Relative Abundance of Nesting Raptors in Southern Idaho
ABSTRACT
During 1975-76 raptor surveys were conducted on 12,473 km 2 of Great Basin desert in Idaho for the purpose of incorporating raptor baseline data and management programs into land-use plans. Over 970 occupied raptor nests of 18 species were located in the Bureau of Land Management planning units. Prairie Falcons (Falco mexicaus) were the most numerous large raptors. Raven (Corvus corax)--Prairie Falcon ratios changed with alterations in land use patterns. Ravens increased in desert lands that were converted to agriculture, crested wheatgrass, or cheatgrass pastures. Comparisons of numbers of raptor nests per 100 km2 in different areas indicate that the Snake River Birds of Prey Natural Area has exceptionally high raptor populations (217.0 occupied raptor nests per 100 km2). All other areas surveyed averaged only 7.8 occupied raptor nests per 100 km2.
