In only the last two decades, populations of a tiny prairie butterfly called the Poweshiek skipperling have disappeared from the heart of their native habitat, the vanishing prairie of the upper American Midwest. Historically found as far west as the Dakotas, as far east as Michigan, and north into Canada, the Poweshiek skipperling is now known only to exist in small isolated prairie fragments in southeastern Michigan and in far southern Manitoba, Canada. In 2015, the U.S. Fish and Wildlife Service listed the Poweshiek skipperling as endangered under the U.S. Endangered Species Act. A partnership, which met last week with CPSG at the Minnesota Zoo, is working together to sustain the last of the skipperlings and, hopefully, grow their numbers in the wild.
The Minnesota Zoo and other members of the partnership have, for a number of years, been “headstarting” Poweshiek skipperlings. Biologists collect eggs from wild females, hatch and raise the caterpillars in captivity, and release the adults back into the wild. This way, individuals are able to survive to a stage in which they are less vulnerable to threats to their survival, and more likely to produce their own offspring.
CPSG is supporting the partnership by contributing its expertise in species population modeling to help focus conservation efforts to save the Poweshiek skipperling. Using a software program called Vortex, CPSG carried out a population viability analysis (PVA). With data from species experts, CPSG used Vortex to model changes in the Poweshiek population abundance over time. With these models, CPSG estimated the probability and timing of the species going extinct or recovering. These estimates help those working to save the butterflies understand how different factors influence the skipperlings’ annual rate of reproduction and survival.
Most importantly, PVA allows conservationists to test different management strategies to reduce the chance of extinction. With Poweshiek skipperlings, for example, experts can evaluate how headstarting benefits the species’ ability to reproduce and how this might impact their recovery. This kind of testing is planned for a future meeting of the Poweshiek skipperling conservation partners.
Nearly 30 attendees from 12 organizations representing local, state, and federal governments, academia, and conservation in two countries participated in the meeting, sponsored by the U.S. Fish and Wildlife Service and hosted by the Minnesota Zoo. Thank you to all participating organizations, including the Assiniboine Park Zoo, Environment and Climate Change Canada, Michigan Natural Features Inventory, Michigan Nature Association, Minnesota Department of Natural Resources, Minot State University, Nature Conservancy of Canada, North Oakland Headwaters Land Conservancy, Springfield Township, and Wisconsin Department of Natural Resources.
Photo credit: Vince Cavalieri, USFWS