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.