Woodhouse’s Toad (Anaxyrus woodhousii)
by Jeff LeClere
Woodhouse’s toad, Anaxyrus woodhousii, calling.
Species of Greatest Conservation Need. The scientific name for this toad was formerly Bufo woodhousei.
This is Iowa’s largest toad species reaching nearly 4 inches in body length. These toads are often lighter than the other Iowa toad species. The ground color may be varying shades of brown or gray to almost white. There are several dark spots on the back, each of which contain one to several warts, but these dark spots are not nearly as large as in the Great Plains toad. A white or light mid dorsal stripe is usually present on the Woodhouse’s toad’s back.
To separate these toads from American toads, look for a plain white belly on the Woodhouse’s toad. In parts of Iowa, Woodhouse’s toads hybridize with the American toad (Christiansen and Bailey, 1991). These specimens may share characteristics of both species (Green 1989, Laurin and Green 1990, Sanders 1987 Johnson 1992). Sanders (1989) states that some hybrids in certain areas are indicated by semi-bossed individuals.
The Rocky Mountain toad, Anaxyrus woodhousii woodhousii, is the only subspecies found in Iowa. Formerly, there were two subspecies recognized in Iowa, the Woodhouse’s toad, Bufo woodhousei woodhousei, and the Fowler’s toad, Bufo woodhousei fowleri. The Fowler’s toad is now considered a full species and the scientific names have changed.
Woodhouse’s toad is found along the western edge of Iowa. It occupies the two westernmost tiers of counties.
Woodhouse’s toad occurs in the Loess Hills of western Iowa in somewhat drier conditions than the American toad, but it can also be found in more wooded lowland valley areas than the Great Plains toad.
Woodhouse’s toads are often active during the day, especially in mild weather. They burrow in the sand for thermoregulation. They are also active on roads at night during rains or hot, humid weather. I have seen some specimens in western Iowa active on extremely hot days. These toads breed May through June. The call is a flat, buzzing sheep like bleat. It is likened to the cry of a newborn child by Christiansen and Bailey (1991); I agree, that is what it sounded like the first time I heard it! From a distance, it also reminds me of a flat buzzing whistle. The call only lasts 3 to 5 seconds long. It can be confused with no other western Iowa toad. Plains spadefoots have a slightly similar call, but it is shorter and sounds more like a quack. Eggs are laid in pools that will hold water until the middle of July, when the toadlets emerge. Flooded cultivated agricultural fields are common breeding sites because the natural swales where this toad bred in the past have been drained.
They eat any insects or earthworms and even feed on harmful invertebrates in agricultural areas. This may also harm them as they inadvertently ingest pesticides and absorb other chemicals living in and near farm fields.