Wing-Tagged Encounters of Golden Eagles Captured in Montana

Abstract

Recently, there has been an increase in concern for Golden Eagle (Aquila chrysaetos) populations in the western U.S. The concern stems from a marked decrease in the number of migrants and future threats from a variety of anthropogenic factors including industrial energy development. Thus, there is a need for more information on Golden Eagles including: where they winter, longevity, causes of mortality and critical habitat needs. Standard banding offers low encounter rates (ca. 7%) and satellite telemetry is cost prohibitive for large sample sizes. We began auxiliary marking Golden Eagles with vinyl wing-tag markers as a cost effective means to gather information on the species. Since 2004, we have wing-tagged 260 eagles, and re-encountered 59 individuals, giving us a 23% encounter rate. This technique is proving considerably more effective than banding alone as a means of identifying individuals and receiving re-encounter information. We attribute this success, in part, to internet information sharing and the increasing use of remote cameras set up on carcasses to view scavenger activity. Given our observed encounter rates, we suggest utilizing wing-tags as a form of auxiliary marking to augment studies where standard banding is the lone marking method.