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Anaxyrus canorus

(Camp, 1916)

Yosemite Toad

G2Imperiled Found in 64 roadless areas NatureServe Explorer →
G2ImperiledGlobal Rank
VulnerableIUCN
HighThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.105396
Element CodeAAABB01040
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVertebrate Animal
IUCNVulnerable
Endemicendemic to a single state or province
KingdomAnimalia
PhylumCraniata
ClassAmphibia
OrderAnura
FamilyBufonidae
GenusAnaxyrus
Synonyms
Bufo canorusCamp, 1916
Other Common Names
Yosemite toad (EN)
Concept Reference
Frost, D. R. 1985. Amphibian species of the world. A taxonomic and geographical reference. Allen Press, Inc., and The Association of Systematics Collections, Lawrence, Kansas. v + 732 pp.
Taxonomic Comments
The genus Anaxyrus was split from Bufo by Frost et al. (2006). However, taxonomy within the genus Bufo remains controversial and many references still use the long-established Bufo.

Multiple studies (e.g., Goebel et al. 2009 and Gordon et al. 2017) have found two phylogenetically distinct mitochondrial DNA clades of this species, corresponding to samples from the southern Sierra Nevada range and northern samples from the same range. Goebel et al. (2009) also reported hybrids between A. boreas and A. canorus. These issues require more research that is expanded to include nuclear DNA (Nicholson 2025).
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2023-07-20
Change Date2023-07-20
Edition Date2023-07-20
Edition AuthorsHammerson, G. (2013), K. Hunting (2023)
Threat ImpactHigh
Range Extent5000-20,000 square km (about 2000-8000 square miles)
Number of Occurrences81 - 300
Rank Reasons
Yosemite toad populations have exhibited significant historical declines and continue to decline today. Management of grazing activities, a reduction in legacy logging effects, and mountain meadow restoration likely benefit some populations. Climate change is already affecting this species and these effects will likely intensify in the future.
Range Extent Comments
This species is endemic to California, USA. It occurs above 6,500 feet in the central Sierra Nevada mountains between the Lake Tahoe Basin (Blue Lakes (Alpine County California)) in the north to the headwaters of the Kings River in the vicinity of the Evolution Lakes, Fresno County, California (Thompson et al. 2016). Based on analysis of location information derived from California Natural Diversity Database (CNDDB) element occurrences, the range extent of the Yosemite toad is about 10,000 km2.
Occurrences Comments
Given the high potential for the Yosemite toad exhibiting a metapopulation structure (Brown et al 2015) with site occupancy varying over time and space, there may be between 180-200 occurrences in a given year (CNDDB 2021).
Threat Impact Comments
Yosemite toad populations are impacted by a series of current threats with varying degrees of severity including outbreaks of chytridiomycosis, caused by infections of the skin in amphibians by Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans , which has been detected in Yosemite toads (Browne et al 2015), excessive livestock grazing (prevalent in some parts of the Yosemite toad range), intensive recreational (hiking, backpacking, and horseback excursions), and the short-term impacts of vegetation and fuels management actions which most often realized in lower elevation populations and can result in direct mortality of Yosemite toads and reductions in vegetation may impact prey species availability. Legacy timber harvest effects and succession in mountain meadows are localized but severe and reduce overall habitat quality for Yosemite toads. Finally, climate change affects the timing and availability of surface waters, potentially disrupting reproduction timing, and likely negatively affects the abundance and availability of prey species.
Ecology & Habitat

Habitat

Habitat includes moist mountain meadows and borders of forests. Individuals shelter in rodent burrows as well as in dense vegetation. Breeding occurs in shallow edges of snow melt pools and ponds or in shallows or along edges of lakes and slow-moving streams. Some breeding sites dry up before larvae metamorphose.

Ecology

Primarily solitary, except during the breeding season.

Reproduction

Breeding occurs May-July, and possibly August, the time depending on the depth of spring snowpack and time of its melt; most females spawn during a 2-3-day peak each year (Kagarise Sherman and Morton 1993). Eggs are laids in strings and clusters, hatch in about 1.5 weeks. Tadpoles metamorphose about 5-7 weeks after egg deposition. Males first breed at 3-5 years, females at 4-6 years. Some individuals may live at least 15 years. Basically a late-maturing, long-lived species (Kagarise Sherman and Morton 1993).
Terrestrial Habitats
Grassland/herbaceous
Palustrine Habitats
TEMPORARY POOLRiparian
Other Nations (1)
United StatesN2
ProvinceRankNative
CaliforniaS2Yes
Threat Assessments
ThreatScopeSeverityTiming
2 - Agriculture & aquacultureRestricted (11-30%)Moderate or 11-30% pop. declineHigh (continuing)
2.3 - Livestock farming & ranchingRestricted (11-30%)Moderate or 11-30% pop. declineHigh (continuing)
2.3.2 - Small-holder grazing, ranching or farmingRestricted (11-30%)Moderate or 11-30% pop. declineHigh (continuing)
6 - Human intrusions & disturbanceRestricted (11-30%)Slight or 1-10% pop. declineHigh (continuing)
6.1 - Recreational activitiesRestricted (11-30%)Slight or 1-10% pop. declineHigh (continuing)
8 - Invasive & other problematic species, genes & diseasesLarge (31-70%)Moderate or 11-30% pop. declineHigh (continuing)
8.1 - Invasive non-native/alien species/diseasesLarge (31-70%)Moderate or 11-30% pop. declineHigh (continuing)
11 - Climate change & severe weatherPervasive (71-100%)Moderate or 11-30% pop. declineHigh (continuing)

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Roadless Areas (64)
California (64)
AreaForestAcres
Bell MeadowStanislaus National Forest7,968
Buckeye RidgeHumboldt-Toiyabe National Forest2,241
Carson - IcebergStanislaus National Forest56,430
Carson - IcebergStanislaus National Forest56,430
Cherry LakeStanislaus National Forest1,106
Dinkey LakesSierra National Forest34,171
Dinkey LakesSierra National Forest34,171
DomeStanislaus National Forest11,085
DomeStanislaus National Forest11,085
EagleStanislaus National Forest16,116
EagleStanislaus National Forest16,116
EbbettsHumboldt-Toiyabe National Forest255
EbbettsHumboldt-Toiyabe National Forest255
Hall Natural AreaInyo National Forest5,236
Hall Natural AreaInyo National Forest5,236
Hoover - Cattle CkHumboldt-Toiyabe National Forest598
Hoover - Emma LakeHumboldt-Toiyabe National Forest1,007
Hoover - Green Ck NoHumboldt-Toiyabe National Forest7,155
Hoover - Mt.olsenHumboldt-Toiyabe National Forest624
Hoover - NorthHumboldt-Toiyabe National Forest1,574
Hoover - NorthHumboldt-Toiyabe National Forest1,574
Hoover - Virginia LksHumboldt-Toiyabe National Forest5,050
Horse Mdw.Inyo National Forest5,687
Horse Mdw.Inyo National Forest5,687
HortonInyo National Forest5,717
HortonInyo National Forest5,717
Iceberg - Mill CreekHumboldt-Toiyabe National Forest26,988
Iceberg - Mill CreekHumboldt-Toiyabe National Forest26,988
Iceberg - Silver Mtn.Humboldt-Toiyabe National Forest294
Iceberg - Wolf Ck LkHumboldt-Toiyabe National Forest175
Iceberg - Wolf Ck LkHumboldt-Toiyabe National Forest175
Kings RiverSierra National Forest52,999
Kings RiverSierra National Forest52,999
Log Cabin SaddlebagInyo National Forest15,165
Log Cabin SaddlebagInyo National Forest15,165
Mokelumne - CharityHumboldt-Toiyabe National Forest202
Mt. RaymondSierra National Forest6,965
Mt. OlsenInyo National Forest2,161
Mt. OlsenInyo National Forest2,161
Mt. RebaStanislaus National Forest3,869
NessieInyo National Forest830
NightStanislaus National Forest3,173
NightStanislaus National Forest3,173
North LakeInyo National Forest2,406
Oat Mtn.Sequoia National Forest12,223
Raymond PeakEldorado National Forest2,518
Raymond PeakEldorado National Forest2,518
Raymond PeakStanislaus National Forest3,646
Raymond PeakStanislaus National Forest3,646
Robinson PeakHumboldt-Toiyabe National Forest5,835
Robinson PeakHumboldt-Toiyabe National Forest5,835
Rock Creek WestInyo National Forest3,626
Rock Creek WestInyo National Forest3,626
San JoaquinSierra National Forest22,474
San JoaquinSierra National Forest22,474
SherwinInyo National Forest3,140
ShuteyeSierra National Forest7,313
Table Mtn.Inyo National Forest4,215
Tioga LakeInyo National Forest829
Tioga LakeInyo National Forest829
WaterhouseStanislaus National Forest4,394
Wheeler RidgeInyo National Forest15,744
Wheeler RidgeInyo National Forest15,744
WoodchuckSierra National Forest267
References (40)
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