Northern Prairie Wildlife Research Center
Center for Medical Education, University School of Medicine, Ball State Indiana University, Muncie, IN 47306; Humboldt State University, Department of Biology, Arcata CA 95521; Iowa Department of Natural Resources, Kettleson Hogsback Management Area, Rural Route Box 7244, Spirit Lake, IA 51360; Iowa Lakes Community College, Department of Biology, 300 South 18th Street, Estherville, IA 51334
We repeated Blanchard's 1920 survey of the amphibians of Dickinson County, Iowa. Five species reported by Blanchard persist: the eastern tiger salamander (Ambystoma tigrinum), the American toad (Bufo americanus), the western chorus frog (Pseudacris triseriata), the grey treefrog (Hyla versicolor), and the northern leopard frog (Rana pipiens). Two species reported by Blanchard were not found: the mudpuppy (Necturus maculosus) and, ironically, Blanchard's cricket frog (Acris crepitans blanchardi). We collected two species not found by Blanchard: the Great Plains toad (Bufo cognatus) and the bullfrog (Rana catesbeiana). The Great Plains toad appears to have migrated into Dickinson County from the west. The bullfrog was introduced by state fisheries biologists. From descriptions of the turn-of-the-century commercial "frogging" industry in Dickinson County, we estimate that the number of leopard frogs has declined by at least two, and probably three, orders of magnitude, reflecting the loss of wetland habitat. Most of the remaining wetlands in this county are now protected. In our opinion, the most immediate threat to the existing populations of native amphibians will come from the impact of the introduced bullfrog.