Montana Field Guide

Columbia Spotted Frog - Rana luteiventris

Adults are light to dark brown, gray, or olive green with dark spots (frequently with lighter centers) on the back, sides, and legs. The number of spots and spotting pattern varies. The back and sides are often covered with small bumps. The undersides of the legs are bright red, salmon or orange; this bright color may extend up to the chin or be replaced by a light, mottled gray on the chin, chest, and/or belly. Adult body length is 2 to 4 inches. Eggs and Tadpoles: Eggs are laid at the water surface in large, globular masses of 150 to 500. Tadpoles are dark green with gold flecking above and iridescent bronze below. They may reach 3 inches in length; their eyes are located on the top of the head.

The bright pigment on the undersides of the legs distinguishes adults of this species from all other frogs in montana. younger individuals lacking bright legs are difficult to distinguish from wood and northern leopard frogs.

Montana Range

Spotted frogs are regularly found at water's edge in or near forest openings. Wetlands at or near treeline are also used, but populations are uncommon in large, open intermountain valleys. Breeding takes place in lakes, ponds (temporary and permanent), springs, and occasionally backwaters or beaver ponds in streams. All the egg masses in a particular pond are often found in the same location at the margin of the pond. Young and adult frogs often disperse into marsh and forest habitats, but are not usually found far from open water (FWP). Reproduction mainly in ponds, occasionally in springs, shallow streams, or puddles (Turner 1958). Found on grassy/swampy banks of mtn water bodies (Black 1969, Franz 1971), although may avoid dense/tall grass (Miller 1978). Feed mainly in riparian habitat, occasionally in bordering meadow/woods. Juv. forage farther from water (Miller 1978).

Larvae: veg (Callitriche/Spirogyra) in Yellowstone (Turner 1959). Adults: mainly ground insects in W MT: coleoptera 35%, hymenoptera 22%, arachnid 15%; others < 10% (Miller 1978). Based mainly on availability (Whitaker et al. 1983, Turner 1959, Moore and Strickland 1955).

Closely restricted to water (Black 1969, Carpenter 1953). Usually found within 15m of shore (Miller 1978). In Yellowstone, does not reach repro maturity 'til yr 4 (male), yr 5-6 (female) (Turner 1960).

Breed mid-Apr to early June (Turner 1958, Schaub and Carson 1978). Eggs are in clusters of 300-800 and hatch in 12-21 days (Turner 1958). Metamorphosis usually occurs about 60 days after hatching (Turner 1958), from late Jul to freezeup. In permanent pools may not transform 'til yr 2. Females may breed alternate yrs (Turner 1958). Males occasionally call, but the call is faint; burst of 4-30 short crocks at a rate of 3-4 per second, with bursts separate by 3 seconds (Turner 1958).