The Prevalence and Status of Conservative Prairie and Sand Savanna Insects in the Chicago Wilderness Region

The identification and inventory of remnant-dependent or conservative species is an essential prerequisite to sound reserve selection and management in severely fragmented regions. We expanded an ongoing study of insect conservatism to include approximately 1200 additional species on 50 prairie and savanna remnants in the Chicago Wilderness Region (CW). Approximately 700 surveys were conducted from 1995 to 2006, with special emphasis placed on 15 high quality reserves. Our objectives were to: (1) gauge the prevalence of conservatism among remnant-inhabiting insects; (2) determine the status of each conservative species' and (3) gauge the extent that small, isolated sites contribute to the preservation of biodiversity in this landscape. Seventeen percent of 2424 species considered were determined to be narrowly associated with remnant habitats, suggesting that the overall prevalence of conservatism among CW insects is low. One hundred and seventy nine (44%) of these species were rarely or never encountered and are considered to be of conservation concern. Species richness for 15 high quality sites of 2 to 600 ha in area ranged from 39 to 167 species, demonstrating that small, isolated sites contribute appreciably to the preservation of biodiversity in this fragmented landscape. A comparison of vulnerable insect, plant, and vertebrate species richness suggests that conservative insect species far outnumber conservative plant and special-concern vertebrate species, and given their apparent rarity, should play a pivotal role in the establishment of conservation priorities within the CW and probably throughout much of the midcontinental United States.