California Reptiles & Amphibians

Bufo alvarius - Sonoran Desert Toad

(= Incilius alvarius or Ollotis alvaria) (= Colorado River Toad)

Click on a picture for a larger view

Historical Range in California: Red

Dot-locality range map

Listen to this toad:

One short call

More Sounds

Formerly present, now possibly extinct in California.

Adult, Yuma County, Arizona

Adult, Pima County, Arizona

Adult, in breeding pool, Pima County, Arizona

Adult, Pima County, Arizona

Adult, Maricopa County, Arizona

Juvenile, Pima County, Arizona

Tadpole, Graham County, Arizona
© Albert Most

Habitat

Former habitat - Imperial valley irrigation canal, Imperial County

B. alvarius was 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 irrigation canal 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?

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

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.

Description

Size

Adults are 4 - 7 1/2 inches from snout to vent (10.1 - 19 cm). The largest toad in California (before its presumed extirpation.)

Appearance

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.

Behavior

Active on rainy nights, most often from May to July during summer rains. 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 handles 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.

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 venom of toads as a controlled substance.)

Longevity in the wild is estimated to be at least 4-5 years.

Diet

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

Reprduction 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, usually when there are not may other frogs present, but they also rely on traveling around and searching for females.

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.

Range

Formerly found in extreme southeast California along the lower Colorado River and in irrigated lowlands of the southern Imperial Valley. Outside California, found in southern Arizona, extreme southwest New Mexico, and in Sonora and northwest Sinaloa, Mexico.

Habitat

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 is also used.
This toad has been renamed Ollotis alvaria, but this nomenlature is not yet standard.

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.

Taxonomy
Family	Bufonidae	True Toads
Genus	Bufo	True Toads
Species	alvarius	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
bufo - toad 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 Ollotis alvaria Incilius alvarius
Related or Similar California Frogs
Bufo boreas halophilus - California Toad Bufo woodhousii - Rocky Mountain Toad Bufo cognatus - Great Plains Toad Bufo punctatus - Red-spotted Toad
More Information and References
Natureserve Explorer California Dept. of Fish and Game AmphibiaWeb Stebbins, Robert C. A Field Guide to Western Reptiles and Amphibians. 3rd Edition. Houghton Mifflin Company, 2003. Behler, John L., & F. Wayne King. The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, 1992. 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 several times each year by the California Department of Fish and Game.
Organization	Status Listing
U.S. Endangered Species Act (ESA)	None
California Endangered Species Act (CESA)	None
California Department of Fish and Game	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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