Avian electrocution in power lines: the overlooked threat for Neotropical raptors

Electrocution with power lines may represent a serious mortality factor for birds of prey. However, the impact of this threat has been largely ignored for raptor populations in the Neotropics. Here we evaluate raptor electrocution risk and power line mortality in semiarid landscapes of central Argentina. Power lines surveys were conducted from July to September 2016 along 160 km of three-phase distribution lines (13.2 Kv) in La Pampa province. A total of 194 individuals belonging to three raptor species were found electrocuted beneath of the 2,024 pylons examined. The bulk of electrocuted birds belonged to the Black-chestnut buzzard-eagle (Geranoetus melanolecus; 162 individuals), followed by the Variable hawk (Buteo polyosoma; 27 individuals) and the Turkey vulture (Cathartes aura; 5 individuals). Electrocution rate was five times higher in pylons made completely of concrete with wire jumpers above the crossarm (4% of all pylons surveyed, 57.6 electrocuted birds/100 pylons) than in pylons with poles made of concrete with wooden crosarmas but without jumpers (65%, 10.9 birds/100 pylons). Pylons with both wooden poles and crossarms represented 31% of the total surveyed but accounted by only one bird electrocuted. Our results reveal the importance of avian electrocution as a mortality factor for Neotropical raptors and highlight the link between avian electrocution risk and pylon design and material used for its construction. Future research should be focus on the impacts of avian electrocution mortality on raptor populations at a broader spatial scale as well as on the implementation of mitigation measures to avoid raptor electrocutions.