Anaxyrus woodhousii (Girard, 1854)

Adults can reach 130 mm, with males (83 to 88 mm) smaller than females (93 to 104 mm). Woodhouse’s Toad presents as a typical toad with a drab coloration and short legs. It is a medium-sized toad with an olive-brown or green brown dorsum and a white mid-dorsal stripe. The prominent cranial crests are often in contact with parotoid glands, the white belly has scattered dark pigment, there are no paired scapular blotches, and there is a white vertebral stripe. This combination of characters will distinguish this species from other Arizona anurans.    It can be distinguished from the Great Plains Toad by the absence of a pair of scapular blotches, and from the Arizona Toad—with which it will hybridize—by its elongated paratoid glands, well-developed cranial crests, and the pale throat of the male. This species was long confused with two other species, the American Toad and the Fowler’s Toad.Voice. The call is an explosive, wheezy, nasal snore, w-a-a-a-ah, lasting one to four seconds at a frequency of 1.4–2.0 kHz, and rapidly pulsed at 80–200 p/s; (Stebbins 1962; Sullivan et al. 1996a).Distribution and Habitat. The distribution is from south-central Washington eastward to North Dakota and southward into Durango, Mexico.  Elevation range is sea level to 2,600 ASL.  While this species evolved in the Great Plains, it is thought to have expanded its range into Arizona in the mid- to late Pleistocene with the expansion of grasslands into the Southwest. This is a geographic pattern seen in several other species (Acris blanchardi, Lithobates blairi, and Sistrurus tergeminus).Lower elevation populations occur along larger washes, canals, and streams, urban ponds, golf courses, and agriculture areas with irrigation. Higher elevation populations are associated with ponds, lakes, and reservoirs. Thus, they adapt well to human modified habitats.It occurs in Semidesert Grasslands, Plains and Great Basin Grasslands, Interior Chaparral (Holycross and Brennan 2006).Reproduction. In areas of permanent water, they breed on warm (15⁰C or above), rainless nights in the spring (February to June), while populations in open desert flats breed immediately after monsoon storms (June to September).  Standing water is apparently preferred for breeding; these may be pools in river channels, artificial ponds, reservoirs, or cattle tanks in open desert flats (Stebbins 1951, Sullivan 2005).Larvae are dark brown or gray with mottling and gold flecking; tadpoles transform at about 23 mm.  Large aggregations of larvae are often observed resting in standing water on muddy substrate. In central Arizona, the length of the larval period was eight weeks for pond breeding populations (31 March–1 June), whereas development lasted as little as five weeks in Oklahoma (Bragg 1940b). Woodward (1987) found that larvae grew more slowly when housed with larger conspecific larvae. Males call in shallow water or on the shore at or near the water’s edge and defend the calling site.  Adults in arid regions may reside in the vicinity of streams or ponds used for breeding year-round. Eggs are small (3 to 4 mm) and laid in long gelatinous strands.  Clutches of up to 28,000 eggs are known for Midwestern populations (Krupa 1995).Stebbins (1962) collected tadpoles in Navajo County, Arizona that were 14.3 to 22.5 mm and described their coloration in life (text slightly altered from original. In life, generally black above with scattered pale orange, pale yellow, or buff blotches on sides of head and body) and upper surface of tail musculature; pale yellow to whitish blotches along lower third of tail musculature; most of underside of body mottled with metallic-appearing, light-colored pigment, iridescent blue-green in sunlight: intestine not visible; throat gray: underside of tail light sooty gray; iris with fine speckling of pale orange, metallic appearing pigment, most abundant immediately around and filling iris above and below pupil. Metamorphosis begins when tadpoles reach a length of about 30 mm total length (Bragg 1940b). Recently metamorphosed toadlets average 12–15 mm SUL (Bragg 1940b; Sullivan 2005).  Tadpoles may form large aggregations in standing water.  In central Arizona, larva development was eight weeks for pond-breeding populations (Sullivan 2005).New metamorphs grow rapidly, almost 10 mm/month has been reported for toadlets (Bragg (1940b). Sullivan (1982b) sample 61 calling males and found a size range of 69–98 mm SUL.; and he samples 38 females and found body lengths of   84–109 mm. In central Texas, 98 calling males ranged in size from 73–104 mm SUL and females (n = 22) in the same population ranged from 79–110 mm SUL (Sullivan, 1989b). Males probably reach reproductive maturity within a year of metamorphosis, and females within two years.Diet includes a variety of invertebrates.  Stebbins (1951) summarized the diverse diet of this toad- it included: isopods, scorpions, centipedes, spiders; representative insects, included orthopterans, lepidopterans, dipterans, hemipterans, beetles, hymenopterans. Pack (1922) reported a congregation of Woodhouse’s Toad associated with an August outbreak of sugar beet webworms in Utah, the toads were the young of the year that were at an estimated density of 100 toad/acre. He examined stomachs and found they were feeding exclusively on the web worms, each toad contained 24 to 40 web worms. He estimated the toads were eating two thirds of their body weight every 24 hours. Predators include gophersnakes, bullfrogs, hawks, and roadrunners.  Fish present at the breeding sites may eat eggs, tadpoles, and new metamorphs.  Skin and parotoid secretions presumably offer some protection against predators. Swart and Taylor (2004) conducted experiments to study the relationship between predaceous water bug Belostoma lutarium and tadpoles of A. woodhousii. They evaluate background preferences by tadpoles and the predaceous water bug and found tadpoles switched preference away from black backgrounds when a chemical signal from the water bug was introduced, earlier stage tadpoles exhibited a stronger behavior than later stage tadpoles in the presence of the predator’s chemical signal, hemipterans were observed randomly on both backgrounds but were mostly found associated with vegetative cover, and the water bug killed significantly more tadpoles on dark backgrounds compared to light backgrounds. Taxonomy. Two subspecies have been recognized as present in Arizona. The Southwestern Toad, A. w. australis is present in eastern and southeastern Arizona.  Rocky Mountain Toad, A. w. woodhousii occurs in the north-central portion of the state. However, these populations appear to be intergrades with A. w. australis. Hallowell (1852:181) described Bufo dorsalis without declaring a type specimen. Stejneger (1890: 117) considered USNM 2531 the holotype from New Mexico. Boulenger (1882:309) considered it a synonymy of Bufo americanus. But the name was preoccupied by Bufo dorsalis Spix, 1824. Baird (1859:44) considered it a synonym of Bufo woodhousii. Girard (1854:86) described Bufo woodhousii  based upon the holotype USNM 2531 (the same type as Bufo dorsalis Hallowell following Kellogg (1932:73) with a type locality of  Territory of New Mexico, having so far been found in the province of Sonora, and in the San Francisco Mts. Stejneger (1890:116) gave the type locality as San Francisco Mountain, New Mexico [now in Coconino County, Arizona].   Cope (1863:50) placed it in the genus Incilius, using the combination Incilius woodhousei. Cope (1867:301) described Bufo frontosus based on a now lost holotype: that was an ANSP or USNM specimen according to Shannon and Lowe, (1955:188).  The type locality was given as Territory of Arizona, . . ., chiefly near the parallel of 35°, and along the valley of the Colorado from Fort Mojave to Fort Yuma.” Some authors regard this name as synonymous with Bufo cognatus.  Cope (1875:29) used the combination Bufo lentiginosus frontosus. Yarrow also (1875:520-521) used the combinations Bufo lentiginosus var. frontosus and Bufo lentiginosus var. woodhousei. Cope (1889:457) described Bufo aduncus based upon the holotype USNM 14100 from the type locality: “probably from Gainsboro, [Cook County,] in Central Northern Texas”, USA. Cochran (1961:31), placed this name in the synonym of A. woodhousii. Cope (1889:278) used the combination Bufo lentiginosus woodhousei. Stejneger (1890 3: 116) used the combination Bufo lentiginosus woodhousii. Nieden (1923:126 used the combination Bufo lentiginosus woodhousi. Smith (1934:456) used Bufo woodhousii woodhousii.  Linsdale (1940: 2060 used Bufo compactilis woodhousii. Bragg and Sanders (1951:366) described Bufo woodhousii velatus based upon the holotype: USNM 131869 with the type locality of Elkhart, Anderson County, Texas. The status of this name is uncertain, it may belong in the synonymy of Bufo fowleri according to Sullivan et al. (1996: 274-280). Shannon and Lowe, (1955:185) used the incorrect spelling Bufo woodhousei woodhousei. Shannon and Lowe (1955:185) described Bufo woodhousei australis based upon the holotype UIMNH with the type locality “in a damp irrigation ditch within the city limits of Tempe, Maricopa County, Arizona.” Mecham, 1959 “1958”: described Bufo woodhousei bexarensis based upon the holotype TNHC 933.3708a, a left femur from the type locality: Friesenhahn Cave is located on Cibolo Creek, 21 miles north of San Antonio in Bexar County, Texas Late Pleistocene, zone 3. This is a fossil taxon. Sanders (1986:1-28) used the combination Bufo velatus with the species status rejected by Collins, 1989:19. Sanders, 1987: 62) described Bufo antecessor , based upon the holotype USNM 25322 with the type locality: “nine miles northwest of Louiston (= Lewiston) Nez Perce County, Idaho”. Collins and Collins (1989: 19) placed it in the synonymy of A. woodhousii. Sanders (1987: 87) described Bufo planiorum based on the holotype USNM 2535, with the type locality: Yellowstone River of Montana. Collins (1989:19) placed it in the synonymy of A. woodhousii. Collins (1997:11) used the combination Bufo woodhousii velatus.  Frost et al. (2006:363) moved it to the genus Anaxyrus and called it A. woodhousii. Frost et al. (2008:3) used the combination Anaxyrus woodhousii australis.  Frost et al. (2008:3) used the combination Anaxyrus woodhousii woodhousii. Fontenoted et al. (2011:68) used the combination Anaxyrus velatus which was an undiscussed taxonomic arrangement. Fouquette and Dubois (2014:311) used the combinations: Bufo (Anaxyrus) woodhousii, Bufo (Anaxyrus) woodhousii woodhousii, and Bufo (Anaxyrus) woodhousii australis.