Anaxyrus baxteri (Porter, 1968)

Wyoming toad, Baxter's toad



Taxonomy & Nomenclature

Synonym/s: Bufo hemiphrys baxteri (Porter, 1964); Bufo baxteri Porter, 1964; Bufo hemiophrys Cope, 1886 (in part?); Anaxyrus baxteri (Porter, 1964) [incorrect year; used by Hammerson (2004b)]


Conservation Status

Extinct in the wild

Last record: 2000's

IUCN RedList status: Extinct in the Wild


Prior to being extinct in the wild it was rediscovered (last record 1980-rediscovered 1987).



Laramie Basin, Wyoming, USA


Biology & Ecology










Original scientific description:

Porter, K. R. (1968). Evolutionary status of a relict population of Bufo hemiophrys Cope. Evolution 22: 583-594.

Other references:

Baxter, G. T. and Stone, M. D. (1980). Amphibians and Reptiles of Wyoming. Wyoming Game and Fish Department.

Blackburn, L., Nanjappa, P. and Lannoo, M. J. (2001). An Atlas of the Distribution of U.S. Amphibians. Ball State University, Muncie, IN, USA.

Carlson, Kara B. et al. (2022). Transcriptome Annotation Reveals Minimal Immunogenetic Diversity Among Wyoming Toads, Anaxyrus baxteri. Research Square Preprints.

Collins, J. T. (1991). Viewpoint: a new taxonomic arrangement for some North American amphibians and reptiles. SSAR Herpetological Review [1991]: 42-43.

Dalrymple, S. E., Abeli, T., Ewen, J. G., Gilbert, T. C., Hogg, C. J., Lloyd, N. A., Moehrenschlager, A., Rodríguez, J. P. and Smith, D. (2023). Addressing Threats and Ecosystem Intactness to Enable Action for Extinct in the Wild Species. Diversity 15: 268.

Dayton, Kelsey. (2014). Once nearly extinct, the Wyoming toad may recover. WyoFile, 13 May.

Dickerson, K. (1999). Pesticides and the Wyoming toad. Endangered Species Bulletin 1999: 20-21.

Dowling, H.G. 1993. Viewpoint: a reply to Collins (1991, 1992). Herpetological Review: 11-13.

Green, D.M. 1983. Allozyme variation through a clinal hybrid zone between the toads Bufo americanus and B. hemiophrys in southeastern Manitoba. Herpetologica: 28-40.

Hammerson, Geoffrey. (2004a). Anaxyrus baxteri. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. ( Downloaded on 10 February 2013.

Hammerson, Geoffrey. (2004b). Anaxyrus baxteri. The IUCN Red List of Threatened Species 2004: e.T54583A11155140. Accessed on 10 June 2022.

Hornyak, Val. (2012). The Wyoming Toad: Partnerships for Recovery. WAZA Magazine 13: 33-35.

Lewis, D.L., Baxter, G.T., Johnson, K.M. and Stone, M.D. (1985). Possible extinction of the Wyoming toad, Bufo hemiphrys baxteri. Journal of Herpetology 19: 166-168.

Linhoff, Luke J. and Donnelly, Maureen A. (2022). Assessing release strategies for reintroductions of endangered Wyoming toads. Wildlife Society Bulletin 2022: e1341.

Martin, Renee M. et al. (2019). Isolation and characterization of twenty-seven novel microsatellite loci in critically endangered Wyoming toad. Publisher?

Matthews, J.R. and Moseley, C.J. (eds). 1990. The Official World Wildlife Fund Guide to Endangered Species of North America. Volume 2. Birds, Reptiles, Amphibians, Fishes, Mussels, Crustaceans, Snails, Insects, and Srachnids. Beacham Publications, Inc., Washington, D.C.

Morrison, Thomas A. et al. (In Press, 2015). Individual Identification of the Endangered Wyoming Toad Anaxyrus baxteri and Implications for Monitoring Species Recovery. Journal of Herpetology. [Abstract]

Parker, J., Anderson, S.H. and Lindzey, F.J. (2000). Natural history notes. Bufo baxteri. Herpetological Review [2000]: 167-168.

Polasik, Julia S., Murphy, Melanie A., Abbott, Tyler and Vincent, Kim. (2015), Factors limiting early life stage survival and growth during endangered Wyoming toad reintroductions. The Journal of Wildlife Management. doi: 10.1002/jwmg.1031 [Abstract]

Poo, Sinlan and Hinkson, Kristin M. (2019). Applying cryopreservation to anuran conservation biology. Conservation Science and Practice. 2019 e91.

Regalado, Pedro Galán. (2015). Los Anfibios y Reptiles Extinguidos: Herpetofauna Desaparecida Desde el Año 1500. Monografías de la Universidade da Coruña 155: 1-509.

Scheffers, Brett R., Yong, Ding Li, Harris, J. Berton C., Giam, Xingli and Sodhi, Navjot S. (2011). The world’s rediscovered species: back from the brink? PLoS ONE 6(7): e22531. [Supporting Information (Table S1)]

Smith, Donal et al. (2023). Extinct in the wild: The precarious state of Earth’s most threatened group of species. Science 379(6634): eadd2889.

Smith, H.M., Chiszar, D., Collins, J.T. and van Breukelen, F. (1998). The taxonomic status of the Wyoming toad, Bufo baxteri Porter. Contemporary Herpetology.

Spencer, B. (1999). The Wyoming toad SSP. Endangered Species Bulletin 1999: 18-19.

Stebbins, R.C. 1985. A Field Guide to Western Reptiles and Amphibians. Second Edition. Houghton Mifflin Company, Boston, Massachusetts.

Taylor, S.K., Williams, E.S., Thorne, E.T., Mills, K.W., Withers, D.I. and Pier, A.C. (1999). Causes of mortality of the Wyoming toad. Journal of Wildlife Diseases 1999: 49-57.

U.S. Fish and Wildlife Service. 1990. Endangered and threatened species recovery program: report to Congress.

U.S. Fish and Wildlife Service. (2002). Wyoming Field Office Annual Wyoming Toad Report FY 02.

U.S. Fish and Wildlife Service. (2015). Wyoming Toad Bufo hemiophrys baxteri now known as Anaxyrus baxteri Revised Recovery Plan, May 2015; Original Approved September 11, 1991. U.S. Fish and Wildlife Service, Cheyenne, Wyoming.


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