Same poison that's being dumped all over New Zealand.

Pesticide bombing of Farallones mice spurs debate

Kelly Zito, Chronicle Staff Writer
San Francisco Chronicle May 12, 2011

Friday, May 13, 2011

Photo (deleted)
Stephen Lam / Special to The Chronicle

Gerry McChesney, manager of the Farallon Islands National Wildlife 
Refuge, fields a question during a public meeting at Fort Mason in 
San Francisco.

Federal wildlife regulators are considering carpet-bombing the 
Farallon Islands next fall with potent pesticides aimed at 
eradicating hordes of house mice, an invasive population grown so 
large officials say it has radically altered the islands' ecology and 
now threatens rare seabirds.

But animal welfare groups contend the lethal chemicals could ruin the 
prized sanctuary and drift throughout the food web, killing not just 
the rodents, but birds, reptiles and even microscopic crustaceans.

A few dozen people from both sides of the issue discussed their views 
Thursday night at a public meeting at San Francisco's Fort Mason, 
where the U.S. Fish and Wildlife Service was expected to gather input 
as it works this year to finish a set of possible solutions to the 
mouse problem. While the agency emphasizes that an aerial drop of 
rodenticide in 2012 is only a proposal at this point, officials 
acknowledge there are few other viable options.

That's not a suitable response, according to at least 1,500 people 
who have signed a petition circulated by WildCare, a 50-year-old 
Marin County animal rehabilitation center that has made pesticide 
reduction its mission in the past several years.

"These are man-made problems," said Maggie Sergio director of 
advocacy for the nonprofit. "Is the aerial dumping of tons of poison 
over a pristine wilderness area really the answer? We don't think so."

Risks to habitat

The controversy roiling around the Farallon Islands National Wildlife 
Refuge - a federally managed island complex about 27 miles west of 
the Golden Gate - underscores not only the risks associated with 
applying lethal compounds to a large swath of delicate habitat, but 
the bigger quandaries posed by nonnative species.

A few lowly house mice were likely brought to the Farallones in the 
1800s as stowaways aboard fur trading ships. With few predators, the 
population ballooned over the last century, now peaking at roughly 
60,000 annually. Those plentiful, bite-size morsels drew the 
attention of burrowing owls, another nonnative species. Once the owls 
chew through most of the rodents each year, they turn their attention 
to the eggs and chicks of the Ashy Storm-petrel, a small gray seabird 
that breeds and nests in the Farallones and just one other spot on the globe.

Exterminating the mice and deterring the owls, the U.S. Fish and 
Wildlife Service said, will reduce mortality among a species whose 
Farallones population tumbled 40 percent over a particularly bad 
20-year period. The petrel is listed as a "species of concern" in 
California and "endangered" by the International Union for 
Conservation of Nature.

Meanwhile, nearly 500 mice ply each of the 120 acres of the South 
Farallon Islands, the biggest landmasses in the array. Biologists 
like to say that during the mice's yearly boom, "the grass moves."

"People are rightly concerned about the incidental impacts of this 
rodenticide, and so are we," said Doug Cordell, spokesman with the 
U.S. Fish and Wildlife Service. "But in this kind of project, you 
have to eradicate every mouse. You can't leave a single one, or the 
problem comes back."

Problem with pesticide

But the probable tactic - airplane- or helicopter-dropped pellets 
soaked with brodifacoum - has its own set of problems, Sergio said. 
An anticoagulant, brodifacoum triggers a massive bleed out from the 
mouth, eyes, rectum and ears. Though the petrels, which consume fish 
and mollusks, wouldn't eat the tainted mice, other birds like gulls 
might. What's more, Sergio said, the pellets could decay into the 
soil and water, harming protected salamanders as well as krill, the 
tiny invertebrates that lie at the base of the food chain.

In a similar but larger project in the Aleutians in 2008, the 
pesticide managed to work its way to the top of that ecosystem.

More than 40 bald eagles were killed after the contractor, Island 
Conservation, dumped 46 tons of pesticides onto Rat Island that fall 
in an effort to eliminate the namesake vermin. In total, 420 birds 
were killed, including gulls, ducks, teals, cormorants, murres and 
ptarmigans, according to a report on the incident by the 
Ornithological Council, a nonprofit policy group. Island Conservation 
is consulting on the Farallones project.

Aside from the risk of unintended consequences, WildCare and other 
allies like the Marin Humane Society and anti-pesticide groups 
question the broader wisdom of saving one protected bird over another.

Owls, petrels protected

Though they are not indigenous to the Farallones, California's 
dwindling burrowing owls, like the Ashy Storm-petrel, are also listed 
as a "species of special concern."

"We've pushed them off the mainland to the Farallones because we've 
encroached on their habitat," Sergio said. "Now they're out there 
trying to survive, which is what nature does, and we want to remove them."

Ellie Cohen, president of the Point Reyes Bird Observatory, said 
man-made problems can be corrected and removing the owls might be the answer.

"Animals are dying now, animals will die in the future," Cohen said. 
"It's not about bad or good, it's about trade-offs."

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This article appeared on page C - 1 of the San Francisco Chronicle

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