Electrocution of Eagles in Mongolia

Abstract

Steppe Eagles (Aquila nipalensis) and Golden Eagles (Aquila chrysaetos) are species of conservation and cultural importance in Mongolia. Electrocution at electricity distribution lines is a threat faced by both species across Central Asia. We present the results of power line surveys conducted in the Mongolian steppe region to elucidate temporal patterns of electrocution and specific danger points on power poles for eagles. There was spatial and temporal variation in electrocution rates for Steppe Eagles and Golden Eagles. Autumn surveys across Mongolia recorded the electrocuted carcasses of 18 Steppe Eagles and 9 Golden Eagles. The distribution of electrocutions revealed that Steppe Eagles are mainly killed at power lines in the central steppe zone; in contrast, only Golden Eagles were found at power lines in the southern ‘gobi’ desert zone. Daily surveys conducted for a year at a single power line in the eastern steppe detected 8 Golden Eagles and 6 Steppe Eagles. All Steppe Eagle electrocutions occurred between April and September as they are predominantly summer visitors in Mongolia, whereas six of the eight Golden Eagle electrocutions occurred in winter indicating that Golden Eagles can range over predominantly flat, open steppe landscapes at this time. Significantly more electrocutions occurred at poles with no crossarm mitigation compared to poles with deflectors, deterrents or covers, indicating that mitigation on the crossarm can reduce eagle electrocution rates. Furthermore, the absence of eagle carcasses at poles with crossarm mitigation suggests that crossarms are the main site of electrocution for eagles in Mongolia. Country-scale retrofitting of insulation to crossarms and pole tops significantly reduced eagle electrocution events.