The Center for Biological Diversity filed a legal petition calling for the U.S. Fish and Wildlife Service to significantly expand their plan for recovering grizzly bears.

The petition pinpoints 110,000 square miles of land that could be inhabitable by grizzly bears, a Center for Biological Diversity news release reported.

This land would be in regions such as "the Gila/Mogollon complex in Arizona and New Mexico, Utah's Uinta Mountains, California's Sierra Nevada and the Grand Canyon in Arizona," the news release reported.

The effort could restore today's grizzly population in the lower 48 from no more than 1,800 to 6,000 bears.

"Grizzly bears are one of the true icons of the American West, yet today they live in a paltry 4 percent of the lands where they used to roam," said Noah Greenwald, the Center's endangered species director. "We shouldn't be closing the book on grizzly recovery but beginning a new chapter - one where these amazing animals live wherever there's good habitat for them across the West."

The petition asks the service to revise its 1992 recovery plan to fit more recent research. New research suggests grizzly bear populations may not be as resilient in the face of factors such as "climate change, invasive species, human population growth, and related conflict and mortality," as researchers previously believed, the news release reported.

The agency has only developed recovery strategies for six grizzly populations so far.

"The good news is that with the safety net of the Endangered Species Act, the health of Yellowstone and Glacier area grizzly bears has improved - but it's way too early to declare victory and walk away," Greenwald said. "All remaining populations are isolated, especially Yellowstone. Yet the science is clear that, if we're serious about recovering grizzly bears, we need more populations around the West, and more connections between them, so they don't fall prey to inbreeding and so they have a chance of adapting to a warming world. If we want these incredible bears around for centuries to come, we've still got a lot of work left to do."