Butterflies (Lepidoptera) on Hill Prairies of Allamakee County Iowa: A Comparison of the Late 1980s With 2013

摘要

In the late 1980s, several hundred butterflies were collected by John Nehnevaj from hill prairies and a fen in Allamakee County, Iowa. Nehnevaj's collection included 69 species, 14 of which are currently listed in Iowa as species of greatest conservation need (SGCN). The goal of this study was to revisit sites surveyed in the 1980s and survey three additional sites to compare the species present in 2013 to the species found by Nehnevaj. A primary objective was to document the presence of rare prairiespecialist butterflies (Lepidoptera), specifically the ottoe skipper (Hesperia ottoe W.H. Edwards; Hesperiidae), which was thought to be extirpated from Iowa. Twelve sites were surveyed 4 to 7 times between June and September 2013 using a meandering Pollard walk technique. A total of 2,860 butterflies representing 58 species were found; eight of these species were SGCN's, including the hickory hairstreak (Satyrium caryaevorum McDunnough; Lycaenidae), and Leonard's skipper (Hesperia leonardus Harris; Hesperiidae), species not collected in the 1980s, and the ottoe skipper and Baltimore checkerspot (Euphydryasphaeton Drury; Nymphalidae), both species also found by Nehnevaj. Species richness for the sites ranged from 14 to 33 species, with SGCNs found at11 of the 12 sites. Significant landscape changes have occurred to hill prairies in Allamakee County over the past 25 years. Invasion by red cedar (Juniperus virginiana) has reduced hill prairie an average of 55.4% at these sites since the 1980s, but upto 100% on some of the sites surveyed by Nehnevaj. These changes in habitat may have contributed to the overall decrease in species richness. This study provides valuable information about the current status of butterflies present on northeastern Iowa hill prairies that can be used in directing future land management and conservation efforts.