Farallon Island is overrun with an invasive mouse species that is threatening local wildlife; environmentalists can either poison the entire rodent population or do nothing.
The island, located off the coast of San Francisco, is home to 25 percent of California's breeding seabirds and 50 percent of the world's population of the ashy storm-petrel, a U.S. Fish and Wildlife Service press release reported.
The invasive mice are a threat because they attract the petrel-eating Wintering Burrowing Owl. The mice also feed on local invertebrates.
"Invasive house mice are taking a serious toll on the seabirds and other wildlife of the Farallon Islands," Anne Morkill, manager of the San Francisco Bay National Wildlife Refuge Complex, which includes the Farallon National Wildlife Refuge, said. "The ecosystem on the islands is out of balance. We want the public to give us feedback on our proposals for eradicating the mice and restoring that balance."
The mice are believed to have been introduced to the island by seal-hunting ships in the 19th century, the San Francisco Chronicle reported.
There are about 500 mice per-acre, and 60,000 of the rodents covering the entire island.
The island is inhabited solely by scientists and wildlife. The researchers have reported the ground around the 124-year-old house they use for an office is so mouse-ridden it appears to be moving.
Researchers could drop food pellets poisoned with diphacinone or brodifacoum, which would cause the mice to bleed to death.
The poison could be a threat to local birds and owls, but experts say the birds will be either scared away or captured during the mass mouse poisoning.
"I don't want to see the suffering of countless other species, especially when we don't know what the long-term impact will be," Maggie Sergios, an environmentalist formerly with Wildcare, a nonprofit animal welfare organization, said.
Sergio said in 2008, a rat island poisoning left 47 bald eagles dead, and was lethal to 420 birds in total.
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