Paradoxes of poweshiek skipperling (Oarisma poweshiek)(Lepidoptera: Hesperiidae): abundance patterns and management of a highly imperiled prairie species

Published source details Swengel A.B. & Swengel S.R. (2014) Paradoxes of poweshiek skipperling (Oarisma poweshiek)(Lepidoptera: Hesperiidae): abundance patterns and management of a highly imperiled prairie species. International Scholarly Research Notices.
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This study is summarised as evidence for the following.

	Action	Category
	Use prescribed fire to maintain or restore disturbance in grasslands or other open habitats Action Link

Use prescribed fire to maintain or restore disturbance in grasslands or other open habitats

A replicated, site comparison study in 1988–1997 in 37 tallgrass prairies in Iowa, Minnesota and North Dakota, USA (Swengel and Swengel 2014) found that after burning, haying and idling management, Powershiek skipperling Oarisma poweshiek abundance differed depending on site vegetation characteristics. In undegraded uplands with diverse vegetation, by one type of average (mean) Poweshiek skipperling abundance was higher at sites managed with burning (17 butterflies/km) than haying (4 butterflies/km) or those left idling (3 butterflies/km), but by another type of average (median) abundance was lower at sites with burning (0 butterflies/km) than haying (2 butterflies/km) or idling (3 butterflies/km). However, in undegraded moist prairie, abundance was lower at sites with burning (0–7 butterflies/km) than haying (2–11 butterflies/km) (no data was provided for idling sites). In undegraded uplands with burning management, abundance was highest two to six years after burning (22–36 butterflies/km), and lowest in the year of burning up to three years after burning (0–3 butterflies/km). Butterfly and habitat management surveys were conducted at 37 sites in northern Iowa, western Minnesota and eastern Dakota in June–August 1988–1997. Not all sites were surveyed for the whole period or every year. Surveys were of varying lengths and conducted simultaneously along one set of parallel transects (5–10 m apart) in each site. These butterfly counts were combined with a butterfly survey dataset from another researcher team, which overlapped in location, and adjusted to account for differences in survey methods (survey details and sites for this dataset were not provided).

(Summarised by: Eleanor Bladon)