Pinniped disturbance lowers reproductive success of black oystercatcher Haematopus bachmani (Aves)

Abstract

Human activities along the Pacific coast of North America have restricted breeding sites of the black oystercatcher H. bachmani to inaccessible stretches of mainland, and offshore islands and islets. These same areas are also used by pinnipeds (exhibiting a similar aversion to human disturbance) for hauling out and breeding. Increasing pinniped numbers are increasing interactions between birds and pinnipeds in these refugia. These interactions result in abandoned nests and crushed eggs and chicks, thus lowering the reproductive success of the black oystercatchers. Complete or partial black oystercatcher colony eradication resulting from pinniped densities, geographical location, and topographic relief.