Minnesota

Prairie Butterflies

Protecting a Home on the Prairie for Rare Butterflies

On a ridgetop prairie in Minnesota, a tiny brown butterfly with big eyes and a few tawny-orange and white spots on its front wings flits among the purple coneflowers sipping nectar from one flower, then another. Periodically, she stops to lay an egg on the underside of a leaf.

This natural phenomenon which occurred each summer on prairies throughout the region has become extraordinary in recent years.

Once numbering in the millions, today Dakota skippers have almost disappeared from the tallgrass prairies of Minnesota, North Dakota, South Dakota and other parts of the Midwest. In Minnesota, the they can still be found at one site, possibly two. And they are not the only casualties. Poweshiek skipperlings, another prairie butterfly, can no longer be found in 96 percent of their historic range; where they do occur, they are also in decline. Half of the Poweshiek’s range was in Minnesota, but it has not been seen in the state since 2008.

Disappearing Butterflies a Mystery

Butterflies like the Dakota skipper and Poweshiek skipperling need high-quality prairie to survive. Unlike monarch butterflies, they do not migrate. They spend the winter in our prairies as caterpillars, either at or just below ground level, or in the case of Poweshieks, sitting on grass stems. In the spring, the caterpillars feed on prairie grasses and sedges, eventually pupating and becoming adult butterflies that nectar on prairie wildflowers.

Prairie butterflies lost most of their habitat at the time of settlement when it was converted to agricultural and other uses. Nonetheless, they managed to hang on until recently in high-quality prairie remnants, some of the best of which were protected by The Nature Conservancy.

In the early 2000s, prairie butterflies began to disappear rapidly. Dakota skippers are now listed as a federally threatened species; Poweshiek skipperlings are federally endangered. Ten of the 15 butterflies on Minnesota’s Endangered, Threatened and Special Concern list are prairie butterflies.

The reason for the precipitous decline of these butterflies over the past decade or two is a mystery.

“Dakota skippers and Poweshieks live in a harsh environment,” said Dr. Robert Dana, Butterfly Conservation Biologist with the Minnesota Department of Natural Resources. “They deal with drought, freezing temperatures and wildfire, yet they have managed to survive in our prairies for millennia.”

So why are they declining again despite efforts in recent years to protect and restore prairie habitat? There are no concrete answers, but there is speculation that a number of things could be going wrong.

“These little butterflies and other insects can definitely tell us about the overall health of our prairie landscapes,” said Marissa Ahlering, the Conservancy’s prairie ecologist in Minnesota, North Dakota and South Dakota. “Something is wrong, but we’re not sure exactly what. Possibilities include the fragmentation of our prairies, which isolates populations of butterflies from each other; pesticide drift from spraying on neighboring lands; and poor management of our remaining prairie remnants.”

Dana also suggested that changes in our climate could play a role: “The prairie has always been an environment of extremes, so you’d think the butterflies would be adapted to these extremes. But combined with the fact that the habitat they rely on is much smaller today than it once was, climate could be impacting them in new ways.”

Butterfly Research and Operation Rescue

Both Dana and Ahlering agree that not enough is known about prairie butterflies and more information is needed. Research takes time, however, and many feel something must be done now so we don’t lose Dakotas and Poweshieks entirely. After discussions with the U.S. Fish and Wildlife Service (USFWS), the Minnesota Department of Natural Resources (MDNR) and others, in 2012, the Minnesota Zoo established a Prairie Butterfly Conservation Program and successfully started breeding Dakota skippers.

The Zoo collects female Dakota skippers from prairies where they are still found, placing them in paper cups with prairie grasses and flowers, giving them time to lay eggs and then releases them back into the wild, all within 72 hours. The eggs are then brought back to the Zoo, where they hatch out into caterpillars and eventually become adult butterflies.

The Zoo is now conducting the first-ever release of Dakota skippers anywhere in the world at The Nature Conservancy’s Hole-in-the-Mountain Prairie preserve in southwestern Minnesota.

Erik Runquist, who directs the Zoo’s butterfly conservation program, said the Zoo has also launched a “head start” program for Poweshieks. “We will collect the eggs as we do with the Dakotas, but we won’t breed them. We’ll raise them to the chrysalis stage and then put them back into the prairies where we collected them. In doing this, we hope to eliminate much of the mortality.”

The Nature Conservancy works with public agencies, farmers, ranchers and communities to protect the best remaining prairie in North America.

“Protecting and restoring our native prairies is essential to the survival of Dakota skippers, Poweshiek skipperlings and other prairie butterflies,” said Marissa Ahlering. “It is their only home.”

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