Western toad (Bufo boreas)

Description

Size

  • The largest of Alberta's toads, the western toad can range from 55 to 125 millimetres (approximately two to five inches) in length.

Appearance

  • Usually green or brown with a light-coloured stripe down the back.
  • Warts may be reddish-brown and surrounded by black.
  • The western toad can be distinguished from the other two true toads of Alberta by the lack of cranial crests between the eyes.
  • Unlike many toads, the western toad tends to walk rather than hop.
  • If threatened they will inflate themselves with air and raise up on their legs.

Voice/call

  • Males call to attract females. Call sounds like soft peeping.

Distribution
western toad distribution in Alberta
  • Found in western and central Alberta, primarily in boreal forest and subalpine environments.
  • Absent from the drier eastern and southern areas of the province.
  • Can be found up to elevations of about 2,300 metres (about 7,500 feet).
  • The distribution of the western toad in the northern region of the province may actually be more extensive, but little monitoring work has been conducted in these areas.

Natural History

Habitat

  • It is generally found near ponds, streams, or lakes.

Food

  • Diet consists mainly of insects, slugs, and worms.

When Active

  • The western toad is active from April to September in Alberta.
  • Although it is usually nocturnal, at higher elevations it can be diurnal (active during the day). Their primarily nocturnal disposition makes western toads difficult to locate outside of the breeding season.

Reproduction and Growth
Life Stage April May June July August Sept.
Breeding Bar
Eggs Hatch Bar
Transformation Bar
or over winter

Breeding behavior

  • In the spring, adults will congregate at breeding ponds and begin calling. The males call with a quiet peeping sound to attract females.
  • In April to June, western toads congregate to breed.
  • Breeding ponds tend to be shallow, with cool water (less than 10°C) and sandy bottoms. The breeding ponds can be permanent or temporary.
  • Eggs range from 1.5 to 1.7 millimetres (0.05 to 0.07 inches) in diameter.
  • Eggs are laid in long strings, often entwined about submerged vegetation.
  • A single female can produce thousands of eggs and within 3 to 12 days, the eggs will hatch.

Appearance of young

  • Tadpoles begin life at about 10 millimetres (0.4 inches) long and grow to 25 to 30 millimetres (about one inch).
  • The tadpoles are black on top and somewhat lighter underneath.

Growth process

  • Because of the great number of eggs laid, tadpole densities can be very high.
  • By six to eight weeks after hatching, the tadpoles transform into juvenile toads.
  • It requires an additional two to three years for the young toads to become sexually mature.

Conservation and Management

Status

The western toad is classified as Sensitive in the current Status of Alberta Wildlife report. See:

Issues

Populations are decreasing elsewhere, but little is known about Alberta populations where they appear to have been reasonably healthy and widespread in the past.

Current management

  • Amphibian Monitoring in Alberta The western toad is being monitored under the Alberta Volunteer Amphibian Monitoring Program (AVAMP) and the Researching Amphibian Numbers in Alberta (RANA) program.

Related links
  • Amphibians
    Learn about Alberta’s amphibians, their biology and how to identify various species. Also learn about the global decline of amphibian species, and efforts made to monitor and conserve them.
  • Toads
    Find out about the common traits of salamanders, and about the different salamander species found in Alberta.

Posted April 20, 2009