Birds on California Island Rebounding from Rat Devastation Following Eradication Effort

Ashy Storm Petrel chick by George Wallace
Ashy Storm-Petrel chick by George Wallace

(Washington, D.C., March 15, 2013) Ten years after tens of thousands of invasive rats were removed from an ecologically significant island off the coast of Southern California, populations of rare seabirds are rebounding. There has been a four-fold increase in the number of Scripps's Murrelet nests, and two species never before known to nest on Anacapa, the Cassin's Auklet and Ashy Storm-Petrel, are now nesting.

Anacapa Island is part of Channel Islands National Park, which is comprised of five of the eight Channel Islands found off the California coast. West Anacapa has long been the home of the world's largest breeding colony of California Brown Pelicans.

The non-native rats that threatened all of these bird species were first reported on Anacapa in the early 1900s. Research that came later found that the rats were eating 70 percent of the eggs of the once common Scripps's Murrelet, which is now a threatened species in the state of California. The rats also ate native deer mice, reptiles, insects, intertidal invertebrates, and a wide variety of 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 the National Oceanic and Atmospheric Administration) in the rigorous planning process for this project.

Island Conservation's North America Regional Director Gregg Howald said, "Nowhere are the threats of extinction higher than on islands, and nowhere do we have greater opportunities to save species at risk. This successful project demonstrates the value of this critical conservation tool for other islands around the globe."

"The Anacapa rat eradication is part of a larger effort to protect and restore biological diversity on the Channel Islands. On Anacapa, ongoing efforts to remove nonnative ice plant and restore native plant communities are important to this recovery," said Channel Islands National Park Superintendent Russell Galipeau.

“ABC was among the many environmental groups who endorsed the project,” said George Wallace, ABC's Vice President for Oceans and Islands. “We are glad the environmental community rallied around this project – it is exactly the kind of well-designed, extensively researched, and responsibly implemented conservation program that is needed to protect native birds on islands from the harmful impacts of exotic species.”

Scientists from the National Park Service, University of California at Santa Cruz, California Institute of Environmental Studies, and Partnership for Interdisciplinary Studies of Coastal Oceans and Island Conservation will publish a report on the results of this noteworthy conservation effort later this year. Rats have ravaged island ecosystems all over the world, researchers say. They are the single largest cause of bird extinctions on islands. They are also said to be responsible for half of the world's recorded bird and reptile extinctions.