Anaxyrus baxteri
(Porter, 1968)
Wyoming Toad
G1Critically ImperiledGlobal Rank
Extinct in the wildIUCN
Very highThreat Impact
U.S. Fish & Wildlife Service, https://www.usa.gov/government-works
Identity
Unique IDELEMENT_GLOBAL.2.101600
Element CodeAAABB01220
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVertebrate Animal
IUCNExtinct in the wild
Endemicendemic to a single state or province
KingdomAnimalia
PhylumCraniata
ClassAmphibia
OrderAnura
FamilyBufonidae
GenusAnaxyrus
Synonyms
Bufo baxteriPorter, 1964Bufo hemiophrys baxteri
Concept Reference
Smith, H. M., D. Chiszar, J. T. Collins, and F. van Breukelen. 1998. The taxonomic status of the Wyoming toad, Bufo baxteri Porter. Contemporary Herpetology 1998(1):http//alpha.selv.edu/ch/1998/1
Taxonomic Comments
The genus Anaxyrus was split from Bufo by Frost et al. (2006). However, taxonomy within the genus Bufo remains controversial and many references still use the long-established Bufo.
Recognized as a distinct species by Smith et al. (1998).
Recognized as a distinct species by Smith et al. (1998).
Conservation Status
Rank MethodLegacy Rank calculation - Excel v3.1x
Review Date2018-11-21
Change Date2001-10-11
Edition Date2018-11-21
Edition AuthorsHammerson, G. (2011); Schuhmann, A (2018)
Threat ImpactVery high
Range Extent<100 square km (less than about 40 square miles)
Number of Occurrences1 - 5
Rank Reasons
Very small range in the Laramie Basin, Wyoming and considered extinct in the wild due to reliance on captive-releases; threats include chytrid fungal infection, prolonged drought, incompatible land use.
Range Extent Comments
Commonly found historically across 1820 sq km of the Laramie Basin in Albany County, Wyoming. Now restricted to Mortenson Lake National Wildlife Refuge and release sites created under Safe Harbor Agreements. All wild-occurring toads are considered the product of reintroductions that started in 1989 (USFWS 2015).
Occurrences Comments
Extant only at Mortenson Lake National Wildlife Refuge and two private land sites protected under the Wyoming Toad Safe Harbor Agreement (USFWS 2015). National Public Radio reported five total sites as of 2017, though none are considered self-sustaining.
Threat Impact Comments
Mortenson Lake site is infected with the amphibian chytrid fungus (Batrachochytrium dendrobatidis) (USFWS 2002). This fungus has been implicated in declines and extinctions of amphibian species worldwide. Retrospective analysis shows that the fungus has been present at Mortenson Lake since at least 1989. In addition, chytridiomycosis is the most commonly seen disease in the captive population. Predation, pesticide use, irrigation practices, and lack of genetic diversity may also limit the abundance of Wyoming toads in the Laramie Basin (USFWS 2015). Mortenson Lake has become more saline (and less suitable for toads) as a result of drought-related increases in evaporation (USFWS 2002).
Ecology & Habitat
Habitat
Historically associated with floodplain ponds along the Big and Little Laramie Rivers; use of lakes may have been limited due to saline conditions; irrigation may have flushed out the lakes and made them more suitable for toads (George Baxter). Currently occurs in the vicinity of lakes and adjacent meadows. Uses rodent burrows for shelter. Eggs and larvae develop in shallow water.
Reproduction
Lays eggs generally from mid-May to mid-June. Larvae metamorphose by early August. Females in the wild likely first breed when 2-3 years old. Breeding aggregations generally are small.
Terrestrial Habitats
Grassland/herbaceous
Palustrine Habitats
TEMPORARY POOLHERBACEOUS WETLANDRiparian
Other Nations (1)
United StatesN1
| Province | Rank | Native |
|---|---|---|
| Wyoming | S1 | Yes |
Threat Assessments
| Threat | Scope | Severity | Timing |
|---|---|---|---|
| 2 - Agriculture & aquaculture | Unknown | Extreme - moderate | High (continuing) |
| 2.1 - Annual & perennial non-timber crops | Unknown | Extreme - moderate | High (continuing) |
| 7 - Natural system modifications | Large - restricted | Moderate or 11-30% pop. decline | High (continuing) |
| 7.2 - Dams & water management/use | Large - restricted | Moderate or 11-30% pop. decline | High (continuing) |
| 8 - Invasive & other problematic species, genes & diseases | Pervasive (71-100%) | Extreme or 71-100% pop. decline | High (continuing) |
| 8.1 - Invasive non-native/alien species/diseases | Pervasive (71-100%) | Extreme or 71-100% pop. decline | High (continuing) |
| 9 - Pollution | Pervasive - restricted | Unknown | High (continuing) |
| 9.3 - Agricultural & forestry effluents | Pervasive - restricted | Moderate or 11-30% pop. decline | High (continuing) |
| 11 - Climate change & severe weather | Pervasive (71-100%) | Extreme - moderate | Moderate - low |
| 11.2 - Droughts | Pervasive (71-100%) | Extreme - moderate | Moderate - low |
Roadless Areas (3)
South Dakota (1)
| Area | Forest | Acres |
|---|---|---|
| Indian Creek | Buffalo Gap National Grassland | 24,666 |
Wyoming (2)
| Area | Forest | Acres |
|---|---|---|
| Sheep Mountain | Medicine Bow-Routt National Forest | 17,626 |
| Sheep Mountain | Medicine Bow-Routt National Forest | 17,626 |
References (26)
- Anonymous. 2005. Statewide programmatic biological assessment for the Wyoming toad (<i>Bufo baxteri</i>). Final report submitted to BLM Wyoming State Office, 5353 Yellowstone Road, Cheyenne, Wyoming 82003-1828.
- Baxter, G. T. 1947. The amphibians and reptiles of Wyoming. Wyoming Wildlife 11:30-34.
- Baxter, G. T., and M. D. Stone. 1980. Amphibians and reptiles of Wyoming. Wyoming Game and Fish Department. 137 pp.
- 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. 1991. Viewpoint: a new taxonomic arrangement for some North American amphibians and reptiles. SSAR Herpetol. Review 22:42-43.
- Crother, B. I. (editor). 2017. Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. 8th edition. SSAR Herpetological Circular 43:1-104. [Updates in SSAR North American Species Names Database at: https://ssarherps.org/cndb]
- Dickerson, K. 1999. Pesticides and the Wyoming toad. Endangered Species Bulletin 24:20-21.
- Dowling, H. G. 1993. Viewpoint: a reply to Collins (1991, 1992). Herpetol. Rev. 24:11-13.
- 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. 2020. Amphibian Species of the World: an Online Reference. Version 6.0. American Museum of Natural History, New York, USA. Online: http://research.amnh.org/herpetology/amphibia/index.html
- Frost, D.R., T. Grant, J. Faivovich, R. Bain, A. Haas, C.F.B. Haddad, R.O. de Sa´, S.C. Donnellan, C.J. Raxworthy, M. Wilkinson, A. Channing, J.A. Campbell, B.L. Blotto, P. Moler, R.C. Drewes, R.A. Nussbaum, J.D. Lynch, D. Green, and W.C. Wheeler. 2006. The amphibian tree of life. Bulletin of the American Museum of Natural History 297: 1-370.
- Green, D. M. 1983. Allozyme variation through a clinal hybrid zone between the toads BUFO AMERICANUS and B. HEMIOPHRYS in southeastern Manitoba. Herpetologica 39: 28-40.
- Jennings, M., R. Beiswinger, S. Corn, M. Parker, A. Pessier, B. Spencer, and P. S. Miller (editors). 2001. Population and habitat viability assessment for the Wyoming toad (<i>Bufo baxteri</i>). Final workshop report. Apple Valley, Minnesota: IUCN/SSC Conservation Breeding Specialist Group.
- Lewis, D. L., G. T. Baxter, K. M. Johnson, and M. D. Stone. 1985. Possible extinction of the Wyoming toad, BUFO HEMIOPHRYS BAXTERI. J. Herpetology 19:166-168.
- Matthews, J.R. and C.J. Moseley (eds.). 1990. The Official World Wildlife Fund Guide to Endangered Species of North America. Volume 1. Plants, Mammals. xxiii + pp 1-560 + 33 pp. appendix + 6 pp. glossary + 16 pp. index. Volume 2. Birds, Reptiles, Amphibians, Fishes, Mussels, Crustaceans, Snails, Insects, and Arachnids. xiii + pp. 561-1180. Beacham Publications, Inc., Washington, D.C.
- National Public Radio (NPR). 2017. Wyoming Toads Begin to Recover as States Seek Endangered Species Act Overhaul. Online. Available at: https://www.npr.org/2017/06/19/533203933/wyoming-toads-rebound-as-states-seek-endangered-species-act-reforms (Accessed 2018).
- Odum, R. A., and P. S. Corn. 2005. Bufo baxteri Porter, 1968. Wyoming toad . Pages 390-392 in M. Lannoo, editor. Amphibian declines: the conservation status of United States species. University of California Press, Berkeley.
- Parker, J., S. H. Anderson, and F. J. Lindzey. 2000. Natural history notes. BUFO BAXTERI. Herpetological Review 31:167-168.
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- Spencer, B. 1999. The Wyoming toad SSP. Endangered Species Bulletin 24:18-19.
- Stebbins, R. C. 1985a. A field guide to western reptiles and amphibians. Second edition. Houghton Mifflin Company, Boston, Massachusetts. xiv + 336 pp.
- Taylor, S. K., E. S. Williams, E. T. Thorne, K. W. Mills, D. I. Withers, and A. C. Pier. 1999c. Causes of mortality of the Wyoming toad. Journal of Wildlife Diseases 35:49-57.
- U.S. Fish and Wildlife Service (USFWS). 1990. Endangered and threatened species recovery program: report to Congress. 406 pp.
- U.S. Fish and Wildlife Service (USFWS). 1991. Wyoming toad recovery plan. U.S. Fish and Wildlife Service, Denver, Colorado. 28 pp.
- U.S. Fish and Wildlife Service (USFWS). 2002. Wyoming Field Office Annual Wyoming Toad Report FY 02.
- U.S. Fish and Wildlife Service (USFWS). 2015. Wyoming Toad Bufohemiphrys baxteri now known as Anayrus baxteri Revised Recovery Plan 2015. Mountain-Prairie Region, Denver, Colorado. Online. Available at: https://ecos.fws.gov/docs/recovery_plan/First%20Revised%20Recovery%20Plan%20for%20Wyoming%20Toad_07.16.2015.pdf (Accessed 2018).