In its effort to restore the native wildlife on the South Farallon Islands, a series of small rocky islands about 30 miles west of San Francisco, the U.S. Fish and Wildlife Service finds itself in a pickle.
The government agency says it needs to kill the nonnative mice that are over-running the island and threatening nesting seabirds. To do this, they propose air dropping highly toxic rodent poison but critics charge the effort could actually endanger birds on the island.
The agency hosted a public meeting in May, as the first step in drafting an Environmental Impact Statement (EIS) for the proposed project. On hand for the meeting were several groups have voiced concerns over using the poison, which can harm or kill other creatures that either eat the pellets directly or consume poisoned rodents. Wildcare, a longtime Marin wildlife advocacy and rehab group, has launched a substantial public campaign arguing against the proposal.
At the May meeting, Refuge Manager Gerry McChesney emphasized that no decisions have been made regarding which method will be used to eradicate the mice. However, the bulk of the meeting was spent discussing the pros and cons of using the poison, which is called brodifacoum, to achieve the agency's goal. The Fish and Wildlife Service has extended to June 10 the deadline for accepting public comments.
It's not surprising that the plan faces opposition. Allen Fish of the Golden Gate Raptor Observatory says the poison affects not only raptors and other birds of prey but foxes, bobcats, cats, and dogs. On the mainland, it's a major problem because it has long been readily available, and it is especially pervasive in urban areas, where people use it to control rodents around homes and other buildings.
In 2008, the federal Environmental Protection Agency approved restrictions on the use of brodifacoum to certified pest applicators, and banned the poison in home improvement stores. That regulation is set to go into effect this June.
Rodenticides are among the worst of poisons, according to WildCare's Maggie Sergio. In her official comments on the proposal, also posted on the Huffington Post.
"The use of rodenticides in our world is prolific and all too easy,” Sergio wrote on her Huffington Post blog. “WildCare experiences the tragic end result of what occurs when a vital food source for wildlife (rodents) becomes poisoned. When wildlife consumes poisoned rodents, they too, die a horrific death."
But when considering the ecology of the Farallones islands to the equation, rules concerning daily use of poisons on the mainland may not apply.
For example, though the Washington, DC-based American Bird Conservancy opposes the use of brodifacoum generally, its official policy states that in certain cases using the poison "can be critical to protecting endangered and/or migratory bird species, e.g., in island situations to protect birds imperiled by rodent predation."
The Farallones provide a refuge for 13 seabird and five marine mammal species. Although project proponents say the entire island ecosystem would benefit from the rodents' removal, the biggest winner would be the ashy storm-petrel, a secretive seabird that nests on the island.
The ashy storm-petrel is listed as a California Species of Special Concern. The Audubon Society has labled the bird as "red," or "declining rapidly" and/or facing "major conservation threats. About 2,000 storm-petrels nest on the southern Farallones, approximately half the world population. But in the last several decades, the Farallon colony has declined by 30 to 40 percent, and the house mice are at least partly to blame, mostly because they attract burrowing owls.