For one butterfly, Michigan may be its last, best hope

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By ERIC FREEDMAN
Capital News Service

LANSING – Going! Going! Soon gone?

That may be the plight of the endangered, awkwardly named Poweshiek skipperling butterfly, now known to survive in the wild in only two places on earth, Michigan and Manitoba.

A new study estimates that only 231 adults survive in Michigan, all in three prairie fens – a type of biologically diverse wetland community – in Oakland County. It is what scientists label the butterfly’s “last remaining stronghold” in the world.

Back in 1995, the butterfly was “so abundant that you’d see so many of them you almost couldn’t count them,” said plant biologist Anna Monfils of the Institute for Great Lakes Research at Central Michigan University. 

Even eight or 10 years ago, butterfly conservation biologist Erik Runquist of the Minnesota Zoo, who was not part of the study, said, “You could go to some of these sites and see 200 in an area the size of a parking lot without even an effort.”

Today, Monfils said, “in terms of urgency, it’s in the ER (emergency room) and we’re trying to keep the patient alive.”

The U.S. Fish & Wildlife Service says the Poweshiek skipperling may have been wiped out in Minnesota, Iowa and the Dakotas which “until recently contained the vast majority of the surviving populations.” 

A 2016 survey counted 104 of them at four Oakland County sites, five at two sites in Manitoba and two at a Wisconsin site, but a later survey spotted none in Wisconsin.

Scientists don’t know for certain what caused the calamitous crash of the Poweshiek skipperling. They speculate that habitat destruction and fragmentation, disease, loss of genetic diversity, climate change and weather variations, invasive woody plants that damage biodiversity, insecticides and prescribed fire may be to blame.

Monfils said, “We can look at it as a canary in the coal mine – for them to crash so drastically indicates something is going on. Could this be an indicator of other dynamics causing problems across the landscape and what is happening with other species?”

The Minneapolis Zoo where Runquist works is the only place in the United States where efforts are underway to rear the Poweshiek skipperling from eggs collected from wild females in Michigan and to release them into an Oakland County site in Springfield Township. 

Fish & Wildlife Service funding for the “managed population” project comes from the Great Lakes Restoration Initiative. 

The program released two adults in 2018 and 14 this year. And although the numbers seem small, they are significant, Runquist said. “When we’re seeing only 50 there for the whole year that might be a pretty good percentage.”

The goal is to increase survivorship and to produce more butterflies than would be produced in the wild, he said. 

“We’re trying to add adults back” who will breed in the wild, Runquist said. “There are so few of them left. We’re trying to keep it from going extinct in the short-term.” 

Meanwhile, the Assiniboine Zoo in Manitoba is undertaking a similar rear-and-release program.

It’s difficult to accurately estimate the abundance or scarcity of rare butterflies in general, according to the study by Monfils and her coauthors from the Michigan Natural Features Inventory and the Florida Museum of Natural History.

As for the Poweshiek skipperling, the study in the Journal of Insect Conservation said “numerous knowledge gaps” about their biology and ecology “limit the potential success of conservation efforts in and out of the wild. Critical knowledge gaps are limiting the ability to manage this federally endangered species.”

For example, Monfils said scientists don’t know where it lays its eggs and “don’t know a lot about its life stages. Meanwhile, the tiny populations make it difficult to observe its behaviors.”

“We just need to get out there and get eyes on these insects and see what they are doing, what their routines are like,” she said.

Referring to the Oakland County fens, the study said efforts to protect the sites “must remain a management priority for the survival of this species.”

Runquist emphasized the larger environmental significance of restoring the Poweshiek skipperling population, calling it a “flagship species” whose fens habitat is important for songbirds and game birds, as well as for natural filtration of water. 

“The water we drink will come through these fens and prairie systems and will improve our quality of life,” he said. 

Credit: U.S. Fish & Wildlife Service