Feds’ plan to eradicate invasive mice on Farallon Islands divides conservationists
The U.S. Fish and Wildlife Service may blanket the South Farallon Islands with poison bait in an effort to eradicate invasive house mice, despite concerns among some environmentalists about accidental spills and potential effects on birds, fish and other wildlife in the waters of the Greater Farallones National Marine Sanctuary.
If the plan goes forward, 2,900 pounds of cereal-grain bait containing a total 1.16 ounces of a rodenticide called brodifacoum will be distributed across 121 acres of the southern islands, mostly using special bait-spreading buckets slung from a low-flying helicopter. Some hard-to-reach areas would be baited by hand or using refillable bait stations to lure mice into places like caves or man-made structures, as well.
The proposed operation is still at least 19 months off and requires additional authorizations before the final go-ahead is granted to managers of the Farallon National Wildlife Refuge, who are spearheading the effort.
The California Coastal Commission also will review the plan for consistency with its regulations. That hearing is expected to occur during the commission’s June 10-12 meeting in Rohnert Park.
The proposal has been under development for several years, inspiring controversy with each recirculation of supporting environmental documents. Like some other efforts to control nonnative animal species in remote, wilderness areas of the United States, it has managed to pit conservation interests against one another.
Point Blue Conservation Science, whose biologists have monitored Farallon Island populations for the past five decades, has supported the science and analysis for the plan, which has backing from many other conservation and bird groups as well, Refuge Manager Gerry McChesney said.
“We are a research and science-based organization,” said Zach Warnow, director of communications for Point Blue, “and what gives us the confidence is the strength of the science that is behind the proposal. This has been studied quite intensively for many years now.”
But for others, people like Richard Charter and Cea Higgins, Bodega Bay residents who have devoted decades of their professional lives to safeguarding the shoreline and coastal waters, the prospect of deliberately dropping toxic pellets anywhere near protected waters teeming with wildlife is anathema.
Their concerns include the possibility of bait pellets rolling down the islands’ steep slopes and into the water, western seagulls picking up stray tidbits and the potential harm for seals and sea lions exposed to the loud noises planned to keep seagulls away from the island.
The potential for secondary poisoning is especially worrisome, they say, although backers of the project say the tiny amount of toxin that would be spread among the nearly 1½ tons of bait is not water soluble, and would sink to the ocean floor and bind there, if it got into the water at all.
“I feel that there’s a lot of unanswered questions,” Higgins, executive director of Coastwalk/California Coastal Trail Association, said in an interview. “And it’s been bothersome to me that the public has been dismissed as emotional when they have questions, when they have concerns.
“People are trying to step away from an emotional reaction, but when they get told, ‘Gosh, there’s no impacts — this is perfect,’ they’re being dismissed, and so that creates mistrust,” she said.
The federal wildlife service has been working for years to develop a plan to address the overwhelming mouse population on the southernmost Farrallon Islands, a cluster of steep, rugged islands about 30 miles west of San Francisco that support a wide variety of wildlife.