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Northern Red-legged Frog

Rana aurora

Family: Ranidae

COSEWIC status:
  • Special Concern
SARA status:
  • Special Concern
IUCN status:
  • Least Concern


The Northern Red-legged Frog is a relatively large frog that can attain a body length of up to 10 cm, with males being smaller than females. Individuals are brown or reddish brown with small black flecks and sometimes larger dark spots. There is often a dark mask that extends from the eye to the back of the mouth that is bordered on the bottom by a cream-coloured line, and the legs often have dark cross-banding. The throat and chest are light grey with black or red flecking, the groin area is a mottled yellow and green with black spots, and adults have red on the undersides of the arms, hind legs and the lower belly. Individuals have smooth skin, prominent dorsolateral folds (folds of skin running down each side of the back), long legs and webbed feet. The skin on the underside of the legs is semi-translucent, allowing the muscles and bones to be visible. Larvae (tadpoles) have long tails with a large tail fin and lack front legs (newly hatched tadpoles are legless). The body is tan to brown with gold flecking, the tail fin has a gold tinge with dark spots and the belly is whitish, often with brassy flecking. The larvae can reach 8 cm in length before metamorphosis. The call of Northern Red-legged Frog is a series of low-pitched pulses, repeated 3-5 times, and is often referred to as a stuttering sound.

Similar Species

The Northern Red-legged Frog may be confused with the Oregon and Columbia Spotted Frogs, which have a similar body shape and reddish underside. However, the skin on the underside of the spotted frogs is not semi-translucent. The eyes of the Oregon and Columbia Spotted Frogs are noticeably angled upward, whereas the eyes of the Northern Red-legged Frog are angled outward. The Oregon and Columbia Spotted Frogs have webbing on hind feet that extends to the tips of the toes, whereas the webbing on the hind feet of Northern Red-legged Frog does not. The distribution of the Northern Red-legged Frog does not overlap with that of the Columbia Spotted Frog, so these two species can also be differentiated based on location.


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In Canada, the Northern Red-legged Frog occurs in southwestern B.C. along the southern coast, in the Fraser River valley, on Vancouver Island and on the gulf islands. This species’ North American distribution extends south along the west coast, west of the coastal mountains ranges, to northern California.


Northern Red-legged Frogs inhabit low elevation forests, where they breed in permanent or temporary wetlands, ponds, the margins of lakes or slow-moving streams. Breeding sites are often fish free and have shallow water with herbs, sedges and grasses. Outside of the breeding season, Northern Red-legged Frogs often disperse into surrounding moist forest habitats. Individuals hibernate underwater at the bottom of wetlands or underground in terrestrial habitats.


In Canada, Northern Red-legged Frogs hibernate during the winter and are active from late February or March until October. Male Northern Red-legged Frogs call from underwater to attract females during the breeding season, which occurs in the early spring immediately after ice recedes from breeding habitats. During breeding, the male grasps the female (amplexus) and fertilization occurs externally in aquatic habitats as the female lays eggs. The female lays 500–1,300 eggs as a large gelatinous mass that is attached to aquatic vegetation, typically more than 40 cm below the water’s surface. The eggs are black on top and creamy white underneath and are surrounded by three indistinct clear jelly envelopes. The eggs hatch in 4–7 weeks and larvae transform into frogs after another 11–14 weeks. Northern Red-legged Frogs reach maturity at 2–4 years of age and can live for more than 10. Individuals eat a wide variety of invertebrates, including spiders, beetles, aphids, leafhoppers and slugs. During the summer, Northern Red-legged Frog may disperse over 4 km from their breeding sites.


Northern Red-legged Frogs occur in one of the most developed regions in Canada, and the conversion of natural areas into urban and agricultural land uses has resulted in significant and ongoing declines of this species. In less developed areas, forestry activities result in habitat destruction and fragmentation. The extensive road network in southwestern B.C. also poses a significant threat to this species, resulting in particularly high rates of mortality when roads bisect breeding sites or travel corridors. Introduced invasive species, particularly the American Bullfrog, have also contributed to declines across much of this species’ range. Pesticides/herbicides, road salt, industrial contamination and other environmental pollutants can be detrimental to frog and toad populations by causing direct mortality as well as developmental deformities. Pathogens, such as chytrid fungus and Ranavirus, can cause mass mortality of frog and toad populations. Climate change may also pose future threats to Canada’s frog and toad populations.

Additional Information About This Species In Canada