The park supports 19 breeding raptor species. Additional species use the Yellowstone landscape during migrations and seasonal movements. The bird program monitors bald eagles, ospreys, and peregrine falcons. Bald eagles and peregrine falcons were previously listed as endangered and threatened species and their monitoring is required by law. The osprey is monitored because a food source, the cutthroat trout, declined in Yellowstone Lake. Other species that occur in the park such as golden eagles and Swainson's hawks are of growing conservation concern throughout their ranges in the United States.
Yellowstone Raptor Initiative
The Yellowstone Raptor Initiative is a five-year, science-based program started in 2011 and designed to learn more about the park's raptors. The initiative inventories and monitors select raptor species to provide baseline information on population size, productivity, and seasonal movements for species other than bald eagles, ospreys, and peregrine falcons. The Yellowstone Raptor Initiative selected golden eagles (Aquila chrysaetos), red-tailed hawks (Buteo jamaicensis), Swainson's hawks (Buteo swainsoni), American kestrels (Falco sparverius), prairie falcons (Falco mexicanus), and owls as focal species. The Yellowstone Raptor Initiative relies on citizen science to acquire valuable data on raptors in the park. Raptor observation forms are available at all visitor centers and ranger stations as well as on the web.