Impact of vagrant predators on the native fauna: a Short-eared Owl (Asio flammeus) preying on Madeiran Storm Petrels (Oceanodroma castro) in the Azores.

• Autor(a) principal: Bried, Joël
• Data de Publicação: 2003
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.3/178
• topic: Coruja-do-nabal; Short-eared Owl; Asio flammeus; Paínho da Madeira; Storm petrels; Oceanodroma castro; Açores; Azores

The impact of introduced predators on the native fauna of oceanic islands has proven to be catastrophic in many cases. In some instances, however, predation is caused by very few individuals arrived without any human assistance. Here, I report on the impact of a vagrant Short-eared Owl on the small population (200 breeding pairs) of cool-season Madeiran Storm Petrels from Praia Islet (0.12 km2), off Graciosa Island, Azores archipelago. The owl fed almost exclusively on storm petrels and killed between one and two individuals every night. The number of prey remains found suggests that it must have been present on the islet ca two weeks before its presence was noticed. Although the Short-eared Owl is a rare vagrant in the Azores, these observations show that a single individual may have a strong impact on a vulnerable population of Madeiran Storm Petrels.