In the Owyhee Mountains of southwestern Idaho, we compared the habitat characteristics of sites at which we captured Columbia spotted frogs (Rana luteiventris) and Pacific treefrogs (Hyla regilla) to habitat characteristics of sites without frogs. Our primary objective was to determine if National Wetland Inventory classifications can be used to predict the presence of these species. Adult spotted frogs tended to be at palustrine, shrubscrub, seasonally flooded sites or at intermittent riverine, streambed, seasonally flooded sites they tended not to be at palustrine, emergent, seasonally flooded or at intermittent riverine, streambed, temporarily flooded sites. Spotted frog sites also tended to have more submerged vegetation and algae and less grass and sagebrush; they were more likely to be located at oxbows, pools, or ponds; and they were more likely to have obvious hiding places than were sites without spotted frogs. Sites where treefrog adults were found tended to be lower in willow and higher in grass and emergent and submerged vegetation; they were more likely to be at a pond or pool than were sites without treefrog adults. Treefrog larvae tended to be found at intermittent riverine, streambed, seasonally flooded sites or at palustrine, emergent, seasonally flooded sites; they tended not to be at palustrine, shrubscrub, seasonally flooded sites. Treefrog larval sites also were higher in silt, emergent vegetation, and algae and lower in sagebrush and willow, and they were more likely to be located at a pond, oxbow, or pool than were sites without treefrog larvae. Although certain National Wetland Inventory classifications were associated with frog presence, none could be used to predict with complete assurance the presence or absence of either species. Logistic regression models using habitat measures were better at predicting the presence of amphibian species than were models using National Wetland Inventory classifications; models using a combination of habitat measures and National Wetland Inventory classifications performed best. Because of their ready availability in geographic information system data bases, however, National Wetland Inventory classifications may in some circumstances provide a valuable indicator of the likelihood of finding certain amphibian species. National Wetland Inventory classifications should be most useful for highly aquatic species in arid environments.
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