Nine years ago, a team of scientists studying a violet-blue, thumb-sized butterfly found only two remaining in a rolling landscape of dunes along southern Lake Michigan.
The last two Karner blue butterflies ever seen in that area emerged two years after an unusually hot spring wiped out most of their ancestors. The warmth caused the caterpillars to hatch from their eggs early, before the lupine plant they eat had emerged from the soil.
Just like that, the southernmost population of the endangered butterfly was gone.
The Karner blue already has lost 99.98% of its habitat. The refuge in Indiana Dunes National Park once had provided the template for efforts to save the insect, but now wildlife managers are looking north.
The remaining populations of the Karner blue face the same fate as their southern cousins. Because of climate change, the butterfly may not be able to survive in its current territory within 30 to 40 years.
“Even if there was a solid line of lupine and habitat going north, they wouldn’t be able to keep up,” said Chris Hoving, climate adaptation specialist with the Michigan Department of Natural Resources. “They just don’t fly fast enough.”
So, Hoving and other wildlife managers nationwide are asking an increasingly urgent question: Should species that might be killed by warming temperatures, sea level rise, droughts and wildfires be moved to places they’ve never lived before?
State and federal wildlife officials want to consider moving the Karner blue north, but federal rules stand in the way. 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 historical range.
That’s on the verge of changing.
In the coming weeks, the federal agency is expected to issue a final rule that would empower wildlife officials to relocate species marooned on shrinking “climate islands.” The proposal, first released a year ago, would allow those species to be moved to areas deemed more suitable for their survival, a tactic known as assisted migration.
“We’re looking at climate change and the rapid spread of invasive species that are imposing increasing threats on native biodiversity,” said Elizabeth Maclin, division chief for restoration and recovery with the U.S. Fish and Wildlife Service. “This proposed rule would allow us to, where we need to, establish experimental populations outside of historic ranges.”
Wildlife managers in Michigan and some other states, along with many environmental organizations and some wildlife scientists, believe the change is desperately needed to give many species a chance to survive a warming planet. 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 the feds 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’re currently found — with ongoing disputes over the wolf’s historic range.
“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. “There’s a whole host of unforeseen, unintended and irreversible ecological consequences of people moving species around. 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 Mexican wolves in northern Arizona. They fear the relocated Mexican wolves could interbreed with other wolf species in that area, causing “genetic swamping” that would further imperil the species. And the wolf’s introduction might damage the wildlife that already calls that region home.
“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. “The negative impacts may outweigh the conservation benefits.”
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.
Much like Michigan and Arizona, some state wildlife agencies have taken widely diverging views on the feds’ proposal. Other states have expressed general support for the need to relocate species but raised concerns about specific elements of the proposal — often calling for more state involvement on such decisions. As they await a final decision, wildlife managers, scientists and environmental activists are still grappling with what the change would mean.
‘Neither of those choices are great’
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. The Fish and Wildlife Service has 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 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. “If we don’t open this opportunity up, some species are going to just disappear.”
Some conservationists have noted that while species naturally migrate over time, climate change is altering conditions faster than they can move, and development and human-made obstacles may block their migration corridors.
“Ranges aren’t set in stone, but we’ve changed so much of the planet that species can’t adopt range shifts like they used to be able to do, so they might need help,” said Andrew Carter, director of conservation policy with Defenders of Wildlife, a conservation 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, 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.
“They are acting as if they can handle the threat of unintended consequences that we see all the time with invasive species,” said Dan Simberloff, environmental science professor at the University of Tennessee. “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.”
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’s just a massive amount of effort if we thought about applying it at scale,” she said. “It will undoubtedly be pursued for some species but not others. It’s not a pathway for conservation for all species.”
As they await a final announcement, researchers and wildlife officials say regardless of the feds’ decision, the conversation is likely 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.”
- 1973: Endangered Species Act passed by Congress.
- 1982: Amendments to the act allow for the introduction of “experimental populations” of endangered species in areas where they used to be found.
- 2022: The U.S. Fish and Wildlife Service proposes a rule change that would allow for experimental populations to be established outside of their historic range, noting that the act’s initial wording did not anticipate the effects of climate change.