Conservationists are suing the federal government to restore nearly 468,000 acres of critical habitat to protect an endangered sheep living in areas like Anza-Borrego Desert State Park.

A lawsuit filed in San Diego on October 7 by the Sierra Club, the Center for Biological Diversity, and other conservation organizations charges that the U.S. Fish and Wildlife Service violated the Endangered Species Act when, in April, it cut protected habitat designations for the peninsular bighorn sheep by 55 percent — from 844,897 to 376,938 acres. The lawsuit also claims this reduction broke up habitat continuity, disrupting migration and interbreeding across populations.

Once the most numerous of the desert bighorns, the peninsular bighorn sheep population in the U.S. dropped to 276 in 1996 and was listed as endangered in 1998. They dwell in low-elevation slopes in desert areas popular with real estate developers.

“It’s a magnificent animal in its own right and, if it’s in trouble, it’s also an indicator that the entire ecosystem is in trouble,” said Joan Taylor, conservation chairman for the Sierra Club in the Coachella Valley.

In 2001, the government marked off 840,000 mountainous and canyon acres in Riverside, San Diego, and Imperial Counties as critical habitat. In part, this means developers face a higher level of environmental review for those areas. A Fish and Wildlife spokeswoman did not return calls seeking comment, but the Associated Press stated in a report that the recent reduction was based on better conservation planning and science about the sheeps’ habits.

Currently, an estimated 800 sheep reside in the area from the San Jacinto Mountains to the border, partly helped by the 2001 designation, said Ileene Anderson, biologist with the Center for Biological Diversity. “They have rebounded in numbers…which shows protecting their habitat does help in bringing the species back from extinction.”