Poison plan for mice on Farallones put on hold
Wildlife agency backs off after tough questions from state Coastal Commission
Federal officials withdrew a request Wednesday for approval of their plan to blanket the Farallon Islands with poison to kill off the hordes of mice that are threatening the ecosystem on the rocky archipelago, after intense questioning from California regulators.
The U.S. Fish and Wildlife Service pulled its request during a California Coastal Commission hearing in San Luis Obispo to determine whether the eradication plan was consistent with the state Coastal Management Program.
The decision came amid requests by commissioners for information on how the air drop of thousands of poisoned pellets would be monitored, how many nontarget animals would be killed, how far the poison could spread and what contingency plans were in place if birds and marine creatures along the coast started dying.
“We withdrew the application with the idea that we would resubmit at a later time to give them all the information that they needed,” said Doug Cordell, the spokesman for the Fish and Wildlife Service, who did not know when the plan would be reintroduced. “This is a good project that has been in the works for a number
of years. A number of conservation organizations support it, so by no means are we dropping the project.”
Opponents called the delay a victory for wildlife on the 211acre island chain 27 miles off the coast of San Francisco.
“What it means is we live to fight another day,” said Richard Charter, senior fellow with the Ocean Foundation who has long opposed the eradication plan. “What happens on the Farallones doesn’t stay on the Farallones. You are poisoning the ecosystem, not just the Farallon Islands.”
The government issued an environmental report in March that recommended dropping by helicopter 2,917 pounds of poisoned food pellets on the 10 rocky islands and islets known as the South Farallon Islands. The idea would be to exterminate tens of thousands of invasive house mice that have taken over the islands.
The pellets would be laced with brodifacoum, an anticoagulant that causes rodents to bleed to death. It has been linked to the deaths of many bobcats, owls and other terrestrial species that have eaten poisoned rodents.
Fish and Wildlife officials said Wednesday that the brodifacoum would be effective for 100 days after the drop. They estimated that 1,050 western gulls would be inadvertently killed.
Commissioners and opponents wondered what would happen if poisoned gulls on the Farallones flew to San Francisco and began dropping dead. They also wanted to know what would happen if a bucket of poison was mistakenly dropped in the ocean.
There is no question the Eurasian house mice, which are believed to have been introduced to the islands by seal hunters in the 19th century, are a serious problem.
Researchers say as many as 1,200 mice can be found per acre during peak breeding season, the highest rodent density of any island in the world. It’s so bad that the ground sometimes appears to be moving around the Victorian house on Southeast Farallon Island that scientists use to study the island ecosystem.
The teeming hordes are devouring the islands’ insects and spiders, the same food that the endemic Farallon arboreal salamander needs to survive. They have also been blamed for spreading invasive plant seeds, which stick to their fur, according to island biologists.
Worst of all, the mice attract burrowing owls, which feed on the rodents until their population crashes in the winter. The owls then begin eating the Ashy storm petrel, a small gray seabird that is listed as a species of special concern in California. Half of the 8,000 Ashy storm petrels in the world feed and nest on the Farallon Islands. Researchers say at least 225 of them are killed each year by burrowing owls.
Several other conservation groups, including California Audubon, the American Bird Conservancy and Point Blue Conservation Science, support the poisoning technique, which has successfully eradicated rodents on islands in Mexico, the Caribbean, the South Pacific, the Aleutians and the Galapagos chains, and the Channel Islands in California.
The commission can’t veto the plan, which also created a furor six years ago when it was last brought up, but it is highly unlikely the government would go forward without buyin from state coastal regulators.
Opponents want them to at least try other methods before bombarding an ecosystem so close to San Francisco with deadly poison.
“The idea that the mice should be caught and gotten rid of, I don’t think anybody disagrees with this,” Charter said. “The question is, does the end justify the means? This type of poison has too many unintended side effects on nontarget species.”