SPATIAL USE AND HABITAT SELECTION OF GOLDEN EAGLES IN SOUTHWESTERN IDAHO

We measured spatial use and habitat selection of radio-tagged Golden E agles (Aquila chrysaetos) at eight to nine territories each year from 1992 to 1994 in the Snake River Birds of Prey National Conservation Ar ea. Use of space did not vary between years or sexes, but did vary amo ng seasons (home ranges and travel distances were larger during the no nbreeding than during the breeding season) and among individuals. Home ranges were large, ranging from 190 to 8,330 ha during the breeding s eason and from 1,370 to 170,000 ha outside of the breeding season, but activity was concentrated in small core areas of 30 to 1,535 ha and 4 85 to 6,380 ha during the breeding and nonbreeding seasons, respective ly. Eagles selected shrub habitats and avoided disturbed areas, grassl ands, and agriculture. This resulted in selection for habitat likely t o contain their principal prey, black-tailed jackrabbits (Lepus califo rnicus). Individuals with home ranges in extensive shrubland (n = 3) d id not select for shrubs in the placement of their core areas or forag ing points, but individuals in highly fragmented or dispersed shrublan ds (n = 5) concentrated their activities and foraged preferentially in jackrabbit habitats (i.e. areas with abundant and large shrub patches ). As home ranges expanded outside of the breeding season, individuals selected jackrabbit habitats within their range. Shrubland fragmentat ion should be minimized so that remaining shrub patches are large enou gh to support jackrabbits.