Quantifying Sources of Mortality and Wintering Ranges of Golden Eagles from Interior Alaska Using Banding and Satellite Tracking

McIntyre, Carol

Documenting the year-round movements and factors affecting the survival of wide-ranging birds is essential for developing effective conservation strategies. This is especially true for long-distance migratory species that spend much of their lives away from their breeding areas. Encounters of banded birds have provided information on the movements and survival of many bird species. More recently, telemetry studies provided new information on movements and survival of migratory birds. Golden Eagles (Aquila chrysaetos) raised in the higher latitudes of northwestern North America are usually migratory, but little is known about their year-round movements or survival. From 1988 to 2009, I banded 307 Golden Eagle nestlings in and near Denali National Park and Preserve in interior Alaska. From 1997 to 1999, I also deployed 90-g satellite transmitters on 48 of these eagles just before they fledged. Ten of the 307 banded eagles (3%) were encountered after the banding event, including five within 1 yr of banding. All encounters with banded eagles were .800 km from the banding location outside Alaska during winter or the migration season. All banded eagles were encountered ,2 km from a road or human settlement and the primary sources of mortality were electrocution and shooting. In contrast, all recoveries of dead radiotagged eagles (14) were .5 km from a road, and post-mortem necropsy indicated that all but one of these eagles died from starvation. Locations of banded eagles encountered in winter ranged from southern Alberta to north-central Mexico. Relocations of radio-tagged eagles in winter ranged from central Alberta to southeastern New Mexico. These results, despite small sample sizes, demonstrate how different marking and tracking tools can produce different results regarding the sources of mortality and the wintering range of Golden Eagles from the same study area.