General Distribution
National Forest habitat potentially capable of supporting the species is limited. Recent surveys by U.S.
Geological Survey have found western spadefoots in Ben, Badger, and Sycamore Canyons in the San
Bernardino Mountains and several individuals in Bautista Canyon in the San Jacinto Mountains (U.S.
Geological Survey unpublished survey data 2002). There are two known locations at the southwestern
edge of the San Bernardino Mountains immediately adjacent to National Forest Systems lands: the first
is in Devils Canyon adjacent to the Forest boundary, and the second is at the mouth of City Creek.
Western spadefoot tadpoles have recently been discovered at the very northwest corner of the San
Gabriel Mountain range on the Angeles National Forest.
However, most known locations in the vicinity of National Forest System lands are in the coastal
foothills of San Diego County (e.g., Japatul Valley, Otay Lakes, Santa Maria Valley, and Warner
Springs) (Stephenson and Calcarone 1999), while the majority of known locations in southern California
are in low-elevation coastal and inland valleys. Western spadefoot is reportedly abundant on the Camp
Pendleton Marine Corps Base on the northern San Diego County coast and in Santa Barbara and San
Luis Obispo Counties (e.g., Santa Maria Valley, Cuyama Valley) (Jennings and Hayes 1994, Stephenson
and Calcarone 1999). The species has also been observed in the foothills of the Santa Ana Mountains at
Starr Ranch (Fisher and Case 1997) and the Santa Rosa Plateau (Jennings and Hayes 1994). Systematics
Western spadefoot toad was differentiated from southern spadefoot toad in 1976 on the basis of
differences in reproduction, morphology, and vocalizations (Brown 1976, Jennings and Hayes 1994).
There is no information on genetic variation within the species (Jennings and Hayes 1994). The current
taxonomy was discussed in Weins and Titus (1991). Habitat Requirements
The western spadefoot toad can be found in dry grassland habitat close to seasonal wetlands such as
vernal pool complexes, typically near extensive areas of friable (but usually not sandy) soil (Barry 2000,
Stebbins 1951, Storer 1925). Although western spadefoot populations primarily occur in grassland
settings, they occasionally occur in valley-foothill woodlands (Zeiner and others 1988), coastal scrub,
and chaparral communities (Stephenson and Calcarone 1999). The western spadefoot can also be found
in creeks, drainages, and ponds (Jones & Stokes file information, Westphal pers. comm.).
The western spadefoot requires seasonal wetlands for reproduction and metamorphosis. The specific
physical attributes that make such wetlands and adjacent uplands suitable for western spadefoot toads
are not well known, but such attributes probably include ponds with sufficient depth and surface area to
persist at least several weeks (Feaver 1971, Jennings and Hayes 1994, Morey 1998, Stebbins 1951). It is
frequently assumed that western spadefoots require loose soils for subsurface dormancy (Jennings and
Hayes 1994); however, there is some evidence that this species may also use rodent burrows (Barry
2000, Stebbins 1951). Reproduction
Adult western spadefoots spend most of the year in self-excavated underground retreats and possibly in
mammal burrows (Stebbins 1951). They emerge from underground retreats during heavy rains in
autumn and winter and spawn in seasonal wetlands, such as vernal pools, in late winter or early spring
(Stebbins 1951, Storer 1925).
Spawning cues are believed to include the onset of heavy warmer winter rains of subtropical origin, the
filling of vernal pools with rainwater, and the increase of ambient temperatures (Barry 2000, Feaver
1971, Jennings and Hayes 1994, Morey 1998). During drought years, spawning pools may not fill, and
western spadefoots may not reproduce.
Eggs hatch in less than a week, and larvae metamorphose in 30-80 days, apparently depending on the
duration of pool depth sufficient to support larvae, and possibly on pool temperature (Feaver 1971,
Morey 1998). Little is known about the behavior of western spadefoot metamorphs once they leave the
pool. They may use a variety of underground retreats, such as burrows and desiccation cracks in dried
pond bottoms (as has been reported for S. intermontanus) (Barry 2000). Daily/Seasonal Activity
Western spadefoot is adapted for survival in dry, upland habitats. To avoid desiccation, these toads are
nocturnal and spend the drier months of the year inactive and hidden underground. Individuals use their
spadelike hind feet to excavate their own retreats in loose or sandy soils. In areas where friable soils are
not available, small mammal burrows may be used.
Western spadefoot toads become active on the ground's surface to forage and breed after relatively warm
rains. Typically, this occurs during late winter, spring, and fall, but the species can be active during any
month between October and April if enough rain has fallen. Diet and Foraging
Adult western spadefoot toads consume a variety of invertebrates including various insects and annelids
(worms and leeches), feeding mostly during the short time they are active on the surface (Morey and
Guinn 1992). Western spadefoot larvae filter feed on smaller materials in the water column and scrape
larger organisms such as algae (McCready pers. comm.). However, the larvae are opportunistic feeders
and will take advantage of dead larvae if present in the pool (McCready pers. comm.). Western
spadefoot larvae are not known to be nearly as cannibalistic as either southern spadefoot toad (S.
muliplicata) or plains spadefoot toad (S. bombifrons), both of which are dimorphic, occurring in
omnivorous and carnivorous morphs (McCready pers. comm.). Predator-Prey Relations
Because western spadefoot toads occur mainly in seasonal wetlands and their breeding cycle is short
(approximately 30 days), aquatic predators, especially of adult toads, are few. California tiger
salamanders, garter snakes, great blue herons, and raccoons are probably the most important predators of
larval and post-metamorphic western spadefoots (Feaver 1971). Literature Cited
Barry, S.J. 2000. Western spadefoot (Pelobatidae: Scaphiopus [Spea] hammondii). Unpublished report
on the biology, status, and distribution of western spadefoot in South Sacramento County. Submitted to
Jones & Stokes.
Brown, H.A. 1976. The status of California and Arizona populations of the western spadefoot toad
(genus Scaphiopus). Contributions in Science of the Natural History Museum of Los Angeles County
286: 1-15.
California Department of Fish and Game. 1999. CWHR version 6.0 personal computer program.
Sacramento, CA
Feaver, P.E. 1971. Breeding pool selection and larval mortality of three California amphibians:
Ambystoma tigrinum californiense Gray, Hyla regilla Baird and Girard, and Scaphiopus hammondii
Girard. Fresno, CA: Fresno State College; M.A. thesis.
Fisher, R.N.; Case, T.J. 1997. Survey of reptile and amphibian species-at-risk in southern California
forests. Unpublished report on file at the Cleveland National Forest, San Diego, CA.
Hayes, M.P.; Warner, J. 1985. Life history notes: Rana catesbeiana, food. Herpetological Review 16(4):
109.
Jennings, M.R.; Hayes, M. 1994. Amphibian and reptile species of special concern in California.
Sacramento, CA: California Dept. of Fish and Game.
Morey, S. 1998. Pool duration influences on age and body mass at metamorphosis in the western
spadefoot toad: Implications for vernal pool conservation. In: Witham, C.W., ed. Ecology, conservation,
and management of vernal pool ecosystems. Sacramento, CA: California Native Plant Society.
Morey, S.; Guinn, D. 1992. Activity patterns, food habits, and changing abundance in a community of
vernal pool amphibians. In: Williams, D.F.; Byrne, S.; Rado, T.A., eds. Endangered and sensitive
species of the San Joaquin Valley, California. Sacramento, CA: California Energy Commission.
NatureServe: An online encyclopedia of life. 2000. Version 1.0. Arlington (VA): [Online]. Accessed:
November 17, 2000.
Stebbins, R.C. 1951. Amphibians of western North America. Berkeley, CA: University of California
Press.
Stebbins, R.C. 1985. A field guide to western reptiles and amphibians. Boston: Houghton Mifflin Co.
Stephenson, J.R.; Calcarone, G.M. 1999. Southern California mountains and foothills assessment:
Habitat and species conservation issues. General Technical Report GTR-PSW-172. Albany, CA: Pacific
Southwest Research Station, Forest Service, U.S. Department of Agriculture.
Storer, T.I. 1925. A synopsis of the amphibia of California. University of California Publications in
Zoology 27: 1-343.
Sullivan, B.K.; Fernandez, P.J. 1999. Breeding activity, estimated age structure, and growth in Sonoran
desert anurans. Herpetologica 55: 334-343.
U.S. Geological Survey 2002. Unpublished reports submitted to forests.
Weins, J.J.; Titus, T.A. 1991. A phylogenetic analysis of Spea (Anura: Pelobatidae). Herpetologica 47
(1): 21-28.
Zeiner, D.C.; Laudenslayer, W.F., Jr.; Mayer, K.E., compiling editors. 1988. California's wildlife.
Volume I: Amphibians and reptiles. Sacramento, CA: California Statewide Wildlife Habitat
Relationships System, California Dept. of Fish and Game.
Information gathered from California DFG - California Interagency Wildlife Task Group
