Wetland and upland use patterns in semi-aquatic snakes: Implications for wetland conservation

Conservation efforts require detailed knowledge of a species' habitat use and movements about the landscape. We radio-tracked sympatric congeners,,the Copperbelly Water Snake (Nerodia erythrogaster neglecta) and the Northern Water Snake (Nerodia sipedon sipedon) in northwestern Ohio and southern Michigan, USA, to investigate differences in the use of wetland and upland habitats between species. Nerodia erythrogaster neglecta used twice as many wetlands (4.1 +/- 0.4) as N. s. sipedon (2.1 +/- 0.3), moved between these wetlands three times more often (9.1 +/- 1.9 times) than N. s. sipedon (2.8 +/- 1.0 times), and moved to small wetlands seven times more often (3.6 +/- 0.7 times) than N. s. sipedon (0.5 +/- 0.3 times). Nearly 30% of N. e. neglecta locations were in uplands, sometimes over 100 m from the nearest wetland. Less than 3% of N. s. sipedon locations were in upland habitats, and all locations were < 30 m from wetlands. We simulated the impact of small wetland loss and demonstrated that N. e. neglecta would need to move longer than normal distances when traveling between wetlands after small wetlands are lost, while N. s. sipedon would not. The northernmost populations of N. e. neglecta are listed as federally threatened and state endangered in Ohio, Michigan, and Indiana; N. s. sipedon remains abundant in this region. Historic and current wetland losses in the midwestern United States may have severely impacted N. e. neglecta populations due to this species' high vagility and use of numerous wetlands. Protection and restoration of wetland landscapes are critical for the long-term persistence of many wetland-associated species, including N. e. neglecta.