CaliforniaHerps.com

A Guide to the Amphibians
and Reptiles of California


Yosemite Toad - Anaxyrus canorus

(Camp, 1916)

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



Yosemite Toad Range Map
Historical Range in California: Red

Dot-locality range map


Listen to this toad:


speaker
One short call



observation link





Adult Males
Yosemite Toad Yosemite Toad Yosemite Toad Yosemite Toad
  Adult male, Alpine County  
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Adult Male, Alpine County Adult Male, Alpine County Adult Male, Alpine County Adult male in calling position, Alpine County, hunkered down in a small self-made cavity in a meadow.
Yosemite Toad Yosemite Toad Yosemite Toad Yosemite Toad
Adult male, Alpine County Adult male, Alpine County Adult male, Mono County
© Douglas Aguillard
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This adult male sat at the edge of a small trickle at the edge of a small lake in Alpine County for several hours, probably feeding on insects. Adult Male, Alpine County  
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Adult male, raised up in a defensive stance, Alpine County © Richard Porter
Adult female (left) and male,
Fresno County © Patrick Briggs
 
     
Adult Females
Yosemite Toad Yosemite Toad Yosemite Toad Yosemite Toad
Adult Female, Alpine County Adult Female, Alpine County Adult Female, Alpine County Adult Female, Alpine County
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Adult female in a small meadow cavity, Alpine County
Adult female, Mono County © Ben Witzke Adult female, Mono County © Ben Witzke Adult female, Mono County © Ben Witzke

       
Juveniles
Yosemite Toad Yosemite Toad Yosemite Toad  
Juvenile, Alpine County
Juvenile, Alpine County  
     
Breeding Season Behavior
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Adults in amplexus with the female depositing her eggs, Alpine County Adults in amplexus, Fresno County with a second male on top of, then underneath the female. He tried to steal the female from the other male, but the other male kicked and made a loud territorial release calluntil the second male finally retreated. Adults in amplexus, Fresno County
© Julie Nelson
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Male, Fresno County, in calling postition, partly-submerged in a snow-melt meadow pool.
Calling male, Alpine County Calling male, Fresno County.  
       
Eggs and Tadpoles
Yosemite Toad eggs Yosemite Toad eggs Yosemite Toad tadpoles  
Eggs, Alpine County Eggs, Fresno County
© Julie Nelson
Tadpoles, Alpine County  
Yosemite Toad tadpoles Yosemite Toad tadpoles    
Tadpoles, Fresno County
© Julie Nelson
Tadpoles, Alpine County    
       
Habitat
Yosemite Toad Habitat Yosemite Toad Habitat Yosemite Toad Habitat Yosemite Toad Habitat
Habitat, 8,900 ft, Alpine County

Breeding habitat, 8900 ft., Alpine County (site of amplexing adults and eggs shown above is in shallow water at lower left) Habitat, Alpine County Toad in habitat in late summer (in the center of the photo on the bank of a small creek) 8,800 ft., Alpine County.
Yosemite Toad Yosemite Toad Yosemite Toad Habitat Yosemite Toad Habitat
Adult male, Alpine County, (at very bottom of pictures) at edge of snow-melt runoff in a meadow in which there are a fewcalling males during the beginning of the breeding season.

Tadpoles habitat, 8,900 ft,. Alpine County Habitat, Alpine County
Yosemite Toad Habitat Yosemite Toad Habitat Yosemite Toad Habitat Yosemite Toad Habitat
Habitat at breeding time - meadow saturated with snow melt 8,900 ft., Alpine County.

Former habitat, 9,100 ft. Mono County Habitat, Mono County © Ben Witzke
Yosemite Toad Habitat Yosemite Toad Habitat    
Two views of breeding habitat at 9200 ft. elevation in Fresno County
during the breeding period just after snow melt in late May.
   
     
Short Videos
Yosemite Toad Yosemite Toad Yosemite Toad Yosemite Toad
Male Yosemite Toads swim and hop around a meadow surrounded by melting snow. Juvenile and adult male Yosemite Toads around a high-elevation lake. This is a 20 second video of a male toad calling in the afternoon from a snow-melt pool in a high-altitude wet meadow surrounded by snow at 9200 ft. elevation in Fresno County. The air temperature was 37 degrees, but the shallow water was over 60 degrees F. due to the sun. Pacific Treefrogs and water sounds are heard in the background.

Many thanks to Stephanie Weber, aquatic biologist and toad Muse, for helping me to get this recording by inspiring some cold and sluggish toads to call.
This is a short video of a male and female in amplexus in Fresno County. A release call, probably made by the female (on the bottom), can be heard as the frogs hop together. A female typically produces this call after she has already laid her eggs and wants the male to release her.
© Julie Nelson


Yosemite Toad Yosemite Toad Yosemite Toad tadpoles Yosemite Toad
These are short videos of a male calling from  on top of and underneath
a piece of buried tree root in a wet meadow in Alpine County.
Tiny recently-hatched tadpoles swim in shallow puddles in a high mountain meadow in Alpine County A juvenile toad in Alpine County.
     
Description
 
Size
Adults are 1.25 - 2.74 inches from snout to vent ( 4.4 - 6.9 cm). (Stebbins, 2003)

Appearance
A robust and stocky toad with dry, uniformly warty skin.
No cranial crests are present.
Paratoid glands are large, flat, and oval.
Eyes are closely set with horizontal pupils.
A dorsal stripe is very faint or absent.

Color and Pattern
Male and females are very different in appearance.

Males are pale yellowish green or olive above, with few or no dark blotches.
Females and young are heavily blotched on a light background.
The throat and belly are pale on both sexes.
Male/Female Differences
Besides the differences in color and pattern described above, males are smaller than females and have fewer and smaller warts.
Young
Young have no dorsal stripe immediately after transformation.
The bottoms of their feet is bright orange or yellow.
Larvae (Tadpoles)
Tadpoles are very dark brown, possibly as a protection from ultraviolet solar radiation which is very strong at the high elevation locations inhabited by these toads
Eyes are inset from the edges of the head on the top.
The tip of the tail is rounded.
Tadpoles grow to about 1.5 inches (3.7 cm) in length before undergoing metamorphosis. (Stebbins & McGinnis 2012)

Life History and Behavior
Activity
Active in daytime, usually in sunny areas, where basking in sunlight is needed to maintain an optimal body temperature.
Activity period is relatively short, from  April - July, to late September - early October.
Overwintering
During winter, Yosemite Toads shelter in the burrows of small mammals, willow thickets, forest edges adjoining meadows, and in clumps of vegetation near water.
Movement
Like most toads, this one is slow moving, often using a walking or crawling motion along with short hops.
Defense
For defense Yosemite toads rely on parotoid glands and warts which can secrete a poison that deters some predators.
They may also retreat into burrows or jump into water to hide from  threats.
Territoriality
Calling males at breeding sites will defend their territory against intrusion by other males.
Longevity
Kagarise Sherman and Morton (1984) estimated that females may live at least 15 years and males at least 12 years.
(Kagarise Sherman, 1980 - referenced in Davidson and Fellers, Lanoo 2005)
Voice (Listen)
A long, loud, rapid musical trill, repeated at frequent intervals.
Diet
Diet consists of a wide variety of invertebrates, including beetles, ants, siders, bees, wasps, flies, and millipedes. The 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.
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 come into breeding condition and migrate to ponds or ditches where the males call to advertise their fitness to competing males and to females. Males and females pair up in 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.

Females are reproductively mature at 4–6 years of age, but do not breed every year.
Males first breed when they are 3–5 years old. (Kagarise Sherman, 1980 - referenced in Davidson and Fellers, Lanoo 2005)

Mating and egg-laying takes place from May to July shortly after the snow melts in shallow pools in meadows, the margins of lakes and quiet streams.
Males arrive at breeding sites a few days before females. (Males stay for 1 - 2 weeks, while females leave after a few days.)
Males set up a territory in shallow water and make a trilled breeding call to attract a female. Calls are made during the day, peaking at mid day. When a female arrives, the male amplexes her and rides her to a location where she decides to lay her eggs.
Eggs
Darkly-pigmented eggs are laid in strings of single or double strands or in a radiating network several eggs deep in shallow pools and slow moving meadow streams.
Females laid an estimated 1,500 to 2,000 eggs at one location.
Eggs hatch in 10 - 12 days.
Tadpoles and Young
Tadpoles metamorphosed in 52 - 63 days at one location. 
Tadpoles are preyed upon by other frogs, birds, diving beetles, and probably gartersnakes.

Juvenile toads feed and overwinter near the breeding pond, in small burrows or root tangles.

Hybrids
Hybridizes with A. b. halophilus in the northern part of its range. (Stebbins 2003.)

Habitat
Inhabits wet mountain meadows, willow thickets, and the borders of forests, usually not more than a hundred meters from permanent water.
After breeding, males and females move from the breeding pond into meadows where they feed for 2 - 3 months before the snows return.

Geographical Range
Endemic to California.
Found only at high elevations in the Sierra Nevada Mountains.
Most authors indicate that the distribution is from the Ebbets Pass area of Alpine County south to the Spanish Mountains area in Fresno County, but there are mentions of Yosemite Toads from farther north than Ebbets Pass: Stebbins (2003/2012) notes their northernmost range as Grass Lake, El Dorado County (just north of the Alpine County line) and there are museum specimens from 1956 taken from Fallen Leaf Lake, El Dorado County, which is just south of Lake Tahoe.
Elevational Range
Found at elevations of 4,800 - 12,000 ft. (1,460 - 3,630 m.) (Stebbins & McGinnis, 2012)

Notes on Taxonomy
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 (in 2013).


Alternate and Previous Names (Synonyms)

Bufo canorus - Yosemite Toad (Stebbins 1954, 1966, 1985, 2003, Stebbins & McGinnis 2012)
Bufo canorus
- Yosemite Toad (Yosemite Park Toad) (Wright and Wright 1949)
Bufo canorus
- Yosemite Park Toad (Storer 1925)
Bufo canorus (Camp 1916)

Conservation Status

It has been estimated from population studies that the Yosemite Toad has disappeared from over 50% of its historic range, even in habitats that still appear to be unaltered. Remaining populations may not be reproducing enough to survive. One population at Tioga Pass, counted for more than 20 years, had declined by 90 percent in 1993.

The causes of the decline are unclear. Disease, degradation of habitat by grazing livestock, increased ultraviolet radiation, introduced predatory fishes, a severe 1980's drought, windborne pesticide contamination, and increased predation by Common Ravens, whose population has increasd greatly due to human activities, are all causes which are thought to have contributed to the decline.

Proposed for Federal ESA Threatened listing 4/25/13.
Federally listed as Threatened under the Endangered Species Act 4/25/14.

In August, 2016, the U.S. Fish and Wildlife Service announced the designation of 1.8 million acres of protected critical habitat in the Sierra Nevada mountains for Rana sierrae, the Sierra Nevada Yellow-legged Frog, the northern population of Rana muscosa, the Southern Mountain Yellow-legged Frog, and Anaxyrus canorus, the Yosemite Toad.   BiologicalDiversity.org


Taxonomy
Family Bufonidae True Toads Gray, 1825
Genus Anaxyrus North American Toads Tschudi, 1845
Species canorus Yosemite Toad

(Camp, 1916)
Original Description
Bufo canorus Camp, 1916 - Univ. California Publ. Zool., Vol. 17, No. 6, p. 59

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
canorus - Latin for tuneful - "melodious trill uttered by this toad" - referring to the male's breeding call

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 boreas
Anaxyrus boreas halophilus

Anaxyrus woodhousii
Anaxyrus californicus
Anaxyrus exsul

More Information and References

NatureServe Explorer

AmphibiaWeb

California Department 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.

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.


Basey, Harold E. Discovering Sierra Reptiles and Amphibians. Yosemite Association and Sequoia Natural History Association, 1976, 1991.

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 and the Endangered and Threatened Animals List which are published by the California Department of Fish and Wildlife.


Special Animals List Notes:

1) Formerly Bufo canorus; Frost, Grant, Faivovich, Bain, Haas, Haddad, De Sá, Channing, Wilkinson, Donnellan, Raxworthy, Campbell, Blotto, Moler, Drewes, Nussbaum, Lynch, Green & Wheeler (2006. The Amphibian Tree of Life. Bulletin of the American Museum of Natural History 297: 1-370) placed this species in the genus Anaxyrus (Tschudi, 1845). The standard common name remains Yosemite toad.

2) The USFWS published a final rule on April 29, 2014, to list the Yosemite toad as Threatened. The effective date for this rule is June 30, 2014.

Organization
Status Listing
NatureServe Global Ranking G2G3 Imperiled - Vulnerable
NatureServe State Ranking S2S3 Imperiled - Vulnerable
U.S. Endangered Species Act (ESA) FT - 4/25/14 Threatened
California Endangered Species Act (CESA) None
California Department of Fish and Wildlife SSC Species of Special Concern
Bureau of Land Management None
USDA Forest Service S Sensitive
IUCN EN Endangered
 

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