Great Plains Toad - Anaxyrus cognatus
State Rank Reason (see State Rank above)
Current trend is unknown due to a scarcity of observations, but long-term declines are possible due to declines in ephemeral waterbodies (bison wallows). Species faces threats from habitat loss including development of native habitat, and reduced availability of burrows due to black-tailed prairie dog declines.
- Details on Status Ranking and Review
ScoreG - 200,000-2,500,000 km squared (about 80,000-1,000,000 square miles)
Comment233,208 square Kilometers from Natural Heritage Program range maps
ScoreA - Very Large Decline (decline of >90%, with <10% of population size, range extent, area occupied, and/or number or condition of occurrences remaining)
CommentHistoic data sugest that this species made extensive use of buffalo wallows for breeding which may indicate a substanital decline in available breeding habitat
ScoreU - Unknown. Short-term trend in population, range, area occupied, and number and condition of occurrences unknown.
CommentRecent calling surveys recorded few observations of this species.
ScoreB - Moderate and imminent threat. Threat is moderate to severe and imminent for a significant proportion (20-60%) of the population or area.
CommentLoss of habitat due to conversion of native prairie to agriculture. Loss of hibernacula/ burrow systems due to prairie dog declines. Water quality of breeding sites. Lack of knowledge to assess threats.
SeverityModerate - Major reduction of species population or long-term degradation or reduction of habitat in Montana, requiring 50-100 years for recovery.
ScopeModerate - 20-60% of total population or area affected
ImmediacyHigh - Threat is operational (happening now) or imminent (within a year).
ScoreC - Not Intrinsically Vulnerable. Species matures quickly, reproduces frequently, and/or has high fecundity such that populations recover quickly (< 5 years or 2 generations) from decreases in abundance; or species has high dispersal capability such that extirpated populations soon become reestablished through natural recolonization (unaided by humans).
CommentSpecies mature in 2-3 years, produce thousands of eggs with low survival
ScoreB - Narrow. Specialist. Specific habitat(s) or other abiotic and/or biotic factors (see above) are used or required by the Element, but these key requirements are common and within the generalized range of the species within the area of interest.
CommentPlains /xeric landscapes near drainages and waterbodies
Raw Conservation Status Score
3.5 + 0 (geographic distribution) + 0 (environmental specificity) + -0.5 (long-term trend) + -0.75 (threats) = 2.25
The skin of adult Great Plains Toads is covered with numerous small warts; cranial crests are prominent, and diverge posteriorly from a hard lump (boss) on top of the snout. The parotoid glands posterior to the eyes are elongated. The back exhibits a somewhat symmetrical pattern of large, light-edged dark spots or patches. The underside of the hind foot often has a sharp-edged tubercle and a smaller dark-tipped tubercle. Females can reach 11.4 centimeters snout-vent length (SVL); males are usually less than 9.5 centimeters SVL. Males have dark, loose throat skin and a dark patch on the inner surface of the innermost digit of the forefeet during breeding. The vocal sac, when inflated, may extend beyond the front of the face. The breeding call is a long continuous trill or pulsating ringing sound.
Juveniles have reddish warts. Tadpoles are initially blackish on the dorsum with light or gold flecking, then become paler and mottled brown; the dorsal pattern of large, paired blotches appears before metamorphosis is complete. The eyes are dorsal, and the dorsal fin is highly arched with some black dentritic lines. The upper mandible is highly arched, and labial tooth rows are usually 2/3, with oral papillae restricted to the sides of the mouth. Total length ranges from 25 to 35 millimeters. Eggs are black above, white below, and about 1.2 to 1.3 millimeters in diameter, usually in a single row in long strings of two-layered jelly that is constricted between individual eggs.
Boreal Toad (Bufo boreas) lacks cranial crests and is found only in mountainous parts of Montana. On Woodhouse's Toad (Bufo woodhousii), the cranial crests are parallel between the eyes, forming two back-to-back L shapes (not convergent between the eyes in a V), and do not merge on the snout in a bony lump or boss. Both Boreal and Woodhouse's Toads lack the symmetrical black-green spots with light halos on on the back and sides . Boreal Toad tadpoles are dark to black on the back, lack any gold flecking, and are found only in mountainous parts of the state. Woodhouse's Toad tadpoles lack the strongly arched tail fin. Woodhouse's Toad eggs are enclosed in a single jelly layer; Boreal Toad eggs are in strings that are not pinched between eggs, and are present only in the mountainous parts of the state.
Western Hemisphere Range
Observations in Montana Natural Heritage Program Database
Number of Observations:
(Click on the following maps and charts to see full sized version)
Map Help and Descriptions
(Observations spanning multiple months or years are excluded from time charts)
No information is available specific to Montana. Elsewhere the species is known to migrate up to several hundred meters between breeding pools and nonbreeding terrestrial habitats.
Little specific information on the habitat of Great Plains Toad is available. It has been reported from sagebrush-grassland, rainwater pools in road ruts, in stream valleys, at small reservoirs and stock ponds, and around rural farms; breeding has been documented in small reservoirs and backwater sites along streams (Mosimann and Rabb 1952, Dood 1980, Hendricks 1999, Hossack et al. 2003).
Information gathered from other locations indicates that when inactive, the Great Plains Toad is found in burrows and under rocks or wood. During the active season, it occupies burrows during the day that are quite shallow. This species enters water only to breed. It breeds in rain pools, flooded areas, and ponds and reservoirs that fluctuate in size, and appears to prefer stock tanks and roadside ponds rather than floodplains (Baxter and Stone 1985). Eggs and larvae develop in shallow water, usually clear or slightly turbid, but not muddy.
Ecological Systems Associated with this Species
- Details on Creation and Suggested Uses and Limitations
How Associations Were Made
We associated the use and habitat quality (common or occasional) of each of the 82 ecological systems mapped in Montana for
vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
- Using personal observations and reviewing literature that summarize the breeding, overwintering, or migratory habitat requirements of each species (Dobkin 1992, Hart et al. 1998, Hutto and Young 1999, Maxell 2000, Foresman 2012, Adams 2003, and Werner et al. 2004);
- Evaluating structural characteristics and distribution of each ecological system relative to the species' range and habitat requirements;
- Examining the observation records for each species in the state-wide point observation database associated with each ecological system;
- Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of "observations versus availability of habitat".
Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.
In general, species were listed as associated with an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.
However, species were not listed as associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system, even if
point observations were associated with that system.
Common versus occasional association with an ecological system was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species as represented in scientific literature.
The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignment of common versus occasional association.
If you have any questions or comments on species associations with ecological systems, please contact the Montana Natural Heritage Program's Senior Zoologist.
Suggested Uses and Limitations
Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.
These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at: http://mtnhp.org/requests/default.asp
) or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.
Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.
Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.
Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).
Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species' known geographic range.
- Adams, R.A. 2003. Bats of the Rocky Mountain West; natural history, ecology, and conservation. Boulder, CO: University Press of Colorado. 289 p.
- Dobkin, D. S. 1992. Neotropical migrant land birds in the Northern Rockies and Great Plains. USDA Forest Service, Northern Region. Publication No. R1-93-34. Missoula, MT.
- Foresman, K.R. 2012. Mammals of Montana. Second edition. Mountain Press Publishing, Missoula, Montana. 429 pp.
- Hart, M.M., W.A. Williams, P.C. Thornton, K.P. McLaughlin, C.M. Tobalske, B.A. Maxell, D.P. Hendricks, C.R. Peterson, and R.L. Redmond. 1998. Montana atlas of terrestrial vertebrates. Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT. 1302 p.
- Hutto, R.L. and J.S. Young. 1999. Habitat relationships of landbirds in the Northern Region, USDA Forest Service, Rocky Mountain Research Station RMRS-GTR-32. 72 p.
- Maxell, B.A. 2000. Management of Montana's amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species. Report to U.S. Forest Service Region 1. Missoula, MT: Wildlife Biology Program, University of Montana. 161 p.
- Werner, J.K., B.A. Maxell, P. Hendricks, and D. Flath. 2004. Amphibians and reptiles of Montana. Missoula, MT: Mountain Press Publishing Company. 262 p.
- Commonly Associated with these Ecological Systems
Shrubland, Steppe and Savanna Systems
Sparse and Barren Systems
Wetland and Riparian Systems
- Occasionally Associated with these Ecological Systems
Forest and Woodland Systems
Human Land Use
Shrubland, Steppe and Savanna Systems
Wetland and Riparian Systems
Although food habits in Montana have not been studied, adult and juvenile Great Plains Toads are generally known to eat a variety of small terrestrial arthropods, including spiders, moths, caterpillars, flies, beetles, termites, and ants (Dimmitt and Ruibal 1980, Hammerson 1999), and require 11 to 22 feedings per year to survive. In the playa wetlands of northwest Texas, carabid beetles were the most common food (Anderson et al. 1999). Larvae eat suspended matter, organic debris, algae, and plant tissue.
Great Plains Toads are uncommon near human habitation (Black 1970). They are mainly nocturnal (Bragg 1940, Black 1970). Post-metamorphic young may form aggregations (Graves 1993).
Great Plains Toads breed only after rain in clear, shallow, temporary pools of flooded grasslands, probably May to July in Montana (Bragg 1940, Black 1970). Two of three females collected in north-central Montana on July 20 had well developed eggs (Mosimann and Rabb 1952).
From information gathered in Oklahoma, breeding choruses usually last a few days but are of variable duration. They lasted up to 14 days in March but only 1 to 2 days in June (Krupa 1994). Clutch size was usually several thousand eggs that hatch in a few days. The larval period was short (as few as 18 days) in June and long (up to 49 days) in early spring. Pools rarely held water long enough for larvae to reach metamorphosis (Krupa 1994). Great Plains Toads are sexually mature in 2 to 5 years. The species commonly exhibits communal egg deposition (Krupa 1994).
No special management needs are currently recognized. However, at permanent and semi-permanent water bodies (reservoirs and stock ponds) where breeding has been observed, portions of the shoreline with emergent vegetation could be fenced to create enclosures that protect breeding adults, eggs, and tadpoles from trampling and the removal of emergent cover by livestock. Another option would be the creation of ponds designed for use by prairie amphibians as breeding sites, with the perimeter surrounded by fencing to prevent access by livestock. Game fish should not be introduced to any of these ponds.
- Literature Cited AboveLegend: View Online Publication
- Anderson, A. M., D. A. Haukos, and J. T. Anderson. 1999. Diet composition of three anurans from the playa wetlands of northwest Texas. Copeia 1999:515-520.
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- Additional ReferencesLegend: View Online Publication
Do you know of a citation we're missing?
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- Additional Sources of Information Related to "Amphibians"