Species: Anaxyrus boreas

Western Toad

Species

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Encyclopedia of Puget Sound

These warty toads are yellowish, dusky, tan, gray, or greenish on top, with dark markings ranging from a few spots to extensive mottling. Usually a light stripe extends along the middle of the back (most prominent in mature females; may be absent or inconspicuous in juveniles, which may have reddish warts). Parotoid glands (glandular swellings behind each eye) are oval. Cranial crests (hard ridges next to the eyes) are absent or indistinct. The tubercles on the underside of hind feet lack a sharp cutting edge; the foot tubercles are yellowish or orange in juveniles. Adult females are as large as 5 inches (12.7 cm) in snout-vent length, but males rarely exceed 3.7 inches (9.5 cm). Mature males have a dark patch on the inner surface of the thumb during the breeding season. Male lack vocal sacs but may produce repeated chirping sounds if grasped by hand (females usually are silent or emit few chirps). Larvae are black or dark brown on top; the tail fin may be heavily speckled with gray or black;and the eyes are about half way between the midline of the head and outside edge of the head. Larvae may reach a maximum total length about 2 inches (5 cm) but often are much smaller. Eggs are about 1.5-1.8 mm in diameter and are arranged in 1-3 rows (often two rows that appear to be a single zig-zag row) in long strings of two-layered jelly. Source: Hammerson (1999).

Classification

Kingdom

Animalia

Phylum

Craniata

Class

Amphibia

Order

Anura

Family

Bufonidae

Genus

Anaxyrus

NatureServe

Source:
ELEMENT_GLOBAL.2.102714

Classification

Other Global Common Names

Boreal Toad - crapaud de l'Ouest

Informal Taxonomy

Animals, Vertebrates - Amphibians - Frogs and Toads

Formal Taxonomy

Animalia - Craniata - Amphibia - Anura - Bufonidae - Anaxyrus - as two distinct species or, conversely, combining it with other minor groups and thus broadening its scope).

Ecology and Life History

Short General Description

A toad.

Migration

false - true - false - In Montana, individuals moved along stream corridors; based on recaptures (not radio-tagging), the longest documented movement was 1.5 km upstream in 6 days (Adams et al. 2005).

Non-migrant

false

Locally Migrant

true

Food Comments

Metamorphosed individuals feed on various small terrestrial invertebrates. Larvae filter suspended plant material or feed on bottom detritus (Nussbaum et al. 1983).

Reproduction Comments

The breeding period varies with local conditions; it may begin in January at low elevations but not until late spring or summer, as the winter snowpack begins to melt, in the high mountains. Females deposit an average of about 12,000 eggs/clutch, in two strands. Eggs hatch in a few days (warm temperatures) or in up to about 12 days (cold conditions). Larvae metamorphose in around 1-3 months, before the next winter; warm conditions result in the fastest larval development. Recently metamorphosed western toadlets sometimes form dense aggregations on the shores of breeding sites. Adult females may skip one or more years between successive breeding events. In northwestern Utah, single-year breeding populations at six sites ranged from a few dozen to nearly 250 individuals (Thompson 2004).<br>

Ecology Comments

Ravens were significant predators on breeding toads in Oregon Cascades (Olson 1989). In Colorado, Corn (1993, Herpetol. Rev. 24:57) observed a high rate of predation on breeding adults, evidently by ravens. Crow predation on adults was observed in Idaho (Brothers, 1994, Herpetol. Rev. 25:117).

Length

Conservation Status

NatureServe Global Status Rank

Global Status Last Reviewed

2008-01-03

Global Status Last Changed

2001-10-15

Distribution

Conservation Status Map

Global Range

GH - 200,000 to >2,500,000 square km (about 80,000 to >1,000,000 square miles) - GH - The range extends along the Pacific Coast from southern Alaska (Wiedmer and Hodge 1996) to Baja California, and eastward through the Rocky Mountains to west-central Alberta, Montana (Werner et al. 2004), Wyoming (Baxter and Stone 1985), Utah (Ross et al. 1995, Thompson et al. 2004), Colorado (Hammerson 1999), and (formerly) northern New Mexico (Degenhardt et al. 1996). The species is absent from most of the desert Southwest (Stebbins 2003). Elevational range extends from sea level to more than 11,000 feet (3.355 meters) in some areas in the Rocky Mountains.

Global Range Code

Global Range Description

200,000 to >2,500,000 square km (about 80,000 to >1,000,000 square miles)

ELEMENT_GLOBAL.2.102714