Anaxyrus woodhousii

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. The misspelling of the specific epithet to woodhousei has been used widely. Three nominal subspecies frequently recognized although these warrant detailed study regarding their evolutionary status (Frost 2017).

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.

Masta et al. (2002) noted that within Anaxyrus woodhousii two distinct mtDNA clades exist which are largely concordant with the subspecies A. woodhousii woodhousii and A. woodhousii australis. Fontenot et al. (2011) discussed hybridization with eastern members of the A. americanus group and; without discussion, recognized A. velatus as a distinct species. Lannoo (2005) and Dodd (2013) discussed the substantial hybridization with A. fowleri along the eastern edge of its range. Sullivan et al. (2015) reported on hybridization of this species and A. microscaphus along the Agua Fria River of central Arizona, USA, on the basis of morphology and mtDNA (Frost 2017).

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). 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.

This species is widespread and abundant through the central U.S. and northern México. The population has suffered historical localized declines but appears to be relatively stable currently. It is threatened by habitat loss, road mortality, and pesticide use.

This species is found throughout most of the central and southwestern United States and portions of adjacent northern México. There are disjunct populations in southern Washington, northern and eastern Oregon, and western Idaho (Dodd Jr. 2023). It is absent from high mountains and the West Coast. Range extent is estimated to be 4.182 million km² (GBIF 2025, RARECAT 2025).

Represented by many and/or large occurrences throughout most of the range.

This species is threatened by habitat loss, road mortality, and pesticides. Development and agriculture have caused local declines across the range (Dodd Jr. 2023). Road mortality is common and can cause large localized losses (Dodd Jr. 2023). At concentrations of 100 micrograms per liter, the antimicrobial triclosan is fatal to tadpoles (Brown et al. 2013). However, at concentrations of 10 micrograms per liter, triclosan suppresses the growth of chytrid fungus (Batrachochytrium dendrobatidis) and increased tadpole survival (Brown et al. 2013).