The occurrence of reindeer calves in the diet of nesting Golden Eagles in Finnmark, northern Norway

Abstract

To assess the importance of semi-domesticated reindeer Rangifer tarandus calves in the diet of Golden Eagles Aquila chrysaetos, in Finnmark (northern Norway), we collected prey remains at 37 nests over six years (2001-2006). The study area was divided into 1) a fjord area, which is an important calving area for reindeer, and 2) an inland area where few reindeer give birth. 469 prey items were collected over the years. The diet of eagles was numerically dominated by birds (73% of collected prey items), especially willow/rock ptarmigan Lagopus spp. (51%), while mammals made up 27%, with mountain hare Lepus timidus as the most common species. Remains of reindeer calves were found in half of the nests studied and made up 8.5% of the collected prey items: 13.2% in the fjord area and 6.5% in the inland area. There was a higher chance of finding reindeer calves at nests in the fjord area than inland, and in nests situated in birch forest than in pine forest. The number of reindeer calves in the Golden Eagle diet in Finnmark corroborates well other studies from northern Fermoscandia. The importance of the Golden Eagle as a predator on reindeer can't, however, be assessed here.