Roadless Areas
Home/Species/ Western Spadefoot

Spea hammondii

(Baird, 1859)

Western Spadefoot

G2Imperiled (G2G3) Found in 87 roadless areas NatureServe Explorer →
G2ImperiledGlobal Rank
Near threatenedIUCN
Very high - highThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.100387
Element CodeAAABF02020
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVertebrate Animal
IUCNNear threatened
Endemicoccurs (regularly, as a native taxon) in multiple nations
KingdomAnimalia
PhylumCraniata
ClassAmphibia
OrderAnura
FamilyScaphiopodidae
GenusSpea
Synonyms
Scaphiopus hammondiiBaird, 1859 "1857"Spea (=Scaphiopus) hammondiiBaird, 1859 "1857"
Other Common Names
western spadefoot (EN)
Concept Reference
Wiens, J. J., and T. A. Titus. 1991. A phylogenetic analysis of Spea (Anura: Pelobatidae). Herpetologica 47:21-28.
Taxonomic Comments
Genetic analysis of nuclear sequence data and RADseq SNPs from the northern and southern populations of western spadefoot, divided by the Transverse Range, indicate two genetically distinct, allopatric clusters that likely make up two species (Neal et al. 2018, Neal 2019). The U.S. Fish and Wildlife Service have determined that the western spadefoot is comprised of two Distinct Population Segments (DPSs), the northern DPS and the southern DPS (USFWS 2023).

Tanner (1989) and Wiens and Titus (1991) recognized Spea as distinct from Scaphiopus, within which it was previously regarded as a subgenus (Crother 2017). Regarded as conspecific with S. multiplicatus until 1976 (Brown 1976).

Garcia-Paris et al. (2003) used mtDNA to examine the phylogenetic relationships of Pelobatoidea and found that the family Pelobatidae, as previously defined, is not monophyletic (Pelobates is sister to Megophryidae, not to Spea/Scaphiopus). They split the Pelobatidae into two families: Eurasian spadefoot toads (Pelobates), which retain the name Pelobatidae, and North American spadefoot toads (Scaphiopus, Spea), which make up the revived family Scaphiopodidae.
Conservation Status
Rank MethodLegacy Rank calculation - Excel v3.1x
Review Date2019-01-03
Change Date2019-01-03
Edition Date2018-12-03
Edition AuthorsClausen, M. K., and G. Hammerson (2005), rev. Misty Nelson (2018)
Threat ImpactVery high - high
Range Extent20,000-200,000 square km (about 8000-80,000 square miles)
Number of Occurrences> 300
Rank Reasons
Nearly endemic to central and southwestern California, also occurs in northwestern Baja California; extirpated from many sites in the Central Valley and coastal southern California; declining due to impacts of urbanization and agricultural development; some populations may be threatened by habitat fragmentation or exotic species (mosquitofish stocked for mosquito abatement, bullfrogs). Climate change likely to have further impacts.
Range Extent Comments
The range includes the Central Valley and bordering foothills of California and the Coast Ranges (south of San Francisco Bay) and extends southward into northwestern Baja California, Mexico. The species has been extirpated throughout much of lowland southern California. Elevational range extends from near sea level to elevations of up to about 1,363 m (Zeiner et al. 1988, cited by Jennings and Hayes 1994; Ervin et al. 2001), but usually below 910 m (Stebbins 1985).
Occurrences Comments
Jennings and Hayes (1994) mapped several dozen localities with extant populations. Recent updates include over 400 occurrences.
Threat Impact Comments
Main threat is development and conversion of habitat to incompatible uses (urbanization, agricultural development) (Davidson et al. 2002). Drought and increasing temperatures associated with climate change are likely to affect the hydrology of vernal pools, which are necessary for breeding and larval development. Invasive species and increasing prevalence of wildfires are also likely to affect at least some areas, but population-level impacts are not currently known.
Ecology & Habitat

Habitat

This species lives in a wide range of habitats; lowlands to foothills, grasslands, open chaparral, pine-oak woodlands. It prefers shortgrass plains, sandy or gravelly soil (e.g., alkali flats, washes, alluvial fans). It is fossorial and breeds in temporary rain pools and slow-moving streams (e.g., areas flooded by intermittent streams).

Ecology

May dig its own burrow or use those of other animals. Skin secretion smells like peanuts and maybe an irritant to handlers.

Reproduction

Breeds January-May. Female lays cylindrical mass of eggs.
Terrestrial Habitats
Woodland - HardwoodWoodland - MixedShrubland/chaparralSavannaGrassland/herbaceousPlaya/salt flatCropland/hedgerow
Palustrine Habitats
TEMPORARY POOL
Other Nations (1)
United StatesN3
ProvinceRankNative
CaliforniaS3Yes
Threat Assessments
ThreatScopeSeverityTiming
1 - Residential & commercial developmentPervasive - largeSerious - moderateHigh (continuing)
2 - Agriculture & aquaculturePervasive - largeSerious - moderateHigh (continuing)
7 - Natural system modificationsRestricted - smallModerate - slightHigh (continuing)
8 - Invasive & other problematic species, genes & diseasesLarge - restrictedModerate - slightHigh (continuing)
11 - Climate change & severe weatherPervasive - largeSerious - moderateHigh - moderate

—

Roadless Areas (87)
California (87)
AreaForestAcres
Arroyo SecoAngeles National Forest4,703
BackboneShasta-Trinity National Forest11,466
Barker ValleyCleveland National Forest11,940
Barker ValleyCleveland National Forest11,940
Bear MountainLos Padres National Forest913
Big Butte ShinboneMendocino National Forest4,265
Big RocksLos Padres National Forest11,866
Black ButteLos Padres National Forest5,116
Black ButteMendocino National Forest15,461
Black MountainLos Padres National Forest16,818
Black MountainLos Padres National Forest16,818
Black Mtn.Sequoia National Forest15,102
BriscoeMendocino National Forest7,212
Cahuilla MountainSan Bernardino National Forest6,952
Cahuilla MountainSan Bernardino National Forest6,952
CajonSan Bernardino National Forest7,548
CalienteCleveland National Forest5,953
Chalk PeakLos Padres National Forest7,472
City CreekSan Bernardino National Forest9,997
City CreekSan Bernardino National Forest9,997
ColdwaterCleveland National Forest8,402
Cucamonga BSan Bernardino National Forest11,933
Cutca ValleyCleveland National Forest14,530
Cutca ValleyCleveland National Forest14,530
Deer MountainMendocino National Forest11,716
Dog CreekShasta-Trinity National Forest5,001
Eagle PeakCleveland National Forest6,481
Eagle PeakCleveland National Forest6,481
East BeegumShasta-Trinity National Forest8,425
East ForkShasta-Trinity National Forest6,201
Elk CreekMendocino National Forest23,182
Fox MountainLos Padres National Forest52,072
Fox MountainLos Padres National Forest52,072
Garcia MountainLos Padres National Forest7,850
Greenhorn CreekSequoia National Forest28,226
GrindstoneMendocino National Forest26,031
Hixon FlatSan Bernardino National Forest8,095
Hixon FlatSan Bernardino National Forest8,095
Horse Creek RidgeSan Bernardino National Forest8,969
Horse Creek RidgeSan Bernardino National Forest8,969
IshiLassen National Forest21,805
La BreaLos Padres National Forest14,031
La BreaLos Padres National Forest14,031
La PanzaLos Padres National Forest4,954
LaddCleveland National Forest5,300
LaddCleveland National Forest5,300
Los Machos HillsLos Padres National Forest11,112
Lpoor CanyonLos Padres National Forest13,762
Lpoor CanyonLos Padres National Forest13,762
Machesna MountainLos Padres National Forest12,271
Magic MountainAngeles National Forest15,542
Mill CreekSequoia National Forest27,643
Mill PeakSan Bernardino National Forest7,884
Mill PeakSan Bernardino National Forest7,884
Murphy GladeShasta-Trinity National Forest1,015
No NameCleveland National Forest4,897
No NameCleveland National Forest4,897
Oat Mtn.Sequoia National Forest12,223
Pine CreekCleveland National Forest503
Pine CreekCleveland National Forest503
Raywood Flat BSan Bernardino National Forest11,373
Red MountainAngeles National Forest8,034
Rouse HillSan Bernardino National Forest13,745
Rouse HillSan Bernardino National Forest13,745
San DimasAngeles National Forest7,160
San Mateo CanyonCleveland National Forest65
San SevaineSan Bernardino National Forest6,866
Sespe - FrazierAngeles National Forest4,254
Sespe - FrazierLos Padres National Forest106,910
Sheep MountainAngeles National Forest21,098
Sill HillCleveland National Forest5,294
Sill HillCleveland National Forest5,294
Skeleton GladeMendocino National Forest9,237
Snow MountainMendocino National Forest14,457
Stanley MountainLos Padres National Forest14,674
Strawberry PeakAngeles National Forest7,245
Tepusquet PeakLos Padres National Forest5,821
Tepusquet PeakLos Padres National Forest5,821
ThatcherMendocino National Forest16,652
Thomes CreekMendocino National Forest16,616
TrabucoCleveland National Forest23,341
TuleAngeles National Forest9,861
West BeegumShasta-Trinity National Forest5,198
WestforkAngeles National Forest4,407
Wilderness ContiguousMendocino National Forest3,606
WildhorseCleveland National Forest1,483
WildhorseCleveland National Forest1,483
References (59)
  1. Baird, S.F. 1859. Report upon the reptiles of the route, in Explorations and Surveys, R.R. Route from the Mississippi River to the Pacific Ocean, 1853-56. Pp.37-45 in: Vol. 10, Williamson's Route. Zoological Report, Part 6, Number 4, Washington, DC.
  2. Balfour, P.S. and J. Ranlett. 2006. Natural history notes: <i>Spea hammondii</i>. Predation. Herpetological Review 37:212.
  3. 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.
  4. Bell, J.L., L.C. Sloan, and M.A. Snyder. 2004. Regional changes in extreme climatic events: a future climate scenario. Journal of Climate 17:81-87.
  5. 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.
  6. Boorse, G.C., and R.J. Denver. 2003. Endocrine mechanisms underlying plasticity in metamorphic timing in spadefoot toads. Integrative and Comparative Biology 43:646-657.
  7. Bragg, A.N. 1965. Gnomes of the night. the spadefoot toads. 127 pp.
  8. Brown, H.A. 1967. Embryonic temperature adaptations and genetic compatibility of two allopatric populations of the spadefoot toad, <i>Scaphiopus hammondii</i>. Evolution 21:742-761.
  9. Brown, H. A. 1976. The status of California and Arizona populations of the western spadefoot toads (genus <i>Scaphiopus</i>). Los Angeles Co. Mus. Nat. Hist. Contr. Sci. 286:1-15.
  10. Burgess, R.C., Jr. 1950. Development of spade-foot toad larvae under laboratory conditions. Copeia 1950:49-51.
  11. Crother, B. I. (editor). 2017. Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. 8th edition. SSAR Herpetological Circular 43:1-104. [Updates in SSAR North American Species Names Database at: https://ssarherps.org/cndb]
  12. 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.
  13. Denver, R.J. 1997a. Environmental stress as a developmental cue: corticotropin-releasing hormone is a proximate mediator of adaptive phenotypic plasticity in amphibian metamorphosis. Hormones and Behavior 31:169-179.
  14. Denver, R.J. 1997b. Proximate mechanisms of phenotypic plasticity in amphibian metamorphosis. Integrative and Comparative Biology 37:172.
  15. Denver, R.J., N. Mirhadi, and M. Phillips. 1998. Adaptive plasticity in amphibian metamorphosis: response of <i>Scaphiopus hammondii</i> tadpoles to habitat desiccation. Ecology 79:1859-1872.
  16. Ervin, E. L., A. E. Anderson, T. L. Cass, and R. E. Murcia. 2001. Spea hammondii. Elevation record. Herpetological Review 32:36.
  17. Ervin, E.L., and R.N. Fisher. 2001. Natural history notes: <i>Thamnophis hammondii</i>. Prey. Herpetological Review 32:265-266.
  18. Ervin, E.L., and T.L. Cass. 2007. Natural history notes: <i>Spea hammondii</i>. Reproductive pattern. Herpetological Review 38:196-197.
  19. Ervin, E.L., and T.R. Burkhardt. 2006. Natural history notes: <i>Ambystoma tigrinum mavortium</i>. Extralimital populations. Herpetological Review 37:435.
  20. Ervin, E.L., C.D. Smith, and S.V. Christopher. 2005. Natural history notes: <i>Spea hammondii</i>. Reproduction. Herpetological Review 36:309-310.
  21. Evelyn, C., and S. Sweet. 2012. Conservation status of amphibians and reptiles on USDA National Forests, Pacific Southwest Region, 2012. U.S.D.A. Forest Service, Region 5
  22. Feaver, P.E. 1971. Breeding Pool Selection and Larval Mortality of Three California Ampibians: <i>Ambystoma tigrinum californiense</i> Gray <i>Hyla regilla</i> Baird and Girard and <i>Scaphiopus hammondi hammondi</i> Girard. Master's thesis. Fresno State College, Fresno, CA.
  23. Fisher, R.N., and H.B. Shaffer. 1996. The decline of amphibians in California's Great Central Valley. Conservation Biology 10:1387-1397.
  24. Frost, D.R. 2020. Amphibian Species of the World: an Online Reference. Version 6.0. American Museum of Natural History, New York, USA. Online: http://research.amnh.org/herpetology/amphibia/index.html
  25. García-París, M., D.R. Buchholtz, and G. Parra-Olea. 2003. Phylogenetic relationships of Pelobatoidea re-examined using mtDNA. Molecular Phylogenetics and Evolution 28:12-23.
  26. Hall, J.A. 1998. <i>Scaphiopus intermontanus</i>. Catalogue of American Amphibians and Reptiles. 650:1-17.
  27. Jennings, M. R., and M. P. Hayes. 1994. Amphibian and reptile species of special concern in California. Final Report submitted to the California Department of Fish and Game, Inland Fisheries Division. Contract No. 8023. 255 pp.
  28. Kluge, A.G. 1966. A new pelobatine frog from the lower Miocene of South Dakota with a discussion of the evolution of the <i>Scaphiopus</i>-<i>Spea</i> complex. Los Angeles County Museum of Natural History 113:1-26.
  29. Lenihan, J.M., D. Bachelet, R.P. Neilson, and R. Drapek. 2008. Response of vegetation distribution, ecosystem productivity, and fire to climate change scenarios for California. Climatic Change 87:S215-S230.
  30. Marty, J.T. 2005. Effects of cattle grazing on diversity in ephemeral wetlands. Conservation Biology 19:1626-1632.
  31. McGriff, Darlene. California Natural Heritage Division, The Resources Agency, Department of Fish and Game, Sacramento, CA
  32. Morey, S. and D. Reznick. 2004. The relationship between habitat permanence and larval development in California spadefoot toads: field and laboratory comparisons of developmental plasticity. Oikos 104:172-190.
  33. Morey, S.R. 1998. Pool duration influences age and body mass at metamorphosis in the western spadefoot toad: implications for vernal pool conservation. Pp.86-91 in: Ecology, Conservation, and Management of Vernal Pool Ecosystems: Proceedings from a 1996 Conference. California Native Plant Society, Sacramento.
  34. Morey, S.R. 2005. <i>Spea hammondii</i>. Pp.514-517 in: M.J. Lannoo, editor. Amphibian Declines: The Conservation Status of United States Species. University of California Press, Berkeley.
  35. Morey, S.R., and D.A. Guinn. 1992. Activity patterns, food habits, and changing abundance in a community of vernal pool amphibians. Pp.149-158 in: D.F. Williams, D.F., S. Byrne, and T.A. Rado, editors. Endangered and Sensitive Species of the San Joaquin Valley, California: Their Biology, Management, and Conservation. California Energy Commission and the Wildlife Society, Western Section, Sacramento.
  36. Morey, S.R., and D. Reznick. 2001. Effects of larval density on postmetamorphic spadefoot toads (<i>Spea hammondii</i>). Ecology 82:510-522.
  37. Neal, K. M. 2019. An integrative population and landscape genomic approach to conservation of a threatened California amphibian at multiple spatial scales. PhD Dissertation. University of California, Los Angeles. 170 pp.
  38. Neal, K. M., B. B. Johnson, and H. B. Shaffer. 2018. Genetic structure and environmental niche modeling confirm two evolutionary and conservation units within the western spadefoot (<i>Spea hammondii</i>). Conservation Genetics 19:937-946.
  39. Pfennig, D. 1990. The adaptive significance of an environmentally-cued developmental switch in an anuran tadpole. Oecologia 85:101-107.
  40. Pomeroy, L.V. 1981. Developmental Polymorphism in the Tadpoles of the Spadefoot Toad <i>Scaphiopus multiplicatus</i>. Ph.D. dissertation. University of California, Riverside.
  41. PRBO Conservation Science. 2011. Projected effects of climate change in California: Ecoregional summaries emphasizing consequences for wildlife. Version 1.0. PRBO Conservation Science, Petaluma, CA. [http://data.prbo.org/apps/bssc/climatechange]
  42. Pyke, C.R. 2005b. Interactions between habitat loss and climate change: Implications for fairy shrimp in the Central Valley Ecoregion of California, USA. Climate Change 68:199-218.
  43. Rose, J.P., B.J. Halstead, and R.N. Fisher. 2020. Integrating multiple data sources and multi-scale land-cover data to model the distribution of a declining amphibian. Biological Conservation 241.
  44. Sattler, P.W. 1980. Genetic relationships among selected species of North American <i>Scaphiopus</i>. Copeia 1980:605-610.
  45. Snyder, M.A., and L.C. Sloan. 2005. Transient future climate over the western United States using a regional climate model. Earth Interactions 9:1-21.
  46. Stebbins, R. C. 1951. Amphibians of western North America. University of California Press, Berkeley. 539 pp.
  47. Stebbins, R. C. 1954a. Amphibians and reptiles of western North America. McGraw-Hill Book Company, New York.
  48. Stebbins, R. C. 1985a. A field guide to western reptiles and amphibians. Second edition. Houghton Mifflin Company, Boston, Massachusetts. xiv + 336 pp.
  49. Stebbins, R. C. 2003. A field guide to western reptiles and amphibians. Third edition. Houghton Mifflin Company, Boston.
  50. Storer, T. I. 1925. A synopsis of the Amphibia of California. University of California Publications in Zoology 27:1-342.
  51. Tanner, W. W. 1989. Status of <i>Spea stagnalis</i> Cope (1875), <i>Spea intermontanus</i> Cope (1889), and a systematic review of <i>Spea hammondii</i> Baird (1839) (Amphibia: Anura). Great Basin Nat. 49:503-510.
  52. Thompson, R.C., A.N. Wright, and B.H. Shaffer. 2016. California Amphibian and Reptile Species of Special Concern. Western Spadefoot Account. Oakland, California: University of California Press. https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=190378&inline
  53. U.S. Fish and Wildlife Service (USFWS). 2015. Endangered and Threatened Wildlife and Plants; 90-Day Findings on 31 Petitions. Federal Register 80(126):37568-37579.
  54. U.S. Fish and Wildlife Service (USFWS). 2023.Endangered and Threatened Wildlife and Plants: Threatened Status With Section 4(d) Rule for the Northern and Southern Distinct Population Segments of the Western Spadefoot. Proposed rule. Federal Register 88(232):84252-84278.
  55. U.S. Fish and Wildlife Service (USFWS). 2023. National Listing Workplan. Online. Available: https://www.fws.gov/project/national-listing-workplan
  56. U.S. Fish and Wildlife Service (USFWS). 2025. Endangered and Threatened Wildlife and Plants; Review of Species That Are Candidates for Listing as Endangered or Threatened; Annual Notification of Findings on Resubmitted Petitions; Annual Description of Progress on Listing Actions. Candidate notice of review (CNOR). Federal Register 90(209):48912-48937.
  57. Westerling, A.L., and B.P. Bryant. 2008. Climate change and wildfire in California. Climatic Change 87:S231-S249.
  58. Westerling, A.L., D.R. Cayan, T.J. Brown, B.L. Hall, and L.G. Riddle. 2004. Climate, Santa Ana winds and autumn wildfires in southern California. EOS, Transactions, American Geophysical Union 85:289-296.
  59. Wiens, J. J., and T. A. Titus. 1991. A phylogenetic analysis of <i>Spea </i>(Anura: Pelobatidae). Herpetologica 47:21-28.