CaliforniaHerps.com

A Guide to the Amphibians
and Reptiles of California


Boreal Toad - Anaxyrus boreas boreas

(Baird and Girard, 1852)

(= Bufo boreas boreas)
Click on a picture for a larger view



boreal toad range map
Range in California: Orange & Gray

Click the map for a guide
to the other subspecies.

Listen to this toad:

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One short call



observation link





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  
Adult, northern Humboldt County Adult, Del Norte County
© Alan Barron
 
     
Juveniles
boreal toad boreal toad boreal toad
Juvenile, northern Humboldt County
Juvenile, Del Norte County
© Alan Barron
Juvenile, Del Norte County
© Alan Barron
     
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 boreal toad
Adult, Vancouver Island, British Columbia. © Guntram Deichsel
Juvenile, Deschutes County, Oregon Juvenile toads arranged on rocks in a slow-moving mountain creek in summer, Deschutes County, Oregon
Boreal Toad Boreal Toad  
Metamorph, Owyhee County, Idaho
© Bill Bachman
Metamorph, Owyhee County, Idaho
© Bill Bachman
 
     
Breeding Adults
boreal toad boreal toad boreal toad
Males in calling position on lake, Thurston County, Washington, access courtesy of Jim Lynch, Ft. Lewis Dept. of Fish and Wildlife
boreal toad boreal toad  
Adults in amplexus, Thurston County, Washington. Access to specimens courtesy of Jim Lynch, Ft. Lewis Dept. of Fish and Wildlife Nuptial pad on front foot of adult male, Thurston County, Washington. Specimen courtesy of Jim Lynch, Ft. Lewis Dept. of Fish and Wildlife  
     
Eggs and Tadpoles
boreal toad boreal toad california toad eggs
Tadpole, Deschutes County, Oregon
Tadpole, Deschutes County, Oregon Eggs are laid in strings similar to those of
California Toads.
boreal toad boreal toad boreal toad
Tadpoles, Deschutes County, Oregon
Eyes are inset from the edge of the head.
Tadpoles, Deschutes County, Oregon
     
Comparisons With Larvae and Tadpoles of Sympatric Species
  Sierran Treefrog Tadpole  
  Comparison of Treefrog Tadpole (Pseudacris regilla group) (Top)
with Toad Tadpole
(Anaxyrus boreas) (Bottom)
(Click on picture for a better view)
 
     
Habitat
boreal toad habitat boreal toad habitat boreal toad
Habitat, temporary pools on coastal plain, Humboldt County Habitat, Humboldt County coast


Breeding habitat with tadpoles, Deschutes County, Oregon

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). (Stebbins, 2003)

Appearance
A large and robust toad with dry, warty skin.
No cranial crests are present.
Parotoid Glands are oval and well-developed.
Pupils are horizontal.
Color and Pattern
The ground color is Greenish, tan, reddish brown, dusky gray, or yellow.
Rusty-colored warts are set on dark blotches.
There is much dark blotching above and below, becoming all dark at times.
The throat is pale on both males and females.
A light stripe is usually present on the middle of the back.
Male/Female Differences
Males are usually less blotched than females and have smoother skin.
Females are larger than males and more stout.
During the breeding season, males have dark nuptial pads on the thumbs and the inner two digits of the hands.
Young
Young have no dorsal stripe immediately after transformation.
The bottoms of their feet is bright orange or yellow.
Larvae (Tadpoles)
Tadpoles are dark brown with eyes inset from the edges of the head.
The tip of the tail is rounded.
They grow to about 2.25 inches (5.6 cm) in length before undergoing metamorphosis.

Comparison with California Toads
A. b. boreas has more dark blotches on the belly than A. b. halophilus.
The head of A. b. boreas is also narrower with smaller eyes with more distance between the upper eyelids, and
the feet are also larger than A. b. halophilus. (Stebbins)

Life History and Behavior
Activity
Diurnal and nocturnal. Often diurnal after winter emergence, becoming nocturnal in the summer after breeding.
Movement
Slow moving, often with a walking or crawling motion along with short hops.
Defense
This toad uses poison secretions from parotoid glands and warts to deter predators. Some 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.
Territoriality
Male Western Toads are not territorial except when breeding. Amplexing males will kick away other males, and males may briefly fight other males at breeding sites.
Longevity
Western Toads have been reported living at least 9 years.
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. Since it is not made to attract distant females, the call is not very loud when compared to the call of the sympatric Pacific Treefrog (or simiilar treefrog species.) 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.
Diet and Feeding
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.
Breeding
Breeding is aquatic.
Fertilization is external, with the male grasping the back of the female and releasing sperm as the female lays her eggs.

The reproductive cycle is similar to that of most North American Frogs and Toads. Mature adults (4 - 6 years old) come into breeding condition and migrate to ponds or ditches. Males and females pair up in axillary amplexus in the water where the female lays her eggs as the male fertilizes them externally. The adults leave the water and the eggs hatch into tadpoles which feed in the water and eventually grow four legs, lose their tails and emerge onto land where they disperse into the surrounding territory.

Breeding can occur any time from January to early July, depending on the elevation, winter snow levels, or rainfall amounts, taking place shortly after toads emerge from their hibernation sites and migrate to the breeding wetlands. Scent cues are used to find the way to the breeding site. In some areas, breeding occurs after snowmelt when breeding ponds refill with water.  Amplexus and egg-laying takes place in still or barely moving waters of seasonal pools, ponds, streams, and small lakes.
Eggs
Eggs are laid in long strings with double rows, averaging 5,200 eggs in a clutch.
Fresh eggs contain some of the toad's 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.
Tadpoles and Young
Tadpoles are dark brown and grow to about 2.25 inches (5.6 cm) in length before undergoing metamorphosis.
Large schools of tadpoles often feed together in shallow water.

Tadpoles enter metamorphosis in 30 - 45 days, usually in summer or early fall, depending on water temperature - colder water delays metamorphosis. In years of extreme winter weather, especially at higher elevations, metamorphosis 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 in various stages of metamorphosis. After most tadpoles undergo metamorphosis, large numbers of newly-transformed toads are often seen hopping around the edges of the 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.

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.

Geographical 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, northern Baja Caifornia, Nevada, Idaho, western Montana, northern and central Utah, western and south central Wyoming, central Colorado, and extreme north central New Mexico, most of Oregon, Washington, British Columbia, western Alberta, and extreme southeastern Alaska. Toads found in the Rocky Mountains have undergone a severe decline.

Full Species Range Map
Elevational Range
Anaxyrus boreas is found from sea level to over 11,800 ft. (3,600 m.) (Stebbins, 2003)

Notes on Taxonomy
The SSAR (Herpetological Circular No. 39, 2012) no longer recognizes this or any subspecies of A. boreas: "Goebel et al. (2009, Mol. Phylogenet. Evol. 50: 209-225) suggested on the basis of molecular evidence that nominal Anaxyrus boreas is a complex of species (as suggested previously by Bogert, 1960, Animal Sounds Commun.: 179) that do not conform to the traditional limits of taxonomic species and subspecies (and which we do not recognize here for this reason) and that some populations assigned to this taxon may actually be more closely related to Anaxyrus canorus and A. nelsoni - a problem that calls for additional elucidation."


Two subspecies of Anaxyrus boreas are traditionally 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.


Alternate and Previous Names (Synonyms)

Bufo boreas boreas - Boreal Toad (Stebbins 1954, 1966, 1985, 2003, Stebbins & McGinnis 2012)
Bufo boreas halophilus
- Northwestern Toad (Baird's Toad, Mountain Toad, Columbian Toad, Small-spaded Toad, Northern      Toad, Western Toad) (Wright and Wright 1933-1949)
Bufo boreas halophilus
- Northwestern Toad (Storer 1925)
Bufo columbiensis (Cope 1889)
Bufo halophila (Baird and Girard 1853)

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 Gray, 1825
Genus Anaxyrus North American Toads Tschudi, 1845
Species boreas Western Toad (Baird and Girard, 1852)
Subspecies boreas Boreal Toad

(Baird and Girard, 1852)
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

Related or Similar California Frogs
Anaxyrus boreas halophilus
Anaxyrus californicus

Anaxyrus woodhousii
Anaxyrus canorus
Anaxyrus exsul

More Information and References
California Department of Fish and Wildlife

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.

Storer, Tracy I. A Synopsis of the Amphibia of California. University of California Press Berkeley, California 1925.

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

The following status listings are copied from the 2017 Special Animals List and the 2017 Endangered and Threatened Animals List which are published by the California Department of Fish and Wildlife.

If no status is listed here, the animal is not included on either CDFW list. This most likely indicates that there are no serious conservation concerns for the animal. To find out more about an animal's status, you can go to the NatureServe and IUCN websites to check their rankings.

Check here to see the most current complete lists.


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

Organization
Status Listing
NatureServe Global Ranking
NatureServe State Ranking
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
IUCN
 

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