A Marin wildlife group is opposing a possible federal plan to spread a rodenticide on the Farallon Islands to eliminate non-native house mice that officials say are harming native species.
The U.S. Fish and Wildlife Service is considering an air-drop of rodenticide pellets on the South Farallon Islands in fall 2012 to eradicate the mice, something San Rafael-based WildCare says is a bad idea.
“It’s a horror, absolute horror,” said Maggie Sergio, director of advocacy for WildCare, an animal rescue and advocacy group. “This is a habitat they are trying to keep pristine, yet they are talking about dumping a couple of tons of rat poison over the island?”
Sergio is concerned other species on the island could ingest the rodenticide, causing health problems for those animals and spreading the poison through the food chain. The agency proposes to use brodifacoum, an anti-coagulant.
“Any animals that come into contact with these pellets could eat them,” she said.
But Melissa Pitkin, education and outreach coordinator for the Point Reyes Bird Observatory Conservation Science, said the islands’ ecosystem has suffered because of the mice.
The rodents were likely inadvertently introduced in the 1800s by fur traders who stopped at the islands, situated some 27 miles west of the Golden Gate. Biologists estimate there are now several thousand mice living on the group of three main islands that constitute the South Farallones.
“The goal is the restoration of a healthy ecosystem,” Pitkin said. “That’s what this is about.”
And the mice have thrown that system way out of whack.
House mice are predators of Ashy Storm-petrel eggs and chicks, sea birds that are a “species of concern” in the state. There are only 15,000 worldwide, half of which breed and nest on the islands.
Every year as much as 12 percent of the eggs and chicks of this species are lost to mice. Meanwhile the native, migratory burrowing owls have become unnatural residents on the islands every winter to munch on mice. As the mouse population declines the owls turn to seabirds for their diet. By spring, hundreds of Ashy Storm-petrels and other seabirds have been killed, according to researchers.
By removing the mice, the Ashy Storm-petrel and other seabirds will avoid further population decline and the islands’ ecosystem will begin to be restored, Pitkin said.
She did acknowledge the approach could affect other species, including western gulls, ravens and the owls.
“There will be due diligence and this will be looked at closely,” she said.
“That said, rodenticides have been used successfully to restore ecosystems on islands around the world.”
A decision on what approach to take has not been made.
“We are in the process of soliciting public input as to what alternatives we should consider,” said Doug Cordell, U.S. Fish and Wildlife Service spokesman for the San Francisco Bay National Wildlife Refuge Complex. “We want people to come forward and comment.”
Contact Mark Prado via email at mprado@marinij.com
if you go
A meeting on an option to use rodenticides to rid the South Farallon Islands of house mice will be held from 6 to 8 p.m. Thursday at Fort Mason, Building 201 in San Francisco. Comments can also be submitted in writing to: Farallon Islands NEPA Scoping Comments, c/o Gerry McChesney, Farallon NWR Manager, 9500 Thornton Ave., Newark, CA 94560; by e-mail to sfbaynwrc@fws.gov; or by fax to 510-745-9285. Respondents should include the heading “South Farallon Islands NEPA Scoping Comments.” For more information on the project, visit: www.restorethefarallones.org.
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