Interactions between eagles and semidomestic reindeer: lessons learned from field surveys and deterrents

Predation by eagles on semi-domesticated reindeer (Rangifer tarandus) is an emerging 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 extent of predation and scavenging by each species, and their distribution and behaviour within the reindeer herding areas. Lethal and non-lethal methods have been suggested to reduce this conflict with eagles. We developed this project to fill the existing knowledge gaps by investigating the patterns of eagle abundance before, during, and after reindeer calving in a herding district in northern Sweden, and testing the effect of two potential deterrents (air ventilators and rotating prisms) in diverting eagles away from reindeer calving areas. During the single study period, we made 12, 47, and 17 eagle observations before, during, and after calving respectively. Out of these observations, 34 were of Golden eagles, 33 of White-tailed eagles, and for 9 observations the species could not be confirmed. Eagle abundance increased during calving and decreased again after calving ended. No attacks by eagles on calves were observed. The odds of observing eagles were significantly higher in the control area compared to areas with deterrents. More sub-adults were observed during calving, and both species were present in the area. The extent of predation was difficult to infer using direct observations and deterrents seem to show promise in diverting eagles away from calving grounds. These studies should be replicated to get a general picture of the issue and testing the efficiency of deterrents in diverting eagles away from reindeer across reindeer herding districts.