Preferred Habitat
Western toads are widespread throughout the mountainous areas of northwestern North America, ranging from sea level to elevations near or above regional treeline, or 10,000 feet (305–3,050 m) in elevation. It is uncommon at the higher elevations. Elevational range in Colorado is from about 7,000 feet to 11,860 feet (2,131–3,615 m). In the mountains of Colorado, the largest western toad populations usually occur from about 9,500 feet to 11,000 feet (2,896–3,353 m) elevation. Western toads occupy desert streams and springs, grasslands, and mountain meadows; they are less common in heavily wooded regions. They are usually found in or near ponds, lakes (including saline lakes), reservoirs, rivers, and streams within the above mentioned habitats. Under laboratory conditions western toads were able to survive in 40% seawater, but died within a week when exposed to 50% seawater.
In Colorado, individual western toads typically maintain distinct ranges which vary greatly in size according to the condition of the habitat. Breeding males may exhibit territoriality, especially in areas where breeding sites are scarce.
Populations of western toads have very limited dispersal, particularly in rugged terrain.
Western toads require open water for breeding. All breeding members of a local population tend to lay their eggs in the same location, which is used repeatedly from year to year. For example, at one site on a permanent lake in the Oregon Cascade Range, western toads returned each year to the same submerged willow clumps. Eggs are usually laid in shallow water, not deeper than 12 inches (30 cm) but usually at least 6 inches (15 cm). The warmth of shallow water increases the rate at which development occurs; shallow water and vegetative matter may contribute to protection of eggs from predation by fish. In western Montana, breeding western toads used gravel pits that were only filled with water during spring runoff. These gravel pits contained cattails (Typha spp.) but no other vegetation, and were 5 feet (1.5 m) deep in the center.
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