Happy News For a California Species Once Thought Extinct

Pacific pocket mouse on April 9, 2014 at the San Diego Zoo | Photo:  Ken Bohn, San Diego Zoo.
Pacific pocket mouse on April 9, 2014 at the San Diego Zoo | Photo: Ken Bohn, San Diego Zoo.

A Southern California mouse species once feared extinct has some good news to share: its numbers are increasing... at least in captivity.

A litter of four Endangered Pacific pocket mice was born at the San Diego Zoo this past weekend, with another litter expected this weekend. The births took place under the care of the San Diego Zoo Institute for Conservation Research, which is running a captive breeding program for the pocket mouse in cooperation with the U.S. Fish and Wildlife Service.

The happy mother who gave birth to last weekend's pups is the first Pacific pocket mouse born as part of the captive breeding program, according to Zoo officials.

Story continues below

Pacific pocket mice, Paragnathus longimembris pacificus, historically ranged from El Segundo to the Mexican border in California, inhabiting dunes, river deltas, and other sandy soils close to the coast. The mice preferred areas of open vegetation, where their preferred food, seed-bearing grasses, had enough room to grow. That's a habitat type that's long been coveted by developers, of course, and almost all of the known populations of the species were displaced by urban and suburban development in the second half of the 20th century.

So much damage was done to the Pacific pocket mouse's habitat that by the 1980s, the species was suspected to have gone extinct. In 1993 a small population was rediscovered around the Dana Point Headlands, and USFWS granted the mouse an emergency listing as Endangered in 1994.

Two more populations subsequently found in Camp Pendleton. But before the Camp Pendleton discovery, the continuing existence of the Dana Point mice seems to have driven at least one Dana Point local to threaten to exterminate the species once and for all. In 1994, USFWS explained that it wouldn't be designating critical habitat for the pocket mice since that would pretty much draw a bullseye on the species:

Section 9 is the part of the Endangered Species Act that makes it illegal to kill listed species.

Since 1994, the Dana Point population's habitat has been protected and fenced off, no more threats have been received, and those two other populations of the mice have been found just southeast on land protected by the Marine Corps. That lessened vulnerability prompted the Center for Biological Diversity, the Endangered Habitats League, and the National Resources Defense Council to petition in 2000 that critical habitat for the mouse be designated.

The petitioners are still waiting for USFWS to act on that. In the meantime, until there's increased protection for the habitat the mice depend on, the new captive litters at the San Diego Zoo are good news indeed.

For ongoing environmental coverage in March 2017 and afterward, please visit our show Earth Focus, or browse Redefine for historic material.
KCET's award-winning environment news project Redefine ran from July 2012 through February 2017.

We are dedicated to providing you with articles like this one. Show your support with a tax-deductible contribution to KCET. After all, public media is meant for the public. It belongs to all of us.

Keep Reading