The National Wildlife Refuge Association joined other environmental and scientific organizations in successfully supporting the proposed mouse eradication project at the December 16, 2021 hearing of the California Coastal Commission. After the seven-hour emotion-laden hearing, the Commission narrowly voted to approve the refuge’s Coastal Consistency Determination for the project.

Background:

Invasive rodents have wreaked havoc on many islands throughout the world and the Farallon Islands NWR is no exception. Starting with Russian fur traders in the mid-1800s, human occupants introduced a number of invasive mammals to these islands. All other invasive mammals, except house mice, have since been removed.

At their annual peak, invasive house mice on the South Farallon islands can reach densities among the highest of any island in the world. Mice cause ecosystem impacts by consuming endemic native invertebrates, altering the makeup of the native invertebrate fauna, and competing with native wildlife such as the endemic Farallon arboreal salamander. Mice also consume large numbers of seeds and other plant parts of native vegetation, reducing native vegetation cover in favor of hardier, invasive plants. Of highest concern, high mice densities appear to attract migrating burrowing owls that switch to preying on rare ashy storm-petrels after the mouse population crashes.

The project has been controversial because the selected alternative includes aerial application of rodenticide baits. This method has been used for successful island rodent eradication projects throughout the world, including NWR islands in the Atlantic and Pacific Oceans. The Farallon project takes into account the lessons learned from these past projects and incorporates measures to prevent potential impacts on non-target species.

Status:

The Service finalized the project Environmental Impact Statement in March 2019, and the National Wildlife Refuge Association plans to continue providing support for the project as it winds its way through the remaining Federal and State permit/approval processes.