Central Valley winter raptor survey (2007-2010): Variation in grassland raptor density among survey routes.

Abstract

We compared density of several wintering raptors in grassland habitat among all 19 of the survey routes and found that the grasslands of three routes at the eastern edge of the northern San Joaquin Valley consistently had the highest densities of three grassland specialists, the Ferruginous Hawk (Buteo regalis), Rough-legged Hawk (Buteo lagopus), and Prairie Falcon (Falco mexicanus).