Pacific Southwest Region
California, Nevada and Klamath Basin

U.S. Fish and Wildlife Service Announces the Availability of New Ashy Storm Petrel Study

Apr 25, 2011

For Immediate Release
April 22, 2011

Primary Contact:  Randy Brown, Arcata Fish and Wildlife Office: (707) 822-7201

U.S. Fish and Wildlife Service Announces the Availability of New Ashy Storm Petrel Study

The U.S. Fish and Wildlife Service today announces the availability of a new study titled, “Assessing an Index of Population Trends of the Ashy Storm-Petrel on Southeast Farallon Island, California, 1992-2010”.  The full report, commissioned by the Service and completed by Point Reyes Bird Observatory (PRBO) Conservation Science, can be accessed at:

The ashy storm-petrel (Oceanodroma homochroa) is a rare medium-sized sea bird that is endemic to California and northwestern Baja California, Mexico.  The largest known nesting colonies occur at the South Farallon Islands in central California, and at Santa Barbara, Prince, and Santa Cruz islands in southern California.

In 2009, the Service completed a status review, or 12-month finding, of the ashy storm-petrel and concluded that listing under the Endangered Species Act was not warranted.  While the information available to the Service in 2009 did not support listing the species, we acknowledged there were limitations regarding information about population status and trends.  Consequently, the Service commissioned this study, conducted by PRBO Conservation Science, to help us gain a better understanding of the population status and trends of the ashy storm petrel. 

In the report, PRBO Conservation science describes their analysis of a long-term data set and development of an index of abundance of ashy storm-petrels over the past 18 years on Southeast Farallon Island.  From the early 1990s abundance was variable from year to year, and declined in 1998, an El Nino year.  From the early 2000s the trend was increasing, but still variable from year to year.  From 2008 to 2010, abundance again declined but overall remained higher than in the 1990s.  Overall, the report does not identify the reason for the year-to-year variation, but indicates that predation, ocean conditions, and moon phase do not completely account for it. 

“This report provides us with important new information regarding abundance of ashy storm-petrels on Southeast Farallon Island, adding to our knowledge and will be used as part of our on-going effort to conserve this species," said Nancy Finley, Field Supervisor, Arcata Fish and Wildlife Office.

The mission of the U.S. Fish and Wildlife Service is working with others to conserve, protect and enhance fish, wildlife, plants and their habitats for the continuing benefit of the American people. We are both a leader and trusted partner in fish and wildlife conservation, known for our scientific excellence, stewardship of lands and natural resources, dedicated professionals and commitment to public service. The U.S. Fish and Wildlife Service works cooperatively with the American public to continue the conservation legacy of America’s great outdoors. For more information on our work and the people who make it happen, visit

For more information contact, Randy Brown, Deputy Field Supervisor, Arcata Fish and Wildlife Office at 707-822-7201.