Sonoran Desert Toad (Incilius alvarius)

Photo by Cecil Schwalbe

Photo by Cecil Schwalbe

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Description

Editor’s Note:  The scientific name has been changed to Incilius alvarius.  It is extirpated from the Colorado River except for one locality on the Parker Strip.

To hear the call of this species, follow this link: http://amphibiaweb.org/cgi-bin/amphib_query?special=call&genus=Incilius&species=alvarius

The largest native toad in the United States. Adults are unmistakably large and can reach over 19cm. (8 in.) in length, and weigh as much as 900 grams. Dorsum is olive brown to dark green, and is covered with a soft, leathery skin. Usually has one large, white, or light colored wart behind each jaw hinge, directly below the large parotoid gland. Hind legs are covered with numerous large warts.

Juvenile Sonoran desert toads bear little resemblance to adults and are often confused for Red-spotted toads (Bufo punctatus). Mature B. alvarius can be extremely long-lived animals with reports of toads reaching 12 years in age.Found in a variety of arid communities primarily in the Sonoran Desert, often near permanent water sources in xeroriparian areas. Occurs at the California/Arizona border in southwestern Yuma Co., north to extreme southeastern Mohave Co., and southeastward below the Mogollon Rim to the southeastern corner of the state. A voracious predator that may be able to consume anything it can overcome, including other amphibians. Strongly nocturnal, this species will breed independently of rainfall but the largest breeding aggregations usually take place after strong downpours in July and August. The advertisement call of this toad is a short, low-volume honk, and is not indicative of its size. Although large, this species is hardly clumsy. If disturbed, it can flee using a fast unamphibian-like gallop that surprises most observers. This most infamous toad of the Southwest and has gained an unfortunate notoriety with the discovery of the hallucinogenic properties of its parotoid glands. Reports of humans dying from these properties are erroneous, however pets have become ill.

Author: Erik F. Enderson
Originally published in the Sonoran Herpetologist “Herpetofauna of the 100-mile Circle” 15 (11) 2002

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