WASHINGTON (CN) - The North American wolverine and Sonoran desert tortoise should be protected under the Endangered Species Act, but their listing as threatened or endangered is precluded by budget restrictions and higher priority species, according to the U.S. Fish and Wildlife Service.
The "warranted but precluded" decision means that the wolverine and desert tortoise will join a long waiting list of species the agency believes are in trouble but whose protection is prevented by budget limitations and species for whom the threat of extinction is considered the highest. The list is called the Candidate Species List.
However, since 1980, 24 species have gone extinct while on the Candidate Species List, according to the Center for Biological Diversity, and there are currently 234 candidate species waiting for protection under the act.
Wolverines in the contiguous 48 states are most threatened by the impact of climate change on their alpine habitat. Steve Guertin, the Service's Director of the Mountain-Prairie Region, said in a press release that the threat is specific to the wolverine's "denning habitat [which is] especially important to assist the species in successfully reproducing."
"If we work with state and other partners to help the wolverine now, we may be able to counter the long-term impacts of climate change on their habitat and keep them from becoming endangered," Guertin said.
Based on data from the University of Washington Climate Impacts Group and the U.S. Forest Service Rocky Mountain Research Station, the Fish and Wildlife Service predicts a 6 percent decline in the snowy habitat the wolverines need for denning, by 2099.
The Sonoran Desert tortoise lives at the other temperature extreme and thrives where ground temperatures exceed 140° Fahrenheit, by spending 95 percent of its long life-30 to 100 years-in underground burrows.
According to the agency, the most significant threat to the tortoise is the invasion of nonnative plants in its desert scrub habitat which, in addition to displacing the more the 200 native plants the tortoise eats, has made its habitat more vulnerable to damage by wildfires.
The introduction of non-native species may be part of an intentional effort to convert desert habitat to grazing range for livestock. For example, the agency estimates that nearly five million acres of tortoise habitat has been lost to bufflegrass pasture.
Like every species on the Candidate Species List, the wolverine and Sonoran Desert tortoise will be reviewed annually by the agency to determine if its budget and listing priorities will allow either to be listed as threatened or endangered under the act.