Rocky Mountain Tailed Frog
Ascaphus montanus
Dorsum, or base color, is either brown or gray and exhibits a bumpy texture; has either brown, gray, or yellow spots throughout body. Rear feet commonly have one outer to…
How to identify
Dorsum, or base color, is either brown or gray and exhibits a bumpy texture; has either brown, gray, or yellow spots throughout body. Rear feet commonly have one outer toe that is noticeably larger than all other toes. Total adult length can range from 1.5 to 2 inches. Only the male has a protrusion that resembles a tail. This acts as a penis during mating which usually takes place from September to November. Even though eggs are laid in early summer at a nest site, larvae can stay at the site for a year. One of the few frogs that breed through internal fertilization.
Range
Western North America in southeastern British Columbia, Canada, southeastern Washington and northeastern Oregon; extend as far east as western Montana and south-central Idaho.
Habitat
Almost exclusively inhabits rocky, cold, forest streams with quickly moving water. If found away from a water source, it is usually only during an especially wet night. When weather is dry, will move to wet areas by water sources like stream banks. Diets differ between larvae and adults with larvae eating diatoms and adults ingesting a diverse mix of invertebrates and insects.
Variations
Populations in Montana go on migrations triggered by seasonal changes. This is most likely their effort to avoid areas that have been seasonally affected with an increase in water temperature. The average distance crossed is unknown.
Similar species
Coastal Tailed Frog - Ascaphus truei Columbia Spotted Frog - Rana luteiventris Foothill Yellow-legged Frog - Rana boylii
Name and etymology
Montanus: From latin meaning mountain, referencing its Rocky Mountain range
At a glance
Range
Western North America in southeastern British Columbia, Canada, southeastern Washington and northeastern Oregon; extend as fa…
Habitat
Almost exclusively inhabits rocky, cold, forest streams with quickly moving water. If found away from a water source, it is u…
Guide
Reptiles and Amphibians of North America
Range map
Approximate range. © Mapbox © OpenStreetMap