Using Autumn Hawk Watch to track raptor migration and to monitor populations of North American birds of prey
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Raptors are secretive, area-sensitive predators whose populations can be logistically difficult and financially prohibitive to monitor. Many North American populations of raptors are migratory however, and on migration raptors are frequently counted at traditional migration watchsites. Experiences at Hawk Mountain Sanctuary (HMS) and elsewhere suggest that long-term migration counts can be used to monitor regional populations of raptors. Hawkwatchers have collected count data on standardized Hawk Migration of North America (HMANA) Daily Report Forms since the mid- 1970s. In 1998 HMS, HMANA, the National Audubon Society, and the Lab of Ornithology at Cornell University began Internet-based data entry of migration watchsite counts at the BirdSource website. By autumn 2002, the Autumn Hawk Watch web page was collecting and displaying daily count reports from 66 watchsites in three Canadian provinces, 26 United States, and in Mexico, Costa Rica, and Bolivia. Autumn Hawk Watch provides participants and interested parties with near real-time maps and tables that document the movements of raptor migration across the Americas each autumn. The web page also captures count data for later use in monitoring raptor populations, and provides HMANA with timely summaries of each count, which are published in the HMANA Journal of Hawk Migration Studies.