Removing Invasive Mice from the Farallon Islands Would Benefit Threatened Birds

By Point Blue Conservation Science

Petaluma, CA–New research from Point Blue Conservation Science shows the significant negative impact that invasive, non-native house mice on the Farallon Islands are having to the threatened ashy storm-petrel. Original modeling by ecologists published today in the journal Ecosphere shows the potential impacts to the petrel’s population if mice are allowed to remain. The super-abundant mice encourage migrating burrowing owls to stay on the island, who later in the winter switch from eating mice to preying on the petrels.

The paper’s authors conclude that the owls are inhibiting population recovery for the ashy storm-petrel. Models show that if mice are removed from the island, reducing the presence of overwintering burrowing owls, the population of threatened petrels is projected to stabilize or potentially increase.

The ashy storm-petrel is a small, grayish-brown nocturnal seabird. Some experts estimate that there are only about 5,000-10,000 breeding ashy storm-petrels, with nearly half of the world’s population breeding on the South Farallon Islands. Because of its small population and the numerous threats it faces, it is listed as Endangered by the International Union for Conservation of Nature (IUCN) and a Species of Conservation Concern by federal and state agencies.

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Read the original article in Ecosphere.