Plan to Kill Farallones Mice a Balancing Act

Byline: Associated Press

FARALLON NATIONAL WILDLIFE REFUGE (AP) — On the craggy, guano-covered Farallon Islands, tiny brown blurs of fur dart furtively across the ground between thousands of holes.

This chain of small rocky islands that jut sharply out of the Pacific Ocean 27 miles west of San Francisco is known as “California’s Galapagos” for its abundance of squawking seabirds, barking sea lions and great white sharks.

Yet amid this native menagerie lives an intruder: brown house mice brought by humans aboard boats from another time. And the rodents have now colonized here in a density unseen anywhere else in the world, researchers said.

The mice pose a serious threat to a number of plants and animals that occur here naturally. However, just how to rid the islands of the pests — by dropping poison pellets or by other methods — has proven to be a lightning rod issue for the U.S. Fish & Wildlife Service, resulting in impassioned opposition. The service has delayed releasing its plans as viable alternatives are sought.

The mice attract hungry migratory burrowing owls, which make homes in the islands’ rough-hewn cliffs. Once the owls are here, the predators also eat a rare gray seabird called the Ashy Storm-petrel, which breeds on the islands and whose numbers are in decline.

But critics worry that introducing poison to these islands will harm too many other interconnected species — like the owls and other birds that may eat the poisoned mice, living packed together like sardines in a can.

Still, many bird experts support plans to eradicate the mice to help the threatened Storm-petrel, saying the risk of decimating the islands’ populations of other species would be worth it, if the Storm-petrel survives in the long run.