California Reptiles & Amphibians

Bufo exsul - Black Toad

(=Anaxyrus exsul)

Click on a picture for a larger view

Range in California: Red

Adult, Inyo County

Underside, Inyo County

Adult, Inyo County

Adult, Inyo county,
© 2005 John Stoklosa

Newly metamorphed juvenile, Inyo County. © Ceal Klingler

Recently-hatched tadpoles, Inyo County

Tadpoles, Inyo County
© 2005 John Stoklosa

Tadpoles, Inyo County © Mark Gary

Eggs, Inyo County © Mark Gary

Habitat

Habitat, Inyo County

Distant view of Deep Springs Valley, Inyo County

Deep Springs Valley, Inyo County, showing dry lake and springs in distance.

Distant view of another spring in Deep Springs Valley

Black Toads blend in well with the dark mud of their habitat, especially at night. (There are no toads in this picture.)

View of toad habitat, Inyo County

Short Videos

Black Toads crawling around in the water at night. It doesn't get more exciting than that.

A Black Toad lunges with its sticky tongue extended, trying to catch something to eat.

Description

Size

Adults are 1 3/4 - 3 inches from snout to vent (4.4 - 7.6 cm).

Appearance

The skin is dry and warty, but relatively smooth for a toad. No cranial crests. Oval parotoid glands. Dark, almost solid black above, with light wavy marks and speckles. Usually has a light stripe down the middle of the back. Belly is light and heavily blotched with black. Throat is pale, less spotted on males than on females. Young are olive colored.

Voice

Black toads do not have vocal sacs and do not make an advertisement call. They produce only a weak chirping release or territorial call, similar to the call of B. b. halophilus but higher in pitch. Calls are made during the day and at night.
(You can listen at AmphibiaWeb.)

Behavior

Active from March to September, hibernating in burrows during winter. Diurnal and crepuscular becoming mostly nocturnal during the heat of late spring and summer. More aquatic than most toads, Black Toads spend most of their time in shallow marshy areas, but they can also be found on dry, sandy soil around springs, foraging among grassy tussocks.
Typical of toads, this one moves slowly, often using a walking or crawling motion along with short hops.
As most toads do for defense, this toad relies on parotoid glands and warts which can secrete a poison that deters some predators.

Diet

Eats a variety of small invertebrates. Prey is located by vision, then the toad lunges with a large sticky tongue to catch the prey and bring it into the mouth to eat.

Reproduction and Young

Reproduction is aquatic. Fertilization is external. Mating and egg-laying occurs from late March into April in shallow water with vegetation to protect eggs and tadpoles. Eggs are laid from late March to late May in shallow waters bordering the larger wetlands. Eggs are laid in strings which are entwined in aquatic plants on or just below the surface. Eggs hatch in 5 days and larvae transform in 3 - 5 weeks. Tadpoles do not overwinter. Transformed juveniles remain in shallow marshy areas with the adults.

Range

Endemic to California. This toad has one of the smallest ranges of any North American Amphibian. It occurs naturally only in a few spring systems in Deep Springs Valley, Inyo county, at elevations of about 4,900 ft. (1,450 m) to 5,600 ft. (1,700 m.)

According to the CA Dept. of Fish & Game, In 1998, a population of B. exsul was found in the Saline Valley in Inyo County, in Death Valley National Park. Most likely this population was introduced.

In 1961, Black toads were released at Cottonwood Springs in the Owens Valley, about 19 miles from Deep Springs Valley, but they have not been reported from that location again.

Habitat

Inhabits springs and marshes in an isolated desert basin between the Inyo and White Mountains. Toads are sometimes found in surrounding grasses. The vegetation around these springs is sparse and conditions are very dry with sandy soil.

Taxonomic Notes

Related to Bufo boreas, but thought to have been isolated from that species for at least 12,000 years.

This toad has been renamed Anaxyrus exsul, but this nomenclature is not yet standard.

Conservation Issues (Conservation Status)

The population of Black Toads appears to be stable. This toad is listed as threatened because it occurs only in a small isolated population that is restricted to very limited and specialized habitat. If the springs that it depends on were to dry up, or if a disease or predator were introduced, the toad would most likely become extinct.

Deep Springs College and the California Department of Fish and Game cooperate to protect Black Toad habitat by managing water diversions and vegetation around the springs. The college grazes cattle in the winter, when the toads are hibernating, which cuts back vegetation that would choke off toad habitat. Cattle droppings also support insect populations on which the toads feed. In this way, the cattle perform a function once performed by now-absent native grazers such as bighorn sheep and antelope.

Taxonomy
Family	Bufonidae	True Toads
Genus	Bufo	True Toads
Species	exsul	Black Toad
Original Description
Myers, 1942 - Occ. Papers Mus. Zool. Univ. Michigan, No. 460, p. 3, pl. 1 and 2 from Original Description Citations for the Reptiles and Amphibians of North America © Ellin Beltz
Meaning of the Scientific Name
Bufo - toad exsul -Latin for exile, refugee - refers to the isolated distribution of this toad from Scientific and Common Names of the Reptiles and Amphibians of North America - Explained © Ellin Beltz
Alternate Names
Anaxyrus exsul
Related or Similar California Frogs
Bufo boreas halophilus
More Information and References
Natureserve Explorer California Dept. of Fish and Game AmphibiaWeb Macey, J. Robert and Theodore Papenfuss."Herpetology." The Natural History of the White-Inyo Range Eastern California. Ed. Clarence Hall. University of California Press, 1991. Thelander, Carl G., editor in chief. Life on the Edge - A Guide to California's Endangered Natural Resources - Wildlife. Berkeley: Bio Systems Books, 1994. 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. 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)	ST	Threatened
California Department of Fish and Game	DFG:FP	Fully Protected
Bureau of Land Management
USDA Forest Service
Natureserve Global Conservation Status Ranks	G1 Q S1	Critically Imperiled
World Conservation Union - IUCN Red List	IUCN:VU	Vulnerable

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