Schlicht, D. 1997b. Population monitoring for prairie butterflies in Minnesota. Final report submitted to the Natural Heritage and Nongame Research Program, Minnesota Department of Natural Resources. Unpaged.
A project of population monitoring for three rare species of prairie butterflies (Dakota Skipper, Hesperia dacotae; Poweshiek Skipper, Oarisma poweshiek; and Regal Fritillary, Speyeria idalia) was established at six prairie preserves in Minnesota. Each site was visited three times during the flight periods in 1995 and 1996. Qualitative comparison of data suggests that while population numbers for S. idalia and O. poweshiek changed little overall, H. dacotae may have fared somewhat better in 1996 at Prairie Coteau but were down at Bluestem Prairie.
Phenological differences among the three species made it difficult to insure that monitoring would include peak flight periods for all three species during each year. In addition, vagaries of weather shifted the phenologies of all three species among the two years. Further development will be necessary to establish the means by which comparability among years can be improved, but the similarity of data between years suggests that with slight adjustment, the established protocol provides a reasonable means for monitoring these prairie butterfly populations.