Use of Estuarine, Intertidal and Subtidal Habitats by Seabirds within the MLPA South Coast Study Region

In this project, ornithologists are evaluating whether the new MPAs are adequately protecting seabirds, specifically pelagic cormorants, Brandt’s cormorants, Western gulls, black oyster-catchers, pigeon guillemots, California least terns and California brown pelicans. They are compiling and analyzing existing records of seabird populations prior to the establishment of the South Coast MPAs and conducting new bird surveys at key sites. In the project’s first two years, scientists monitored seabird breeding colonies, rooting sites and foraging rates on Santa Cruz Island, in La Jolla (where there is also a Brandt’s cormorant colony), at Cabrillo National Monument on Point Loma in San Diego and along the Palos Verdes peninsula in Los Angeles. The MPAs and special closures were established, in part, to protect roosting and breeding seabirds from passing ships, fishing lines and other human activities. As a result, scientists will be looking for evidence that the new regulations are reducing seabird behaviors like nest abandonment that indicate disturbance. During the 2012 field surveys, researchers observed high mortalities of least tern chicks. Fecal samples suggest the reproductive failure was caused by a lack of 1-year-old Northern anchovy and young rockfishes near the bird’s breeding colonies. The scientists report that 2013 appears to be a mixed year for least tern chicks, with some colonies doing better than others. Analyses of least tern fecal pellets and other seabird monitoring data will be conducted this fall and next year. Findings from this project will be used to enhance and encourage science-based approaches to seabird conservation.