Columbia spotted frog (Rana luteiventris)

Description
Columbia Spotted Frog

Size

  • A medium-sized frog, the Columbia Spotted Frog ranges from 45 to 100 millimetres (about two to four inches) long, including head and body.
  • Female frogs are generally larger than males for this species.

Appearance

  • Is generally a dark brown on the back, but can also be light brown or greyish. Is covered on the back with small, irregular, dark brown spots.
  • Underside is salmon pink, red or yellow. Throat or underside may be spotted or mottled with gray.
  • Dorsolateral folds are present along the full length of the back, but are somewhat indistinct.
  • Spotted frogs have a dark mask that runs from the tip of the nose to the tympanum (the hearing membrane for frogs and toads, located on the head behind the eye).
  • A light coloured stripe along the upper jaw, running from snout to forelimb, is present.
  • Eyes are angled slightly upwards.

Voice/call

  • Spotted frogs become vocal during mating season. The call is a series of rapid, low-pitched clicks.
Distribution
Columbia spotted frog distribution in Alberta
  • The spotted frog is limited to the mountainous areas of Alberta. It is found in alpine and subalpine regions up to elevations of just over 2,000 metres (6,600 feet).
  • It is widely distributed throughout most of British Columbia and even occurs in southern Alaska.
Natural History

Habitat

  • This frog is generally aquatic and is found near permanent bodies of cold water such as streams or marshes in relatively mountainous areas.
  • Spotted frogs are primarily nocturnal, making them difficult to locate outside of the breeding season.

Food

  • Prey items include:
    • crustaceans
    • insects, especially beetles and flies
    • snails
    • spiders
    • worms

When active

  • Active from spring to late summer. May overwinter in Alberta.
Reproduction and Growth
Life Stage Apr May Jun Jul Aug Sep
Breeding Breeding Bar: April 8 to June 17
Eggs Hatch Eggs Hatch Bar: April 15 to June 24
Transformation Transformation Bar: August 3 to September 22

Breeding behavior

  • In the spring, adults will congregate at breeding ponds and begin calling.
  • Because of their high elevation locations, spotted frogs breed later than some other frogs. Breeding can be as late as May or June, depending upon snowmelt.
  • Males emit quick, low-pitched calls, which sound vaguely like a helicopter.
  • Females lay large eggs, five to eight millimetres (0.20 to 0.31 inches) in diameter in communal masses in shallow water.
  • Each female can lay up to about 1,500 eggs, which will hatch in about four days.

Appearance of young

  • The tadpoles are dark brown or dark green and are speckled with gold. Their underside is iridescent bronze or pale gold.
  • Tail is broad finned, and about twice the length of the body.

Growth process

  • Depending upon water temperature and the length of the summer season, the tadpoles will either transform late in the summer or overwinter as tadpoles. The newly transformed frogs are about 25 millimetres (about one inch) long.
  • It can take up to four to six years for spotted frog young to reach sexual maturity.
Conservation and Management

Status

The Columbia spotted frog is classified as Sensitive in the current Status of Alberta Wildlife report. For more details, see the Columbia Spotted Frog Profile at:

Issues

  • Populations are extremely limited in distribution and threatened by introduced fish.

Current management

  • Amphibian Monitoring in Alberta
    The Columbia spotted frog is being monitored under the Alberta Volunteer Amphibian Monitoring Program (AVAMP) and the Researching Amphibian Numbers in Alberta (RANA) program.
Similar Species
  • Northern leopard frog
    although it is about the same size as the northern leopard frog, the spotted frog lacks the light-coloured dorsolateral folds.

    In addition, spotted frogs tend to have smaller spots and they lack the light rings circling the spots.
  • Wood frog
    The spotted frog may have a "mask" covering the eyes and snout like the wood frog, but the spotted frog is much larger.

 

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Posted: Mar 6, 2009