Seabird Restoration:
Restore Seabirds to Santa Cruz Island
The goal of restoration efforts focused on Scorpion rock, Orizaba rock, and within sea caves surrounding Santa Cruz Island 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.
Future restoration actions will 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 Santa Cruz Island, 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.
Scorpion rock is a small islet located off the northeast coast of Santa Cruz
Island. 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 will be installed to provide a stable and secure nesting
area for Cassin's auklets.
The estimated cost of this restoration action is $326,000.
Project Updates
Biological Monitoring
In 2008, biologists will continue 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.
Habitat Restoration
Preliminary vegetation mapping on Scorpion rock was completed in summer 2007.
The vegetation restoration phase of this project will begin in early 2008. A
small pilot outplanting effort is planned for early spring 2008 to aid with
logistical planning. Further seed collection trips will take place in summer
and fall 2008 and the plants should be ready for out-planting in late fall
2008. Soil stabilization and non-native vegetation removal efforts are planned
to occur immediately prior to the fall 2008 outplanting.
In addition in 2008, 50 artificial nest sites (25 at Orizaba rock and 25 in
the Cavern Point Cove caves) will be installed. The nesting habitat improvement
efforts will be augmented with a social attraction system. An audio system for
broadcasting vocalizations of Ashy storm-petrels will be installed at Orizaba
rock.
