Because of climate change, the remaining populations of the Karner blue could face the same fate — unless state and federal wildlife officials move the butterfly farther north. But the U.S. Fish and Wildlife Service, which oversees plants and animals listed under the Endangered Species Act, prohibits the relocation of endangered species outside their historic range.

That could be on the verge of changing.

Soon, the federal agency is expected to issue a final rule that would empower wildlife officials to relocate species marooned on shrinking climate islands, a tactic known as assisted migration.

Wildlife managers in Michigan and some other states, along with many environmental organizations and some wildlife scientists, believe it makes sense to relocate species that might be killed by warming temperatures, sea level rise, droughts and wildfires. But other states, backed by other wildlife scientists, fear the proposal could lead to disaster.

‘A very risky experiment’

In Arizona, state biologists have long worked with federal officials to bring back the Mexican gray wolf, a species native to the Southwest with only a few hundred individuals remaining in the wild. Some conservation groups want the wolves introduced farther north than they are currently found.

“The Mexican wolf is the best example of why this [proposed rule change] is a bad idea,” said Jim Heffelfinger, wildlife science coordinator with the Arizona Game and Fish Department. “Taking animals outside of the ecological and evolutionary pressures that shaped them is a very risky experiment.”

Heffelfinger and his colleagues fear the rule change could be used to establish the wolves in northern Arizona, where they could interbreed with other wolf species, causing “genetic swamping” that would further imperil the species.

“It basically becomes an exotic species in that new habitat and may have very harmful impacts on existing species that have not evolved together to adapt,” said Jim Odenkirk, general counsel with the Arizona agency.

Some conservation groups dispute the state’s assertions, arguing that habitat to the north is needed to support a growing population of wolves. The fierce divide over where the wolves belong could be a preview of the fights to come.

Some states have expressed general support for the need to relocate species while also raising concerns about specific elements of the proposal — often calling for more state involvement.

Neither is a ‘great’ choice

Federal officials already have some power to move species. Under a provision of the Endangered Species Act, federal wildlife managers can introduce experimental populations of plants and animals in areas where they previously lived.

Fish and Wildlife Service officials say they have used that provision to establish 73 experimental populations, representing 47 species. The National Marine Fisheries Service has also reintroduced some marine species under that authority.

The law also allows for such introductions to happen outside a species’ historic range, but only in rare circumstances in which its original habitat has been “unsuitably and irreversibly altered or destroyed.” The agency is proposing to use that exemption to relocate, for example, the Guam kingfisher to a new habitat, helping it escape an invasive snake that threatens the bird’s survival in its historic territory.

Some states say that wording gives the agency the authority to help imperiled species. But the new proposal would allow species to be moved before their habitat is completely lost, giving wildlife managers a head start against the oncoming threats of climate change.

“If we wait until the species’ habitat is underwater, it’s too late,” said Elise Bennett, Florida director and senior attorney with the Center for Biological Diversity, an environmental advocacy group.

Some wildlife researchers say they see the need for the rule change, but they also see how it could go wrong.

“You either have to allow for species to go extinct because they’re no longer compatible where they are or move them to a new area where they may turn into an invasive species or cause other kinds of problems,” said Alejandro Camacho, faculty director for the Center for Land, Environment and Natural Resources at the University of California’s Irvine School of Law. “Neither of those choices are great.”

While Camacho and others have expressed cautious support for the proposal, some believe it’s likely to cause more problems than it solves.

“To do a serious risk assessment would take about a doctoral dissertation’s worth of research, and they’re not going to spend that kind of money or take that kind of time to do that,” said Dan Simberloff, an environmental science professor at the University of Tennessee.

Even if the rule is changed, said Jessica Hellmann, executive director of the University of Minnesota’s Institute on the Environment, the number of species threatened by climate change far outweighs the resources and political will to relocate them.

“It will undoubtedly be pursued for some species but not others,” Hellman said.

Regardless of the feds’ decision, the conversation is probably just beginning.

“In order to save some species, you have to look outside of where they’ve been — unless you give up on the species, and none of us want to do that,” said Kyle Briggs, chief deputy director of the North Carolina Wildlife Resources Commission. “But you can’t put a species somewhere it’s never been and not expect some level of impact.”

Stateline is part of States Newsroom, a national nonprofit news organization focused on state policy.