A RIPARIAN ZONE IN SOUTHERN ILLINOIS AS A POTENTIAL DISPERSAL CORRIDOR FOR REPTILES AND AMPHIBIANS

We surveyed reptiles and amphibians in a core area (Wildcat Bluff/Hero n Pond) and at four sites along the Cache River in southern Illinois, USA, to assess whether the existing riparian zone would serve as a dis persal corridor for these species. Only 14 of the 37 species found in the core area were detected at all sites along the river, and 17 speci es were not found at the three sites furthest downriver from the core area. In contrast to our expectations, wide (greater than or equal to 1000 m) areas of riparian habitat did not support greater numbers of s pecies of reptiles and amphibians than narrow (less than or equal to 1 00 m) areas. Proximity to the core area and local habitat heterogeneit y appeared to best explain species richness at the sites surveyed. Exa mination of the literature on habitat requirements for the species fou nd in the core area suggested that lack of upland habitats and of fish less pools, along with regular inundation of remaining riparian habita t, inhibit many species from occurring consistently throughout the cor ridor. Our results demonstrate the importance of including specific na tural history requirements in the design of corridors, rather than sim ply relying on easy-to-measure parameters such as corridor width, espe cially for species with low vagility. (C) 1998 Elsevier Science Ltd. A ll rights reserved.