Adult and Juvenile Frogs of Whatcom County – A Picture Guide
Whatcom County Amphibian Monitoring Project
(Photos © Stephen Nyman)
Northern red-legged frog (Rana aurora)
• Common species
• Usually brown or tan, with dark eye mask
• White lip line
• Prominent dorsolateral folds
• Adults usually reddish under hind legs
• Colorful groin mottling
• Juveniles may be yellow, honey-colored
or pink under hind legs
• Eyes outward facing
• Relatively smooth skin
• Usually responds to approach by leaping away
• May be seen in forested areas far from water
Pacific chorus frog
(Pseudacris regilla)
• Very common species
• Small and delicate appearance
• Color variable (green or brown)
• Dark eye mask
• Often with irregular blotches on back
• Toe tips enlarged
• Our most often heard native frog
• May be heard far from water
Western toad
(Anaxyrus boreas)
• Dry, “warty” skin
• Large gland behind each eye
• Light colored mid-dorsal stripe
(not present in small juveniles)
• Walks or makes small hops
• Often observed far from water
• May be a declining species – report
your observations!
American bullfrog
(Lithobates catesbeianus) • Introduced species
• Aquatic, usually at permanent
water-bodies
• Large!
• Usually brown and/or green
• May have dark blotches
• Dorsolateral fold short, bending
partly around eardrum
• Breeding call a deep “jug-a-rum”
or “br-wum”
• Juveniles often heard (“eeep!” –
followed by a splash)
juvenile
juveniles
juvenile
juvenile
Green frog
(Lithobates clamitans) • Introduced species
• Aquatic, usually at permanent bodies of water
• Large (not as large as bullfrog)
• Green to brown
• Dorsolateral fold extends from the eye to hip
• Coloration green to brown, similar to bullfrog
• Breeding call is a low-pitched “k’tung”, resembling a banjo note
• Distribution in Whatcom County is poorly documented – report
your observations!
Cascades frog
(Rana cascadae) • Found above 2,000 ft elevation
• Usually brown or tan, with dark eye mask
• White lip line
• Prominent dorsolateral folds
• Yellow under hind legs
• Adults usually with inky spots
• Eyes outward facing
• May allow close approach
• Usually aquatic, including along streams
Oregon spotted frog
(Rana pretiosa) • Very limited known distribution
• Federally threatened species
• Aquatic
• Brown, olive, or brick-red
• White or tan lip line
• Dorsolateral folds present – may not be prominent
• Red or orange under hind legs
• Adults with small, indistinct spots
• Eyes upturned – gold or chartreuse
• May allow close approach
• Often assumes a low, crouched posture
Coastal tailed frog
(Ascaphus truei)
• Found in mountain streams
• Adults are small (maximum 2 inches body length)
• Vertical (cat-like) iris
• Males have a tail-like intromittent organ
• Nocturnal, but sometimes active during rainy days
juvenile
Whatcom County Amphibian Monitoring Project (www.whatfrogs.org)
(Photos © Stephen Nyman)