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Twin Cities Field Office biologist Phil Delphey searches for endangered Poweshiek skipperlings at a Wisconsin prairie. Photo by Tamara Smith/USFWS.

Twin Cities Field Office biologist Phil Delphey searches for endangered Poweshiek skipperlings at a Wisconsin prairie. Photo by Tamara Smith/USFWS.

Looking for Endangered Poweshieks

Staff from the Twin Cities Field Office joined staff from the Wisconsin Department of Natural Resources to survey for the Poweshiek skipperling, a federally endangered butterfly now thought to be present only in Wisconsin, Michigan and Manitoba. Employees spent several days conducting transect surveys, over the course of the butterfly's short flight period, in native prairie remnants in eastern Wisconsin.

The Poweshiek skippering, a small brown butterfly with a wingspan of about one inch, was once abundant in native prairie remnants (untilled areas) in Indiana, Illinois, Iowa, Manitoba, Michigan, Minnesota, North Dakota, South Dakota and Wisconsin. However, this butterfly has been extirpated from Illinois and Indiana and has not been observed in the Dakotas, Minnesota and Iowa within the last several years. It is now known only from Wisconsin, Michigan and Manitoba. Despite extensive surveys in 2014, the species was only found, in very low numbers, at one site in Wisconsin, at a single site in Manitoba, and a few sites in a single Michigan county. The Service, Wisconsin Department of Natural Resources and our counterparts conducting surveys in Michigan and Manitoba hoped to have better luck finding the species this year.

Prior to 2003, the Poweshiek skipperling was once so abundant that it was regarded as ‘‘the most frequently and reliably encountered prairie-obligate skipper in Minnesota’’ (Dana 2008). In North Dakota, Poweshiek skipperling could ‘‘be collected two at a time on the blossoms of Longheaded coneflower ” (McCabe and Post 1977). Since 2003, however, the species was encountered less frequently, and then not observed at all, at nearly 300 of the locations where the species was once documented.

What happened?

Loss and degradation of native prairie habitats led to the initial decline of the species from its historical levels, but the causes of the recent sharp and widespread decline largely remain a mystery. There are several suspected stressors that may be acting on the species independently or cumulatively. The species may be affected by an unknown disease or parasite, for example. It is also possible that one or more pesticides could be contributing to the decline. Research has been initiated on several fronts to narrow down the cause of decline. At the same time, research has also begun on captive rearing methods to head-start populations and for future re-introductions or augmentations of existing populations. The Poweshiek skipperling was listed as endangered under the Endangered Species Act in 2014, while another Midwestern prairie butterfly, the Dakota skipper, was listed at the same time as threatened.

Although no Poweshieks were found at one site and only a handful were found at a second site in Wisconsin, we hope that the federal protections, the knowledge gained from research and conservation efforts of our state and local partners and citizens, will help prevent the Poweshiek skipperling from disappearing altogether. For more info on the Poweshiek skipperling, please visit: http://www.fws.gov/Midwest/endangered/insects/posk/index.html

By Tamara Smith

and

Kelly Nail
Both Twin Cities Ecological Services Field Office

While no Poweshiek skipperlings were found during recent surveys in Wisconsin, other prairie butterflies, like this Baltimore checkerspot, were spotted. Photo by Tamara Smith/USFWS.

While no Poweshiek skipperlings were found during recent surveys in Wisconsin, other prairie butterflies, like this Baltimore checkerspot, were spotted. Photo by Tamara Smith/USFWS.

 

Citations:
Dana, R. 2008. Southwest Minnesota prairie Lepidoptera study, 2007 - Draft., Minnesota Department of Natural Resources - Minnesota County Biological Survey, St. Paul, MN.

McCabe, T. L., and R. L. Post. 1977. Skippers (Hesperioidea) of North Dakota. North Dakota Insects Publication No. 11, Department of Entomology, Agricultural Experiment Station, North Dakota State University.

 

Last updated: August 3, 2015