Restore Seabirds to San Miguel Island
This action aims to restore seabird nesting habitat on San Miguel Island in the Channel Islands National
Park by eradicating the introduced black rat (Rattus rattus).
San Miguel Island and its associated islets, Prince Island and Castle Rock, support regionally important
and diverse seabird colonies, including one-third of the breeding seabirds in
the Channel Islands. Introduced rats are responsible for approximately 40 to 60
percent of all bird and reptile extinctions from islands and are known to have
ecosystem-wide impacts on California islands.
Target bird species for restoration include burrow/crevice nesting seabirds such as the ashy
storm-petrel, Cassin’s auklet, and Xantus’s murrelet, as well as other seabirds
such as the western gull, Brandt’s cormorant, and pigeon guillemot. Eggshell
thinning and/or elevated levels of DDTs were documented in the eggs of all of
these species in the Southern California Bight.
Because of the presence of several endemic species on San Miguel Island, including the federally
endangered island fox, this action requires substantial planning and the
development of a comprehensive mitigation program. Should the Trustees
determine that this project is feasible, the National Park Service, with the
assistance of the Trustees, will prepare additional NEPA documentation for this
action that will undergo public review and comment. The supplemental document
will detail the specific methodologies of the action, the expected benefits and
impacts, and the proposed mitigation measures.
The estimated costs of this restoration action are still being determined.
In 2007, MSRP funded a survey of seven species of breeding seabirds at the San
Miguel Island group that provided updated information on seabird abundance,
distribution, and trends.
MSRP also funded a review of the historical literature and unpublished data on
the abundance, distribution, trends, and conservation issues for all 15 species
of breeding seabirds.
- MSRP has determined that the feasibility of rat
eradication on this island group is not cost effective and the concerns or
potential impacts to non-target species during eradication were too great to
proceed at this time.