1. Outer digit on hind foot broader than other digits; no tympanum; males with tail-like extension of the cloaca.....Tailed frogs, Ascaphus truei and A. montanus
  2. Outer digit on the hind foot not broader than other digits; tympanum present; males without cloacal extension.....2


  1. Intercalary cartilage (extra step-like joint) present before the terminal phalanx of each digit; toe pads present.....Pacific Treefrog, Pseudacris regilla
  2. No intercalary cartilages; no toe pads.....3


  1. One or more cornified cutting tubercles on soles of hind feet.....4
  2. No enlarged cutting tubercles on soles of hind feet.....6


  1. Parotoid glands present behind eyes; two cornified cutting tubercles on soles of hind feet; pupil horizontal; no teeth in upper jaw.....5
  2. No parotoid glands; a single black cutting tubercle on soles of hind feet; pupil vertically elliptical; teeth present in upper jaw.....Great Basin Spadefoot, Spea intermontana


  1. Prominent L-shaped cranial crest around each eye.....Woodhouse's Toad, Anaxyrus woodhousii
  2. No prominent cranial crests.....Western Toad, Anaxyrus boreas


  1. Dorsolateral folds present.....7
  2. Dorsolateral folds absent.....Bullfrog, Lithobates catesbeianus


  1. Large, conspicuous dark spots on the back, outlined with color lighter than ground color.....Northern Leopard Frog, Lithobates pipiens
  2. Dorsal spots if present not large and not set off with light halos.....8


  1. Dorsolateral folds do not extend posteriorly past sacral hump; no eye mask.....Green Frog, Lithobates clamitans
  2. Dorsolateral folds extend to groin region; eye mask present.....9


  1. Eye mask extends forward past nostril almost to upper lip, bordered below by white jaw stripe; light vertebral stripe present or absent; no dark spots between dorsolateral folds; no red, orange, or yellow on ventral surface in life.....Wood Frog, Rana sylvatica (may occur)
  2. Eye mask less extensive; no light vertebral stripe; usually with spots between dorsolateral folds; red, orange, or yellow ventral surfaces in life.....10


  1. Heel does not reach nostril when hind leg is extended along body; webbing between hind toes nearly to tips of toes; dorsal spots with fuzzy or indistinct edges; eyes dorsally oriented; bright color on ventral surfaces of body and hind legs appears to be "painted" on.....Spotted frogs, Rana pretiosa and R. luteiventris
  2. Heel reaches to nostril or beyond; last 1-2 joints of hind toes usually free of webbing; dorsal spots with sharp edges; eyes laterally oriented; colors appear to lie deep in skin.....11


  1. Ventral surfaces of posterior body and hind legs rosy red in life; groin area heavily mottled with black and creamy white; central abdominal region with dark mottling.....Northern Red-legged Frog, Rana aurora
  2. Ventral surfaces of posterior body and hind legs tannish-yellow in life; groin area lightly mottled; central abdominal region without mottling.....Cascades Frog, Rana cascadae

Modified from key in Nussbaum,R. A., E. D. Brodie, Jr., and R. M. Storm. 1983. Amphibians & Reptiles of the Pacific Northwest. Univ. Press of Idaho, Moscow.

Dennis Paulson, January 1993; names revised December 2013.