Western Toad

Western Toad – Anaxyrus boreas

Species: Western Toad – Anaxyrus boreas
B.C. Status: Yellow
COSEWIC Status: Special Concern

Key Information:

The Western Toad is frequently encountered on roads (in wet weather during spring and fall migrations), near water in breeding season (spring), and in meadows or forests throughout the other seasons. When handled, adults often vocalize making a sound like a peeping chick, although this is not advised as this can introduce disease. They eat any type of insect they can catch, and will occasionally eat crayfish or mollusks. Tadpoles, on the other hand, are herbivores and munch on plant matter and algae in the water. These toads are typically seen walking rather than hopping, but they can jump a considerable distance for a toad.

Breeding timing correlates to the season and the ecosystem in which these toads reside. Generally breeding occurs between March and July in higher elevations, and as early as January in lower-elevation regions. The eggs of western toads are laid in open water from February to July, with peak activity occurring in April. Timing of egg-laying activity varies with elevation and weather conditions and egg development depends on factors within their local climate.

Western toads lay their eggs around 15 cm into water in areas surrounded by rich vegetation. Woody debris or submerged vegetation is used to protect egg masses. The western toads return to the same breeding spot year after year. Female western toads reproduce every 1 to 3 years. Metamorphosis is usually completed within three months of egg laying.

Once the breeding season is complete, they move in colonies to meadows or forests using roads and ditches as corridors. Although they leave the open water after breeding season, they always prefer areas that are damp. Western toads are great diggers and they burrow either in woody debris or mammal cavities to hibernate. Some burrows are 1.3 m underground!

COSEWIC lists the western toad as a species of “special concern” because they are particularly sensitive to human activities and changes in climate and to ecosystem. There are many factors that put these toads at risk such as, disease (including fungal diseases that affects amphibians), habitat loss as a result of logging/development practices, getting hit by vehicles, introduction of invasive species, and chemical contamination of the environment.

One of the chief chemical threats is the overuse of the fertilizer urea. This fertilizer is often applied in high dosages to forest environments to increase biomass productivity and economic return.

On Cortes we are still working at understanding what significant change occurred in their habitats that have caused their population to nearly disappear on the island. If you see a western toad, please call us and tell us the location!

Identification:

• Stocky bodies, short legs
• Thick, dry and bumpy skin
• Ranges in colour from pale green to gray, dark brown to red
• Pale coloured bellies with black spots
• White or cream stripe down their back
• They typically walk rather than hop
• Dusky gray or greenish skin glands on back
• Swellings behind eyes (aka, parotid glands) are oval and larger than the upper eyelids
• Males have smoother skin, compared to females
• Adults around 5.5 cm to 14.5 cm
• In juveniles the dorsal stripe is weak or absent
• Large young have prominent spotting and yellow feet
• Tadpoles are dark in colour and have a round fin along their tail

Where are they found?

• Shallow ponds, bogs, wetlands, streams during spring/breeding season
• Meadows and forests outside of breeding season
• Eastern Rocky Mountains to the Pacific Ocean: Yukon, British Columbia, southern Alaska, down the western states into Mexico
• On Cortes, western toads have been historically documented in and around Linnaea Farm

Cool facts!

• Males have large pads on their thumbs to stick/cling to the female while mating
• Eggs are laid in strings around 2.5cm in length in masses of up to 16,500 per clutch!
• Eggs look like little black pearls
• 99% of their eggs will not mature into adulthood but those that do can live up to 10 years!
• Tadpoles metamorphose into toadlets when they are as small as 6mm long and look like miniature adults (around 3 months)
• Tadpoles prefer warm and shallow waters with a sandy bottom
• All local toads deposit their eggs in the same body of water year after year
• They can travel up to 7 km in a season!
• The western toad is the only true toad found in British Columbia
• Western toads are usually nocturnal except at high elevations

Useful Links:

COSEWIC Status Report (PDF): Western Toad
B.C. Government: Western Toad Report
SCCP: South Coast Conservation Program
SARA: COSEWIC Assessment and Status Report