Hill prairie butterflies of Allamakee County, Iowa: A comparison of the late 1980s to 2013

Between 1987 and 1990, over 345 butterflies representing 69 species were collected by John Nehnevaj from hill prairies and fens in Allamakee County, Iowa.  Nehnevaj’s collection includes several species of butterflies that have not been recorded in Iowa since his study, and 14 species listed in Iowa as species of greatest conservation need (SGCN).  The goal of this study was to revisit sites surveyed in the 1980s and several additional sites to compare the species present in 2013 to the species found by Nehnevaj. Twelve sites were surveyed 4 to 7 times between June and September 2013 using a modified Pollard walk technique.  Over 2,500 butterflies representing 60 species were found, eight of these were SGCNs, including the hickory hairstreak and Leonard's skipper, species not found in the 1980s, and the ottoe skipper and Baltimore checkerspot, species also found by Nehnevaj.   Species richness for the sites ranged from 13 to 32 species, with SGCNs found at 11 of the 12 sites.  Significant landscape changes have occurred to hill prairies in Allamakee County over the past 25 years, including invasion by red cedars that have reduced hill prairie size and increased use of fire for management at some sites formerly managed by grazing.  These changes in land use may have contributed to the overall decrease in species richness. This research provides valuable information about the current status of butterflies present on Northeastern Iowa hill prairies, information that can be used in directing future land management and conservation efforts.