Helicopters to drop poison on California’s Farallon Islands amid ‘plague’ of mice

Wildlife officials and ecologists say urgent and drastic measures are needed to eradicate mice, a threat to island’s endemic speciesMaanvi Singh in San FranciscoFri 17 Dec 2021 

A plan to eradicate a “plague-level infestation” of invasive mice on California’s Farallon Islands by dropping poisoned bait from helicopters has been approved by state officials.

After hours of impassioned debate, coastal commissioners voted 5-3 in favor of the long-controversial plan put forth by the US Fish and Wildlife Service (FWS). The approval comes despite the objections of local environmental activists who fear that rodenticide will kill not only the invasive mice, but also gulls and burrowing owls.

If the FWS regional director approves the plan as well, a poison drop over the islands, located just off the San Francisco coast, could take place by the fall of 2023, the wildlife agency said.

Wildlife officials and ecologists conducting research on the island have argued that urgent and drastic measures are needed to eradicate the mice, which are a threat to endemic species – including native arboreal salamanders, camel crickets and birds like the ashy storm petrel. Proponents of the plan have said using the rodenticide brodifacoum is the only way to quickly achieve total eradication of the mice, which were inadvertently introduced to the islands by sailors in the 19th century, and to protect native species that are projected to decline in the coming decades.

Supporters of the proposal also include conservation groups like the National Audubon Society and the Nature Conservancy.

However, during hours of emotional debate before the vote, opponents warned that FWS plans to minimize collateral damage to seabirds, raptors and other animals weren’t foolproof. The proposal details that FWS staff would begin by “hazing” gulls to ward them away from the islands before the rodenticide is deployed, using techniques including lasers, pyrotechnics and effigies. Burrowing owls and other raptors – who might eat poisoned mice and themselves get poisoned – would be gathered up and transported off the island.

Hungry raptors flying along California’s coast won’t be able to stay away from a feast of ailing, poisoned mice on the island, said Sara Wan of Western Alliance for Nature and will die of poisoning. “I cry at the thought,” she said. “If I sound angry to you it’s because I am.