U.S. National Wetland Inventory Classif ications as Predictors of the Occurrence of Columbia Spotted Frogs (Rana luteiventris) and Pacific Treefrogs (Hylaregilla)

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 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. Clasificaciones del Inventario Nacional de Humedales de E.U.A. como Predictores de la Aparicion de la Rana Moteada de Columbia (Rana luteiventris) y la Rana Arboricola del Pacifico (Hyla regilla) En las montanas Owyhee el suroeste de Idaho, comparamos las caracteristicas del habitat de sitios donde capturamos la rana moteada de Columbia (Rana luteiventris) y la rana arboricola del Pacifico (Hyla regilla) con sitios sin ranas. Nuestro objetivo principal fue el de determinar si las clasificaciones del Inventario Nacional de Humedales pueden ser utilizados para predecir la presencia de estas especies. Los adultos de la rana moteada tienden a utilizar sitios palustres, arbustivos, estacionalmente inundados, o sitios reverinos intermitentes, camas de arroyos, estacionalmente inundados, pero no sitios palustres, emergentes, estacionalmente inundados o intermitentemente riverinos, camas de arroyos, temporalmente inundados. Los sitios para la rana moteada tambien tienden a tener mas vegetacion sumergida y algas y menos pasto y salvia; fue mas probable localizarlas en estanques, meandros y charcos, donde es probable localizar mas sitios de refugio que en sitios sin ranas moteadas. Los sitios donde se encontraron ranas arboricolas adultas tendian a tener pocos sauces, mucho pasto y vegetacion emergente y sumergida, tambien fueron mas comunes los estanques y charcos, que en sitios sin ranas arboricolas. Las larvas de las ranas arboricolas tienden a ser encontradas en sitios riverinos intermitentes, camas de arroyo, estacionalmente inundados, o en sitios palustres, emergentes, estacionalmente inundados; pero no en sitios palustres, arbustivos, estacionalmente inundados. Las larvas de la rana arboricola frecuentan sitios con alto contenido de arcilla, vegetacion emergente y algas, bajas en salvia y sauces y fueron mas probables de localizar en estanques, meandros y charcos que en sitios sin larvas de ranas arboricolas. Aunque algunas clasificaciones del Inventario Nacional de Humedales estan asociadas con la presencia de ranas, ninguna puede ser usada para predecir con completa certeza la presencia o ausencia de alguna de las dos especies. Modelos de regresion logistica con datos del habitat resultaron ser mejores en la prediccion de la presencia de especies de anfibios que los modelos con las clasificaciones del Inventario Nacional de Humedales. Los mejores modelos resultaron ser aquellos que combinaron las mediciones del habitat y las clasificaciones del Inventario Nacional de Humedales. Debido a su facil acceso a traves del bases de datos de Sistemas de Informacion Geografica, las clasificaciones del Inventario Nacional de Humedales podrian sin embargo en algunas circunstancias proveer un indicador valioso de la probabilidad de encontrar ciertas especies de anfibios. Las clasificaciones del Inventario Nacional de Humedales podrian tener mas aplicacion para especies altamente acuaticas en ambientes aridos.