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A Guide to the Amphibians
and Reptiles of California


Anaxyrus boreas boreas - Boreal Toad

(=Bufo boreas boreas)


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boreal toad range map
Range in California: Green

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to the other subspecies.

Listen to this toad:

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One short call


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boreal toad boreal toad boreal toad
  Adult, northern Humboldt County  
boreal toad boreal toad boreal toad
Adult, northern Humboldt County Adult, northern Humboldt County Adult, covered with dirt,
northern Humboldt County
boreal toad boreal toad boreal toad
Adult, Del Norte County
© Alan Barron
Juvenile, Del Norte County
© Alan Barron
Juvenile, Del Norte County
© Alan Barron
  boreal toad  
  Juvenile, northern Humboldt County

 
Boreal Toads From Outside California
boreal toad boreal toad boreal toad
Adult male, Thurston County, Washington, access
courtesy of Jim Lynch, Ft. Lewis Dept. of Fish and Wildlife
Juvenile, Deschutes County, Oregon
boreal toad  
Adult, Vancouver Island, British Columbia. © Guntram Deichsel

Juvenile, Deschutes County, Oregon  
Breeding and Tadpoles
boreal toad boreal toad boreal toad
Nuptial pad on front foot of adult male, Thurston County, Washington. Specimen courtesy of Jim Lynch, Ft. Lewis Dept. of Fish and Wildlife Adults in amplexus, Thurston County, Washington. Access to specimens courtesy of Jim Lynch, Ft. Lewis Dept. of Fish and Wildlife Male in calling position on lake, Thurston County, Washington, access courtesy of Jim Lynch, Ft. Lewis Dept. of Fish and Wildlife
boreal toad boreal toad  
Tadpole, Deschutes County, Oregon

Tadpole, Deschutes County, Oregon  
Habitat
boreal toad habitat boreal toad habitat  
Habitat, temporary pools on coastal plain, Humboldt County Habitat, Humboldt County coast


 

More pictures of this toad and its habitat in the Nortwest are available on our Northwest Herps page.

Short Videos
boreal toad boreal toad  
A toad gives a release call after he is picked up and gently grasped across the back. (It may sound like this toad is suffering, but it is not being harmed. This is a warning call, the same one he makes when another male toad comes into his territory or climbs onto his back and grabs him tightly with his legs.) An adult Boreal Toad hops around a coastal plain in Humboldt County.


 
Description

Size
Adults grow to 2 - 5 inches from snout to vent ( 5.1 - 12.7 cm).
Appearance
Large and robust with dry, warty skin. No cranial crests. Oval parotoid glands. Tarsal fold is well-developed. Pupils are horizontal. Coloring is greenish, tan, reddish brown, dusky gray, and yellow above with a light-colored stripe down the middle of the back. Warts are often rusty and set on dark blotches. There is much dark blotching above and below, becoming all dark at times. Males are usually less blotched than females and have smoother skin. Male and female throats are pale. Young have no dorsal stripe immediately after transformation.
More blotched below than A. b. halophilus. The head is also narrower with smaller eyes with more distance between the upper eyelids and the feet are also larger than A. b. halophilus. (Stebbins)
Voice  (Listen)
Most male Boreal Toads do not have a pronounced vocal sac, but they do make a call during breeding aggregations. Their call has been described as a high-pitched plinking sound, like the peeping of a chick, repeated seveal times. The sound of a group of males calling has been compared to the sound of a distant flock of geese. Some Boreal Toads have been found to make advertisement calls with a pronounced vocal sac. (See Zachary Long's findings below.)

Calls are produced at night and during the day during the short breeding season. Males make their call primarily when they are in close contact with other males. Rather than being advertisement calls made to attract females, these calls are generally considered encounter or aggressive calls, or release calls, which serve to maintain territory and spacing between males. The calls may also serve other purposes - a lone male toad has been observed calling.1 It could also be possible that female toads are attracted to the sounds of male encounter calls, and can judge a male's condition by his call, similar to the function of an advertisement call.

Unreceptive females may also produce a release call when grasped on the back by a male. Males and females sometimes make a release call when grabbed across the back by a human hand. (See video above.)

On his website, and in his note in Herp Review (Zachary Long, Herpetological Review 41(3), 2010.), Zachary Long presents video and audio evidence of Boreal Toads making advertisement vocalizations in a wetland south of Whitecourt, Alberta, Canada. In his videos, you can clearly see that the toad has a vocal sack. When compared with the calls I have recorded in Washington State, you can easily hear the difference between them. You can listen to his recordings and watch his videos here.
Behavior
Diurnal and nocturnal. Often diurnal after winter emergence, becoming nocturnal in the summer after breeding.
Toads are not territorial except when breeding. Amplexing males will kick away other males, and males may briefly fight other males at breeding sites.
For defense, this toad relies on parotoid glands and warts which can secrete a poison that deters some predators. Other predators are immune to the poison, and will consume toads. Still other predators such as ravens have learned to avoid the poisons by eating only their viscera through the stomach.
Slow moving, often with a walking or crawling motion along with short hops.
Toads have been reported living at least 9 years.
Diet
Diet consists of a wide variety of invertebrates, including worms, spiders, moths, beetles, and ants. The prey is located by vision, then the toad lunges and quickly extends its large sticky tongue to catch the prey and bring it into the mouth to eat. Tadpoles consume algae and detritus, including the scavenged carrion of fish and other tadpoles.
Reproduction and Young
Reproduction is aquatic. Fertilization is external. Adults are mature enough to breed when they are 4 - 6 years old. They breed shortly after they emerge from their hibernation sites and migrate to the breeding wetlands, using scent cues to find their way. In some areas, breeding occurs after snowmelt when breeding ponds refill with water. Mating and egg-laying can occur any time from January to early July, depending on the elevation and winter snow levels.

Egg-laying takes place in still or barely moving waters of seasonal pools, ponds, streams, and small lakes.
Eggs are laid in long strings with double rows, averaging 5,200 eggs in a clutch. Fresh eggs contain some of the toads toxin to protect them from predation, but this poison decreases over time. Eggs hatch in 3 to 10 days, often longer in the colder waters of higher elevations.

Large schools of tadpoles often feed in shallow water. Tadpoles are dark brown, and grow to about 1 inch in length before metamorphosis. Tadpole development also depends on water temperature; tadpoles enter metamorphosis in 30 - 45 days, usually in late summer or early fall. In years of extreme winter weather, this might be only a few weeks before snow begins to accumulate again. When in the process of metamorphosis, many tadpoles are often seen in aggregations at the edge of a pond. Large numbers of newly-transformed toads are often seen hopping around the shores of breeding water. They may stay and spend the winter at the border of their natal wetland, or they may disperse to nearby sites away from the pond.
Range
The subspecies Anaxyrus boreas boreas is found across the northern tip of California, east through Nevada, Utah, and Wyoming, and north through western Oregon and Washington, through British Columbia, all the way to southern Alaska.

The species Anaxyrus boreas is found in most of California except the deserts, northern Baja Caifornia, northern Nevada, Idaho, western Montana, northern and central Utah, western and south central Wyoming, central Colorado, and extreme north central New Mexico, Oregon, Washington, British Columbia, western Alberta, and extreme southeastern Alaska. Toads found in the Rocky Mountains have undergone a severe decline.
Habitat
Inhabits a variety of habitats, including marshes, springs, creeks, small lakes, meadows, woodlands, forests, and desert riparian areas. In the spring and early summer, toads are often found at the edge of water, sometimes basking on rocks and logs. At other times of the year they are also found farther from the water where they spend much of their time in moist terrestrial habitats.Toads use rodent holes, rock chambers, and root system hollow as refuges from heat and cold.
Bufo boreas is found from sea level to over 11,800 ft. (3,600 m.)
Taxonomic Notes
Two subspecies of Anaxyrus boreas are recognized in California - Anaxyrus boreas boreas, and Anaxyrus boreas halophilus.
(Anaxyrus nelsoni
has also been treated as a subspecies of Anaxyrus boreas: A. b. nelsoni, but this is controversial.)

Formerly included in the genus Bufo. In 2006, Frost et al replaced the long-standing genus Bufo in North America with Anaxyrus, restricting Bufo to the eastern hemisphere. Bufo is still used in most existing references.
Conservation Issues  (Conservation Status)
Anaxyrus boreas is becoming uncommon in many areas of the Pacific Northwest, the Rocky Mountains and other areas, probably due to environmental changes caused by habitat loss, especially loss of wetlands, and chemical contamination of wetlands. Toads are also slow-moving and are frequently run over by traffic as they cross roads at night during their breeding migrations, which could also contribute to their loss.

Taxonomy
Family Bufonidae True Toads
Genus Anaxyrus North American Toads
Species boreas Western Toad
Subspecies boreas Boreal Toad

Original Description
Bufo boreas Baird and Girard, 1852 - Proc. Acad. Nat. Sci. Philadelphia, Vol. 6, p. 174
Bufo boreas boreas Baird and Girard, 1852 Boreal Toad

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

Meaning of the Scientific Name
Bufo - toad
Anaxyrus - Greek - A king or chief
Boreas - Greek meaning north wind or northern - which refers to the northern range

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

Alternate Names
Bufo boreas boreas

Related or Similar California Frogs
Anaxyrus boreas halophilus
Anaxyrus californicus

Anaxyrus woodhousii
Anaxyrus canorus
Anaxyrus exsul

More Information and References
Natureserve Explorer

California Dept. of Fish and Game

AmphibiaWeb

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

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.

Corkran, Charlotte & Chris Thoms. Amphibians of Oregon, Washington, and British Columbia. Lone Pine Publishing, 1996.

Jones, Lawrence L. C. , William P. Leonard, Deanna H. Olson, editors. Amphibians of the Pacific Northwest. Seattle Audubon Society, 2005.

Leonard et. al. Amphibians of Washington and Oregon. Seattle Audubon Society, 1993.

Nussbaum, R. A., E. D. Brodie Jr., and R. M. Storm. Amphibians and Reptiles of the Pacific Northwest. Moscow, Idaho: University Press of Idaho, 1983.

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.
Conservation Status

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

This toad is not on the Special Animals List. There are no significant conservation concerns for it in California.

Organization
Status Listing
U.S. Endangered Species Act (ESA) None
California Endangered Species Act (CESA) None
California Department of Fish and Wildlife None
Bureau of Land Management None
USDA Forest Service None
Natureserve Global Conservation Status Ranks
World Conservation Union - IUCN Red List




 

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