Mice eradication plan at Farallon 
Islands weighs rodenticides

08/22/2013

A federal wildlife agency is enlisting public comments for a draft environmental impact statement that analyzes options to eradicate an invasive mouse from the South Farallon Islands. The draft EIS, produced by the U.S. Fish and Wildlife Service in partnership with nonprofits Island Conservation and Point Blue Conservation Science, proposes two action alternatives. 

The house mouse has afflicted populations of native plants, seabirds, salamanders and other species since boatmen introduced it in the 19th century, according to the service. In particular, half of the world’s ashy storm-petrel, a “species of concern,” use the island to breed. The mice, however, lure winter burrowing owls that feast on the birds. “They are breeding there in plague-like numbers,” Wildlife spokesperson Doug Cordell said.

The two action proposals involve aerially spraying rodenticide. One option employs Brodifacoum, an anticoagulant considered extremely toxic to human and animal life and noxious to the environment; it would be sprayed twice over a two-week period. The other action option would spray the weaker, though still highly toxic, anticoagulant Diphacinone three times over a three-week period. A no-action alternative would allow the mice to remain.

Mr. Cordell said that 49 different options were considered and noted that invasive rodents had been eradicated from Anacapa Island, off the coast of Southern California, with the use of Brodifacoum.

Each plan would take measures to protect species that at risk of ingesting the poisons, which are highly toxic through contact and lethal through ingestion.

The over 700-page draft EIS can also be found, and comments can be submitted online, by visiting http://www.regulations.gov and entering the docket ID, FWS-R8-NWRS-2013-0036, in the search box. A public meeting will be held on August 29, from 6 to 8 p.m., in the General’s Residence at the Fort Mason Center in San Francisco.