HABITAT USE AND TIME BUDGETING BY WINTERING FERRUGINOUS HAWKS

From 1992-1995 we studied the winter ecology of Ferruginous Hawks (But eo regalis) in Colorado. Hawks spent 84% of the daylight interval perc hing. Time-budgets indicated that on average hawks perched 18 times da y(-1) (range 3-50), with perches averaging 30 min in duration. Diurnal perching was in trees, on poles, and on the ground. Utility poles and other human-made structures were used more than ground and deciduous tree perches. Tree perches were used for the longest mean duration. Th e mean daily Minimum Convex Polygon (MCP) home range of 36 hawks was 3 .53 km(2). The black-tailed prairie dog (Cynomys ludovicianus) was the most important prey species, and extant prairie dog colonies characte rized winter habitat for Ferruginous Hawks.