Vanishing Prairies Endanger Butterflies

WASHINGTON (CN) - Disappearing prairie habitat threatens two small brown and orange butterfly species that have been proposed for protection under the Endangered Species Act. The U.S. Fish and Wildlife Service has proposed threatened status for the Dakota skipper and endangered status for the Powershiek skipperling in a recent action, which also includes a special rule. Critical habitat has been proposed in a separate action.

The listing proposal is part of the agency's court-approved five-year workplan that resulted from a 2011 settlement with the Center for Biological Diversity (CBD) to fast track listing decisions for 757 species across the country.

Once found in native prairies in five U.S. states and two provinces in Canada, the Dakota skipper is now only found in remnants of native prairie in parts of North and South Dakota, Minnesota, Manitoba and Saskatchewan. It is locally extinct in Iowa and Illinois.

The Poweshiek skipperling has experienced even more significant declines, and is believed to have disappeared from nearly 90 percent of its historic sites. Once common through prairies in eight states and in Manitoba, it is now found only "at a few native prairie remnants in two states and one location in Manitoba, Canada," according to the action.

"Protecting the last high-quality prairie habitats for the skipper will keep these special places safe, along with the plants and animals that need them to survive," Tierra Curry, a conservation biologist with the CBD, was quoted as saying in the group's response to the proposal.

Conversion and fragmentation of tallgrass and mixed-grass prairie began in 1830. The U.S. and Canadian prairies have vanished under the plow for agriculture, under concrete for housing and under asphalt for roads. Gravel mining, energy development, and even wind farms continue to claim the butterflies' habitat because they contribute to the bisection of the region with access roads. There is evidence that the skipperling does not cross roads, the action noted.

In addition, roads and other human-caused changes to the prairie create opportunities for invasive non-native plants to take hold, crowding out the nectar-plants and native grasses the butterflies need.

"Exotic cool season grasses, such as Kentucky bluegrass and smooth brome, are not growing when Dakota skipper and Poweshiek skipperling larvae are feeding, thus a prevalence of these grasses reduces food availability for the larva," the action said.

Other threats include pesticide use, fire pattern alteration, drought, groundwater reduction and climate change.

The listing proposal includes a special rule in the case of the Dakota skipper. The Endangered Species Act (ESA) provides for special rules for animals listed as threatened. "The special rule would allow incidental [harm] of Dakota skippers as the result of routine ranching activities such as construction of fences, corrals and watering facilities; haying and mowing; and in some areas, grazing," the agency noted in its press release.

In a separate action, the USFWS has proposed to designate 54 tracts, ranging from 31 acres to 2,887 acres, in North and South Dakota and Minnesota as critical habitat for the Dakota skipper, and 63 tracts, from 23 acres to 2,887 acres, in Iowa, Michigan, Minnesota, North and South Dakota and Wisconsin as critical habitat for the Poweshiek skipperling. Some of the critical habit of one butterfly overlaps the other's.

Comments on both actions are due Dec. 23. The USFWS has also scheduled five informational meetings.

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