Movements and home range size of bald eagles from Glacier Bay National Park and Preserve, Alaska: with an analysis of satellite telemetry

Abstract

During 1991-1993, I studied movements of 23 adult and 7, 8-10 week old nestling bald eagles captured in Glacier Bay National Park and Preserve, Alaska. I estimated locations by homing and satellite telemetry. During the breeding season, the distances adult eagles moved from successful, unsuccessful, and mixed-success nests were not significantly different (£ = 0.148). Regardless of nest success, the proportion of adult eagle locations within 750 m of their nest were not significantly different during the breeding season (£ = 0.152) and between the breeding and non-breeding seasons (£ = 0.075). On average, bald eagles were perched 91 % of the time; and perching was the most frequently observed activity (£ < 0.001). Adult eagles perched more often in conifers than cottonwoods, snags, or intertidal debris (£ < 0.001). Perch types selected (£ = 0.473), as well as eagle activity (£ = 0.126) were not significantly different during the breeding and non-breeding seasons. Fifty-eight percent of radio-ma~ked adult eagles used 3 watersheds in Glacier Bay from August through January 1991-1993. Six adult (26%) and 6 (86%) fledgling eagles moved out of Glacier Bay during the non-breeding season. Four adult eagles (17%) traveled to the Chilkat Bald Eagle Preserve in late November and December (mean distance from nest to preserve = 74 km) and 57% of the fledgling eagles were on the Chilkat River in October, where they remained for 2-12 weeks. After leaving the Chilkat River, all fledgling eagles traveled in a southeasterly direction; one male fledgling traveled 435 km in 28 days to Prince Rupert, British Columbia.