Adult Ashy Storm-petrel on nest, Santa Cruz Island Photo: Robert McMorran

Young Ashy Storm-petrel, Santa Cruz Island Photo: Robert McMorran

Robert McMorran working on artificial nest structure Photo: Bill McIver

Artificial nest sites Photo: Bill McIver

Orizaba Rock, Santa Cruz Island Photo: Laurie Harvey

Robert McMorran and Bill McIver
On April 1, 2008, biologists Bill McIver of the Arcata Fish and Wildlfe Office, Laurie Harvey of the Montrose Settlements Restoration Program at Channel Islands National Park, Ventura, California, Jim Howard, a Channel Islands National Park volunteer), and Robert McMorran  of the Service's, Ventura Field Office, conducted seabird habitat restoration work at Orizaba Rock, an off-shore rock off the north coast of Santa Cruz Island, Santa Barbara County, California.

The ashy storm-petrel (Oceanodroma homochroa) is a seabird species endemic to California and northwestern Baja California, with a world population near 10,000 individuals.  At Santa Cruz Island, certain offshore rocks (notably Orizaba Rock) and sea caves host small nesting colonies of this smoke-gray colored storm-petrel.  Ashy storm-petrels are nocturnal in their return to and departure from breeding colonies and nest in rock crevices, under small rocks or boulders, under driftwood, or in open sites along cave walls.  Much of the habitat available to storm-petrels is extremely fragile, and small colony sizes and unstable habitats make ashy storm-petrels susceptible to natural or human impacts.

Seabird habitat restoration work is funded by the Montrose Settlements Restoration Program.  The goal of restoration efforts at Orizaba Rock is to restore ashy storm-petrel nesting habitat by installing artificial nesting boxes and reducing human disturbance.  A small ashy storm-petrel colony persists on Orizaba Rock, but nest numbers are lower than those observed in the mid-1990’s.  

At Orizaba Rock, the biologists installed approximately 20 artificial nest sites to provide structurally stable nesting cavities for ashy storm-petrels with the goal of preventing avian predation and/or human disturbance.  Lightweight cement shake roofing tiles were used to create the artificial nests, which were augmented with sand and fine gravel to provide suitable nesting substrate.

To attract prospecting ashy storm-petrels to the artificial nest sites, the biologists installed an automated, solar-powered audio system to broadcast recordings of breeding Ashy Storm-Petrels..  A speaker was installed directly behind the artificial nest sites to attract ashy storm-petrels to this area.  In addition, mirrors were attached on the outside of each nest site; for nocturnal Ashy Storm-Petrels, ambient light levels at the colony site were expected to allow the mirrors to function as “decoys” which, coupled with vocalization broadcasting, may aid this colonial seabird in selecting nest sites. 

This technique has become known as "social attraction" and was developed by Stephen Kress of the National Audubon Society in the 1970s to attract Atlantic Puffins  (Fratercula arctica) back to Eastern Egg Rock in Maine.  Social attraction has since been successfully used to attract seabirds and restore colonies of common murres (Uria aalge), short-tailed albatrosses (Phoebastria albatrus), dark-rumped petrels (Pterodroma phaeopygia), Leach’s storm-petrels (Oceanodroma leucorhoa) and Madeiran storm-petrels (O. castro).

Work will continue at Santa Cruz Island in 2008 to monitor nesting activities of ashy storm-petrels and gauge the effectiveness of the social attraction restoration work at Orizaba Rock.  These restoration efforts are made possible through the involvement and cooperation of:  the Montrose Settlements Trustee Council (U.S. Fish and Wildlife Service, National Oceanic and Atmospheric Administration, National Park Service, California Department of Parks and Recreation, California State Lands Commission, and California Department of Fish and Game); Carter Biological Consulting (Victoria, British Columbia); Ocean Sports Private Charters (Santa Barbara, California); the Arcata, Carlsbad, and Ventura Fish and Wildlife Offices; Channel Islands National Park; and numerous volunteers.

For more information on the Montrose Settlements Restoration Program, please see http://www.darrp.noaa.gov/southwest/montrose/msrphome.html.  For more information on other seabird social attraction projects, please see http://www.projectpuffin.org/

and http://www.fws.gov/SFBAYREFUGES/MURRE/murrehome.htm.