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)