Age-class differences in wintering distributions among broad-winged hawks


SOCIETY FOR INTEGRATIVE AND COMPARATIVE BIOLOGY
2021 VIRTUAL ANNUAL MEETING (VAM)
January 3 – Febuary 28, 2021

Meeting Abstract


79-1  Sat Jan 2  Age-class differences in wintering distributions among broad-winged hawks Heveran, PH*; Goodrich, LJ; Leese, JM; DeSales University; Hawk Mountain Sanctuary; DeSales University ph8986@desales.edu

Recent studies on endangered species, including the Kirtland’s warbler (Setophaga kirtlandii) and the piping plover (Charadrius melodus), have shown the importance of knowing a species’ wintering range for effective conservation efforts. These species were protected on their breeding grounds, but when their wintering range was described, new threats were identified. Despite the broad-winged hawk (Buteo platypterus) being an easily observed North American raptor during migration, much is still unknown about its non-breeding distribution. This study’s goal was to uncover patterns in adult and immature broad-winged hawk distribution in winter. Public eBird data from 2000-2017 between December and February were analyzed. We found no significant difference between mean wintering latitudes of adults and immatures south of the United States. This was true at most regional levels in the US as well. A few patterns did not concern mean wintering latitude but did show differences in distribution between age groups. All regions had more sightings of immature than adult individuals. The Florida ratio was unexpected, given previous indications of a mostly immature population. Sightings of adults were concentrated in higher-elevation forests in areas such as Costa Rica and Colombia. Immature sightings were more widespread in forests and lowland habitats. These findings have direct implications for more effective conservation measures in protecting the species. If a significant number of immature birds are wintering farther north than previously thought, conservation efforts may need to expand from the traditional core winter range. Although broad-winged hawks are still common, threats in these different habitats could contribute to a population decline if not identified.

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