Abstract

We studied home-range size using 15 GPS-tracked adult Golden Eagles (Aquila chrysaetos) in nine different territories, two in 2011 and those two as well as seven others in 2012, in northern Sweden. Home ranges were represented by 50 and 95% minimum convex polygons (MCPs) and 50, 80 and 95% kernel density estimates (KDE). In 2012, 95% MCPs ranged from 100-525 km(2) for males (n = 8), and 60-605 km(2) for females (n = 7). Mean home-range sizes for the eagles in our study were among the largest reported. Moreover, we found an inverse relationship between home-range size and the percent of clear-cuts within the range. Together these suggest that eagles in Sweden may compensate for low availability of hunting areas, e.g., lower proportion of clear-cuts in their range, by expanding their range. Some eagles displayed different forms of post-nesting movements (i.e., movements not related to breeding) during the normal breeding season in addition to the ranging within their home ranges: (i) long-distance directional movements (n = 3), (ii) intermediate-distance movements (n = 4), and (iii) movements within an unusually large home range (n = 1). These movements varied considerably, with some eagles travelling nearly 700 km north into northern Finland and Norway. No adults with transmitters reproduced successfully in 2012; in four territories, nests failed and in five territories occupied by pairs we did not know if eggs were laid. Post-nesting movements, which occurred after nesting or breeding failure, occurred in a year with apparently low food supply and may have been triggered by local food shortage.

Keywords

Golden Eagle; Aquila chrysaetos; clear-cuts; forestry; GPS tracking kernel density estimates; minimum convex polygons

Published in

Journal of Raptor Research
2014, Volume: 48, number: 2, pages: 93-105

SLU Authors

• Moss, Edward

  • Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences
    

• Hipkiss, Tim

  • Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences
    

• Ecke, Frauke

  • Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences
    
  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    

• Dettki, Holger

  • Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences
    

• Sandström, Per

  • Department of Forest Resource Management, Swedish University of Agricultural Sciences
    

• Hörnfeldt, Birger

  • Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Ecology
Forest Science


Publication identifier

DOI: https://doi.org/10.3356/JRR-13-00044.1

Permanent link to this page (URI)

https://res.slu.se/id/publ/56129