Depredación de aves marinas nocturnas en islotes de Isla Guadalupe, México

Abstract

In early June 2000 we surveyed 3 islets at the southern end of Isla Guadalupe, Mexico: Islote de Afuera (or Islote Zapato), Islote de Adentro (or islote Toro), and Islote Negro, to document nesting seabirds. We found vestiges of over 100 Leach's Storm-petrels (Oceanodroma leucorhoa), 31 Xantus Murrelets (Synthliboramphus hypoleuca), and 1 Cassin's Auklet (Ptychoramphus aleuticus) that had been depredated. The evidences point to Burrowing Owls (Athene cunicularia) as the predator of the storm-petrels, but, because of its size, probably other birds were involved in murrelet and auklet predation. Based on the characteristics of the remains, the depredated Leach Storm-petrels belonged to the population that had nested during the previous winter. The information is not sufficient to determine whether such predation represents a conservation problem for small seabirds on Isla Guadalupe, but suggest that the issue should be studied further.