Distribution of Raptor Foraging in Relation to Prey Biomass and Habitat Structure

Abstract

The spatial distribution of Red-tailed Hawks (Buteojamaicensis) and Northern Harriers (Circus cyaneus) overwintering in central Arkansas was studied in relation to perch availability, plant cover, and small rodent biomass in six habitat patch types. In general, raptor foraging was distributed nonrandomly among patch types. Red-tailed Hawks occupied corn stubble and old-field patches more frequently than expected by chance and occupied tall corn and bare patches less frequently than expected. Adult male Northern Harriers used corn stubble and wetland patches more frequently than expected and used tall corn and bare patches less frequently than expected, while adult female and juvenile harriers used wetland patches more frequently than expected and used bare patches less frequently than expected. The general distribution of Northern Harriers is interpreted as a response to prey biomass availability (rodent biomass index x 1/plant cover density), while Red-tailed Hawk distribution is interpreted as a response to both prey biomass availability and perch availability.