Incilius alvarius - (Girard in Baird, 1859)
Colorado River Toad
Synonym(s): Bufo alvarius Girard, 1859 ;Ollotis alvaria (Girard in Baird, 1859)
Taxonomic Status: Accepted
Related ITIS Name(s): Incilius alvarius (Girard in Baird, 1859) (TSN 773562)
Unique Identifier: ELEMENT_GLOBAL.2.104462
Element Code: AAABB01010
Informal Taxonomy: Animals, Vertebrates - Amphibians - Frogs and Toads
 
Kingdom Phylum Class Order Family Genus
Animalia Craniata Amphibia Anura Bufonidae Incilius
Genus Size: D - Medium to large genus (21+ species)
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Concept Reference
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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.
Concept Reference Code: B85FRO01HQUS
Name Used in Concept Reference: Bufo alvarius
Conservation Status
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NatureServe Status

Global Status: G5
Global Status Last Reviewed: 29Mar2002
Global Status Last Changed: 10Oct2001
Rounded Global Status: G5 - Secure
Nation: United States
National Status: N5 (05Nov1996)

U.S. & Canada State/Province Status
United States Arizona (S3S4), California (SH), New Mexico (S2)

Other Statuses

IUCN Red List Category: LC - Least concern

NatureServe Global Conservation Status Factors

Range Extent Comments: This species occurs from extreme southeastern California, southern Arizona and extreme southern New Mexico in the United States, south in to Mexico. It has nearly been extirpated in California. It occurs from sea level to 1,610m asl (Stebbins 1985).

Number of Occurrences:  
Number of Occurrences Comments: Represented by many and/or large occurrences throughout most of the range.

Population Size Comments: The total adult population size for this species is unknown but surely is many thousands. It is common throughout its range.

Overall Threat Impact: Medium
Overall Threat Impact Comments: No major threats have been identified (other than localized ones) for this species.

Short-term Trend Comments: Likely relatively stable in extent of occurrence, unknown trend in population size, area of occurrence, and number/condition of occurrences.

Long-term Trend: Decline of 30-50%
Long-term Trend Comments: Likely relatively stable in extent of occurrence, unknown degree of decline in population size, area of occurrence, and number/condition of occurrences.

Intrinsic Vulnerability: Moderately vulnerable

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

Other NatureServe Conservation Status Information

Distribution
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Global Range: This species occurs from extreme southeastern California, southern Arizona and extreme southern New Mexico in the United States, south in to Mexico. It has nearly been extirpated in California. It occurs from sea level to 1,610m asl (Stebbins 1985).

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 AZ, CA, NM

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 Imperial (06025)*, San Bernardino (06071)*
NM Hidalgo (35023)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
13 Playas Lake (13030201)+
15 Havasu-Mohave Lakes (15030101)+*, Imperial Reservoir (15030104)+*, Lower Colorado (15030107)+*, Animas Valley (15040003)+, San Simon (15040006)+, San Bernardino Valley (15080302)+, Cloverdale (15080303)+*
18 Salton Sea (18100204)+*
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Reproduction Comments: Breeding occurs May-August, usually for a short period (one or two nights), 1-3 nights following a major rainfall event; relatively few of the males produce persistent advertisement calls (Sullivan and Malmos, 1994, Herpetologica 50:146-156). May lay up to about 8,000 eggs in long strands (Stebbins 1972)
Non-Migrant: N
Locally Migrant: Y
Long Distance Migrant: N
Mobility and Migration Comments: Migrates short distances between breeding and nonbreeding habitats.
Riverine Habitat(s): CREEK, Low gradient, Pool
Lacustrine Habitat(s): Shallow water
Palustrine Habitat(s): HERBACEOUS WETLAND, Riparian, TEMPORARY POOL
Terrestrial Habitat(s): Cropland/hedgerow, Desert, Grassland/herbaceous, Shrubland/chaparral, Suburban/orchard, Woodland - Hardwood
Special Habitat Factors: Benthic, Burrowing in or using soil
Habitat Comments: This species ranges from arid mesquite/creosotebush lowlands and arid grasslands to oak/sycamore/walnut groves in mountain canyons. It is often near permanent water but is also found near temporary water or far from water. It may take refuge in rodent burrows. It breeds and lays eggs in ponds, slow-moving streams, etc.
Adult Food Habits: Carnivore, Invertivore
Food Comments: Feeds on insects and spiders as well as lizards and other toads (Behler and King 1979).
Adult Phenology: Hibernates/aestivates, Nocturnal
Immature Phenology: Hibernates/aestivates, Nocturnal
Phenology Comments: Inactive in cold temperatures and hot, dry weather. Most active during the breeding season, May-July. Activity stimulated by rainfall, but not dependent on rainfall for breeding (Stebbins 1985).
Colonial Breeder: Y
Length: 18 centimeters
Economic Attributes Not yet assessed
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Management Summary Not yet assessed
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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
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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: 29Mar2002
NatureServe Conservation Status Factors Author: Hammerson, G.
Element Ecology & Life History Edition Date: 23Sep1994
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.

  • Crother, B. I. (editor). 2008. Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. Sixth edition. Society for the Study of Amphibians and Reptiles Herpetological Circular 37:1-84. Online with updates at: http://www.ssarherps.org/pages/comm_names/Index.php

  • Fouquette, M.J. 1970. Bufo alvarius. Catalogue of American Amphibians and Reptiles. 93:1-4.

  • 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.

  • 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.

  • Frost, D. R., R. W. McDiarmid, and J. R. Mendelson III. 2008. Anura: Frogs. IN B. I. Crother (ed.), Scientific and Standard English Names of Amphibians and Reptiles of North America North of Mexico, pp. 2-12 SSAR Herpetological Circular 37.

  • 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.

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