Aerial Surveys of Cliff- Nesting Raptors in the National Petroleum Reserve-Alaska 1999, with Comparison to 1977

In summer 1999, an extensive aerial survey of cliff-nesting raptors was conducted in the National Petroleum Reserve-Alaska (NPR-A) on Alaska's North Slope. No similarly extensive survey had been conducted since 1977. In the interim, the regional population of the Arctic peregrine falcon (Falco peregrinus tundrius) had increased, as shown by monitoring along the Colville River. The 1999 survey assessed the present abundance and distri-bution of the peregrine falcon, as well as the gyrfalcon (Falco rusticolus), golden eagle (Aquila chrysaetos), and rough-legged hawk (Buteo lagopus) in most of the NPR-A. Specifically excluded from the 1999 survey were the Kogosukruk and Kikiakrorak Rivers and the Colville River below its junction with the Etivluk River. These areas had been included in other recent surveys. Peregrine falcons were found occupying 67 sites in 1999, 61 of which were in the area surveyed in 1977 and in which only four occupied sites were found.