Seabird Restoration:
Restore Seabirds to Santa Cruz Island

The goal of restoration efforts are focused on Scorpion rock, Orizaba rock, and within sea caves surrounding Santa Cruz Island (SCI) is to restore seabird habitat by removing non-native vegetation, installing artificial nesting boxes, and reducing human disturbance. Eggshell thinning and/or elevated levels of DDTs were documented in the eggs of these species in the Southern California Bight.

Restoration actions involve installing artificial nest sites for Ashy storm-petrels to prevent or reduce impacts from avian predation or human disturbance. Ashy storm-petrels are rare and endemic to California and northwestern Baja California, with a world population of less than 10,000 individuals. At SCI, certain offshore rocks (notably Orizaba Rock) and sea caves continue to host small nesting colonies. Nests are primarily found 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 thus extremely fragile. Small colony sizes and fragile habitats make Ashy storm-petrels highly susceptible to natural or human impacts. Recorded vocalizations were used to attract Ashy storm-petrels to the artificial nests on Orizaba Rock.

Scorpion Rock is a small islet located off the northeast coast of SCI. Natural auklet burrows are present in relatively small numbers on the rock, mainly due to the scarce vegetation and associated high rate of soil erosion. Restoration actions on Scorpion Rock will improve and enhance existing natural habitat for Cassin's auklets by restoring native vegetation, stabilizing soil to minimize erosion, and eradicating invasive, nonnative vegetation. Nest boxes were installed to provide a stable and secure nesting area for Cassin's auklets.

Biological Monitoring
In 2008, biologists continued to conduct baseline surveys of Cassin's auklets and Ashy storm-petrel populations at Scorpion and Orizaba Rocks and in the sea caves off Santa Cruz Island. Five monthly monitoring trips will be conducted from June to October in 2009 using previously established protocols.

Habitat Restoration
Preliminary vegetation mapping on Scorpion rock was completed in summer 2007. In 2008, outplanting was completed in four stages. A small pilot outplanting effort took place in early spring to aid with logistical planning. Further seed collection trips occurred in summer and fall. The soil was then stabilized and non-native vegetation removal efforts were performed before a final outplanting took place in fall 2008. A second season of outplanting will take place in 2009. Twelve different species of commonly found coastal bluff plants will be used in this effort. Growing solutions (www.growingsolutions.org) is a non-profit that is a partner in this project and supporting the majority of the planting activities on SCI.

In addition in 2008, 50 artificial nest sites for Ashy storm-petrels (25 at Orizaba Rock and 25 in the Cavern Point Cove caves) were installed. Several artificial sites were successfully used in 2008. The nesting habitat improvement efforts were also augmented with a social attraction system. An audio system for broadcasting vocalizations of Ashy storm-petrels was installed at Orizaba rock. Monitoring of these nests will continue in 2009 with nine trips planned from March through July.

Project Reports

• Montrose Seabird Restoration ASSP Report, 2008
• ASSP Preliminary Report, 2007

	Photo of Orizaba Rock that supports nesting of Ashy Storm-petrels. An audio system was installed on the rock in Fall 2008 to encourage nesting.			Biologists are sexing an adult Cassin's Auklet by measuring bill depth.
Laurie Harvey / National Park Service			Josh Adams / U.S. Geological Survey