Great Plains Toad - Anaxyrus cognatus
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 elongate. 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 on the back and sides the symmetrical black-green spots with light halos. 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.
Summary of Observations Submitted for Montana
Number of Observations:
(Click on the following maps and charts to see full sized version)
Map Help and Descriptions
(Records associated with a range of dates 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, P. Hendricks personal communication).
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 (high, medium, or low) 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 2001, 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 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 associated as using 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 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.
High, medium, and low habitat quality was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species in the 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 assignments of habitat quality.
If you have any questions or comments on species associations with ecological systems, please contact Bryce Maxell at email@example.com
or (406) 444-3655.
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.
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- 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.
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- Commonly Associated with these Ecological Systems
Open Water / Wetland and Riparian Systems
Shrubland, Steppe and Savanna Systems
Sparse and Barren Systems
- Occasionally Associated with these Ecological Systems
Forest and Woodland Systems
Open Water / Wetland and Riparian Systems
Shrubland, Steppe and Savanna 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). Postmetamorphic 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 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, 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 exhibited 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 exclosures 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 WorldCat Record View Online Publication
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- Additional ReferencesLegend: View WorldCat Record View Online Publication
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- Sullivan, B.K. 1985. Sexual selection and mating system variation in anuran amphibians of the Arizona-Sonoran desert. Great Basin Naturalist 45(4): 688-696.
- Sullivan, B.K. 1990. Natural hybrid between the Great Plains toad (Bufo cognatus) and the red-spotted toad (Bufo punctatus) from central Arizona. Great Basin Naturalist 50(4) 1990: 371-372.
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- Tuegal, M. 2004. Skunk predation on the Great Plains toad (Buco cognatus). Sonoran Herpetologist 17(12):118.
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- Waage, Bruce C., 1996, Western Energy Company Rosebud Mine, Colstrip, Montana: 1995 Annual Wildlife Monitoring Report; December 1, 1994 - November 30, 1995. February 28, 1996.
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- Additional Sources of Information Related to "Amphibians"