Effects of the Cabinet Gorge Kokanee Hatchery on Wintering Bald Eagles in the Lower Clark Fork River and Lake Pend, Oreille, Idaho: Final Report

摘要

The abundance and distribution of bald eagles (Haliaeetus leucocephalus) on the lower Clark Fork River, Lake Pend Oreille, and the upper Pend Oreille River, Idaho were documented during the winters of 1985--86 and 1986--87. Peak counts of bald eagles in weekly aerial censuses were higher in 1985--86 (274) and 1986--87 (429) than previously recorded in mid-winter surveys. Differences in eagle distribution within and between years were apparently responses to changes in prey availability. Eight bald eagles were captured and equipped with radio transmitters in the winter and spring of 1986. Residencies within the study area averaged 13.9 days in 1985--86 and 58.3 days for the four eagles that returned in 1986-87. The eagles exhibited considerable daily movement throughout the study area. After departing the area, one eagle was later sighted approximately 1185 km to the southwest in northern California. Eagle behavioral activity was recorded at time budget sessions at areas of heavy use. Perching in live trees was the most common behavior observed. 34 refs., 39 figs., 17 tabs. (ERA citation 14:007579)