View source for Yosemite toad

{{Short description|Species of amphibian}}
{{Speciesbox
| name = Yosemite toad
| image = Anaxyrus_canorus 2.jpg
| image_caption = Adult female in Kings Canyon
| status = VU
| status_system = IUCN3.1
| status_ref =<ref name="iucn status 9 December 2022">{{cite iucn |author=IUCN SSC Amphibian Specialist Group |date=2022 |title=''Anaxyrus canorus'' |volume=2022 |page=e.T3180A118972917 |url=https://www.iucnredlist.org/species/3180/118972917 |access-date=16 December 2022}}</ref>
|status2=LT
|status2_system=ESA
|status2_ref=<ref>{{cite web|url=https://ecos.fws.gov/ecp/species/7255|title=Yosemite toad (''Anaxyrus canorus'')|website=Environmental Conservation Online System|publisher=U.S. Fish & Wildlife Service|access-date=28 April 2023}}</ref><ref>{{Federal Register|79|24256}}</ref>
| taxon = Anaxyrus canorus
| authority = ([[Charles Lewis Camp|Camp]], 1916)
| synonyms = ''Bufo canorus'' <small>Camp, 1916</small>
| range_map = Anaxyrus canorus range map.png
}}
The '''Yosemite toad''' ('''''Anaxyrus canorus''''', formerly ''Bufo canorus'') is a species of true toad in the family [[Bufonidae]]. [[Endemic]] to the [[Sierra Nevada (U.S.)|Sierra Nevada]] of California, the species ranges from the [[Alpine County, California|Alpine County]] to [[Fresno County, California|Fresno County]]. Yosemite toads are only found in the montane to subalpine elevational zone of {{convert|1950|–|3445|m|abbr=on}} [[Above sea level|asl]].<ref name=":2" /><ref name=":11">{{Cite book|title=Animal life in the Yosemite|last=Grinnell|first=Joseph|publisher=University of California Press|year=1924|location=Berkeley, California|pages=1–752}}</ref><ref name=":3" /><ref name=":0" /> The Yosemite toad is similar to the nearby [[western toad]] (''A. boreas''), but in many ways adapted to a high elevation lifestyle. It was initially described during the [[Joseph Grinnell#Yosemite|Grinnell Survey of California]], by an undergraduate student of [[Joseph Grinnell]] named [[Charles Lewis Camp|Charles Camp]].

==Description==

=== Adults ===
{{multiple image
 | align = left
 | footer = Yosemite toads are the most sexually dichromatic anuran in North America. Males and females are colored and patterned differently.
 | image1 = Yosemite toad female (Tuolumne County).jpg
 | caption1 = adult female
 | image2 = Yosemite toad male (Fresno County).jpg
 | caption2 = adult male
 }}
Yosemite toads are medium-sized ({{convert|48|–|84|mm|in|abbr=off|disp=or}} [[wiktionary:svl|SVL]]) stocky [[True toad|toads]], with females averaging larger than males.<ref name=":0">{{Cite journal|last=Karlstrom|first=Ernest L.|year=1962|title=The toad genus ''Bufo'' in the Sierra Nevada of California|journal=University of California Publications in Zoology|volume=62|pages=1–104}}</ref><ref name=":1">{{cite thesis|last=Sherman|first=Cynthia Kagarise|title=A comparison of the natural history and mating system of two anurans: Yosemite toads (''Bufo canorus'') and Black toads (''Bufo exsul'')|year=1980|publisher=University of Michigan|type=PhD|pages=1–394}}</ref> They generally lack cranial crests, but males will rarely have weakly developed ones. Their eyes have a dark brown iris with gold iridophores.<ref>{{cite report|last1=Jennings|first1=M.R.|last2=Hayes|first2=M.P.|title=Amphibian and reptile species of special concern in California|year=1994|pages=50–53|publisher=California Department of Fish and Game|location=Rancho Cordova|url=https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=83971&inline|type=PDF|access-date=28 April 2023}}</ref> In comparison with the closely related [[Western toad|western toad (''A. boreas'')]], the [[parotoid gland]]s are large, narrowly spaced, and irregularly shaped (oval or flattened), less than one gland width apart.<ref name=":2">{{Cite journal|last=Camp|first=Charles L.|year=1916|title=Description of Bufo canorus, a new toad from the Yosemite National Park|journal=University of California Publications in Zoology|volume=17|pages=59–62}}</ref><ref name=":3">{{Cite book|title=Amphibians of western North America|last=Stebbins|first=Robert C.|publisher=University of California Press|year=1951|pages=1–539}}</ref><ref name=":0" /><ref name=":1" /> Like the parotoids, the eyes are spaced narrowly apart, usually less than the width of the upper eyelid.<ref name=":2" /><ref name=":3" /> The warts are large, smooth, and the dorsal skin between warts is smooth as compared to the [[western toad]]. It is the most [[Sexual dimorphism|sexually dichromatic]] species of anuran in North America, with males and females displaying strikingly divergent patterns and coloration at maturity.<ref name=":2" /><ref name=":3" /> Females are dorsally covered in black blotches that have white or cream borders, with a tan, copper, or ruddy background; males are more uniformly colored, ranging from yellow-green, to olive drab, to greenish brown, sometimes with scattered black flecks near warts.<ref name=":0" /> Juveniles resemble adult females, except with a thin mid-dorsal stripe, which gradually fades during development (faster in males than females). A prominent mid-dorsal stripe is lacking in this species, unlike the [[western toad]]. As juvenile males mature, their black blotches shrink and ultimately disappear, whereas they expand and reticulate in developing females.

Unlike other members of the ''A. boreas'' species group (''[[Western toad|A. boreas]]'', ''[[Amargosa toad|A. nelsoni]]'', ''A. nestor'' [extinct], ''A. canorus'', and ''[[Black toad|A. exsul]]''), Yosemite toad males have a vocal sac and produce an advertisement call to attract females during breeding.<ref name=":5">{{cite thesis|last=Pauly|first=Gregory B.|title=Phylogenetic Systematics, Historical Biogeography, and the Evolution of Vocalizations in Nearctic Toads (''Bufo'')|year=2008|publisher=University of Texas|type=PhD|pages=1–165}}</ref> The call is a high-pitched, melodious, flute-like trill repeated frequently.<ref name=":0" /> Charles Camp chose the specific epithet "canorus" (meaning tuneful) for the species based on its advertisement call.<ref name=":2" /> The trill contains 26–51 evenly spaced notes that last an average of 2.6 seconds.<ref name=":0" />

=== Eggs ===
[[File:Yosemite toad tadpoles.jpg|right|thumb|Yosemite toad tadpoles]]
Eggs are darkly pigmented and laid in 1 or 2 strands (1 per ovary, the oviducts fuse just before the cloaca in toads), however egg masses may fold during deposition into radiating clusters 4–5 eggs wide.<ref name=":4">{{Cite journal|last=Karlstrom|first=Ernest L.|year=1955|title=The eggs and larvae of the Yosemite toad Bufo canorus Camp|journal=Herpetologica|volume=11|pages=221–227}}</ref><ref name=":1" /> 1000–2000 eggs beaded in two envelopes are laid by females in shallow pools, tangled in vegetation. Individual eggs are 2.1&nbsp;mm wide on average, and 4.1&nbsp;mm including the two envelopes.<ref name=":4" />

=== Tadpoles ===
[[Tadpole]]s are {{convert|10|–|37|mm|in}} [[Total length|TL]]<ref name=":3" /> and jet black throughout, and hence the intestines are not visible ventrally. Their eyes are set dorsally (in contrast to the co-occurring [[Pseudacris sierra|Sierra chorus frog]], which has eyes on the outline of the head when viewed from above). In contrast to the [[western toad]], the snout is shorter and blunted in lateral view, the tail fins are mostly opaque, the tail is deepest about halfway down its length, and the tail tip is more rounded.<ref name=":3" /><ref name=":4" /><ref name=":0" /> The labial tooth row formula is 2/3 (2 upper and 3 lower labial tooth rows), and the ratio of lengths of the last 2 rows is 1.6 (in [[western toad]]s it is 1.2).<ref>{{Cite book|title=A field guide to western reptiles and amphibians|last=Stebbins|first=Robert C.|publisher=Houghton Mifflin Harcourt|year=2003|pages=1–560}}</ref>
{{multiple image
 | align = left
 | footer = Subadult stages. Sexual maturity takes 3–6 years, depending on sex.
 | image1 = Metamorphs.jpg
 | caption1 = metamorphs
 | image2 = Yosemite toad juvenile.jpg
 | caption2 = 2-year-old juvenile
 }}

=== Subadults ===
Metamorphs (recently metamorphosed tadpoles) are highly pigmented like tadpoles, and quite small, usually {{convert|9|–|14|mm|in|abbr=off|disp=or}} SVL.<ref name=":0" /><ref name=":1" /> Juveniles (1+ years in age) reach sexual maturity after 3–5 years (males) or 4–6 years (females), at which time sex-specific colors and patterns emerge.<ref name=":1" /><ref name=":6">{{Cite journal|last=Sherman|first=Cynthia Kagarise|year=1984|title=The toad that stays on its toes|journal=Natural History|volume=93|pages=72–78}}</ref> Until then, juveniles resemble adult females: they have a background color varying from brown to grey with generally unconnected black blotches encircling the warts. Unlike adult females, juveniles have a thin mid-dorsal stripe that is white or cream-colored, and orange tubercles on the undersides of their hands and feet. As juveniles mature, their black blotches expand and interconnect if they are females, or shrink if they are males, and the mid-dorsal stripe shrinks and mostly disappears.

==Natural history==

=== Breeding ===
Yosemite toads are explosive breeders (breed within a short time period), migrating to breeding pools and flooded areas in late spring while snowbanks still veil the frozen meadows.<ref name=":0" /><ref name=":1" /> They have been termed the "toad that stays on its toes" or "tiptoeing toad" due to their habit of crossing snowdrifts without touching their abdomen to the cold snow.<ref name=":6" /> Breeding time varies greatly with elevation and yearly snowpack (April to July), and depends on timing of snowmelt.<ref name=":0" /><ref name=":1" /><ref name=":7">{{Cite journal|last=Brown|first=Cathy|year=2012|title=Advantages of long-term, multi-scale monitoring: assessing the current status of the Yosemite toad (Anaxyrus canorus) in the Sierra Nevada, California|journal=Herpetological Conservation and Biology|volume=7|pages=115–131}}</ref> Males arrive to breeding ponds synchronously when the meadow is ca. 50% covered in snow. Depending on the population density they will either join a breeding chorus by making an advertisement call to females, or will actively search for them.<ref name=":1" /> Their vocalization is a high-pitched, sonorous trill lasting an average of 2.6 seconds and repeated frequently.<ref name=":0" /><ref name=":5" /> Males intermittently call from pool margins, under logs, or inside willows to attract females. When females arrive, they are immediately grasped in [[amplexus]] by one or multiple males as the males fight for a limited number of mating opportunities. Breeding sex ratios can be very skewed toward males since females breed less frequently than males, although both sexes typically do not breed in consecutive years.<ref name=":1" /><ref name=":6" /> While in amplexus, females will lay one clutch of 1,000–2,000 eggs. Eggs hatch after 1–2 weeks, and the length of time depends heavily on ambient temperature and fluctuations in temperature. Females generally breed once and leave after 2–3 days, while males remain for 1–2 weeks.<ref name="AmphibiaWeb">{{cite web|url=http://www.amphibiaweb.org/cgi/amphib_query?where-genus=Anaxyrus&where-species=canorus&account=lannoo|title=''Anaxyrus canorus'' Yosemite Toad|year=2015|work=AmphibiaWeb: Information on amphibian biology and conservation. [web application]|publisher=Berkeley, California: AmphibiaWeb|access-date=19 December 2015}}</ref><ref name="californiaherps" />

=== Habitat use ===
[[File:Yosemite toad breeding pool.jpg|thumb|Yosemite toad breeding pool (note "golf ball" texture)]]
The species primarily uses [[Montane ecosystems|montane]] and subalpine wet meadows for breeding, but will occasionally breed in ephemeral ponds, lake margins, or other riparian areas.<ref name=":8">{{Cite journal|last=Mullally|first=Don. P.|year=1953|title=Observations on the ecology of the toad Bufo canorus|journal=Copeia|volume=1953|issue=3|pages=182–183|doi=10.2307/1439932|jstor=1439932}}</ref><ref name=":4" /><ref name=":0" /><ref name=":1" /> Flatter, southwesterly meadows, with more precipitation, containing warmer waters seem to be favored by the species.<ref name=":12">{{cite thesis|last=Liang|first=Christina|title=Habitat modeling and movements of the Yosemite toad (Anaxyrus (=Bufo) canorus) in the Sierra Nevada, California|year=2010|publisher=University of California, Davis|type=PhD|pages=1–116}}</ref><ref>{{Cite journal|last=Wang|first=Ian|year=2012|title=Environmental and topographic variables shape genetic structure and effective population sizes in the endangered Yosemite toad|journal=Diversity and Distributions|volume=18|issue=10|pages=1033–1041|doi=10.1111/j.1472-4642.2012.00897.x|s2cid=82880526 |doi-access=free}}</ref> More specifically, breeding takes place in shallow snowmelt ponds or flooded areas, and eggs are usually deposited in water less than 5&nbsp;cm deep.<ref name=":0" /><ref name=":1" /> Shallow water makes eggs vulnerable to freezing, because nighttime temperatures are particularly low during springtime snow melt off. Females will sometimes split their clutch into multiple areas, or deposit their clutch communally with other pairs in a single area.<ref name=":1" /> The relatively large amount of pigmentation in eggs and tadpoles is thought to help expedite development, and tadpoles will congregate in the shallowest, warmest margins of ponds during the day.<ref name=":8" /><ref name=":0" /><ref name=":1" /> At nighttime tadpoles settle down into the silty detritus where they are more insulated from the cold nighttime temperatures. This often gives their pools the appearance of "golf ball" texture, because tadpoles leave divots in the silt (see picture of breeding pool). It is not uncommon for a large number of breeding ponds to desiccate each season before tadpoles successfully metamorphose, hence there is apparently a selective tradeoff between shallow ponds (which accelerate tadpole development) and ponds with long hydroperiods (which ensure survival).<ref name=":0" /> Time from hatching to tadpole metamorphosis is 4–6 weeks, and this is highly dependent upon environmental factors (elevation, weather, food, competition) and possibly genetic background.<ref name=":0" /><ref name=":1" /> Tadpoles are apparently unable to overwinter.

Subadult and adult habitat use patterns are poorly understood. Metamorphs appear to move away from breeding ponds soon after transformation, however they probably overwinter nearby in stream channels and associated vegetation (willows, sedges, and grasses).<ref name=":1" /><ref name=":9">{{cite thesis|last=Martin|first=David L.|title=Decline, movement and habitat utilization of the Yosemite toad (Bufo canorus): an endangered anuran endemic to the Sierra Nevada of California|year=2008|publisher=University of California, Santa Barbara|type=PhD|pages=1–393}}</ref> Many juveniles (1+ years in age) probably disperse farther upland into adult foraging habitat, especially by mid-summer of their second year, but they can also be found nearby breeding ponds. Adult upland foraging habitat tends to be covered in seeps and springs, willows, tall forbs, granitic boulders, or (at lower elevation) forest clearings.<ref name=":9" /><ref name=":12" /> Rodent burrows play an essential role in providing shelter from predation and weather, as do willows, logs, and rocks.<ref name=":8" /><ref name=":0" /><ref name=":1" /><ref name=":9" /><ref name=":12" /> Overwintering habitat is also includes the burrows of rodents such as [[Smooth-toothed pocket gopher|pocket gophers]], [[vole]]s, and [[Belding's ground squirrel]]s, along with willow root tangles, which all probably keep an optimal thermal and mesic environmental for hibernating toads.<ref name=":1" /><ref name=":9" />

=== Movement patterns ===
Yosemite toads show high site fidelity to both breeding and upland foraging habitat, often using the same breeding pools and refuges in subsequent years.<ref name=":9" /><ref name=":10" /><ref name=":7" /> After breeding, adults forage in upland riparian areas of the breeding meadows, or (less commonly) disperse into the surrounding forest or subalpine environmental matrix. Although adult toads are capable of significant dispersal away from breeding pools, they are generally found within 90 m of permanent water;<ref name=":0" /><ref name=":9" /> occasionally they are found in xeric forest habitat.<ref name=":12" /> Female toads disperse farther than males, and have been found to move up to 1.26 kilometers from their breeding grounds in one season.<ref name=":9" /><ref name=":10">Liang, C.T. 2010. Habitat modeling and movements of the Yosemite toad (Anaxyrus (=Bufo) canorus) in the Sierra Nevada, California. PhD Dissertation, University of California, Davis. (September) 126 pp.
</ref> However, dispersal between meadows appears to be very low, estimated to be about 2% between 400 m meadows.<ref name=":1" />

=== Over wintering ===
This is possibly due to unfavorably dry habitat between meadow complexes.<ref name=":3" /> Overwintering sites are rodent burrows or willow thickets (see "Habitat Utilization"), and the first freezing nighttime temperatures seem to cue adult toads to seek hibernacula.<ref name=":9" /> Hibernation usually begins in the late summer or early fall, between September and October.

=== Feeding ===
Like other toads, Yosemite toads are ambush predators. They lunge at prey and open their mandibles, causing their sticky tongue to unfold, flip downward, and pull the animal into their mouths. Adult stomach contents have included: [[Darkling beetle|tenebrionid beetles]], [[Coccinellidae|ladybird beetles]], [[weevil]]s, [[Crane fly|craneflies]], [[mosquito]]s, [[caterpillar]]s, [[carpenter ant]]s, [[dragonfly]] naiads, [[centipede]]s, [[Julida|julid millipedes]], and spiders.<ref name=":11" /><ref name=":13">{{cite thesis|last=Wood|first=T.S.|title=Food habits of Bufo canorus|year=1977|publisher=Occidental College|type=MS}}</ref><ref name=":14">{{Cite journal|last=Martin|first=David L.|year=1991|title=Captive husbandry as a technique to conserve a species of special concern, the Yosemite toad|journal=North California Herpetological Society's Conference on Captive Propagation and Husbandry Conference|pages=16–32}}</ref> Juvenile stomach contents have included: [[ant]]s, spiders, and [[wasp]]s.<ref name=":14" /> Metamorph stomach contents have included: [[Ascalaphidae|owl flies]], [[Fly|flies]], [[springtail]]s, [[spider mite]]s, and spiders.<ref name=":14" /> There appears to be an ontogenetic shift from eating mostly [[spider mite]]s (metamorphs), to eating a mix of [[spider mite]]s, spiders, and tiny wasps (2 months post-metamorphosis), to eating mostly larger [[hymenoptera]]ns, mostly [[ant]]s (juveniles), to eating 80% [[hymenoptera]]ns, consisting of [[bee]]s and [[wasp]] (adults).<ref name=":11" /><ref name=":13" /><ref name=":14" /> Tadpoles are grazers on detritus and algae, however it remains unclear whether they ingest those items, bacteria, [[rotifer]]s, or something else.<ref>{{Cite journal|last=Altig|first=Ronald|year=2007|title=What do tadpoles really eat? Assessing the trophic status of an understudied and imperiled group of consumers in freshwater habitats|journal=Freshwater Biology|volume=52|issue=2|pages=386–395|doi=10.1111/j.1365-2427.2006.01694.x|s2cid=37927942}}</ref> Tadpoles are also known to opportunistically scavenge conspecific tadpoles, [[Pseudacris sierra|Sierra chorus frog]] tadpoles, [[Belding's ground squirrel]]s, and [[Dytiscidae|predaceous diving beetle]] larvae, as well as graze on [[Pinus contorta|lodgepole pine]] pollen grains.<ref name=":14" />

===Adaptations to high elevation===
Yosemite toads have several apparent adaptations to high elevation. Males live to be at least 12 years, and females until at least 15 years.<ref name=":1" /><ref name=":6" /> Their longevity probably helps them outlast years of low snowpack that cause poor breeding conditions, and thus low metamorphic recruitment. They are largely [[Diurnality|diurnal]] in contrast to the majority of anurans, probably owing to the cold mountain temperatures.<ref name=":1" /><ref name=":0" /> Aligning their activities with diel peaks in warmth allows them to absorb solar energy to catch and [[Biosynthesis|biosynthesize]] food. The high level of melanism in eggs and tadpoles (and possibly in adult females), as well as the tendency for tadpoles to congregate in the warm shallows, probably serves the same purpose.<ref name=":0" /> Similarly, the selection of shallow breeding sites by adults, and shallow water margins by tadpoles, probably reflects the intense pressure to metamorphose in a short season, and hence the importance of using high temperature for rapid development.<ref name=":0" /><ref name=":6" /> The marked dichromatism between males and females is still an evolutionary mystery. One possible explanation sexual selection. Females could be sexually selecting for lighter coloration in males, as some kind of proxy for male fitness, or males could be signaling their maleness to attract females and ward off over-zealous males. Males of the Yosemite toad and many other bufonid species change into a lighter color during breeding (e.g. [[western toad]]s, [[American toad]]s), and other notable high elevation bufonids outside North America are highly sexually dichromatic (e.g. [[golden toad]]s, [[Incilius luetkenii|yellow toads]], [[Incilius marmoreus|marbled toads]]). Another more likely hypothesis is that males and females occupy largely different habitats, and evolution has de-coupled [[camouflage]] between the sexes.<ref name=":0" /> Males spend disproportionately more time in shallow, brown, silty breeding ponds, where they are highly exposed to predators. In contrast, females quickly leave pond habitat for rocky upland habitat where [[disruptive coloration]] may be more suitable. More than 60% of adults toads found in upland habitat during the late summer are females, whereas less than 10% are males.<ref name=":15">{{Cite journal|last=Morton|first=Martin L.|year=2010|title=Habitat use by Yosemite toads: life history traits and implications for conservation|journal=Herpetological Conservation and Biology|volume=5|pages=388–394}}</ref> In lowland breeding habitat, this pattern is reversed: 54% of adult toads are males, and only 19% are females.<ref name=":15" /> Regardless of which hypothesis is correct, their diurnal habits make color and pattern subject to increased selection.

=== Lineage diversification and fusion ===
Karlstrom<ref name=":0" /> was the first to hypothesize, based on the distribution of ''A. canorus'' in Yosemite National Park, that glaciers had helped the species differentiate from ''A. boreas''. The idea was that repeated glacial action had helped isolate the species in montane areas, and gradual adaptation there had helped it competitively exclude ''A. boreas'' from high elevation terrain. Recent work has showed this is likely true, and part of a larger pattern of glacial action bifurcating the species into new lineages.<ref name=":16">{{Cite journal|last1=Maier|first1=Paul A.|last2=Vandergast|first2=Amy G.|last3=Ostoja|first3=Steven M.|last4=Aguilar|first4=Andres|last5=Bohonak|first5=Andrew J.|title=Pleistocene glacial cycles drove lineage diversification and fusion in the yosemite toad (Anaxyrus canorus)|journal=Evolution|language=en|volume= 73|issue= 12|doi=10.1111/evo.13868|pmid=31661155|issn=1558-5646|year=2019|pages=2476–2496|s2cid=204954251|url=https://figshare.com/articles/Pleistocene_glacial_cycles_drove_lineage_diversification_and_fusion_in_the_Yosemite_toad_Anaxyrus_canorus_/10260362}}</ref> The species likely originated in the early Pleistocene, and many of the glacial cycles since then have isolated toads into western and eastern refugia; here they have adapted to different climatic conditions, reinforcing the formation of new lineages.<ref name=":16" /> Where the lineages came back into secondary contact, they occasionally fused into additional hybrid lineages, in cases where pre-post-zygotic barriers were low enough to allow hybridization, but high enough to allow hybrids to become distinct from parental types.<ref name=":16" /> Four distinct lineages were discovered in Yosemite National Park, in addition to three fused (hybrid) lineages; two lineages were also found in Kings Canyon National Park.<ref name=":16" />

==Conservation==
Yosemite toads are reported to have declined substantially in distribution and abundance across their restricted range. Although threats to persistence of the species are less understood than in other California amphibians such as the [[Sierra Nevada yellow-legged frog]], the two most significant appear to be drought (increasing with [[climate change]]) and disease (primarily [[chytridiomycosis]]). Interactions between the two are not well understood. The species is listed as "Vulnerable" by the International Union for Conservation of Nature ([[International Union for Conservation of Nature|IUCN]]),<ref name="iucn status 9 December 2022" />  "Threatened" by the US Fish & Wildlife Service ([[United States Fish and Wildlife Service|USFWS]]) under the [[Endangered Species Act of 1973|ESA]],<ref>{{cite web|url=http://www.fws.gov/cno/press/release.cfm?rid=601 |title=Three California Amphibians to Get Federal Protections under the Endangered Species Act |date=25 April 2014 |publisher=U.S. Fish and Wildlife Service |access-date=19 December 2015 |url-status=dead |archive-url=https://web.archive.org/web/20160304120049/http://www.fws.gov/cno/press/release.cfm?rid=601 |archive-date=March 4, 2016 }}</ref> and "[[California species of special concern]]" by the California Department of Fish & Wildlife ([[California Department of Fish and Wildlife|CDFW]]).<ref name=californiaherps>{{cite web |url=http://www.californiaherps.com/frogs/pages/a.canorus.html |title=Yosemite Toad – Anaxyrus canorus |author=Nafis, Gary |year=2023 |website=A Guide to the Amphibians and Reptiles of California |access-date=28 April 2023}}</ref>

==Systematics==
{{cladogram|title=Phylogeny of Anaxyrus
|align=center
|caption=The placement of A. canorus is shown with (***). The relationships of the A. boreas group and the A. americanus group need further systematic study and taxonomic revision. The displayed cladogram is a consensus of Pauly 2008,<ref name=":5" /> Fontenot et al. 2011,<ref>{{cite journal|last1=Fontenot|first1=Brian E.|title=Nuclear–mitochondrial discordance and gene flow in a recent radiation of toads|journal=Molecular Phylogenetics and Evolution|year=2011|volume=59|issue=1|pages=66–80|pmid=21255664|doi=10.1016/j.ympev.2010.12.018}}</ref> and Peralta-García et al. 2016.<ref>{{cite journal|last1=Peralta-Garcia|first1=Anny|title=The Phylogenetic Position of the Little Mexican Toad, Anaxyrus kelloggi, Using Molecular Data|journal=Journal of Herpetology|year=2016|volume=50|issue=3|pages=471–475|doi=10.1670/15-105|s2cid=87923727}}</ref> [[Anaxyrus compactilis|A. compactilis]] and [[Anaxyrus mexicanus|A. mexicanus]] are excluded because of exclusion from those studies, and A. williamsi because of insufficient evidence for splitting off from A. boreas.
|cladogram={{clade| style=font-size:85%;line-height:75%;width:515px;
|cladogram= cladogram, constructed with Template:Clade
    |label1=[[Anaxyrus]]  
    |1={{clade
        |label1=boreas group
        |1={{clade
        	|1=[[Western toad|A. boreas]]
        	|2=[[Amargosa toad|A. nelsoni]]
        	|3=[[Black toad|A. exsul]]       	
        	|4=A. canorus ***
        	}}
        |label2=
        |2={{clade
            |1=[[Anaxyrus punctatus|A. punctatus]] 
            |2={{clade
                |1=[[Anaxyrus quercicus|A. quercicus]]   
                |2={{clade
                        |label1=debilis group
                	|1={{clade
                    	|1=[[Little Mexican toad|A. kelloggi]]
                    	|2={{clade
                    	    |1=[[Anaxyrus debilis|A. debilis]]
                    		|2=[[Anaxyrus retiformis|A. retiformis]]
                    		}}
                    	}}
                    |2={{clade
                    	|1=[[Anaxyrus speciosus|A. speciosus]]
                    	|2={{clade
                    		|1=[[Anaxyrus cognatus|A. cognatus]]
                                |label2=americanus group
                    		|2={{clade
                    			|1={{clade
                    				|1=[[Anaxyrus californicus|A. californicus]]
                    				|2=[[Anaxyrus microscaphus|A. microscaphus]]
                    				}}
                    			|2={{clade
                    				|1=[[Anaxyrus americanus|A. americanus]]
                    				|2=[[Anaxyrus baxteri|A. baxteri]]
                    				|3=[[Anaxyrus fowleri|A. fowleri]]
                    				|4=[[Anaxyrus hemiophrys|A. hemiophrys]]
                        			|5=[[Anaxyrus houstonensis|A. houstonensis]]
                    				|6=[[Anaxyrus terrestris|A. terrestris]]
                    				|7=[[Anaxyrus velatus|A. velatus]]
                    				|8=[[Anaxyrus woodhousii|A. woodhousii]]
                    				}}
                    			}}
                    		}}
                    	}}
                    }}
                }}
            }}
        }}
    }}
}}

==References==
{{Reflist|2}}

==External links==
*[http://www.californiaherps.com/frogs/pages/a.canorus.html California Herps Guide]
*[https://amphibiaweb.org/species/135 AmphibiaWeb Page]
*[http://www.mountainmanmaier.com/research/ Paul Maier Research on Yosemite toads]
*[https://www.fws.gov/sacramento/es_species/Accounts/Amphibians-Reptiles/yosemite-toad/ US Fish & Wildlife Page]
*[http://www.biologicaldiversity.org/species/amphibians/Yosemite_toad/index.html Center for Biological Diversity Page]
*[https://www.sierraforestlegacy.org/FC_SierraNevadaWildlifeRisk/YosemiteToad.php Sierra Forest Legacy Page]
{{Taxonbar|from=Q302397}}

[[Category:Anaxyrus]]
[[Category:Amphibians described in 1916]]
[[Category:Amphibians of the United States]]
[[Category:Endemic fauna of California]]
[[Category:Fauna of the Sierra Nevada (United States)]]
[[Category:Yosemite National Park]]
[[Category:Taxonomy articles created by Polbot]]