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Anaxyrus californicus

(Camp, 1915)

Arroyo Toad

G1Critically Imperiled (G1G2) Found in 66 roadless areas NatureServe Explorer →
G1Critically ImperiledGlobal Rank
EndangeredIUCN
HighThreat Impact
Arroyo (=arroyo southwestern) toad (Anaxyrus californicus). Photo by U.S. Fish & Wildlife Service, Public Domain (U.S. Government Work), via ECOS.
U.S. Fish & Wildlife Service, https://www.usa.gov/government-works
Identity
Unique IDELEMENT_GLOBAL.2.106312
Element CodeAAABB01230
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVertebrate Animal
IUCNEndangered
Endemicoccurs (regularly, as a native taxon) in multiple nations
KingdomAnimalia
PhylumCraniata
ClassAmphibia
OrderAnura
FamilyBufonidae
GenusAnaxyrus
Synonyms
Bufo californicusCamp, 1915Bufo microscaphus californicus
Other Common Names
Arroyo (=arroyo southwestern) toad (EN)
Concept Reference
Gergus, E.W.A. 1998. Systematics of the Bufo microscaphus complex: allozyme evidence. Herpetologica 54:317-325.
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.

Bufo californicus formerly was included in B. microscaphus. Gergus (1998) examined allozyme variation in the B. microscaphus complex and found discrete differences among the three subspecies (microscaphus, californicus, and mexicanus), though the morphological differences that they discussed are minor. Gergus concluded that under the phylogenetic species concept they should be recognized as species.
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2025-06-22
Change Date2025-06-22
Edition Date2025-06-22
Edition AuthorsGundy, R. L. (2025)
Threat ImpactHigh
Range Extent20,000-200,000 square km (about 8000-80,000 square miles)
Number of Occurrences6 - 20
Rank Reasons
This species has a limited range in southern California and northern Baja California Norte. The range extent declined by approximately 76% and abundance has also suffered steep declines. The population continues to decline due to invasive species, habitat degradation, and drought.
Range Extent Comments
This species is found in southwestern California, United States and northwestern Baja California, México (Dodd Jr. 2023, USFWS 2023). Using Global Biodiversity Information Facility (GBIF) (2025) records from 2015-2025, range extent is estimated to be 79,966 km² (RARECAT 2025).
Occurrences Comments
There are approximately 19 occurrences (USFWS 2023).
Threat Impact Comments
This species is primarily threatened by issues regarding habitat quality. The greatest threat is likely the increasing frequency and duration of droughts due to climate change that will eliminate, or render unsuitable, stream habitat (Dodd Jr. 2023, USFWS 2023). Habitat degradation is occurring due to incompatible water management in dammed streams, off-road vehicle use, overgrazing, and urbanization (Dodd Jr. 2023). This species is declining where invasive fishes (e.g. largemouth bass, Micropterus sp.), crayfish, and amphibians (e.g. bullfrogs, Lithobates catesbeianus) are present (Griffin and Case 2002, Dodd Jr. 2023). Pesticide pollution is also a likely threat (Davidson et al. 2002). In Baja California, habitat in some areas has been altered by grazing, agriculture, dredging, and sand-mining activities, but artifical ponds and stream terraces resulting from these activities may be partially beneficial in the short-term by creating suitable habitat such as results naturally from high-energy dynamic streams (Mahrdt et al. 2002).

The threat of gravel mining has been eliminated thanks to prohibition of this extractive practice in 2016 (USFWS 2023).
Ecology & Habitat

Description

A uniformly warty toad with the eyelids and the front of the oval parotoid glands usually pale; usually there is a light area on each sacral hump and in the middle of the back; cranial crests weak or absent; dorsum dark-spotted; both males and females have a pale throat; snout-vent length 5-8 cm; young have red-tipped tubercles on dorsum and the underside of the feet is yellow (Stebbins 1985).

Diagnostic Characteristics

Differs from A. microscaphus in having many dark dorsal spots and rougher skin (Stebbins 1985).

Habitat

Washes, streams, and arroyos, and adjacent uplands (desert, shrubland). On sandy banks in riparian woodlands (willow, cottonwood, sycamore, and/or coast live oak) in California. Along rivers that have shallow gravelly pools adjacent to sandy terraces (USFWS 1993). Adults obtain shelter by burrowing into sandy soil.

Lays eggs among gravel, leaves, or sticks, or on mud or clean sand, at bottom of shallow quiet waters of streams or shallow ponds, in areas with little or no emergent vegetation. Newly metamorphosed individuals remain near pools for up to several weeks (until pools dry).

Ecology

Of 22 repeatedly captured males, 10 were sedentary over a two-month period whereas 12 moved 1-5 times each, traveling up to 0.8 miles along the stream; females and subadults were sedentary (Sweet, Froglog, December 1992).

Individuals have been observed up to 2 km from the streams in which they breed, but most often they are within 0.5 km of those streams (see USFWS 2001).

Reproduction

Breeding is independent of rainfall. In California, breeds apparently from March to early June; 1.4-inch larvae were found in the Mojave River in mid-June (Stebbins 1954). Metamorphosis occurs in June-July (USFWS 1993).
Terrestrial Habitats
Woodland - HardwoodShrubland/chaparralDesert
Palustrine Habitats
Riparian
Other Nations (1)
United StatesN2
ProvinceRankNative
CaliforniaS2Yes
Threat Assessments
ThreatScopeSeverityTiming
1 - Residential & commercial developmentRestricted (11-30%)Serious - moderateHigh (continuing)
1.1 - Housing & urban areasRestricted (11-30%)Serious - moderateHigh (continuing)
1.2 - Commercial & industrial areasRestricted (11-30%)Serious - moderateHigh (continuing)
1.3 - Tourism & recreation areasRestricted - smallSlight or 1-10% pop. declineHigh (continuing)
2 - Agriculture & aquacultureRestricted (11-30%)Moderate - slightHigh (continuing)
2.1 - Annual & perennial non-timber cropsRestricted - smallSerious - moderateHigh (continuing)
2.3 - Livestock farming & ranchingRestricted (11-30%)Moderate - slightHigh (continuing)
3 - Energy production & miningRestricted - smallExtreme - moderateInsignificant/negligible or past
3.2 - Mining & quarryingRestricted - smallExtreme - moderateInsignificant/negligible or past
4 - Transportation & service corridorsRestricted (11-30%)Moderate - slightHigh (continuing)
4.1 - Roads & railroadsRestricted (11-30%)Moderate - slightHigh (continuing)
6 - Human intrusions & disturbanceLarge - restrictedSlight or 1-10% pop. declineHigh (continuing)
6.1 - Recreational activitiesLarge - restrictedSlight or 1-10% pop. declineHigh (continuing)
7 - Natural system modificationsLarge (31-70%)Moderate - slightHigh (continuing)
7.1 - Fire & fire suppressionUnknownModerate - slightHigh (continuing)
7.2 - Dams & water management/useLarge (31-70%)Moderate - slightHigh (continuing)
8 - Invasive & other problematic species, genes & diseasesPervasive - largeModerate or 11-30% pop. declineHigh (continuing)
8.1 - Invasive non-native/alien species/diseasesPervasive - largeModerate or 11-30% pop. declineHigh (continuing)
11 - Climate change & severe weatherPervasive (71-100%)Moderate or 11-30% pop. declineModerate (short-term)
11.2 - DroughtsPervasive (71-100%)Moderate or 11-30% pop. declineModerate (short-term)

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Roadless Areas (66)
California (66)
AreaForestAcres
Arroyo SecoAngeles National Forest4,703
Arroyo SecoAngeles National Forest4,703
Barker ValleyCleveland National Forest11,940
Barker ValleyCleveland National Forest11,940
Cahuilla MountainSan Bernardino National Forest6,952
Cahuilla MountainSan Bernardino National Forest6,952
CajonSan Bernardino National Forest7,548
CajonSan Bernardino National Forest7,548
CalienteCleveland National Forest5,953
CalienteCleveland National Forest5,953
CamuesaLos Padres National Forest8,209
City CreekSan Bernardino National Forest9,997
ColdwaterCleveland National Forest8,402
Cucamonga AAngeles National Forest1,249
Cucamonga BSan Bernardino National Forest11,933
Cucamonga CSan Bernardino National Forest4,106
Cutca ValleyCleveland National Forest14,530
Cutca ValleyCleveland National Forest14,530
Deep CreekSan Bernardino National Forest23,869
DiableLos Padres National Forest19,597
DiableLos Padres National Forest19,597
Dry LakesLos Padres National Forest17,043
Dry LakesLos Padres National Forest17,043
Eagle PeakCleveland National Forest6,481
Fish CanyonAngeles National Forest29,886
Fox MountainLos Padres National Forest52,072
Hixon FlatSan Bernardino National Forest8,095
Hixon FlatSan Bernardino National Forest8,095
Horse Creek RidgeSan Bernardino National Forest8,969
JuncalLos Padres National Forest12,289
JuncalLos Padres National Forest12,289
La BreaLos Padres National Forest14,031
LaddCleveland National Forest5,300
Little PineLos Padres National Forest1,315
Little PineLos Padres National Forest1,315
Magic MountainAngeles National Forest15,542
Malduce BuckhornLos Padres National Forest14,177
ManzanaLos Padres National Forest2,101
MatilijaLos Padres National Forest5,218
MatilijaLos Padres National Forest5,218
MonoLos Padres National Forest28,141
MonoLos Padres National Forest28,141
No NameCleveland National Forest4,897
NordhoffLos Padres National Forest12,031
NordhoffLos Padres National Forest12,031
Pine CreekCleveland National Forest503
Pine CreekCleveland National Forest503
Pleasant ViewAngeles National Forest26,395
Rouse HillSan Bernardino National Forest13,745
Salt CreekAngeles National Forest11,022
San DimasAngeles National Forest7,160
San Mateo CanyonCleveland National Forest65
San SevaineSan Bernardino National Forest6,866
Santa CruzLos Padres National Forest21,182
Sawmill - BadlandsLos Padres National Forest51,362
Sespe - FrazierAngeles National Forest4,254
Sespe - FrazierLos Padres National Forest106,910
Sespe - FrazierLos Padres National Forest106,910
Sheep MountainAngeles National Forest21,098
Sill HillCleveland National Forest5,294
Strawberry PeakAngeles National Forest7,245
Strawberry PeakAngeles National Forest7,245
TrabucoCleveland National Forest23,341
White LedgeLos Padres National Forest18,632
White LedgeLos Padres National Forest18,632
WildhorseCleveland National Forest1,483
References (37)
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