The Avian Research and Conservation Institute (ARCI), under the direction of Dr. Ken Meyer, is currently conducting a 4-year study of Swallow-tailed Kite adult survival (2000 marks the 13th consecutive year of kite study) with funding from the Florida Fish and Wildlife Conservation Commission. The goal of this 4-year study is to derive good estimates of this important demographic variable, which will then be combined with previously obtained data to build a population model. Such a model will help identify the Florida population's needs for maintaining healthy numbers into the future.
For the current study, capture and radio-tagging of adult Swallow-tailed Kites, using VHF transmitters with a two-year plus life, began during the summer of 2000. Additional adults will be radio-tagged in 2001 and ARCI will begin broad-reaching aerial and ground surveys to locate the previously marked birds to determine survival and breeding efforts.
In May of 2000, Microwave Telemetry, Inc. (MTI) of Columbia, Maryland, donated four prototype solar-powered satellite transmitters to ARCI for testing in this survival study. These prototype transmitters weigh only 18 grams, yet contain activity, temperature and battery-level sensors. MTI has manufactured all the battery-powered satellite transmitters ARCI has used on migrating Swallow-tailed Kites since 1996. Swallow-tailed Kites are ideal test subjects because they are long distance migrants and remain airborne most of the day, thus exposing the transmitters to sufficient sunlight. Previous tracking studies determined the species' migration route and wintering destination in southwestern Brazil, which were entirely unknown prior to this work.
Because the prototype transmitters were completed late in the nesting season, ARCI was unable to deploy all the test models on wild-caught adults, as hoped for. Thus, the Lake Woodruff kite offered a welcome opportunity to gather more information this year and avoid losing valuable time before beginning to use the solar-powered radios to their fullest advantage. Testing these prototype transmitters now will allow ARCI to begin a much more detailed study of annual movements and survival next year, including very specific areas on which the species relies in Latin America. Such information is extremely difficult to acquire, and yet vitally important to conservation planning for Swallow-tailed Kites. The "conventional" (i.e., battery powered) satellite transmitters, which provided the first glimpse of kite migration and wintering biology, have not performed well in South America during the last three years, resulting in the loss of highly valuable data. In addition, the battery powered radios last only a few months, whereas the solar-powered models should operate for several years.
An adult kite captured in Polk County, Florida, was the first to be fitted with one of the prototype satellite transmitters. This bird reached Brazil by late August. The transmitter provided excellent data along the entire route. A second solar-powered transmitter was placed on a juvenile kite in southern Georgia, but this bird did not survive past the start of its migration (data from previous tracking work indicates that about 85% of young kites hatched annually in Florida will not survive their first year).
The Lake Woodruff adult, rehabilitated by Audubon of Florida's National Center for Birds of Prey, was the third bird to be fitted with a prototype solar-powered satellite transmitter. Normally, ARCI would tag such an adult only if the bird had recovered extremely well from its injuries, as, apparently, was the case with the Lake Woodruff kite. Since this bird had been in captivity a relatively short time, it probably had not lost too much of its conditioning. ARCI had two satellite transmitters remaining to test, and saw not only an opportunity to gather additional migration data, but also a rare chance to learn the fate of a rehabilitated bird. With only a VHF transmitter, a released bird could quickly travel beyond range and become untrackable except at extraordinary expense. The prototype transmitter could provide long-range information.
Since the Lake Woodruff kite was injured and spent time in captivity, it will
not be used as part of the adult survival study. Because of the potential
for imposing biases on the survival analysis, only wild-caught kites will be
used in the study process. There is no doubt, however, that the Lake
Woodruff Kite is contributing greatly to the ability to study, understand and
protect Swallow-tailed Kites here in the U.S. as well as throughout the
species' hemispheric range.
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