Western toad (Anaxyrus boreas)

Close up of an adult western toad among vegetation on the ground
An adult western toad.
A tiny young western toad sits in the hand of a biologist
A tiny western toadlet. 
Category: Amphibians
State status: Candidate
Vulnerability to climate change (More details)

Moderate-
High

If you see this species, please share your observation using the WDFW wildlife reporting form. Providing detailed information such as a photo and exact coordinates will improve the confidence and value of this observation to WDFW species conservation and management.

The population of western toad is unknown in the lowland Puget Trough. Declines have been documented there and in the lower Columbia River below Bonneville Dam. Of about 107 historical sites in those areas, only about 19 are thought to remain. Elsewhere in the state, these toads are locally common in many areas 

Description and Range

Physical description
Two western toads mating in shallow water
A pair of western toads mating in the water---note the dark egg strings.

This is a medium-sized to large toad with a blunt head, stout body, broad waist, short legs, and “warty” skin. Adults range in size from 2 to 5 inches in length. Females attain larger sizes than males. Prominent oval glands (parotoid glands) are present on the head behind the eyes. The topside of the body may be brown, green, olive, gray, or reddish-brown. The warts are usually surrounded by dark blotches and may be reddish. A distinct, thin, light stripe runs along the middle of the back from top of the head to the rear end. The underside is light with irregularly distributed dark markings. The pupil of the eye is horizontal oval.

See the Washington Herp Atlas for more details about this species, including description of tadpoles.

Ecology and life history  

This species occurs in a variety of terrestrial habitats including prairies, forests, canyon grasslands and ponderosa pine-Oregon oak habitat. They appear absent from most of the shrubsteppe and steppe zones with the exception of the canyon grasslands in southeast Washington. Breeding waters are usually permanent and include wetlands, ponds, lakes, reservoir coves and the still-water off-channel habitats of rivers, as well as river edges.

In lowland western Washington, individual toads have been found in mid-February within duff under sword ferns suggesting that some individuals overwinter terrestrially in areas with mild winters or at least occur terrestrially during the mild portions of winters. 

Western toads eat a variety of invertebrates, mostly insects, but also worms. Tadpoles eat algae and detritus (organic material) in the aquatic environment.  

In general, breeding starts in mid-April at low elevation sites in western Washington and in late April or early May at low elevation sites in eastern Washington. Toads at higher elevations tend to breed later.

A mass of dark colored western toad tadpoles in shallow water
A mass of western toad tadpoles in the water.

Toads breed in the still waters of lakes and ponds, but they also breed within slower moving sections of rivers. Onset of egg laying at each location varies from one to three weeks each year depending on site conditions such as snow melt. 

Tadpole development to metamorphosis takes approximately two months depending on temperature and food availability. Watch this amazing underwater footage of masses of western toad tadpoles during their aquatic journey and metamorphosis into toadlets.

The newly metamorphosed toads disperse from the breeding sites in groups for 1 to 2 weeks. Informal observations indicate that many populations return to the same breeding location each year. Transformed toads are primarily terrestrial, but often occur near water bodies, especially in drier climates. 

Western toads can produce a poisonous substance from their skin, which helps protect them from predators. 

Geographic range

Western toads occur in all nine Washington ecoregions: Northwest Coast, West Cascades, Puget Trough, North Cascades, Columbia Plateau, Okanogan, East Cascades, Canadian Rocky Mountains, and Blue Mountains. Ecoregions are broad areas that share similar flora and fauna, geology, hydrology, and landforms. Within the Washington portion of the Columbia Plateau, the species’ distribution is limited to the edges of the ecoregion except in the southeast corner of the state. The toads are locally abundant in some areas, but local declines have been documented in others. 

For worldwide distribution of western toad and other species' information, check out NatureServe Explorer and the International Union for Conservation of Nature Red List.

Climate vulnerability

Sensitivity to climate change

Moderate-
High

Sensitivity of the western toad to climate change is primarily driven by its dependence on intermittent and permanent aquatic habitats (e.g., streams, seeps, wetlands, ponds, etc.) that may be lost or degraded due to changes in precipitation and altered hydrology. A significant portion of western toad breeding in western Washington occurs in low-gradient portions of rivers, such as the Chehalis and its tributaries, after the hydrographs have dropped to a level that is unlikely to risk scouring their unattached eggs. Greater, more variable, and episodic rainfall (all current predictions of climate change in the PNW) are likely to put these river-breeding populations at risk. High-elevation populations may be at risk because of reduced hydroperiods in breeding habitat that result either in reproductive failure or eliminate that ability of a significant portion of annual cohorts to reach metamorphosis. Desiccation of streams and pools along dispersal routes may create barriers to movement. Synergistic impacts such as climate changes combined with disease outbreaks increases sensitivity of this species. Physiological sensitivity of this species is unclear - some references cite sensitivities to temperature and moisture conditions while others cite high adaptability to changes in these conditions.

Confidence: Moderate

Exposure to climate change

Moderate-
High

  • Changes in precipitation (rain and snow)
  • Altered hydrology
  • Greatest impacts to montane wetland-reliant taxa will most likely occur when landscapes primarily contain shallow wetlands at high risk of drying and are composed of multiple wetland types but deeper habitats are unsuitable (e.g., due to presence of introduced fish)
Confidence: Moderate

Conservation

This species is identified as a Species of Greatest Conservation Need (SGCN) under the State Wildlife Action Plan (SWAP). SGCN-classified species include both those with and without legal protection status under the Federal or State Endangered Species programs, as well as game species with low populations. The WDFW SWAP is part of a nationwide effort by all 50 states and five U.S. territories to develop conservation action plans for fish, wildlife and their natural habitats—identifying opportunities for species' recovery before they are imperiled and more limited.
This species is identified as a Priority Species under WDFW's Priority Habitat and Species Program. Priority species require protective measures for their survival due to their population status, sensitivity to habitat alteration, and/or recreational, commercial, or tribal importance. The PHS program is the agency's main means of sharing fish and wildlife information with local governments, landowners, and others who use it to protect priority habitats for land use planning.

Note: WDFW’s SGCN classification only applies to western toads in the Puget Trough Ecoregion.

Conservation Threats and Actions Needed 

  • Fish and wildlife habitat loss or degradation 
    • Threat: Transportation and service corridors – roads and railroads.  
    • Action Needed: Avoid road building near breeding sites.  
    • Threat: Road mortality when moving to and from breeding sites. Newly metamorphosed toads disperse en masse and gather in piles. When this happens on roads, thousands of toads can be killed by a single vehicle. Adults are also killed as they move to and from breeding sites.  
    • Action Needed: 1. Identify and map known crossings; 2. Avoid road building near breeding sites; 3; When possible, close roads to vehicles during dispersal periods (e.g., ATV use on gated dirt roads); 4. Create passage structures to circumvent roads. 
    • Threat: Loss of upland habitat through the development on shorelines and around water bodies used for breeding.  
    • Action Needed: Protect known pockets of abundance and breeding areas.  
    • Threat: Habitat alteration and degradation.  
    • Action Needed: Protect known pockets of abundance and breeding areas.  
  • Resource information collection needs  
    • Threat: Lack of information on status and distribution.  
    • Action Needed: Research, surveys, and monitoring to understand species distribution and status. 
    • Threat: Taxonomic uncertainty may mean one or more taxa are in greater decline; causes of decline are not understood.  
    • Action Needed: Conduct genetic studies. 
  • Invasive and other problematic species  
    • Threat: Chytrids and other fungi, and parasites have contributed to declines throughout the species’ range; however, chytrids have not yet been detected in Washington toads.  
    • Action Needed: Include testing for chytrids, fungal infections, and trematode infections in survey and monitoring protocols. 

See the Climate vulnerability section for information about the threats posed by climate change to this species.

Our Conservation Efforts

The Washington Connected Landscapes Project 

A WDFW biologist holds a pair of mating western toads.
A WDFW biologist holds two mating western toads found during a monitoring project at Northwest Trek Wildlife Park in Eatonville.

WDFW participated in the Washington Wildlife Habitat Connectivity Working Group, formed in 2007, whose mission was to promote the long-term viability of wildlife populations in Washington State through a science-based, collaborative approach that identified opportunities and priorities to conserve and restore habitat connectivity.  Other participants were:

  • Washington State Department of Transportation
  • Washington Department of Natural Resources
  • The Nature Conservancy
  • U.S. Dept. of Agriculture – Forest Service
  • U.S. Fish and Wildlife Service
  • University of Washington
  • Montana State University – Western Transportation Institute

This working group initiated the Washington Connected Landscapes Project, which provided a systematic approach with multiple components and a sustained effort to support the group’s mission. They produced a statewide analysis, published in 2010. This analysis quantified current connectivity patterns at three different spatial scales for Washington State and neighboring areas in British Columbia, Idaho, and Oregon.

Assessing the current condition of wildlife habitat connectivity in the state was an important step for connectivity conservation. Animals move across landscapes to find food and other resources, migrate between seasonal habitats, find mates, and shift to new habitats in response to environmental changes. The ability to successfully move between habitats is essential for the long-term survival of many wildlife species, from large, migratory species such as elk and mule deer, to smaller animals like white-tailed jackrabbits, greater sage-grouse, and western toads.

Focal wildlife species were selected using criteria designed to favor species with geographic ranges, habitat associations, and vulnerabilities to human-created barriers that made them representative of the habitat connectivity needs of many terrestrial species at a statewide scale. Western toads were selected as a focal species because they were a good representative of habitat connectivity needs of wildlife with similar life history needs in the three forest vegetation classes (Rocky Mountain, Vancouverian, and Subalpine Forests). In addition, the toads‘ broad coverage across the landscape, reliance on connectivity between populations, and in particular, their association with wetlands and aquatic systems led to inclusion in the statewide analysis. Check out the analysis for more details.

Resources

WDFW Publications

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