Anaxyrus californicus - (Camp, 1915)
Arroyo Toad
Synonym(s): Bufo californicus Camp, 1915 ;Bufo microscaphus californicus
Taxonomic Status: Accepted
Related ITIS Name(s): Anaxyrus californicus (Camp, 1915) (TSN 773514)
Unique Identifier: ELEMENT_GLOBAL.2.106312
Element Code: AAABB01230
Informal Taxonomy: Animals, Vertebrates - Amphibians - Frogs and Toads
 
Kingdom Phylum Class Order Family Genus
Animalia Craniata Amphibia Anura Bufonidae Anaxyrus
Genus Size: D - Medium to large genus (21+ species)
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Concept Reference
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Concept Reference: Gergus, E.W.A. 1998. Systematics of the Bufo microscaphus complex: allozyme evidence. Herpetologica 54:317-325.
Concept Reference Code: A98GER01NAUS
Name Used in Concept Reference: Bufo californicus
Taxonomic Comments: 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
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NatureServe Status

Global Status: G2G3
Global Status Last Reviewed: 23Apr2014
Global Status Last Changed: 23Apr2014
Rounded Global Status: G2 - Imperiled
Reasons: Small range in southern California and northwestern Baja California; large decline; continuing threats from habitat degradation and exotic species; small populations; small number of viable populations.
Nation: United States
National Status: N2N3 (21May2001)

U.S. & Canada State/Province Status
United States California (S2S3)

Other Statuses

U.S. Endangered Species Act (USESA): LE: Listed endangered (16Dec1994)
Comments on USESA: In a 90-day petition finding, USFWS (2012) has initiated a status review to see if downgrading this species from endangered to threatened is warranted. In a 12-month petition finding, USFWS (2014) proposes to reclassify the arroyo toad as threatened. FWS (2015) withdrew the proposed rule to reclassify this species as threatened. This withdrawal is based on their conclusion that the types of threats to the arroyo toad remain the same as at the time of listing and are ongoing, and new threats have been identified.
U.S. Fish & Wildlife Service Lead Region: R8 - California-Nevada
IUCN Red List Category: EN - Endangered

NatureServe Global Conservation Status Factors

Range Extent: 20,000-200,000 square km (about 8000-80,000 square miles)
Range Extent Comments: Formerly ranged from San Luis Obispo County, California, south to northwestern Baja California (see Gergus et al. [1997] for southernmost record; see also Mahrdt et al. 2003 and Mahrdt and Lovich 2004 for occurrences in Baja California Norte). Now apparently extirpated in San Luis Obispo County; populations persist in headwater areas of streams in Santa Barbara, Ventura, Los Angeles, Riverside, and San Diego counties; recent sightings of scattered individuals have been reported from Orange, San Bernardino, and southern Imperial counties (USFWS 1994). The majority of the remaining populations in Santa Barbara and Ventura counties are in Los Padres National Forest (five viable populations); Sespe Creek in Ventura County has the largest known population; other populations occur in the Sisquoc, Santa Ynez, and upper and lower Piru drainages (USFWS 1994). Occurs also in San Diego County along the Santa Margarita, Guejito, Sweetwater, Vallecito, San Luis Rey, Santa Ysabel, Witch, Cottonwood, Temescal, Agua Caliente, Santa Maria, Lusardi, Pine Valley, Noble, Kitchen, Long Potrero, Upper San Diego, San Vicente, and Morena drainages; populations in the Temescal, Agua Caliente, Pine Valley, and Cottonwood drainages may be considered viable (USFWS 1994). Recently recorded in Whitewater Canyon in Riverside County (Patten and Myers, 1992, Herpetol. Rev. 23:122). Recent surveys located very small populations in four creeks in southwestern Riverside County (Temecula, Arroyo Seco, San Mateo, and Tenaja creeks) (USFWS 1994). The single recent record in San Bernardino County is from Deep Creek in the San Bernardino National Forest. Also still extant in northwestern Baja California: coastal plains, inland foothills, peninsular range of Sierra San Pedro Matir, and south to Arroyo Simon (Gergus et al. 1997, Mahrdt et al. 2002).

Number of Occurrences: 6 - 20
Number of Occurrences Comments: Occurs in at least a couple dozen sites, but viable populations may remain in only five drainages (USFWS 1993). Known in California from 22 river basins in 9 counties (USFWS 1999).

Population Size: 2500 - 10,000 individuals
Population Size Comments: Total estimated breeding population is less than 3,000 individuals (USFWS, Federal Register, 6 May 1998). Only 6 of the 22 extant populations south of Ventura are known to contain more than a dozen adults (USFWS 1994).

Overall Threat Impact: High
Overall Threat Impact Comments: Threats include habitat degradation (mainly through urbanization, dam construction and ill-timed water releases, agriculture, road construction, off-road vehicle use, overgrazing, and mining activities, and also via drought and wildfires), recreational use of habitat (causes habitat degradation and direct mortality), predation by introduced fishes and bullfrogs (Griffen and Case 2002), and small population sizes (see USFWS 1993 and 1994 for further details; see also 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).

Short-term Trend: Decline of 10-30%
Short-term Trend Comments: Reproductive success has been poor in recent years (USFWS 1993).

Long-term Trend: Decline of 50-90%
Long-term Trend Comments: Extirpated from an estimated 75% of former range in U.S. (Sweet, in USFWS 1993).

Intrinsic Vulnerability: Moderately vulnerable

Environmental Specificity: Moderate. Generalist or community with some key requirements scarce.

Other NatureServe Conservation Status Information

Protection Needs: See recovery plan (USFWS 1999).

Distribution
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Global Range: (20,000-200,000 square km (about 8000-80,000 square miles)) Formerly ranged from San Luis Obispo County, California, south to northwestern Baja California (see Gergus et al. [1997] for southernmost record; see also Mahrdt et al. 2003 and Mahrdt and Lovich 2004 for occurrences in Baja California Norte). Now apparently extirpated in San Luis Obispo County; populations persist in headwater areas of streams in Santa Barbara, Ventura, Los Angeles, Riverside, and San Diego counties; recent sightings of scattered individuals have been reported from Orange, San Bernardino, and southern Imperial counties (USFWS 1994). The majority of the remaining populations in Santa Barbara and Ventura counties are in Los Padres National Forest (five viable populations); Sespe Creek in Ventura County has the largest known population; other populations occur in the Sisquoc, Santa Ynez, and upper and lower Piru drainages (USFWS 1994). Occurs also in San Diego County along the Santa Margarita, Guejito, Sweetwater, Vallecito, San Luis Rey, Santa Ysabel, Witch, Cottonwood, Temescal, Agua Caliente, Santa Maria, Lusardi, Pine Valley, Noble, Kitchen, Long Potrero, Upper San Diego, San Vicente, and Morena drainages; populations in the Temescal, Agua Caliente, Pine Valley, and Cottonwood drainages may be considered viable (USFWS 1994). Recently recorded in Whitewater Canyon in Riverside County (Patten and Myers, 1992, Herpetol. Rev. 23:122). Recent surveys located very small populations in four creeks in southwestern Riverside County (Temecula, Arroyo Seco, San Mateo, and Tenaja creeks) (USFWS 1994). The single recent record in San Bernardino County is from Deep Creek in the San Bernardino National Forest. Also still extant in northwestern Baja California: coastal plains, inland foothills, peninsular range of Sierra San Pedro Matir, and south to Arroyo Simon (Gergus et al. 1997, Mahrdt et al. 2002).

U.S. States and Canadian Provinces
Color legend for Distribution Map
Endemism: occurs (regularly, as a native taxon) in multiple nations

U.S. & Canada State/Province Distribution
United States CA

Range Map
Note: Range depicted for New World only. The scale of the maps may cause narrow coastal ranges or ranges on small islands not to appear. Not all vagrant or small disjunct occurrences are depicted. For migratory birds, some individuals occur outside of the passage migrant range depicted. For information on how to obtain shapefiles of species ranges see our Species Mapping pages at www.natureserve.org/conservation-tools/data-maps-tools.

Range Map Compilers: IUCN, Conservation International, NatureServe, and collaborators, 2004


U.S. Distribution by County Help
State County Name (FIPS Code)
CA Los Angeles (06037), Monterey (06053), Orange (06059), Riverside (06065), San Bernardino (06071), San Diego (06073), Santa Barbara (06083), Ventura (06111)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
18 Salinas (18060005)+, Santa Maria (18060008)+, Santa Ynez (18060010)+, Santa Clara (18070102)+, Los Angeles (18070105)+, San Jacinto (18070202)+, Santa Ana (18070203)+, Aliso-San Onofre (18070301)+, Santa Margarita (18070302)+, San Luis Rey-Escondido (18070303)+, San Diego (18070304)+, Cottonwood-Tijuana (18070305)+, Antelope-Fremont Valleys (18090206)+, Coyote-Cuddeback Lakes (18090207)+*, Mojave (18090208)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
Help
Basic Description: A toad.
General 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 subspecies MICROSCAPHUS in having many dark dorsal spots and rougher skin (Stebbins 1985).
Reproduction Comments: 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).
Ecology Comments: 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).

Non-Migrant: N
Locally Migrant: Y
Long Distance Migrant: N
Mobility and Migration Comments: Migrates between nonbreeding terrestrial habitats and breeding pools.
Riverine Habitat(s): CREEK, Low gradient, Moderate gradient, Pool
Lacustrine Habitat(s): Shallow water
Palustrine Habitat(s): Riparian
Terrestrial Habitat(s): Desert, Shrubland/chaparral, Woodland - Hardwood
Special Habitat Factors: Benthic, Burrowing in or using soil
Habitat Comments: 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).

Adult Food Habits: Invertivore
Immature Food Habits: Herbivore
Food Comments: Diet includes: snails, crickets, beetles, ants; sometimes cannibalizes newly metamorphosed individuals. Forages on open sandy ground under riparian trees. Larvae probably eat algae, organic debris, and plant tissue.
Adult Phenology: Hibernates/aestivates, Nocturnal
Immature Phenology: Hibernates/aestivates, Nocturnal
Phenology Comments: Inactive in cold temperatures. Adults are primarily nocturnal except during the breeding season (Stebbins 1985). Adults are active at ambient temperatures of about 22-35 C. Newly metamorphosed individuals are active during daylight hours.
Colonial Breeder: Y
Length: 8 centimeters
Economic Attributes Not yet assessed
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Management Summary
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Stewardship Overview: See recovery plan (USFWS 1999).
Management Requirements: See recovery plan (USFWS 1999).
Monitoring Requirements: See recovery plan (USFWS 1999).
Population/Occurrence Delineation
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Group Name: Bufonid Toads

Use Class: Not applicable
Subtype(s): Breeding Site
Minimum Criteria for an Occurrence: Occurrences are based on evidence of historical presence, or current and likely recurring presence, at a given location. Such evidence minimally includes collection or reliable observation and documentation of one or more individuals (including larvae or eggs) in or near appropriate habitat where the species is presumed to be established and breeding.
Separation Barriers: Busy major highway such that toads rarely if ever cross successfully; roads with nonpermeable barriers to toad movement; urbanized areas dominated by buildings and pavement.
Separation Distance for Unsuitable Habitat: 1 km
Separation Distance for Suitable Habitat: 5 km
Separation Justification: Opportunistic observations of various toad species in lowland habitats indicate regular movements of up to at least several hundred meters from the closest known breeding site (G. Hammerson, pers. obs.). Sweet (1993) recorded movements of up to 1 km in Bufo californicus. In defining critical habitat for B. californicus, USFWS (2000) included breeding streams and upland areas within a 25-m elevational range of each essential stream reach and no more than 1.5 km away from the stream. In northwestern Utah, Thompson (2004) recorded movements of Bufo boreas of up to 5 km across upland habitat between two springs during the summer-fall season. Another toad moved 1.3 km between May of one year and May of the next year; the following June it was back at the original breeding location (Thompson 2004). Most studies of toad movements have not employed radiotelemetry and were not designed to detect long-range movements or dispersal.

The separation distance for unsuitable habitat reflects the nominal minimum value of 1 km. The separation distance for suitable habitat reflects the good vagility of toads, their ability to utilize ephemeral or newly created breeding sites, and the consequent likely low probability that two occupied locations separated by less than several kilometers of suitable habitat would represent truly independent populations over the long term.

Inferred Minimum Extent of Habitat Use (when actual extent is unknown): .5 km
Date: 27Apr2005
Author: Hammerson, G.
Population/Occurrence Viability
Help
U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 04Apr2011
NatureServe Conservation Status Factors Author: Hammerson, G.
Element Ecology & Life History Edition Date: 26Feb2001
Element Ecology & Life History Author(s): Hammerson, G.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

References
Help
  • Behler, J. L., and F. W. King. 1979. The Audubon Society field guide to North American reptiles and amphibians. Alfred A. Knopf, New York. 719 pp.

  • Blackburn, L., P. Nanjappa, and M. J. Lannoo. 2001. An Atlas of the Distribution of U.S. Amphibians. Copyright, Ball State University, Muncie, Indiana, USA.

  • Collins, J. T. 1991. Viewpoint: a new taxonomic arrangement for some North American amphibians and reptiles. SSAR Herpetol. Review 22:42-43.

  • Davidson, C., H. B. Shaffer, and M. R. Jennings. 2002. Spatial tests of the pesticide drift, habitat destruction, UV-B, and climate-change hypotheses for California amphibian declines. Conservation Biology 16:1588-1601.

  • Frost, D. R. 2002. Amphibian Species of the World: an online reference. V2.21 (15 July 2002). Electronic database available at http://research.amnh.org/herpetology/amphibia/index.html.

  • Frost, D. R. 2010. Amphibian Species of the World: an Online Reference. Version 5.4 (8 April 2010). Electronic Database accessible at http://research.amnh.org/herpetology/amphibia/index.php. American Museum of Natural History, New York, USA.

  • Gergus, E. W. A., L. L. Grismer, and K. Beaman. 1997a. Geographic distribution: Bufo californicus. Herpetological Review 28:47.

  • Gergus, E.W.A. 1998. Systematics of the Bufo microscaphus complex: allozyme evidence. Herpetologica 54:317-325.

  • Gergus, E.W.A., B. K. Sullivan, and K. B. Malmos. 1997b. Bufo microscaphus complex call variation: species boundaries and mate recognition. Ethology 103:1-11.

  • Griffin, P. C., and T. J. Case. 2002. Bufo californicus. Predation. Herpetological Review 33:301.

  • Mahrdt, C. R., R. E. Lovich, S. J. Zimmitti, and G. D. Danemann. 2003. Geographic distribution: Bufo californicus (California arroyo toad). Herpetological Review 34:256-257.

  • Mahrdt, C. R., R. E. Lovich, and S. J. Zimmitti. Bufo californicus: habitat and population status. Herpetological Review 33:123-125.

  • Mahrdt, C. R., and R. E. Lovich. 2004. Geographic distribution. Bufo californicus. Herpetological Review 35:280.

  • NatureServe. Central Databases. Arlington, Virginia. U.S.A. Online. Available: http://www.natureserve.org/explorer/

  • Price, A. H., and B. K. Sullivan. 1988. BUFO MICROSCAPHUS.Cat. Am. Amph. Rep. 415.1-415.3.

  • Stebbins, R. C. 1954a. Amphibians and reptiles of western North America. McGraw-Hill Book Company, New York.

  • Stebbins, R. C. 1972. California Amphibians and Reptiles. University of California Press, Berkeley, California.

  • Stebbins, R. C. 1985a. A field guide to western reptiles and amphibians. Second edition. Houghton Mifflin Company, Boston, Massachusetts. xiv + 336 pp.

  • Stebbins, R. C. 2003. A field guide to western reptiles and amphibians. Third edition. Houghton Mifflin Company, Boston.

  • Sullivan, B. K. 1992. Calling behavior of the southwestern toad (BUFO MICROSCAPHUS). Herpetologica 48:383-389.

  • U.S. Fish and Wildlife Service (USFWS). 12 February 2001. Final designation of critical habitat for the arroyo toad. Federal Register 65(26):9414-9474.

  • U.S. Fish and Wildlife Service (USFWS). 1993. Proposed endangered status for the arroyo southwestern toad. Federal Register 58(147):41231-41237. 3 August 1993.

  • U.S. Fish and Wildlife Service (USFWS). 1994. Determination of endangered status for the arroyo southwestern toad. Federal Register 59(241):64859-64866. 16 December 1994.

  • U.S. Fish and Wildlife Service (USFWS). 1999. Arroyo southwestern toad (Bufo microscaphus californicus) recovery plan. U.S. Fish and Wildlife Service, Portland, Oregon. vi + 119 pp.

  • U.S. Fish and Wildlife Service (USFWS). 8 June 2000. Proposed designation of critical habitat for the arroyo southwestern toad. Federal Register 65(111):36512-36548.

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