Man-induced sex-biased mortality in the Spanish imperial eagle

Abstract

Sex-biased mortality in the Spanish imperial eagle Aquila adalberti was found, with more females than males dying. When classifying deaths by cause, very significant differences were found only in electrocution: females formed 78·12% of eagles killed on power lines. In other electrocuted dimorphic raptors, female mortality is also significantly higher than expected, which supports size difference as a possible cause of most mortality cases in females. Electrocution on power lines in the main known cause of death for the Spanish imperial eagle (60%). The development of a strong bias in the sex ratio of a small monogamous population with a low renewal rate could cause a rapid population decline.