Anaxyrus retiformis - (Sanders and Smith, 1951)
Sonoran Green Toad
Synonym(s): Bufo retiformis Sanders and Smith, 1951
Taxonomic Status: Accepted
Related ITIS Name(s): Anaxyrus retiformis (Sanders and Smith, 1951) (TSN 773529)
Spanish Common Names: Sapo Verde-sonorense
Unique Identifier: ELEMENT_GLOBAL.2.102279
Element Code: AAABB01140
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
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 retiformis
Conservation Status

NatureServe Status

Global Status: G4
Global Status Last Reviewed: 03May2011
Global Status Last Changed: 03May2011
Rounded Global Status: G4 - Apparently Secure
Reasons: Small range in Arizona and Sonora, Mexico; evidently relatively stable in distribution; no significant existing threats are known.
Nation: United States
National Status: N3 (01Nov1996)

U.S. & Canada State/Province Status
United States Arizona (S3)

Other Statuses

IUCN Red List Category: LC - Least concern

NatureServe Global Conservation Status Factors

Range Extent: 20,000-2,500,000 square km (about 8000-1,000,000 square miles)
Range Extent Comments: South-central Arizona (Sullivan et al. 1996) south to south-central Sonora, Mexico. Elevations of about 500-2,400 ft (150-730 m) (Stebbins 1985). In Arizona, known from Organ Pipe Cactus National Monument east across the Tohono O'odham Reservation to San Xavier Mission, throughout Pima County, to 9 miles north of Pima/Pinal County line in Santa Rosa Valley, Pinal County. Probably also in Vekol Valley (Arizona Game and Fish Department 1992).

Number of Occurrences: 21 - 300
Number of Occurrences Comments: Forty documented sites in Arizona (Schwartz, pers. comm., 1997). Hulse (1978) mapped 17 collection sites in Mexico. Sullivan et al. (1996) mapped 51 historical collection locations. During a 1993-1994 Arizona survey, the species was relocated at or near all historical locations surveyed and at additional new sites for a total of 25 collection localities (Sullivan et al. 1996). The species is difficult to survey due to limited property access (most of Arizona range on Tohono O'odham Reservation, access denied) and secretive nature (B. Sullivan, pers. comm., 1997); inactive more than 10 months each year, and emerges only following intense rainfall events during the summer monsoon season (Sullivan et al. 1996).

Population Size: 10,000 - 1,000,000 individuals
Population Size Comments: Total adult population size is unknown but likely is at least 10,000. Less common on periphery of range: near Organ Pipe Cactus National Monument in the west, near Mobile in the north, and in the Altar Valley in the east (Sullivan et al. 1996).

Overall Threat Impact: Low
Overall Threat Impact Comments: Stebbins (1975) considered overcollecting the chief threat (see Bury et al. 1980). It occurs in large aggregations during breeding events. Overcollecting of females (for the pet trade or research) at this time could be detrimental but is not currently a problem (B. Sullivan, pers. comm., 1997). It naturally hybridizes with B. punctatus but given the apparent rareness of hybrids, it is unlikely that this presents a significant concern for the population status (Sullivan et al. 1996). The effects of grazing practices or agriculture are unknown; not enough information available to determine threats (B. Sullivan, pers. comm., 1997).

Short-term Trend: Relatively Stable (<=10% change)
Short-term Trend Comments: Ashton (1976) reported that Arizona populations were stable (see Bury et al. 1980). Recent documentation (1993-1994) at most historical sites and additional new localities in Arizona suggests no widespread declines (Sullivan et al. 1996). However, there is no solid population information available to assess trends (B. Sullivan, pers. comm., 1997). No information available for Mexico.

Long-term Trend: Decline of <30% to increase of 25%
Long-term Trend Comments: Likely relatively stable in extent of occurrence, probably less than 25% decline in population size, area of occurrence, and number/condition of occurrences, but better information is needed for Mexico.

Intrinsic Vulnerability: Moderately vulnerable

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

Other NatureServe Conservation Status Information

Inventory Needs: Determine distribution in Mexico and on Tohono O'odham Reservation and abundance rangewide; conduct long term monitoring at selected sites to determine population dynamics (B. Sullivan, pers. comm., 1997).

Global Range: (20,000-2,500,000 square km (about 8000-1,000,000 square miles)) South-central Arizona (Sullivan et al. 1996) south to south-central Sonora, Mexico. Elevations of about 500-2,400 ft (150-730 m) (Stebbins 1985). In Arizona, known from Organ Pipe Cactus National Monument east across the Tohono O'odham Reservation to San Xavier Mission, throughout Pima County, to 9 miles north of Pima/Pinal County line in Santa Rosa Valley, Pinal County. Probably also in Vekol Valley (Arizona Game and Fish Department 1992).

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

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

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

U.S. Distribution by County Help
State County Name (FIPS Code)
AZ Maricopa (04013), Pima (04019), Pinal (04021)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
15 Upper Santa Cruz (15050301)+*, Lower Santa Cruz (15050303)+, Brawley Wash (15050304)+, Aguirre Valley (15050305)+, Santa Rosa Wash (15050306)+, Lower Gila-Painted Rock Reservoir (15070101)+, Tenmile Wash (15070202)+*, San Cristobal Wash (15070203)+, San Simon Wash (15080101)+, Rio Sonoyta (15080102)+*
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
Basic Description: A bright green toad.
Reproduction Comments: Breeding extends from July-August.
Ecology Comments: Secretive.
Non-Migrant: N
Locally Migrant: Y
Long Distance Migrant: N
Mobility and Migration Comments: Migrates between breeding and nonbreeding habitats.
Palustrine Habitat(s): Riparian, TEMPORARY POOL
Terrestrial Habitat(s): Desert, Grassland/herbaceous
Special Habitat Factors: Benthic, Burrowing in or using soil
Habitat Comments: This species inhabits semi-arid plains, mesquite grassland and creosote bush desert. Well drilling and irrigation may create suitable habitat (Hulse 1978). It breeds in rain pools and wash bottoms bordered by grass and scattered shrubs (Stebbins 1985).
Adult Food Habits: Invertivore
Immature Food Habits: Herbivore
Adult Phenology: Hibernates/aestivates, Nocturnal
Immature Phenology: Hibernates/aestivates, Nocturnal
Phenology Comments: Inactive in cold temperatures and hot, dry weather. Begins breeding with onset of summer rains, July-August (Stebbins 1985).
Colonial Breeder: Y
Length: 6 centimeters
Economic Attributes Not yet assessed
Management Summary
Biological Research Needs: Determine habitat and life history (Arizona Game and Fish Department 1992) and threats.
Population/Occurrence Delineation
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
U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
NatureServe Conservation Status Factors Edition Date: 03May2011
NatureServe Conservation Status Factors Author: Clausen, M. K., and G. Hammerson
Element Ecology & Life History Edition Date: 20Sep1988
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).

  • Arizona Game and Fish Department. 1992. Bufo retiformis. Unpublished abstract. 3 pp.

  • 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.

  • Blomquist, S. M. 2004. Review of draft Red List assessment for Bufo retiformis. Unpublished report submitted to NatureServe. 2 pp.

  • Bogert, C.M 1962. Isolation mechanisms in the toads of the Green toad group in Arizona and western Mexico. American Museum Novitates. 2100:1-37.

  • Bury, R. B., C. K. Dodd, Jr., and G. M. Fellers. 1980. Conservation of the Amphibia of the United States: a review. U.S. Fish and Wildlife Service, Washington, D.C., Resource Publication 134. 34 pp.

  • 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

  • Frost, D. R. 2010. Amphibian Species of the World: an Online Reference. Version 5.4 (8 April 2010). Electronic Database accessible at 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.

  • Hulse, A.C. 1978. Bufo retiformis. Catalogue of American Amphibians and Reptiles. 207:1-2.

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

  • Sullivan, B. K., R. W. Bowker, K. B. Malmos, and E. W. A. Gergus. 1996. Arizona distribution of three Sonoran Desert anurans: BUFO RETIFORMIS, GASTROPHRYNE OLIVACEA, and PTERNOHYLA FODIENS. Great Basin Naturalist 56:38-47.

  • Sullivan, B.K., Malmos, K.B., Gergus, E.W.A. and Bowker, R.W. 2000. Evolutionary implications of advertisement call variation in Bufo debilis, B. punctatus, and B. retiformis. Journal of Herpetology. 34:368-374.

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