© 1997 Walt Dineen Society

Walt Dineen Society Annual Conference '97

Session III: Posters Abstract #: 97302


Cindy B. Brashear and Philip K. Stoddard
Florida International University, Miami, FL


The Florida Keys are a migratory bottleneck for approximately 16 species of raptors en-route to the Antilles and South America. Project goals for our study include a complete autumn raptor migration census by species, a study of meteorological conditions affecting flight behavior, and raptor use of stopover habitat. Our primary overflight census is conducted on Grassy Key, 58 miles NE of Key West. The site is narrow (allowing observations across the entire key), not immediately before or after a water crossing (eliminating potential double counts of hesitating raptors), and is not a major forage or roost site (eliminating double counts of looping raptors). Migrating raptors fly either SW (down) or NE (back up) through the Keys. Tracking NE-bound raptors provides evidence of which species and how many individuals turn around, presumably to avoid water crossings. Weather factors affecting the raptor migration include wind direction, wind speed, cloudcover, and frontal systems. This is the first complete raptor census performed in the Keys. In 1996 (1 Sep - 15 Nov), our count exceeded 15,000 raptors, including over 1,300 Peregrine Falcons. Our one-day total of 335 Peregrines is the highest seen in North America. According to satellite telemetry studies, Peregrines from as far west as Alaska migrate through the Keys. This suggests we are observing a different subset of the Peregrine population than seen at other U. S. raptor watch-sites. Our results indicate that the Florida Keys are a major migratory flyway; thus, critical resources should be identified and protected.


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