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A Guide to the Amphibians
and Reptiles of California

Incilius alvarius - Sonoran Desert Toad

(= Bufo alvarius)

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sonoran desert toad range map
Historical Range in California: Red

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Listen to this toad:

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One short call

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Formerly present, now possibly extinct in California. All pictures are of toads found outside California.

Sonoran Desert Toad Sonoran Desert Toad sonoran desert toad
Adult, Yuma County, Arizona Adult, Pima County, Arizona
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Adult, Pima County, Arizona Adult, in breeding pool,
Pima County, Arizona
Adult, Pima County, Arizona
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Adult, Pima County, Arizona Adult, Pima County, Arizona Adult, Pima County, Arizona
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Adult, Maricopa County, Arizona
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Juvenile, Pima County, Arizona Juvenile, Pima County, Arizona
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Adult, Graham County, Arizona. Adults in amplexus, Pima County, Arizona © 2005 Jason Penny

Tadpole, Graham County, Arizona
© Albert Most
Former California Habitat / Current Habitat in Arizona
sonoran desert toad habitat sonoran desert toad habitat sonoran desert toad habitat
Former habitat - Imperial valley agricultural drain, Imperial County Sonoran Desert Toads were once recorded from this area between Winterhaven and the Laguna Dam in Imperial County which is now all farmland. The toad from Yuma County, Arizona, shown above on the top left, was found one night in August on a road between two plowed agricultural fields next to this agricultural drain northeast of Yuma Arizona, about 20 miles east of California. The Sonoran Desert Toad utilized similar developed habitat in California along with undisturbed desert habitat before its disappearance in the state (see the Imperial County photos to the left.) This begs the question, why does this toad still persist in similar agricultural habitat nearby in Arizona and not in California?
sonoran desert toad habitat sonoran desert toad habitat sonoran desert toad habitat
Breeding habitat, temporary rain pool, Maricopa County, Arizona

Breeding pool in a flooded wash, Pima County, Arizona. The night before this picture was taken, Sonoran Desert toads sat in the water and on the ground nearby.
 Short Video
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Sonoran Desert Toads in a rain pool at night in Arizona, including an interaction between two toads where one makes a release call. Lowland Burrowing Treefrogs and Couch's Spadefoots are calling loudly in the background, which might be why these weak-voiced toads were not calling, only waiting around on the banks and in the water for females to come. Several Sonoran Desert Toads out at night in Arizona, hopping and running quickly across desert roads.  

Adults are 4 - 7 1/2 inches from snout to vent (10.1 - 19 cm). The largest toad in California (before its presumed extirpation.)
Olive, dark brown, or dark gray, with relatively smooth skin, cranial crests, and long, large parotoid glands behind the eyes. There is a large white wart near the corner of the mouth, and large warts on the hind legs. Young have light warts set in dark spots.
Voice (Listen)
A weak, low-pitched whistling screech, 1/2 - 1 second in duration. Calls at night, following summer rains, in small groups.
Active on rainy nights, most often from May to July during summer rains. Capable of moving very quickly with huge leaps, and by running across the ground on all four legs. Often seen on desert roads in Arizona during the summer monsoons where they often suffer from road mortality. During daylight and hot periods, they will take refuge in rodent burrows amd rocky outcrops. How this toads aestivates or survives over long periods of heat and cold is not known, but one radio-tracked toad remained in the same hiding burrow from late September to mid June, where it may have been in a state of torpor. When not at the breeding pool,

For defense, this toad has parotoid glands that contain poisons which may cause paralysis and even death if ingested by dogs and, presumably, other small animals. Toads will assume a butting pose, aiming the parotoid glands at an adversary. they also inflate to increase their body size. The skin secretions have hallucinogenic properties. (This is the toad involved in reports of toad licking or the smoking of dried parotoid gland secretions. Some states have passed laws against toad licking, and classify the secretions of these toads as a controlled substance.)

Longevity in the wild is estimated to be at least 4-5 years.
This toad eats anything that it can overtake and capture, mainly a variety of invertebrates, but lizards, mice, and toads have also been observed in its stomach contents. Sometimes this toad can be seen sitting at night under a street light, eating passing flying insects.
Reproduction and Young
Reproduction is aquatic. Fertilization is external. Adults breed late spring through early fall, May to September, with the onset of the summer rains. Breeding often occurs on one night 1 to 3 days after a heavy rain. Adults travel up to several hundred meters to water. Males give an advertisement call, either alone or in a small chorus, but they also travel around and search for females, or sit without calling waiting for females to come to the breeding pool.

Breeding locations include seasonal and permanent pools, stock tanks, and irrigation ditches.

An average of 7,500 - 8.000 eggs are laid in still or slow-moving water, in long, single, jelly-coated strings. Eggs hatch into tadpoles which are gray to golden brown. Presumably, they eat algae along with detritus. Metamorphosis takes place quickly, usually in less than a month.
Formerly found in extreme southeast California along the lower Colorado River and in irrigated lowlands of the southern Imperial Valley. Beyond California,the species is found in southern Arizona, extreme southwest New Mexico, and in Sonora and northwest Sinaloa, Mexico.
Inhabits grasslands, arid desert lowlands, mountain canyons with oaks and sycamores, and pinyon-oak-juniper mountain forests. Found in washes, river bottoms, springs, reservoirs, canals, irrigation ditches, streams, temporary pools, and away from water.
From sea level to 5,700 ft. (1,760 m.)
Taxonomic Notes
The name Colorado River Toad was formerly used for this toad.

Formerly included in the genus Bufo. In 2006, Frost et al replaced the long-standing genus Bufo in North America, restricting Bufo to the eastern hemisphere. Bufo is still used in most existing references.

Changed from Bufo to Ollotis until Frost et al in 2009 showed that Ollotis should be changed to Incilius, Cope 1863.

Darrel R. Frost, Joseph R. Mendelson III, and Jennifer Pramuk Copeia 2009(2): 418
Conservation Issues  (Conservation Status)
In their survey of 1994, Jennings and Hayes noted that this toad is apparently extirpated from most or all of its sites in California. This is likely due to loss of habitat and to pesticide use brought about by modern agricultural methods. According to a California Department of Fish and Game report, no toads have been collected or observed in California since 1955. This toad has also declined in New Mexico, but is abundant in many parts of Arizona.

Family Bufonidae True Toads
Genus Incilius Middle American Toads

alvaria Sonoran Desert Toad
Original Description
Bufo alvarius Girard, 1859 - in Baird, Report U.S. Mex. Bound. Surv., Vol. 2, Rept., p. 26, pl. 41, figs. 1-6

from Original Description Citations for the Reptiles and Amphibians of North America © Ellin Beltz

Meaning of the Scientific Name

I can't find a definition of Incilius.
Incilius appears to be first used for toads by Cope, 1863.

Assuming it's a Latin word, incile or incilis means a ditch or trench.
The Latin suffix -ius is used to form adjectives from nouns ( similar to -ious in English.)  (Eg. Rex = king, Regius = kingly)

Using these roots, Incilius should mean - characterized by a ditch or trench.
Toads are often found in ditches with water in them, so this could be the meaning. Or it might refer to a feature on toads, but I can't think of one that fits, other than for toads with cranial crests.


arius - belonging to
alvus - the womb or belly

from Scientific and Common Names of the Reptiles and Amphibians of North America - Explained © Ellin Beltz

Alternate Names
Colorado RiverToad
Bufo alvarius
Ollotis alvaria
Related or Similar California Frogs
Anaxyrus boreas halophilus - California Toad
Anaxyrus woodhousii - Rocky Mountain Toad
Anaxyrus cognatus - Great Plains Toad
Anaxyrus punctatus - Red-spotted Toad

More Information and References
Natureserve Explorer

California Dept. of Fish and Game


Stebbins, Robert C., and McGinnis, Samuel M.  Field Guide to Amphibians and Reptiles of California: Revised Edition (California Natural History Guides) University of California Press, 2012.

Stebbins, Robert C. California Amphibians and Reptiles. The University of California Press, 1972.

Stebbins, Robert C. A Field Guide to Western Reptiles and Amphibians. 3rd Edition. Houghton Mifflin Company, 2003.

Behler, John L., and F. Wayne King. The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, 1992.

Powell, Robert., Joseph T. Collins, and Errol D. Hooper Jr. A Key to Amphibians and Reptiles of the Continental United States and Canada. The University Press of Kansas, 1998.

Bartlett, R. D. & Patricia P. Bartlett. Guide and Reference to the Amphibians of Western North America (North of Mexico) and Hawaii. University Press of Florida, 2009.

Elliott, Lang, Carl Gerhardt, and Carlos Davidson. Frogs and Toads of North America, a Comprehensive Guide to their Identification, Behavior, and Calls. Houghton Mifflin Harcourt, 2009.

Lannoo, Michael (Editor). Amphibian Declines: The Conservation Status of United States Species. University of California Press, June 2005.

Wright, Anna. Handbook of Frogs and Toads of the United States and Canada. Cornell University Press, 1949.

Degenhardt, William G., Painter, Charles W. , & Price, Andrew H. Amphibians and Reptiles of New Mexico. University
of New Mexico Press, 1996

Davidson, Carlos. Booklet to the CD Frog and Toad Calls of the Pacific Coast - Vanishing Voices. Cornell Laboratory of Ornithology, 1995.
Conservation Status

The following status listings come from the Special Animals List which is published by the California Department of Fish and Wildlife.

Status Listing
U.S. Endangered Species Act (ESA) None
California Endangered Species Act (CESA) None
California Department of Fish and Wildlife DFG:SSC California Species of Special Concern
Bureau of Land Management
USDA Forest Service
Natureserve Global Conservation Status Ranks G5 SH Secure
World Conservation Union - IUCN Red List

IUCN:LC Least Concern

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