Endangered Species Program
Conserving the Nature of America

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Achieving Balance: Anacapa Island 10 Years After Rat Removal
Partners: Channel Islands National Park, Island Conservation, California Department of Fish and Wildlife, U.S. Fish and Wildlife Service, and the National Oceanic Atmospheric Administration
Produced by: channelislandsnps


Ten years after removing nonnative rats the ecosystem on Anacapa Island, including rare seabirds, is showing profound results of recovery.

Ashy storm-petrels are nesting on the island for the first time ever recorded and Cassin's auklets have expanded their territories in the absence of rats as predators. Significantly, the number of Scripps's murrelets nests has quadrupled with a 50 percent increase of eggs hatched.

Rats are known to have negative impacts to island ecosystems. Rats are the most significant cause of bird extinctions on islands and are estimated to be responsible for half of bird and reptile extinctions worldwide.

Nonnative black rats, which were first reported on Anacapa Island in the early 1900s, threatened critical breeding habitat for these rare seabirds. They were eating approximately 70 percent of the eggs of the once common Scripps's murrelet, a state-listed threatened species. They also preyed upon native deer mice, reptiles, insects, intertidal invertebrates, and plants.

To restore balance to the island ecosystem, black rats were removed in 2001 and 2002 using an aerial application of rodenticide bait. Some of the world's leading island experts and scientists from the United States, Canada, and New Zealand assisted project partners from Channel Islands National Park, Island Conservation, and the American Trader Trustee Council (comprised of the California Department of Fish and Wildlife, U.S. Fish and Wildlife Service, and NOAA) in the rigorous planning process for this project.

Last updated: March 8, 2013