Anaxyrus woodhousii - (Girard, 1854)
Woodhouse's Toad
Other English Common Names: Woodhouse's toad
Synonym(s): Bufo woodhousii Girard, 1854
Taxonomic Status: Accepted
Related ITIS Name(s): Anaxyrus woodhousii (Girard, 1854) (TSN 773532)
French Common Names: crapaud de Woodhouse
Unique Identifier: ELEMENT_GLOBAL.2.103855
Element Code: AAABB01180
Informal Taxonomy: Animals, Vertebrates - Amphibians - Frogs and Toads
 
Kingdom Phylum Class Order Family Genus
Animalia Craniata Amphibia Anura Bufonidae Anaxyrus
Genus Size: D - Medium to large genus (21+ species)
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Concept Reference
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Concept Reference: Frost, D. R. 1985. Amphibian species of the world. A taxonomic and geographical reference. Allen Press, Inc., and The Association of Systematics Collections, Lawrence, Kansas. v + 732 pp.
Concept Reference Code: B85FRO01HQUS
Name Used in Concept Reference: Bufo woodhousii
Taxonomic Comments: Bufo fowleri formerly was included in this species. Sullivan et al. (1996) examined advertisement call variation and concluded that B. fowleri should be recognized as a distinct species and that subspecies australis and woodhousii should continue to be regarded as western forms of the B. woodhousii complex.

Bufo woodhousii (sensu lato) hybridizes with B. americanus in several areas (Green 1984). Bufo woodhousii and B. punctatus sometimes hybridize in Colorado (Hammerson 1999) and northern Arizona (Malmos et al. 1995, Great Basin Nat. 55:368-371). See Sullivan and Lamb (1988) and Malmos et al. (2001) for information on hybridization with B. microscaphus in central Arizona.

In a taxonomic revision that has been rejected or ignored by other herpetologists, Sanders (1987) divided B. woodhousii into multiple species as follows: B. woodhousii (Utah, Arizona, New Mexico, Texas), B. antecessor (southeastern Washington, Oregon, Idaho, Utah, western Colorado, part of New Mexico), B. planiorum (northern and central Great Plains), B. hobarti (range of B. w. fowleri of most authors, excluding northeastern U.S.), and B. fowleri (mostly restricted to southern New England). Sanders (1986) also elevated Bufo woodhousii velatus to full species status. Dundee and Rossman (1989) regarded velatus as a racial variant of woodhousii produced from various gene introgressions from other species of toads. Conant and Collins (1991) did not recognize velatus as valid at any taxonomic rank.
Conservation Status
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NatureServe Status

Global Status: G5
Global Status Last Reviewed: 01Apr2002
Global Status Last Changed: 11Oct2001
Rounded Global Status: G5 - Secure
Reasons: Common and widespread; tolerant of various kinds of habitat disturbance; no evidence of significant regional or rangewide declines.
Nation: United States
National Status: N5 (05Nov1996)

U.S. & Canada State/Province Status
United States Arizona (S5), California (SNR), Colorado (S5), Idaho (S2), Iowa (S3), Kansas (S5), Louisiana (S5), Missouri (SNR), Montana (S4), Navajo Nation (S5), Nebraska (S5), Nevada (S5), New Mexico (S5), North Dakota (SNR), Oklahoma (S5), Oregon (S2), South Dakota (S5), Texas (SU), Utah (S5), Washington (S3), Wyoming (S4)

Other Statuses

IUCN Red List Category: LC - Least concern

NatureServe Global Conservation Status Factors

Range Extent: 200,000-2,500,000 square km (about 80,000-1,000,000 square miles)
Range Extent Comments: This species is found throughout most of the central and southwestern United States and portions of adjacent northern Mexico. It is absent from high mountains and the West Coast.

Number of Occurrences: 81 to >300
Number of Occurrences Comments: Represented by many and/or large occurrences throughout most of the range.

Population Size: >1,000,000 individuals
Population Size Comments: Total adult population size is unknown but surely greater than 1,000,000.

Number of Occurrences with Good Viability/Integrity: Very many (>125)

Overall Threat Impact: Medium
Overall Threat Impact Comments: Overall, not threatened. Locally threatened by human-caused habitat degradation and destruction and by mortality on roads near breeding sites.

Short-term Trend: Relatively Stable (<=10% change)
Short-term Trend Comments: The population trend varies with location but is probably stable in most areas. See Sullivan and Lamb (1988) for evidence that B. woodhousii is displacing B. microscaphus in central Arizona.

Long-term Trend: Decline of <30% to increase of 25%
Long-term Trend Comments: In some areas this species has increased in area of occurrence and population size through human augmentation of breeding habitat.

Intrinsic Vulnerability: Moderately vulnerable

Environmental Specificity: Moderate to broad.

Other NatureServe Conservation Status Information

Distribution
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Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) This species is found throughout most of the central and southwestern United States and portions of adjacent northern Mexico. It is absent from high mountains and the West Coast.

U.S. States and Canadian Provinces
Color legend for Distribution Map
Endemism: occurs (regularly, as a native taxon) in multiple nations

U.S. & Canada State/Province Distribution
United States AZ, CA, CO, IA, ID, KS, LA, MO, MT, ND, NE, NM, NN, NV, OK, OR, SD, TX, UT, WA, WY

Range Map
Note: Range depicted for New World only. The scale of the maps may cause narrow coastal ranges or ranges on small islands not to appear. Not all vagrant or small disjunct occurrences are depicted. For migratory birds, some individuals occur outside of the passage migrant range depicted. For information on how to obtain shapefiles of species ranges see our Species Mapping pages at www.natureserve.org/conservation-tools/data-maps-tools.

Range Map Compilers: IUCN, Conservation International, NatureServe, and collaborators, 2004


U.S. Distribution by County Help
State County Name (FIPS Code)
ID Ada (16001), Canyon (16027), Elmore (16039)*, Franklin (16041), Nez Perce (16069)*, Owyhee (16073), Washington (16087)
OR Malheur (41045), Sherman (41055)
WA Benton (53005)+, Franklin (53021)+, Grant (53025)+, Klickitat (53039)+, Walla Walla (53071)+
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
16 Middle Bear (16010202)+
17 Upper Columbia-Priest Rapids (17020016), C. J. Idaho (17050101)+, Bruneau (17050102)+, Middle Snake-Succor (17050103)+, Upper Owyhee (17050104)+, Lower Owyhee (17050110)+, Lower Boise (17050114)+, Lower Malheur (17050117)+, Weiser (17050124)+, Lower Snake-Asotin (17060103)+*, Lower Snake (17060110), Middle Columbia-Lake Wallula (17070101), Lower John Day (17070204)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: A toad.
General Description: Dorsum yellowish brown, grayish, or olive, with unsymmetrical pattern of small dark spots that usually contain 1-2 warts; usually a light stripe along middle of back; cranial crests (supraorbital ridges) more or less parallel between eyes; parotoid glands about twice as long as wide; maximum snout-vent length about 12.7 cm), females grow much larger than males. Mature male: during breeding season, throat dark and dark patches present on inner surfaces of first and second digits of front feet; expanded vocal sac spherical or slightly elongated; breeding call: a loud waaaaaah lasting about 1-4 seconds and emitted up to several times per minute. Juvenile: middorsal stripe absent or inconspicuous, usually some warts reddish, often misidentified as red-spotted toad. Larvae: dorsum brown or dark gray, often with light mottling/dense gold flecking; head narrow when viewed from above (snout end more pointed and overall body shape more triangular than in red-spotted toad); belly gold with black mottling; eyes dorsal; fins mainly clear with sparse pigment flecks, more in upper fin than in lower; tail musculature dark with light mottling/gold flecking, pale along lower margin; labial tooth rows 2/3; oral papillae restricted to sides of mouth; anus on midline at front end of ventral tail fin; maximum total length at least 35 mm in Colorado. Eggs: black above, tan below, 1.0-1.5 mm in diameter, deposited in long strings in a single jelly envelope; single or double row of eggs in each jelly string. Source: Hammerson (1999).
Reproduction Comments: Breeding occurs in spring or summer, generally after rains. Several dozen adults may aggregate for breeding. Breeding choruses may last a few weeks. Females deposit a clutch of up to 25,000 eggs in long strings. Larvae metamorphose into tiny toadlets within 1-2 months. Individuals become sexually mature usually in 2-3 years.


Non-Migrant: N
Locally Migrant: Y
Long Distance Migrant: N
Mobility and Migration Comments: Migrates up to several hundred meters between breeding pools and adjacent nonbreeding terrestrial habitats.
Riverine Habitat(s): CREEK, Low gradient, Pool
Lacustrine Habitat(s): Shallow water
Palustrine Habitat(s): HERBACEOUS WETLAND, Riparian, TEMPORARY POOL
Terrestrial Habitat(s): Cropland/hedgerow, Desert, Grassland/herbaceous, Old field, Savanna, Shrubland/chaparral, Suburban/orchard
Special Habitat Factors: Benthic, Burrowing in or using soil, Fallen log/debris
Habitat Comments: Woodhouse's toads inhabit grasslands, desert and semi-desert shrublands, river valleys and floodplains, and agricultural areas, usually in areas with deep friable soils. When inactive, they burrow underground or hide under rocks, plants, or other cover. These toads live on land except during the brief breeding season. Breeding occurs in marshes, rain pools, ponds, lakes, reservoirs, flooded areas, stream pools or backwaters, and other bodies of water with a shallow margin lacking a strong current, including both permanent and temporary pools, generally in sites with few if any fishes.
Adult Food Habits: Invertivore
Immature Food Habits: Herbivore
Food Comments: Metamorphosed toads eat mainly various small terrestrial arthropods. Larvae eat suspended matter, organic debris, algae, and plant tissue.
Adult Phenology: Circadian, Hibernates/aestivates
Immature Phenology: Circadian, Hibernates/aestivates
Phenology Comments: Inactive during cold months of fall, winter, and early spring. Mostly nocturnal but diurnal activity is not uncommon. Active in wet or dry weather.
Colonial Breeder: Y
Length: 13 centimeters
Economic Attributes Not yet assessed
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Management Summary Not yet assessed
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Population/Occurrence Delineation
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Group Name: Bufonid Toads

Use Class: Not applicable
Subtype(s): Breeding Site
Minimum Criteria for an Occurrence: Occurrences are based on evidence of historical presence, or current and likely recurring presence, at a given location. Such evidence minimally includes collection or reliable observation and documentation of one or more individuals (including larvae or eggs) in or near appropriate habitat where the species is presumed to be established and breeding.
Separation Barriers: Busy major highway such that toads rarely if ever cross successfully; roads with nonpermeable barriers to toad movement; urbanized areas dominated by buildings and pavement.
Separation Distance for Unsuitable Habitat: 1 km
Separation Distance for Suitable Habitat: 5 km
Separation Justification: Opportunistic observations of various toad species in lowland habitats indicate regular movements of up to at least several hundred meters from the closest known breeding site (G. Hammerson, pers. obs.). Sweet (1993) recorded movements of up to 1 km in Bufo californicus. In defining critical habitat for B. californicus, USFWS (2000) included breeding streams and upland areas within a 25-m elevational range of each essential stream reach and no more than 1.5 km away from the stream. In northwestern Utah, Thompson (2004) recorded movements of Bufo boreas of up to 5 km across upland habitat between two springs during the summer-fall season. Another toad moved 1.3 km between May of one year and May of the next year; the following June it was back at the original breeding location (Thompson 2004). Most studies of toad movements have not employed radiotelemetry and were not designed to detect long-range movements or dispersal.

The separation distance for unsuitable habitat reflects the nominal minimum value of 1 km. The separation distance for suitable habitat reflects the good vagility of toads, their ability to utilize ephemeral or newly created breeding sites, and the consequent likely low probability that two occupied locations separated by less than several kilometers of suitable habitat would represent truly independent populations over the long term.

Inferred Minimum Extent of Habitat Use (when actual extent is unknown): .5 km
Date: 27Apr2005
Author: Hammerson, G.
Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 25Jan2010
NatureServe Conservation Status Factors Author: Reichel, J. D., and G. Hammerson.
Element Ecology & Life History Edition Date: 25Jan2010
Element Ecology & Life History Author(s): Hammerson, G.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

References
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  • Blackburn, L., P. Nanjappa, and M. J. Lannoo. 2001. An Atlas of the Distribution of U.S. Amphibians. Copyright, Ball State University, Muncie, Indiana, USA.

  • Collins, J. T. 1982. Amphibians and reptiles in Kansas. Second edition. Univ. Kansas Mus. Nat. Hist., Pub. Ed. Ser. 8. xiii + 356 pp.

  • Conant, R. and J. T. Collins. 1991. A field guide to reptiles and amphibians: eastern and central North America. Third edition. Houghton Mifflin Co., Boston, Massachusetts. 450 pp.

  • Dundee, H. A., and D. A. Rossman. 1989. The amphibians and reptiles of Louisiana. Louisiana State University Press, Baton Rouge.

  • Frost, D. R. 1985. Amphibian species of the world. A taxonomic and geographical reference. Allen Press, Inc., and The Association of Systematics Collections, Lawrence, Kansas. v + 732 pp.

  • Frost, D. R. 2002. Amphibian Species of the World: an online reference. V2.21 (15 July 2002). Electronic database available at http://research.amnh.org/herpetology/amphibia/index.html.

  • Frost, D. R. 2010. Amphibian Species of the World: an Online Reference. Version 5.4 (8 April 2010). Electronic Database accessible at http://research.amnh.org/herpetology/amphibia/index.php. American Museum of Natural History, New York, USA.

  • Frost, D. R., R. W. McDiarmid, and J. R. Mendelson III. 2008. Anura: Frogs. IN B. I. Crother (ed.), Scientific and Standard English Names of Amphibians and Reptiles of North America North of Mexico, pp. 2-12 SSAR Herpetological Circular 37.

  • Green, D. M. 1984. Sympatric hybridization and allozyme variation in the toads Bufo americanus and B. fowleri in southern Ontario. Copeia 1984:18-26.

  • Hammerson, G. A. 1982b. Amphibians and reptiles in Colorado. Colorado Division of Wildlife, Denver. vii + 131 pp.

  • Hammerson, G. A. 1999. Amphibians and reptiles in Colorado. Second edition. University Press of Colorado, Boulder. xxvi + 484 pp.

  • Johnson, T.R. 1977. The Amphibians of Missouri. University of Kansas Museum of Natural History, Public Education Series 6: ix + 134 pp.

  • Malmos, K. B., B. K. Sullivan, and T. Lamb. 2001. Calling behavior and directional hybridization between two toads (Bufo microscaphus X B. woodhousei) in Arizona. Evolution. 55:626-630.

  • Mulcahy, D. G., M. R. Cummer, J. R. Mendelson, III, B. L. Williams, and P. C. Ustach. 2002. Status and distribution of two species of Bufo in the northeastern Bonneville basin of Idaho and Utah. Herpetological Review 33:287-289.

  • Sanders, O. 1986. The heritage of Bufo woodhousei Girard in Texas. Baylor Univ., Occas. Pap. Strecker Mus. No. 1. 28 pp.

  • Sanders, O. 1987. Evolutionary hybridization and speciation in North American indigenous bufonids. Strecker Museum, Baylor Univ., Waco, Texas. 110 pp.

  • Stebbins, R. C. 1985a. A field guide to western reptiles and amphibians. Second edition. Houghton Mifflin Company, Boston, Massachusetts. xiv + 336 pp.

  • Stebbins, R. C. 2003. A field guide to western reptiles and amphibians. Third edition. Houghton Mifflin Company, Boston.

  • Sullivan, B. K. and T. Lamb. 1988. Hybridization between the toads Bufo microscaphus and Bufo woodhousii in Arizona: variation in release calls and allozymes. Herpetologica 44:325-333.

  • Sullivan, B. K., K. B. Malmos, and M. F. Given. 1996. Systematics of the Bufo woodhousii complex (Anura: Bufonidae): advertisement call variation. Copeia 1996:274-280.

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