Interactions between eagles and semi-domestic reindeer – lessons learned from field surveys and deterrents

Abstract 1) Predation by eagles on semi-domesticated reindeer ( Rangifer tarandus ) is a known human-wildlife conflict in Fennoscandia. Both the Golden ( Aquila chrysaetos ) and the White-Tailed Eagle ( Haliaeetus albicilla ) are believed by herders to predate on reindeer, however, there is a considerable knowledge gap regarding the extent of predation and scavenging. Herders believe that predation levels are higher than assumed and that current compensation in Sweden, based on herd size, is insufficient. 2) We developed this pilot Before-After-Control-Impact project to fill the existing knowledge gaps by investigating the patterns of eagle abundance before, during, and after reindeer calving in a reindeer herding district in northern Sweden and testing the effect of two potential deterrents (air ventilators and rotating prisms) in diverting eagles from reindeer calving areas. 3) During the single study period, we made 12, 47, and 17 eagle observations before, during, and after calving respectively. Eagle abundance increased during calving and decreased again after calving ended. Predation levels were difficult to infer and neither direct attacks nor dead calves killed by eagles have been observed. Most eagle observations were made in the control area, with significantly higher odds of observing eagles in the control area compared to areas with deterrents. 4) We show that eagle abundance increased during the calving period and declined afterwards, with subadults particularly fluctuating. Deterrents appear promising in diverting eagles, though further studies are needed to fully assess their effectiveness and the broader issue of eagle predation on reindeer.