Boreal Toad
The boreal toad is a native amphibian and is Colorado's only alpine species of toad.
About This Species
Once common in montane habitats between 7,000-12,000 feet in the Southern Rocky Mountains, the boreal toad (Anaxyrus boreas boreas) has experienced dramatic population declines over the past two decades. The declines appear to be related to infection by the chytrid fungus Batrachochytrium dendrobatidis (Bd), which can cause a disease with a very high mortality rate. Other factors such as habitat loss may also play a role.
The boreal toad is presently listed as an endangered species by the states of Colorado and New Mexico and is a protected species in Wyoming. The U.S. Fish and Wildlife Service (FWS) classified the Southern Rocky Mountain population of the boreal toad in 1995 as a candidate species for federal listing under the Endangered Species Act. In 2005, this designation was removed while the genetic distinctness of the Southern Rocky Mountain population was reevaluated. In 2012, the FWS issued a 90-day finding and initiated a status review, the result of which was to not federally list the boreal toad.
Conservation
State Endangered Species
Formerly widespread and common, these small toads are now extremely scarce. The main cause of decline is the amphibian chytrid fungus, a skin fungus which has also attacked many other amphibian species worldwide. Because of declining populations, Colorado listed the boreal toad as a state endangered species in 1993.
Conservation
Returning the Boreal Toad to Colorado
Colorado Parks and Wildlife's Native Aquatic Species Restoration Facility has played a critical role in efforts to restore boreal toads to Colorado ecosystems. Biologists are hopeful that future translocations will establish additional breeding sites throughout the state. Colorado Parks and Wildlife also provides funding and other support to university researchers who are studying promising approaches to helping toads and other amphibians resist chytrid fungus.
2014
biologists document a breeding population of boreal toads near Cameron Pass—the first translocation effort that has resulted in known survival to the age of reproduction (4 or 5 years old).
133,546
tadpoles, toadlets and adult toads have been raised by Colorado Parks and Wildlife's Native Aquatic Species Restoration Facility, which have been translocated to help reestablish boreal toads in their historical habitat.
Protecting the Boreal Toad
Amphibian Research
Researching the Boreal Toad
Although Colorado Parks and Wildlife is not actively conducting boreal toad research at this time, the agency has devoted significant resources in the past two decades toward researching the cause of boreal toad declines in the state and exploring ways to recover the species.
In 2012, Colorado Parks and Wildlife researchers and biologists partnered with Dr. Larissa Bailey at Colorado State University to define the survey effort required to determine if toads occupied potential boreal toad breeding sites. Colorado Parks and Wildlife then applied this survey methodology to search for suitable habitat for new toad populations and to identify potential translocation sites. Presently, there are several potential translocation sites in Colorado that are being monitored for the fungus. Provided the deadly fungus is not found at these sites, these will likely become new translocation sites.
Researchers from Colorado Parks and Wildlife and Cheyenne Mountain Zoo in Colorado Springs also investigated methods for identifying individual boreal toads, which can help researchers estimate survival, movement, abundance and recruitment. Boreal toads display unique markings on their bellies, which researchers determined could be used to successfully identify individual animals. Using digital photographs, researchers catalogued all toads housed at Native Aquatic Species Restoration Facility to help ensure the integrity of the breeding program there.
Colorado Parks and Wildlife's Native Aquatic Species Restoration Facility plays a critical role in the state's efforts to restore boreal toads. The facility houses over 700 adult boreal toads, providing a key link in the production of these animals for translocation efforts and research, as well as serving as a genetic bank for this state endangered species. Protocols used in maintaining boreal toads at the facility can be found in the Boreal Toad Husbandry Manual.
More Information:
Physical Characteristics
Boreal toads have warty skin, an oval glandular lump behind each eye, no distinct bony ridges bordering eyes and bumps on underside of hind feet lack a sharp cutting edge.
Size
Females generally grow to 11 centimeters and males to 9 centimeters. Head and body length rarely more than 11 cm (4.3 inches) in females, rarely more than exceed 9.5 cm (3.7 inches) in males.
Warts
Both sexes appear warty and usually have a light stripe along the middle of the back. Juveniles may have red warts.
Color
The toads usually a light stripe along middle of back (most prominent in mature females). The light stripe on the back may be absent or inconspicuous in juveniles. Yellowish in juveniles.
Commonly Found
Beaver pond complexes are key, especially blown out ones with dark bottoms that collect a lot of the sun's energy. Breeding sites start around 8,000 feet, peaking between 9,400 to 10,400 feet, then tapering off just below 12,000 feet. Emergent vegetation is important for stringing egg masses around. Boreal toad eggs are laid in a single strand and are jet black. Unfertilized eggs turn bright white with fungus.
Range
The species occurs throughout most of western North America, from southeastern Alaska to northern Baja California, Utah and northern New Mexico. The distinct Southern Rocky Mountain population is distributed from southern Wyoming to southern Colorado, and is currently believed to be extirpated from northern New Mexico.
Habitat
In Colorado, the boreal toad is distributed throughout the Rockies from the northern state border to Mineral and Hinsdale counties in the south at elevations between 7,500 and 12,000 feet. Throughout most of the Rocky Mountains, usually at elevations between 8,500 feet and 11,500 feet. Formerly widespread and common, now scarce except in localized areas. The boreal toad is restricted to areas with suitable breeding habitat in spruce-fir forests and alpine meadows. Breeding habitat includes lakes, marshes, ponds, and bogs with sunny exposures and quiet, shallow water. Vicinity of mountain lakes, ponds, meadows, and wetlands in subalpine forest (for example, spruce, fir, lodgepole pine, aspen).
Diet
Boreal toads feed on a wide range of invertebrates and insects, including flies, mosquitoes, grasshoppers, beetles and moths. Adults often feed in meadows and forest openings near water but sometimes in drier forest habitats.
Reproduction
Toads breed in still waters in marshy areas from May to late July. Unlike many species of toad, the boreal does not have a loud mating call. Males will emit a soft chirp, and sometimes call in groups. Females typically lay 3,000 to 8,000 eggs and larvae development takes two months or more. A mature male has dark patch on the inner surface of the innermost toe on the front feet during breeding season; vocal sac absent. Their breeding call is soft chirping sounds.
Larvae
Body and tail (including fins) black or dark brown; eyes about halfway between midline and outside edge of head; 2 rows of tiny teeth on upper lip, 3 rows on lower lip; up to about 34–37 mm (1.3-1.5 inches) long.
Eggs
Black, in 1–3 rows (often 2 rows that appear to be a single zigzag row) in long strings of double-layered jelly; laid in shallow water, may become tangled in vegetation or covered by silt/detritus.
Life History
Breeds in shallows of lakes and ponds in spring or early summer. Larvae metamorphose into small toads from late July through mid-September, mainly in August.
Threats to Species
- Invasive, Problematic, Native Species, Pathogens
- Energy Development and Land Use