Impact of Salt Pond Restoration on California Gull Displacement and Predation on Breeding Waterbirds. Report Prepared for the South Bay Salt Pond Restoration Project and Resources Legacy Fund.

摘要

The California Gull (Larus californicus) population in the South San Francisco Bay has increased from fewer than 200 breeding Gulls in 1982, to a peak of 52,172 in 2012. Specific to this study, there were 46,030 breeding Gulls in 2010 and 37,716 Gulls in 2011. The expanding California Gull population may negatively impact other ground nesting birds in the South Bay through harassment, encroachment on nesting sites, and predation on eggs and chicks. We investigated the effects of California Gulls on other breeding waterbirds within the South Bay Salt Pond Restoration Project area. We examined predation by California Gulls on Forster's Tern (Sterna forsteri) chicks (Objective 1) and Western snowy plover (Charadrius alexandrinus nivosus) eggs (Objective 2). We also examined the distribution of color-marked California Gulls after Pond A6 was breached to tidal flow and flooded (Objective 3), and population growth and location of breeding California Gulls within South San Francisco Bay (Objective 4). Elsewhere, we have investigated predation by California Gulls on the two other most numerous nesting waterbirds in the South Bay, American Avocets (Recurvirostra americana) and Black-necked Stilts (Himantopus mexicanus) (Ackerman et al. 2006b), so those species were not included in this study.