The presence of raptors in the wild serves as a barometer of ecological health. Birds of prey are predators at the top of the food chain; because threats like pesticides, habitat loss, and climate change have the most dramatic impact on top predators, we refer to them as indicator species. Researching the population trends of raptors provides a cost-effective and efficient means to detecting environmental change, allowing us to take conservation action that is driven by the latest scientific data. Raptors also play an important ecological role by controlling populations of rodents and other small mammals.
There are around 450 species of ratpros worldwide. In North America, there are about 34 common diurnal species (active during the day) and 20 common nocturnal species (active at night). On the INL Site, there are 22 documented raptors:
Each January, hundreds of volunteers and wildlife professionals throughout the United States count eagles along standardized, non-overlapping survey routes as part of the Midwinter Bald Eagle Survey. These annual surveys commenced in 1979 and today are managed by the U.S. Geological Survey (USGS). The Midwinter Bald Eagle Surveys were originally established to develop a population index of wintering bald eagles in the lower 48 states, determine bald eagle distribution, and identify previously unrecognized areas of important winter habitat.
On the INL Site, Midwinter Bald Eagle Surveys have taken place since 1983. In early January of each year, two teams drive along established routes across the north and south of the INL Site and record the number and locations of all bald and golden eagles that they see. Observers also record the same information for other raptors, common ravens, shrikes (Lanius spp.), and black-billed magpies they observe along each route. Data are submitted to the regional coordinator of the USGS Biological Resource Division to be added to the nationwide database.
*Added to the Raptor Count in 1992 because ravens function ecologically as raptors.
** Added to the Raptor Count in 1992 because of concerns about declining shrike populations.
***Added to Raptor Count in 2013
****Added to Raptor Count in 2006
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