Senior U.S. District Judge William Stafford issued the order, which could lead to putting habitat for the St. Andrew Beach Mouse off-limits to human encroachment.
The U.S. Fish and Wildlife Service had voluntarily agreed to reconsider its decision after being sued by the Center for Biological Diversity and losing several similar cases in regard to other species, agency spokesman Tom MacKenzie said.
An estimated 300 to 500 of the nocturnal beach mice live in dunes mostly in the St. Joseph Peninsula State Park on Cape San Blas, a remote sand spit about 35 miles south-east of Panama City.
Habitat designation could result in prohibiting development or other action to mitigate harm to the mice such as requiring that cats be kept off the beach and revising plans to protect areas where the rodents live, MacKenzie said.
The environmental group accused the federal agency of failing to comply with the Endangered Species Act by refusing to specify habitats critical to the species' recovery or measures that should be taken to preserve those areas. Stafford ordered the agency to complete its reconsideration by Sept. 30, 2006.
The Fish and Wildlife Service has resisted habitat designation in many cases because it is expensive and officials believe limited dollars could be better spent in other ways to protect endangered and threatened species, MacKenzie said.
The agency would have to come up with additional evidence to again find that the beach mouse habitat designation is "not prudent," he said.
Environmentalists say the mice are threatened by development, erosion, and vehicle damage to the dunes.
"The beach mouse has waited too long for habitat protection and its population has suffered as a result," said Earthjustice lawyer Monica Reimer, who represented the center.