Seabird Monitoring Project

San Clemente Island, California

IWS has partnered with the California Institute for Environmental Studies (CIES) to survey seabirds that use San Clemente Island’s habitats for foraging, roosting and nesting. Population sizes and information about where seabird species are nesting on the island will provide the U.S. Navy with an understanding of how resources should be managed. We are conducting boat surveys for multiple seabird species as well as other birds when they are encountered. Based on high levels of threat or concern, we are focusing on the following species: Scripps's Murrelet (Synthliboramphus scrippsi), Guadalupe Murrelet (S. hypoleucus), ashy storm-petrel (Oceanodroma homochroa), black oystercatcher (Haematopus bachmani), and brown pelican (Pelecanus occidentalis).

Scripps's, © Greg Gillson

Scripps's Murrelet and Guadalupe Murrelet

In 2012, these two species were split from Xantus's Murrelet (S. hypoleucus), which was listed as threatened by the state of California in 2004 and proposed for listing under the U.S. Endangered Species Act.

San Clemente is one of only two islands where both species are thought to be regularly sympatric (same area, not interbreeding).

A long-term monitoring plan is being developed and implemented by CIES, with the assistance of the Navy.

A 2009 summary indicated a breeding population of less than 100 murrelets on the island.

Monitoring (at-sea counting and capture, nest searches) is required to determine breeding status and timing and to measure population trends.

Population and habitat use data may assist the Navy in future conservation efforts.

Ashy Storm-Petrel

Proposed for listing under the U.S. Endangered Species Act but a decision to not list this species was made by the U.S. Fish and Wildlife Service in 2013.

CIES and the Navy are developing a long-term monitoring plan for storm-petrels.

In 2009 the breeding population was less than 100 on the island.

Monitoring (mist-net captures and nest searches) is required to determine breeding status and timing and to measure population trends.

Population and habitat use data may assist the Navy in future conservation efforts.

Black Oystercatcher

Listed as a species of high concern by several shorebird conservation plans, the U.S. Fish and Wildlife Service and the Audubon Society’s Watch List.

Based on such concern, understanding the role of San Clemente Island to the nesting and conservation of this species is an important goal.

Brown Pelican

Recently removed from the federal endangered species list after making a remarkable recovery following the ban on the use of the insecticide DDT.

In 2011, a nesting colony was established on San Clemente Island for the first time on record.

IWS is responsible for monitoring nesting chronology, productivity and spatial extent on the island.