Comparison of Managed and Unmanaged Wedge-Tailed Shearwater Colonies on O'ahu: Effects of Predation

• DOI: 10.1353/psc.2002.0044
• Publication Date: 2007-02-07T03:31:44Z
• Authors: David G. Smith; John T. Polhemus; Eric A. VanderWerf
• Keywords: Shearwater

On O'ahu, Wedge-tailed Shearwaters (Puffinus pacificus) and other seabirds nest primarily on small offshore islets, but fossil evidence shows that many seabirds formerly bred O'ahu itself. Predation by introduced mammals is suspected to be the primary factor preventing shearwaters other seabirds from reestablishing large nesting colonies O'ahu. We investigated effects of predation comparing three unmanaged colonies at Malaekahana State Recreation Area where feral cats are fed public, with a managed colony nearby Moku'auia Island Seabird Sanctuary, predators absent. During visits on 19 April, 16 June, 23 October 2000, we located 69 occupied burrows in three 85 in four monitoring plots Moku'auia. Many more nests produced chicks Moku'auia (62%) than at (20%). Among plots Malaekahana, reproductive success was lowest (zero) closest cat feeding site. In addition, 44 adult shearwater carcasses were found near Predation, most likely cats attracted supplemental food, had devastating impact Malaekahana. At one there was complete reproductive failure almost all adults killed. Populations of long-lived species like sensitive adult mortality, may act as a sink, draining birds away from areas.