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Reared Poweshiek skipperling. Photo courtesy of Erik Runquist/Minnesota Zoo.

Reared Poweshiek skipperling. Photo courtesy of Erik Runquist/Minnesota Zoo.

Stopping Extinction of a Prairie Butterfly – Poweshiek Skipperling

Poweshiek skipperlings are blinking out fast. Since they only live in native prairies that have never been plowed, one might not find this too surprising. But until very recently, Poweshiek skipperlings were the most frequently and reliably encountered prairie-obligate skipper in Minnesota (Dana 2008).Yet, between 2003 and 2015, surveyors observed an abrupt and rapid decline as population after population was lost. Even in Minnesota and South Dakota - once considered the species’ stronghold, all were lost. Surveyors can no longer find Poweshiek skipperlings at nearly 300 previously known locations. The skipperling appears to survive only in very low numbers at one site in Wisconsin, one location in Manitoba and a few prairie fens in a single Michigan county. Today there are far fewer Poweshiek skipperlings in the world than there are wild giant pandas.

Prairie loss and degradation led to the initial decline of Poweshiek skipperlings, but causes of the recent sharp decline remain a mystery. We suspect several threats may be responsible, such as an unknown disease or parasite, climate change or use of pesticides. Research has begun in an effort to narrow down the cause or causes of the decline.

We listed the Poweshiek skipperling as endangered in 2014, so recovery is in its infancy. Because of the very limited populations that remain, we believe both off-site conservation strategies (strategies not conducted in habitat where the butterfly is currently found) and on-site management and research are needed immediately to prevent extinction. We participated in a workshop in October 2015 facilitated by the Conservation Breeding Specialist Group at the Minnesota Zoo, part of the Species Survival Commission of the International Union for Conservation of Nature, with a 30-year history of worldwide threatened species conservation efforts. The group has guided challenging conservation planning for other critically imperiled species such as the Indian rhino, the giant panda and the Hainan gibbon.

The workshop group recommended that a head-start program for the Poweshiek skipperling begin in 2016 using eggs from two wild populations in Michigan. Staff from the Minnesota Zoo will collect eggs from a portion of adult females observed during the flight period. The adult butterflies then will be released back to the capture site within 48-72 hours, where they can continue laying eggs in the wild. The collected eggs will be reared over the winter at the Minnesota Zoo, and then released in spring 2017 as late-instar larvae or pupae back at the egg collection site in Michigan. The idea behind a head-start program is that captive-reared eggs will have a much higher rate of survival than the very low survival rate expected in the wild. In the future, if large numbers of larvae survive the head-start program, it will trigger a decision whether to reintroduce those larvae to extirpated sites and if an insurance program is needed.

While carrying out the head-start program, research on captive breeding and husbandry techniques will be conducted using a species closely related to Poweshieks (i.e., surrogate species research). If the surrogate research is successful, a long-term insurance program may be created using captive-reared individuals. Additional research will occur at current and extirpated Poweshiek sites to determine suitability for future reintroductions.

We hope the head-start program will add to existing populations and that simultaneous research on captive rearing methods will provide for future reintroductions. Through these programs and strategies, our ultimate goal is to bolster existing populations and restore populations that have been lost. The existence of the Poweshiek skipperling depends on it.

By Tamara Smith
Twin Cities Ecological Services Field Office

Last updated: June 8, 2020