following other Snail Kites, either by typical low-level flight or, conditions permitting, while soaring at higher (and less conspicuous to human observers) altitudes (R. Bennetts, personal communication). For detecting and tracking such rapid movements, VHF tracking protocols offered demonstrated mediocre performance relative to satellite telemetry. It would be interesting to look more closely at age and sex correlates of these long-distance, directed flights. In the present study, such comparisons were precluded by the relatively small sample size. Bennetts and Kitchens (2000) made relevant observations and offered some interesting speculation. In bad foraging conditions, when water levels support virtually no snail prey, Snail Kites are forced to move or die, and long-distance movements probably result (Bennetts and Kitchens 2000). However, also showed that movement probabilities were even higher when food conditions were


relatively high and were not associated with water levels. They suggested that such movements were exploratory. Detectability of downed transmitters We have no experience searching for VHF signals from dead Snail Kites in real field conditions, and there are many variables that will influence detectability, including water depth, orientation of the antenna, vegetation or the carcass covering the antenna, etc. In general, however, VHF transmitters provide some opportunity to locate a dead bird, including when the remains are submerged. Even if satellite transmitters continue to operate (solar-powered radios will not do so for long), they probably will not provide enough location information to permit retrieval, especially for standard, non-GPS equipped satellite transmitters that produce locations that may be several kilometers from the actual position. VHF transmitters, however, are more difficult to detect by standard means (i.e., from the ground or from aircraft at moderate altitudes) than satellite transmitters simply because their signals are more likely to be impeded by intervening vegetation and topography. Of course, even a large number of relatively inaccurate (>100 meters) satellite-derived locations will not make retrieval possible. This is where combination satellite/GPS transmitters offer a substantial advantage by collecting locations with 10 to 15-meter accuracy that they then broadcast upward to satellites, resulting in better-than-VHF accuracy coupled with the advantages of satellite transmission that overcomes the handicaps imposed by vegetation and terrain on the propagation of VHF radio waves. Adult survival Our small sample size did not support a rigorous estimate of annual survival for Snail Kites by either telemetry method. However, after 20 exposure-years (10 marked kites for 2 years), true survival for this small sample was 100%. This assessment was based on presence data only, so there was no potential for false positives. False negatives, which can occur when undetectable individuals are assumed but never confirmed to be dead, also were impossible because all 10 birds were known to be alive at the end of the study. Our 2007 survival estimate for the same 10 individuals based on VHF aerial tracking, 67%, was similar to the UF research teamâ&#x20AC;&#x2122;s 73% estimate for 2007 (Reichert et al. 2011). This estimate, based mainly on resightings of color-banded Snail Kites with some VHF detections, came from their longterm population monitoring study, which continually adjusts previous yearsâ&#x20AC;&#x2122; estimates in light of subsequent sightings of marked individuals (in this case, through 2010). This estimate of adult survival contrasts with those for most previous years, which were relatively constant at about 87% (Cattau et al. 2008) to 92% (Bennetts and Kitchens 1997) for the period 1992 to 2005. Low survival in 2007 was attributed to extreme drought conditions that peaked during the year. Their cumulative estimate of Snail Kite survival for 2007 (73%) and 2008 (86%) was 63%, the same period in which the cumulative 2-year survival for our sample was 100% based on satellite telemetry.

Relative cost effectiveness of the two tracking methods At about $170 each, VHF transmitters are relatively inexpensive, but the flight and personnel time for finding and fixing the positions of marked birds are quite costly. Satellite transmitters are far more expensive, about $3,000 each ($4,000 if they have GPS capability), and the tracking data must be purchased (CLS America, Inc.) for about $1,300 per year for each transmitter. Satellite data, however, are obtained without any additional expense in the field. When all expenses are taken into


account, the cost per VHF location in our study was nearly 20 times the per-location cost for the satellite locations. In addition, the satellite cost declines sharply after 2 years (then approaches an asymptote). The quantity of useable satellite data, furthermore, far exceeds that available from all but the most expensive VHF-telemetry studies, with 1 to 3 relatively locations typically produced every 30 to 58 hours (i.e., satellite transmitters typically operate continuously for 8 to 10 hours, then rest for 24 to 48 hours to allow the solar panels to recharge the storage batteries). Accuracy also varies between the two methods. Birds carrying VHF transmitters can be located visually from the ground, which permits mapping accuracy within 10 to 15 meters if a GPS fix is taken, and direct visual observation allows identification of habitat type and behavior. Animals tracked by VHF signals, however, are rarely approached closely enough to permit visual detection. Besides disturbing the animal and affecting its behavior, the cost of obtaining such finely-scaled locations usually is prohibitive. Instead, most VHF tracking is performed from the air. This allows much broader search coverage and increases the number of detections in a given time period, but it is expensive and accuracy is limited by flight logistics, cost, and safety considerations. Each location produced by satellite telemetry is reported by CLS America, Inc., with one of six accuracy estimates, the best within a 250-meter radius of the actual location, the third best within 1,500 meters, and the poorest being of indeterminate accuracy (User Manual, CLS America, Inc., 2008). More finely-scaled location data are not available with basic satellite telemetry. Recently, manufacturers have begun producing satellite transmitters with on-board GPS receivers that store fixes of 10 to 15 meter accuracy (the same as a handheld GPS receiver), then periodically transfer the data to the researcher via satellite. Such transmitters, however, weigh more than basic satellite transmitters and the smallest-available unit at the start of this study exceeded the weight limit (3% of body weight) imposed by the Bird Banding Laboratory (U. S. Geological Service). There are far fewer inherent observer biases associated with satellite-derived locations regarding detectability. As long as the transmitter remains attached and continues to operate, detection probability is virtually 100% anywhere on the surface of the earth. Location accuracy is also is less biased than for VHF telemetry, especially when satellite transmitters have on-board GPS capability. Finally, study duration permitting, satellite-based tracking studies greatly improve our chances of determining whether a study population is open or closed. There is not a more efficient or costeffective method for detecting permanent emigration from a breeding population, which is particularly important for maintaining the integrity of long-term monitoring programs.

ACKNOWLEDGMENTS We thank: USFWS for engaging us in Snail Kite research by providing funding and guidance for this study; Tylan Dean, Cindy Schultz, Heather Tipton, and Sandra Sneckenberger, and Dana Hartley,USFWS, for administering the project and offering assistance along the way; Peter Mahoney, for outstanding fieldwork; and Kristen Hart and Ikuko Fujisaki for contributing their time and skills for the analyses and for reviewing prior drafts. We are grateful for Rob Bennettsâ&#x20AC;&#x2122; kind support and generous offers of time and insight. We also appreciate the logistic support provided by Wiley Kitchens and his students, including Chris Cattau, Andrea Bowling, Sara Stocco, Kyle Pias, Jean Olbert, and Brian Reichert.


LITERATURE CITED Beissinger, S. R. 1988. The Snail. Kite. Pages 148-165 in R. S. Palmer, editor, Handbook of North American Birds. Volume IV. Yale University Press, New Haven, Connecticut. Beissinger, S. R. 1994. Experimental analysis of diet specialization in the Snail Kite: the role of behavioral conservatism. Oecologia 100:54-65. Bennetts, R. E., M. W. Collopy, and J. A. Rodgers, Jr. 1994. The Snail Kite in the Florida Everglades: a food specialist in a changing environment. Pages 507-532 in S. M. Davis and J. C. Ogden, editors. Everglades: the ecosystem and its restoration, St. Lucie Press, Delray beach, Florida. 848 pp. Bennetts, R. E., and W. M. Kitchens. 1997. The demography and movements of Snail Kites In Florida. U. S. G. S. Biological Resources division, Florida Cooperative Fish and Wildlife Research Unit. Technical Report Number 56. 169 pp. Bennetts, R. E., and W. M. Kitchens. 2000. Factors influencing movement probabilities of a nomadic food specialist: proximate foraging benefits or ultimate gains from exploration? Oikos 91:459-467. Bennetts, R. E., P. C. Darby, and L. B. Karunaratne. 2006. Foraging patch selection by snail kites in response to vegetation structure and prey abundance and availability. Waterbirds 29:88-94. Beyer, H. L. 2004. Hawth's Analysis Tools for ArcGIS. Available at http://www.spatialecology.com/htools. Cattau, C., W. Kitchens, A. Bowling, B. Reichert, and J. Martin. 2008. Snail Kite Demography Annual Report 2007. U. S. Geological Survey, Florida Cooperative Fish and Wildlife Research Unit, Gainesville, Florida. Reichert, B., Christopher Cattau, Wiley Kitchens, Robert Fletcher, Jean Olbert, Kyle Pias, Christa Zweig, and Jeremy Wood. 2011. Snail Kite Demography Annual Report 2009. U. S. Geological Survey, Florida Cooperative Fish and Wildlife Research Unit, Gainesville, Florida. 2008. Snail Kite Demography Annual Report 2007. U. S. Geological Survey, Florida Cooperative Fish and Wildlife Research Unit, Gainesvill, Florida. ESRI. 1996. ArcView GIS. Earth Systems Research Institute, Redlands, California. Forsman, E. D., T. J. Kaminski, J. C. Lewis, K. J. Maurice and S. G. Sovern. 2005. Home range and habitat use of Northern Spotted Owls on the Olympic Peninsula, Washington. Journal of Raptor Research 39:365-377. Hooge, P. N., and B. Eichenlaub. 1997. Animal movement extension to ArcView. Version 1.1.1. Alaska Biological Science Center, U. S. Geological Survey, Anchorage, Alaska.


James MC, Ottensmeyer A, Myers RA. 2005. Identification of high-use habitat and threats to leatherback sea turtles in northern waters: new directions for conservation. Ecology Letter 8:195–201 Krebs, C. J. 1998. Ecological methodology. Benjamin Cummings, Menlo Park, California. Mahoney, P. J., K. D. Meyer, G. M. Zimmerman, and C. Cattau. 2010. An aquatic bal-chatri for trapping Snail Kites (Rostrhamus sociabilis). Southeastern Naturalist 9:721-730. Martin, J., J. D. Nichols, W. M. Kitchens, and J. E. Hines. 2006. Multiscale patterns of movement in fragmented landscapes and consequences on demography of the snail kite in Florida. Journal of Animal Ecology 75:527-539. Martin, J., W. M. Kitchens, and J. E. Hines. 2007. Importance of well-designed monitoring programs for the conservation of endangered species: Case study of the snail kite. Conservation Biology 21:472-481. Rodgers, A.R., and A.P. Carr. 1998. HRE: The Home Range Extension for ArcView. Ontario Ministry of Natural Resources, Centre for Northern Forest Ecosystem Research, Thunder Bay, Ontario, Canada. Samuel, M. D., and M. R. Fuller. 1994. Wildlife radiotelemetry, p. 370–418. In T. A. Bookhout [ED.], Research and management techniques for wildlife and habitats. 5th ed. The Wildlife Society, Bethesda, Maryland. Seaman, D. E., and R. A. Powell. 1996. An evaluation of the accuracy of kernel density estimators for home range analysis. Ecology 77:2075–2085. Sokal, R. R., and F. J. Rohlf. 1995. Biometry: The principles and practice of statistics in biological research, 3rd ed. W. H. Freeman, New York. Sykes, P. W., Jr. 1984. The range of the Snail Kite and its history in Florida. Bulletin of the Florida State Museum 29:211-264. Sykes, P. W., Jr., J. A. Rodgers, Jr., and R. E. Bennetts. 1995. Snail Kite (Rostrhamus sociabilis). In The Birds of North America, Number 171 (A. Poole and F. Gill, editors). The Academy of Natural Sciences, Philadelphia, and The American Ornithologists Union, Washington, D. C. Worton, B.J. 1989. Kernel methods for estimating the utilization distribution in home-range studies. Ecology 70:164-168.


36308

36309

36316

41244

Figure 1. Maps comparing the central-Florida locations of 10 Snail Kites tagged in central Florida and tracked by 2 telemetry methods during 7 months in 2007. The blue locations were derived from aerial VHF tracking, while the pink dots represent the corresponding satellite-derived fixes taken within 24 hours.


Figure 1, continued.

67450-pair between lakes removed due to incorrect time period

40565

67451

40566


Figure 1, continued.

40567

40568


36308

36309

36316

41244

Figure 2. All satellite locations of Location Quality 1, 2, or 3 for 10 Snail Kites tagged in central Florida in early 2007 and tracked through 31 December 2008. Green locations were during 2007; pink were during 2008. The yellow star indicates tagging location and the blue dot is the last location.


Figure 2, continued.

67450

67451

40565

40566


Figure 2, continued.

40567

40568


36308

36309

36316

41244

Figure 3. All Snail Kite locations (VHF in blue, satellite in pink) during the 7-month VHF tracking period in 2007.


Figure 3, continued.

67450

67451

40565

40566


Figure 3, continued.

40567

40568


Figure 4. Home range estimates (minimum convex polygons, MCPs) for 10 Snail Kites in Florida tracked during 7 months in 2007 based on VHF (top left) and satellite telemetry (top right). The lower left map depicts home ranges during 2 years, from early 2007 to early 2009, based only on satellitederived locations.


Figure 5. Kernel Density Estimates for 25, 50 and 95% of Snail Kite activity within central Florida. Here we compare the VHF (blue) and satellite-derived estimates (pink) for 3 kites during 7 months in 2007.


Figure 6. Kernel Density Estimates (KDE) for 25, 50 and 95% of Snail Kite activity in central Florida. Here we compare the VHF (blue) and satellite-derived estimates (pink) for 3 kites during 7 months in 2007, and add a KDE for the entire 2-year satellite tracking period (green).


Figure 7. Kernel Density Estimates for 25, 50 and 95% of Snail Kite activity for 4 birds determined by VHF aerial tracking in central Florida in 2007.


Figure 8. Satellite-derived locations (colored dots) in 2007 and 2008 for 10 Snail Kites tagged in central Florida in relation to the wetland survey areas (purple) searched annually (March through June) for marked kites and nesting activity for ongoing demography and population-monitoring studies (Catteau et al., 2008).


Table 1. Trapping location and tagging data on 10 Snail Kites captured in Central Florida in February and March 2007.

PTT # 36309 36316 67451 40565 40566 40567 40568 67450 41244 36308* 67451**

VHF frequency 164.249 164.263 164.218 164.360 164.277 164.297 164.348 164.329 164.314 164.237 164.218

Date 2/5/07 2/9/07 2/11/07 2/20/07 2/20/07 2/21/07 2/26/07 3/1/07 3/2/07 3/3/07 3/14/07

Sex

Age

Bands USFWS-left leg Color-right leg 936-24836 A/W Black/Red 936-25810 B/C Black/Red 936-25811 M/7 936-25812 A/B 936-25813 8/S 936-25814 6/R 936-25815 6/C 936-25816 8/U 936-25817 4/M 936-25811 M/7 936-25818 5/U

F 3+ F 3+ F 1+ F 3+ M 5+ M 2+ F 3+ F 2+ M 3+ F 1+ F 1+ * Retrapped 3/3/07 to replace malfunctioning PTT #67451, deployed 2/11/07, with functional #36308. ** PTT # 67451 was refurbished and put on this bird

Trap location Lake Latitude Tohopekaliga 28.27620 Tohopekaliga 28.27032 Tohopekaliga 28.27032 Tohopekaliga 28.26940 Tohopekaliga 28.27278 Kissimmee 27.95646 Kissimmee 27.92282 Kissimmee 27.92282 Kissimmee 27.92301 Tohopekaliga 28.27032 Kissimmee 27.93576

Longitude

# Trap attempts

-81.40459 -81.41035 -81.41035 -81.41030 -81.40863 -81.29489 -81.22709 -81.22709 -81.22728 -81.41035 -81.22790

1 1 16 3 2 1 1 1 5 1 1


Table 2. VHF location data for 4 Snail Kites tracked from the air in the Kissimmee chain of lakes region from March to October 2007. Individual info VHF frequency PTT# Lake trapped Age Sex Flight Date 3/14/07 3/23/07 3/30/07 4/5/07 4/12/07 4/19/07 4/25/07 5/3/07 5/8/07 5/14/07 5/21/07 5/30/07 6/13/07 6/18/07 6/26/07 7/7/07 7/15/07 7/19/07 8/3/07 8/13/07 8/23/07 8/30/07 9/10/07 9/18/07 10/5/07 10/12/07 10/19/07

Time 12:00:00 PM 12:00:00 PM 3:15:00 PM 3:15:00 PM 10:40:00 AM 10:30:00 AM 4:00:00 PM 12:30:00 PM 11:30:00 AM 1:30:00 PM 11:00:00 AM 4:45:00 PM 2:30:00 PM 2:00:00 PM 1:15:00 PM 3:10:00 PM 11:30:00 AM 8:30:00 AM 11:00:00 AM 9:30:00 AM 9:30:00 AM 12:00:00 PM 12:00:00 PM 12:00:00 PM 11:45:00 AM 9:00:00 AM 12:30:00 PM

164.218 67451 Kissimmee 1+ Female

164.237 36308

164.249 36309

164.264 36316

Tohopekaliga 1+ Female

Tohopekaliga 3+ Female

Tohopekaliga 3+ Female

NE L Kiss NE L. Kiss SE of L. Kiss no signal NW L. Toho NW L. Toho NW L. Toho N L. Toho N L. Toho N L.Toho N of SE Toho N L. Toho N L. Toho N of Goblet's Cove, L. Toho NW L.Toho N L.Toho E L.Toho, Goblet's mouth NE L. Toho no signal no signal no signal no signal no signal no signal no signal no signal no signal

NW L. Toho NW L. Toho NW L. Toho NW L. Toho L. Toho, Goblet's Cove L. Toho, Goblet's Cove L. Toho, Goblet's Cove L. Toho, Goblet's Cove L. Toho, Goblet's Cove L. Toho, Goblet's Cove L. Toho, Goblet's Cove L. Toho, Goblet's Cove S L. Toho no signal SE L. Toho NNE L. Toho W or NW of L. Toho N end of L.Toho N end of L.Toho N end of L.Toho N of L. Toho N or NW of L. Toho N L. Toho E of L. Toho E of L. Toho E of L. Toho E of L. Toho

NE L. Toho NE L. Toho N L. Toho, Paradise Island L. Toho, Goblet's Cove L. Toho, Goblet's Cove L. Toho, Goblet's Cove L. Toho, Goblet's Cove NW L. Toho L. Toho, Goblet's Cove SW L. Toho NE L. Kiss NE L. Kiss E L. Kiss NE L. Kiss NE L. Kiss L. Toho, Goblet's Cove NE of L.Toho S L.Toho, or S of L.Toho Mouth of Goblet's Cove L. Toho Mouth of Goblet's Cove L. Toho L. Toho, Goblet's Cove L. Toho, Goblet's Cove L. Toho, Goblet's Cove NE L.Toho near or on lake NE L.Toho near or on lake NE L.Toho near or on lake NE L.Toho near or on lake

NW L. Toho L. Toho, Goblet's Cove N L. Toho N L. Toho N L. Toho N L. Toho NWN L. Toho W of L. Toho W of airport W of L. Toho W of airport W L. Toho N L. Toho NNW L. Toho N L.Toho N L. Toho N L. Toho no signal no signal N L. Toho NE L. Toho NW L. Toho N L.Toho or just N N L. Toho N L. Toho N L. Toho N L. Toho N L. Toho N L. Toho


Table 2, continued. Idividual info VHF frequency PTT# Lake trapped Age Sex Flight Date 3/14/07 3/23/07 3/30/07 4/5/07 4/12/07 4/19/07 4/25/07 5/3/07 5/8/07 5/14/07 5/21/07 5/30/07 6/13/07 6/18/07 6/26/07 7/7/07 7/15/07 7/19/07 8/3/07 8/13/07 8/23/07 8/30/07 9/10/07 9/18/07 10/5/07 10/12/07 10/19/07

Time 12:00:00 PM 12:00:00 PM 3:15:00 PM 3:15:00 PM 10:40:00 AM 10:30:00 AM 4:00:00 PM 12:30:00 PM 11:30:00 AM 1:30:00 PM 11:00:00 AM 4:45:00 PM 2:30:00 PM 2:00:00 PM 1:15:00 PM 3:10:00 PM 11:30:00 AM 8:30:00 AM 11:00:00 AM 9:30:00 AM 9:30:00 AM 12:00:00 PM 12:00:00 PM 12:00:00 PM 11:45:00 AM 9:00:00 AM 12:30:00 PM

164.278 40566 Tohopekaliga 5+ Male

164.297 40567 Kissimmee 2+ Male

164.314 41244 Kissimmee 3+ Male

164.328 67450 Kissimmee 2+ Female

164.348 40568 Kissimmee 3+ Female

NW L. Toho NW L. Toho NW L. Toho no signal N L. Toho N L. Toho NW L. Toho NW L. Toho NW L. Toho N L.Toho N L.Toho N L.Toho SE of L. Toho L. Toho, Goblet's Cove NW L.Toho no signal NE of L.Toho NE L. Toho or E NW L. Toho NW L. Toho NE of L. Toho N or NW of L. Toho N Toho or N of L. Toho N of NE L Toho N of NE L Toho N of NE L Toho N of NE L Toho

NE L. Toho L. Toho, Goblet's Cove L. Toho, Goblet's Cove W L. Toho L. Toho, Goblet's Cove L. Toho, Goblet's Cove NW L. Toho L. Toho, Goblet's Cove L. Toho, Goblet's Cove N L. Toho NW L. Toho NW L. Toho N L. Toho N L. Toho L. Toho, Goblet's Cove L. Toho, Goblet's Cove N of Toho or near N shore no signal NW L. Toho WNW L. Toho NE L. Toho E of L.Toho L. Toho, Goblet's Cove N end L. Toho N end L. Toho N end L. Toho N end L. Toho

W L. Kiss SE of L. Kiss no signal no signal no signal SE L. Kiss SE L. Kiss SE L. Kiss SE L. Kiss no signal SE L.Kiss SE L. Kiss no signal no signal SE L. Kiss no signal no signal no signal no signal S L. Kiss, near canal S end L. Kiss S of L. Kiss no signal E of L. Kiss at mid-lake E of L. Kiss at mid-lake E of L. Kiss at mid-lake didn't fly area

NE L. Kiss NE L. Kiss L. Toho, Goblet's Cove NW L. Toho WSW L. Toho WSW L. Toho SW L. Toho NW L. Toho L. Toho, Goblet's Cove N L. Toho NW L. Toho W L. Toho N L. Toho N L. Toho no signal no signal no signal no signal no signal no signal Near Lake Easy no signal NE L. Kiss NE L. Kiss NE L. Kiss NE L. Kiss didn't fly area

S of NE BR, L. Kiss S of NE BR, L. Kiss S of NE BR, L. Kiss S of NE BR, L. Kiss S of NE BR, L. Kiss S of NE BR, L. Kiss S of NE BR, L. Kiss S of NE BR, L. Kiss S of NE BR, L. Kiss no signal NE L. Kiss NE L. Kiss Central L. Kiss NE L. Kiss NE L. Kiss NE L. Kiss NE L. Kiss NE L. Kiss NE L. Kiss NE L. Kiss NE L. Kiss NE L. Kiss NE L. Kiss NE L. Kiss NE L. Kiss NE L. Kiss didn't fly area


Table 2, continued. Idividual info VHF frequency PTT# Lake trapped Age Sex Flight Date 3/14/07 3/23/07 3/30/07 4/5/07 4/12/07 4/19/07 4/25/07 5/3/07 5/8/07 5/14/07 5/21/07 5/30/07 6/13/07 6/18/07 6/26/07 7/7/07 7/15/07 7/19/07 8/3/07 8/13/07 8/23/07 8/30/07 9/10/07 9/18/07 10/5/07 10/12/07 10/19/07

164.353 40565 Tohopekaliga 3+ Female Time 12:00:00 PM 12:00:00 PM 3:15:00 PM 3:15:00 PM 10:40:00 AM 10:30:00 AM 4:00:00 PM 12:30:00 PM 11:30:00 AM 1:30:00 PM 11:00:00 AM 4:45:00 PM 2:30:00 PM 2:00:00 PM 1:15:00 PM 3:10:00 PM 11:30:00 AM 8:30:00 AM 11:00:00 AM 9:30:00 AM 9:30:00 AM 12:00:00 PM 12:00:00 PM 12:00:00 PM 11:45:00 AM 9:00:00 AM 12:30:00 PM

SW L. Toho W L. Toho WNW L. Toho WSW L. Toho WSW L. Toho WSW L. Toho WNW L. Toho NW L. Toho W L. Toho NW L. Toho NW L. Toho NW L. Toho no signal no signal no signal no signal no signal no signal no signal no signal no signal no signal no signal no signal no signal no signal no signal


Table 3. Re-classification to 11 habitat types from the 43 original classes created by the State of Florida in 2003. Dark shading indicates habitats not represented in VHF or satellite location buffers; light shading indicates habitats represented only within satellite locations buffers. COMBINED HABITAT CLASSES Coastal Strand Sand/Beach Salt Marsh Mangrove Swamp Scrub Mangrove Tidal Flat Xeric Oak Scrub Sand Pine Scrub Sandhill Shrub and Brushland Mixed Pine-Hardwood Forest Hardwood Hammocks and Forest Cabbage Palm-Live Oak Hammock Tropical Hardwood Hammock Pinelands Freshwater Marsh and Wet Prairie Sawgrass Marsh Cattail Marsh Shrub Swamp Bay Swamp Cypress Swamp Cypress/Pine/Cabbage Palm Mixed Wetland Forest Hardwood Swamp Hydric Hammock Bottomland Hardwood Forest Open Water Grassland Bare Soil/Clearcut Improved Pasture Unimproved Pasture Dry Prairie Sugar cane Citrus Row/Field Crops Other Agriculture Exotic Plants Australian Pine Melaleuca Brazilian Pepper High Impact Urban Low Impact Urban Extractive

NAME OF COMBINED CLASS

Coastal forested and unforested

Upland scrub and shrub

Upland forest

Freshwater marsh

Forested wetlands

Open water

Dry grassland and open

Sugar cane Other agriculture

Exotics

Urban


Table 4. Distances separating VHF locations from satellite locations gathered within 24 hours for 10 Snail Kites tracked in central Florida in 2007.

PTT # 36308 36308 36308 36308 36308 36308 36309 36309 36309 36309 36309 36309 36309 36316 36316 36316 36316 40565 40565 40565 40566 40566 40566 40566 40566 40566 40566 40566 40566 40566 40566 40566 40566 40566 40566 40567 40567 40567 40567 40567 40567 40567

Satellite location Date 5/30/2007 6/13/2007 6/27/2007 10/5/2007 10/12/2007 10/19/2007 3/15/2007 3/22/2007 5/30/2007 6/18/2007 7/19/2007 8/22/2007 8/29/2007 5/9/2007 5/21/2007 6/19/2007 7/18/2007 3/14/2007 3/31/2007 5/21/2007 3/24/2007 3/29/2007 4/25/2007 5/2/2007 5/7/2007 5/22/2007 5/29/2007 6/27/2007 7/14/2007 7/19/2007 8/30/2007 9/9/2007 9/19/2007 10/4/2007 10/19/2007 3/15/2007 4/13/2007 4/18/2007 5/3/2007 5/22/2007 5/29/2007 6/27/2007

LC 3 1 1 3 1 3 1 1 1 3 1 3 2 2 1 2 3 1 1 1 3 1 2 3 1 1 2 3 1 2 2 2 2 2 3 2 3 3 1 2 1 2

Distance between satellite fix and corresponding VHF fix (km) 1.489 7.177 10.662 8.394 6.995 1.93 1.9 9.172 3.769 2.305 11.049 2.154 1.896 5.875 3.845 3.206 0.609 14.019 0.882 1.193 1.274 1.92 0.905 0.472 3.592 3.002 0.721 9.02 10.913 1.026 6.518 2.37 7.06 2.22 1.887 5.023 2.468 11.369 2.452 5.461 3.299 1.165


Table 4, continued PTT # 40567 40567 40567 40568 40568 40568 40568 40568 41244 41244 67450 67450 67450 67450 67450 67450 67450 67451 67451 67451 67451 67451

Satellite location Date LC 8/3/2007 3 8/30/2007 2 10/5/2007 1 3/23/2007 3 3/30/2007 3 4/26/2007 1 5/8/2007 1 5/30/2007 3 6/27/2007 2 10/13/2007 2 4/25/2007 2 5/3/2007 3 5/8/2007 3 5/30/2007 2 6/12/2007 1 9/10/2007 2 10/5/2007 3 4/26/2007 3 5/29/2007 3 6/13/2007 2 7/6/2007 2 7/19/2007 3 Mean Variance Standard Deviation

Distance between satellite fix and corresponding VHF fix (km) 6.874 6.231 5.427 0.636 0.202 2.596 0.917 2.02 2.556 1.39 10.674 4.56 6.488 4.018 6.732 1.256 1.2 0.852 1.251 4.587 5.455 4.134 4.105 11.132 3.336


Table 5. Number of paired locations used to compare VHF and satellite derived locations for 10 Snail Kites tracked in 2007 in central Florida. Paired locations represent VHF and satellite fixes taken within 24 hr of each other. Number of locations PTT 36308 36309 36316 40565 40566 40567 40568 41244 67450 67451 Total

Satellite 7 7 5 8 16 10 6 2 11 9 81

VHF 26 27 24 12 25 26 25 15 19 17 216

Total 33 34 29 20 41 36 31 17 30 26 297

Number of paired locations 6 7 4 3 15 10 5 2 7 5 64


Table 6. Area and perimeter lengths of 100% minimum convex polygons created around sets of VHF and Satellite locations (respectively) for each of 10 Snail Kites tracked in central Florida from March to October 2007.

PTT # 36308 36309 36316 40565 40566 40567 40568 41244 67450 67451 Average Variance Standard Deviation

Area (sq km) 348.57 197.89 70.76 26.65 235.01 83.44 27.63 171.00 828.51 404.89 239.44 59517.12

VHF Perimeter (km) 78.17 96.21 36.27 32.35 74.92 38.89 21.23 73.16 131.09 142.10 72.44 1728.97

# location 26 27 24 12 25 26 25 15 19 17 21.60 28.93

Area (sq km) 2066.20 672.55 38.11 3656.77 95.06 50.91 18.21 692.87 1009.67 112.27 841.26 1393528.25

Satellite Perimeter (km) 498.69 114.44 27.50 468.81 38.04 35.68 19.40 325.49 137.40 91.98 175.74 34427.98

# location 31 37 26 15 71 77 29 10 85 35 41.60 698.49

243.96

41.58

5.38

1180.48

185.55

26.43


Table 7. Comparisons of activity-range areas based on Kernel Density Estimates based on VHF- and satellite-derived location sets for 10 Snail Kites in Central Florida from March to October 2007.

PTT # 36308 36308 36308 36308 36308 36309 36309 36309 36309 36309 36316 36316 36316 36316 36316 41244 41244 41244 41244 41244 67450 67450 67450 67450 67450 67451 67451 67451 67451 40565 40565 40565 40565 40566 40566 40566 40566 40567 40567 40567 40567 40567 40568 40568 40568 40568 40568

VHF Data # points 26 26 26 26 26 27 27 27 27 27 24 24 24 24 24

Volume 1.00 0.99 0.95 0.75 0.50 1.00 0.99 0.95 0.75 0.50 1.00 0.99 0.95 0.75 0.50

H 0.149 0.149 0.149 0.149 0.149 0.065 0.065 0.065 0.065 0.065 0.278 0.278 0.278 0.278 0.278

Area (sq km) 529.410 201.814 129.653 52.811 20.876 189.475 94.000 62.916 26.134 11.713 283.271 65.608 39.781 14.049 5.622

0.99 0.95 0.75 0.50

0.239 0.239 0.239 0.239

15 15 15 15

212.852 142.964 64.509 25.305

0.99 0.95 0.75 0.50 0.99 0.95 0.75 0.50 0.99 0.95 0.75 0.50 0.99 0.95 0.75 0.50 1.00 0.99 0.95 0.75 0.50

0.078 0.078 0.078 0.078 0.069 0.069 0.069 0.069 0.360 0.360 0.360 0.360 0.186 0.186 0.186 0.186 0.264 0.264 0.264 0.264 0.264

19 19 19 19 17 17 17 17 12 12 12 12 25 25 25 25 26 26 26 26 26

221.153 154.809 68.662 25.822 134.252 86.381 30.728 9.561 100.041 70.685 34.795 16.761 171.932 104.067 38.766 14.622 421.572 106.440 75.515 32.798 14.015

0.99 0.95 0.75 0.50

0.166 0.166 0.166 0.166

25 25 25 25

14.641 9.909 4.678 1.962

Satellite Data # points

Volume

H

Area (sq km)

0.99 0.95 0.75 0.50 1.00 0.99 0.95 0.75 0.50

0.058 0.058 0.058 0.058 0.064 0.064 0.064 0.064 0.064

31 31 31 31 37 37 37 37 37

503.752 307.629 118.165 33.699 158.534 111.207 75.009 29.232 10.167

0.99 0.95 0.75 0.50 1.00 0.99 0.95 0.75 0.50 1.00 0.99 0.95 0.75 0.50 0.99 0.95 0.75 0.50 0.99 0.95 0.75 0.50 0.99 0.95 0.75 0.50 1.00 0.99 0.95 0.75 0.50 1.00 0.99 0.95 0.75 0.50

0.211 0.211 0.211 0.211 0.070 0.070 0.070 0.070 0.070 0.049 0.049 0.049 0.049 0.049 0.057 0.057 0.057 0.057 0.065 0.065 0.065 0.065 0.215 0.215 0.215 0.215 0.070 0.070 0.070 0.070 0.070 0.269 0.269 0.269 0.269 0.269

26 26 26 26 10 10 10 10 10 85 85 85 85 85 35 35 35 35 15 15 15 15 71 71 71 71 77 77 77 77 77 29 29 29 29 29

43.358 28.234 10.980 4.714 4825.818 1064.112 720.993 292.698 114.522 291.037 182.602 120.053 42.273 16.904 57.249 39.937 14.609 4.541 1471.105 880.293 386.834 141.188 62.285 39.622 12.866 4.091 6.825 5.692 4.108 1.371 0.619 55.654 13.171 8.351 3.237 1.457


Table 8. Statistical results comparing Kernel Density Estimates of activity ranges between VHF- and satellite-derived location sets for 10 Snail Kites in Central Florida from March to October 2007. Volume of locations (%) 50 75 95 99

Paired t-test t 1.228 1.319 1.380 1.388

P 0.251 0.220 2.000 0.199

1-way ANOVA F 1.158 1.542 1.741 1.792

P 0.695 0.230 0.203 0.197


Table 9. Comparison of habitat use within 1,500 m buffers around 216 VHF versus satellite locations for 10 Snail Kites in central Florida in 2007. The habitat proportions based on the VHF locations did not differ from those determined for either the total set of 416 satellite locations or for a set of 216 randomly selected satellite locations.

Habitat Upland scrub and shrub Upland forest Freshwater marsh Forested wetlands Open water Dry grassland and open Other agriculture Urban

Satellite Proportion SE 0.011 0.001 0.034 0.002 0.114 0.004 0.049 0.003 0.529 0.013 0.126 0.007 0.054 0.005 0.082 0.007

All Snail Kite Locations VHF Proportion SE 0.014 0.001 0.050 0.003 0.102 0.006 0.062 0.004 0.461 0.018 0.176 0.010 0.032 0.007 0.103 0.009

t 2.970 4.801 1.620 2.843 3.150 3.923 2.477 1.798

P 0.003 < 0.0001 0.106 0.005 0.002 < 0.0001 0.014 0.073

Equal number of locations Satellite Proportion SE t P 0.012 0.001 2.655 0.041 0.032 0.003 4.050 < 0.0001 0.110 0.006 1.080 0.281 0.050 0.004 2.202 0.028 0.520 0.017 2.527 0.012 0.124 0.010 3.798 0.000 0.054 0.006 2.405 0.017 0.095 0.010 0.589 0.560


Table 10. Tests of habitat use versus availability for 10 Snail Kites tracked in central Florida in 2007. We compared the habitat proportions within 1,500 meter buffers around each kite location (VHF and satellite analyzed separately) with the proportions found within each birds respective VHFor satellite-derived minimum convex polygon.

Habitat Upland scrub and shrub Upland forest Freshwater marsh Forested wetlands Open water Dry grassland and open Other agriculture Urban Sugar cane Exotics

Proportion 0.018 0.073 0.124 0.081 0.140 0.300 0.088 0.046 0.129 0.001

Satellite t P -9.537 < 0.0001 -19.714 < 0.0001 -2.161 0.031 -12.955 < 0.0001 28.249 < 0.0001 -22.632 < 0.0001 -6.244 < 0.0001 5.537 < 0.0001 -123.640 0.000 -0.915 0.361

Selection? Against Against Against Against For Against Against For Against Against

Proportion 0.041 0.113 0.089 0.119 0.171 0.310 0.055 0.101 none none

VHF t -28.545 -24.128 2.538 -14.227 20.558 -14.573 -6.130 0.185 N/A N/A

P < 0.0001 < 0.0001 0.012 < 0.0001 < 0.0001 < 0.0001 < 0.0001 0.853 N/A N/A

Selection? Against Against For Against For Against Against Not significant


Table 11. Totals of straight-line distances between successive satellite locations (and descriptive statistics) for each of 10 Snail Kites tracked over peninsular Florida from tag date in 2007 to 31 December 2008. Line segment lengths (km)

PTT 36308 36309 36316 40565 40566 40567 40568 41244 67450 67451 Average Variance Standard deviation

Total km n 2417.82 280 1020.53 288 1185.63 197 3241.60 270 1735.44 427 2578.21 664 577.49 232 2388.30 180 2965.06 424 871.42 135 1898.15 309.70 890960.39 24595.79 943.91

156.83

Minumum 0.02 0.03 0.04 0.16 0.04 0.05 0.08 0.06 0.07 0.07 0.06 0.00

Maximum 204.64 38.07 167.02 215.05 199.25 103.03 17.11 168.33 265.74 99.35 147.76 6508.18

Average 8.64 3.54 6.02 12.01 4.06 3.88 2.49 13.27 6.99 6.45 6.74 13.14

0.04

80.67

3.62

Variance 769206.97 47675.69 332259.27 1101453.63 188554.44 90256.19 8984.36 1204175.48 569316.52 221935.39

Standard deviation 27.73 6.90 18.23 33.19 13.73 9.50 3.00 34.70 23.86 14.90


Seasonal Movements and Habitat Use of Snail Kites in Florida