A Guide to the Amphibians
and Reptiles of California

Western Spadefoot - Spea hammondii

(Baird, 1859 “1857”)

Click on a picture for a larger view

Description • Taxonomy • Species Description • Scientific Name • Alt. Names • Similar Herps • References • Conservation Status

Red: Historic range in California

Click on the map for a topographical view

Map with California County Names

Listen to this spadefoot:

A short example

More Sounds of
Western Spadefoot

Baja California Page

Adult, San Joaquin County

A small hardened black "spade" on each rear foot helps with digging and gives the "spadefoot" family of frogs its name.

Juvenile, San Joaquin County

Adult, Butte County
© Jackson Shedd

Adult, San Joaquin County
© Mark Gary

Adult, Santa Barbara County © Ryan Sikola

Adult, Alameda County © Zachary Lim

Adult observed at a breeding puddle in early March in Ventura County
© Adam G. Clause

Adult male and female observed at a breeding puddle in early March in Ventura County © Adam G. Clause

Pale adult, San Joaquin County © Chad Lane

Adult, Alameda County © Jared Heald

Adult, Riverside County
© Dave Zeldin

Adult, Orange County © Ryan Wolter

Adult, San Diego County. © Gary Nafis
Specimen courtesy of Jim Melli
San Diego Natural History Museum

Adult, San Diego County © Paul Maier

Adults, San Diego County © Paul Maier

Adult, Sacramento County
© Richard Porter

Adult, Kings County
© Patrick Briggs

Adult and juvenile, Kings County
© Patrick Briggs

This adult was photographed after it was rescued from an unchlorinated swimming pool in Kern County in May. © Melinda Mohamed

Adults, San Joaquin County © Tara deSilva

The juvenile spadefoots shown above were all photographed at one location in Sacramento County, illustrating how diverse the appearance of this species can be.
© Richard Porter

Adult, San Luis Obispo County © Tony Kurz

Juvenile, San Luis Obispo County
© Andrew Harmer

Mating Adults

Male in amplexus with female underwater in daylight, San Joaquin County. In Western Spadefoots, amplexus is inguinal - the male clasps the female around her pelvis, unlike most of our frogs which use axial amplexus in which the male grasps the female around her forelimbs.

Adult male calling, San Diego County
© Chris Gruenwald

Adults in amplexus, Riverside County
© Jeff Ahrens

Adults in amplexus, San Diego County
© Kyle McCann

Calling adult male in February, Sacramento County © Jon Hirt

Adult male, San Diego County,
showing its breeding dark throat patch.
© Andrew Borcher

A California Toad attempts amplexus with a Western Spadefoot in San Diego County. © Andrew Borcher
Interspecific amplexus such as this is not uncommon.

Eggs

Eggs in breeding pool, Riverside County
© Jeff Ahrens

Tadpoles errupting from eggs, Riverside County © Jeff Ahrens

Eggs, Ventura County © Jeff Ahrens

Scaphiopus couchii Couch's Spadefoot Eggs

Eggs on a stick out of breeding pool, Orange County © Jeff Ahrens

Eggs in breeding pool, San Luis Obispo County © Andrew Harmer

Egg masses of two frog species laid next to each other in the same pool:
Top - Baja California Treefrog eggs
Bottom - Western Spadefoot eggs
Riverside County © Nathan Kudla

Tadpoles and Recently-metamorphosed Juveniles

Tadpoles feeding in a turbid rain pool, Alameda County

Tadpole, Riverside County

Mature tadpole, Orange County
© Jeff Ahrens Animal capture and handling authorized under SPC or specific authorization from CDFW.

Tadpole, Riverside County

Metamorphosing tadpole, Monterey County (captured and handled under state Scientific Collecting Permit and released at point of capture.)
© Adam Clause

Tadpole, Kings County © Patrick Briggs

Mature tadpole, Monterey County © Rob Schell

Young tadpole underwater, Kern County

Young tadpole, Kern County

Young tadpole underwater, Kern County

These tadpoles, including several white ones presumed to be albinos, were observed in a shallow road rut pool in San Diego County. A short time later the albinos were observed to have sprouted legs. © Anicka Kratina-Hathaway

Short Video of the albino tadpoles.
© Anicka Kratina-Hathaway

It's a hard life for opportunistic breeders (Ervin and Cass 2007 Herp. Rev. 38:2, 196-197) such as Western Spadefoots who depend on big rain events that will leave a pool of water that lasts long enough for their eggs to hatch and the tadpoles to transform. That takes from four to eleven weeks for this species, but sometimes the water disappears faster than that.

The tadpole and recently-metamorphosed toadlet seen in the two pictures above on the left were found in a vernal pool only a few feet away from the dead tadpoles in the dried up pool shown in the two pictures above on the right. Kyle McCann points out that this "shows the plasticity in development with similar environmental conditions." Something he's seen dozens of times. San Diego County
© Kyle McCann

Recently-metamorphosed juveniles taking shelter in shaded cracks in the mud of their natal pool, San Joaquin County
© Tara de Silva

Recently-metamorphosed juvenile, San Joaquin County © Tara de Silva

Metamorphosing juvenile on the banks of its natal pool, San Joaquin County
© Tara de Silva

Recently metamorphosed juvenile with tail, Kings County © Patrick Briggs

Recently metamorphosed juvenile with tail, San Diego County
© PuraVidaAquatic.com

Juvenile emerging from cracked mud, Los Angeles County © Jeff Ahrens

Juvenile Los Angeles County
© Jeff Ahrens

Juvenile hiding in a crack, Los Angeles County © Jeff Ahrens

Juvenile Los Angeles County
© Jeff Ahrens

Swimming juvenile Los Angeles County
© Jeff Ahrens

Recently metamorphosed juveniles sheltering in cracks in the mud of their dried out natal pool, San Joaquin County
© Tara deSilva

Sean Powell runs across the cracked dry bed of a rain pool in San Bernardino County that was full of water in the spring and a breeding area for Western Spadefoots. After an August thunderstorm, hundreds of tiny recently-metamorphosed spadefoots, including the one shown on the right, were found emerging from cracks in the mud. © Christian Powell

Tadpole preyed upon by some type of aquatic larva, perhaps that of a water beetle or a dragonfly, Orange County © Jeff Ahrens

Habitat

Brteeding habitat, slow creek,
San Joaquin County

Breeding habitat, rain pools, Alameda County

Shallow breeding pool with tadpoles,
San Diego County

Breeding habitat, Riverside County

Breeding pool, Butte County

Habitat, Glenn County

Habitat, San Joaquin County

Breeding habitat trampled by irresponsible off-road vehicle activity, Butte County

Habitat, San Diego County

Breeding habitat, Riverside County

Protected breeding pool at Alameda County state park.

Breeding habitat, inner coast range flooded field, Kern County

Short Videos

A male and a female spadefoot in amplexus underwater in a breeding area of a rocky creek bed in San Joaquin County. You can also see some eggs by the pair and floating nearby. (The first shot is of the female after the male left her.)

A tiny juvenile spadefoot, which probably transformed about 2 - 3 months earlier, is found crossing a road at night in San Joaquin County. Disturbed by our lights, it started digging into the ground in typical spadefoot fashion - using the hind legs to dig and slowly sinking down backwards to hide. But it could not dig deep enough due to the hard ground, so it hopped away into the dry grass.

Watch more video of Western Spadefoots at naturebytesvideo.com

Tadpoles in muddy rain puddles in Riverside County in early April.

Western Spadefoot tadpoles swim and feed in a murky rain puddle in Alameda County. The have to eat as much as possible so they will grow large enough to transform into terrestrial spadefoots before the puddle completely dries up.

Description

Size

Adults are 1.5 - 2.5 inches long from snout to vent (3.8 - 6.3 cm). (Stebbins & McGinnis, 2012)

Appearance

A small stout-bodied toad with short legs and warty skin.
The eyes are wide-set with no boss inbetween.
Pupils are vertical.
A glossy black spade shaped like a wedge or teardrop is present on each hind foot.
Parotoid glands are not present.

Color and Pattern

Color is greenish, brown, cream, or gray above, often with 4 irregular light stripes and dark blotches on the back,
and reddish spots at tips of skin tubercles.
Unmarked and whitish below.
Eyes are pale gold with vertical pupils.

Breeding males develop a dark throat patch.

Larvae (Tadpoles)

Tadpoles can grow up to 3 inches in length (7.5 cm.) but typically they transform at a smaller size.
Color is olive-brown, gray, greenish black with a pale irridescent vent.

Life History and Behavior

Activity

Nocturnal.
Almost completely terrestrial, entering water only to breed.

This spadefoot is able to inhabit hot dry environments by burrowing underground uning the hardened spades on its hind feet.
Rarely seen, spending most of its life buried underground in earth-filled burrows, and active for only a short period each year, typically between October to May, depending on rainfall. Occasionally emerges during rains at other times of the year. The burrows are probably away from the dried breeding pool.

Defense

Skin secretions smell like peanuts, and probably deter predators. Exposure to them can cause a runny nose and watery eyes in humans.

Territoriality

There is little evidence of territorial behavior.

Longevity

Unknown.

Voice (Listen)

The call of the Western Spadefoot is a short loud trill, like a quick snore, lasting less than one second.
Males call at night while floating on the water, often in large aggregations.

Diet and Feeding

Eats a variety of invertebrates, including adult beetles, larval and adult moths, crickets, flies, ants, and earthworms.
Probably consumes enough in several weeks to survive the long period of underground dormancy.

Predators

Tadpoles are susceptible to predation by California Tiger Salamander larvae, American Bullfrogs, garter snakes, racoons, and dabbling ducks such as Mallards. When the pools dry up exposing the tadpoles, various vertebrate predators including birds prey on the tadpoles.
A biologist studying Western Spadefoots in San Joaquin County told me that a Western Pond Turtle discovered a pool of tadpoles and preyed on them.

Amphibians, reptiles, wading and passerine birds, and mammals are known to prey on transformed individual spadefoots. Documented predators of Western Spadefoots are Two-striped Gartersnakes and American Bullfrogs, and recent discoveries of predation by a racoon and by burrowing owls.
(Herpetological Review 38(2), 2007)

Reproduction

Reproduction is aquatic.
Fertilization is external, with the male grasping the back of the female and releasing sperm as the female lays her eggs.

The reproductive cycle is similar to that of most North American Frogs and Toads. Mature adults come into breeding condition and the males call to advertise their fitness to competing males and to females. Males and females pair up in amplexus in the water where the female lays her eggs as the male fertilizes them externally. The eggs hatch into tadpoles which feed in the water and eventually grow four legs, lose their tails and emerge onto land where they disperse into the surrounding territory.

Males are probably ready to breed 1 - 2 years after metamorphosis, females probably mature the second breeding season after metamorphosis.

Breeding sites include vernal pools and other temporary rain pools, cattle tanks, and occasionally in pools of intermittent streams. Typically the pools are turbid with little or no cover.

Breeding takes place after heavy rainfall and the formation of temporary shallow rain pools, typically from January to May, peaking in February and March, but this species of spadefoot is an opportunistic breeder, physiologically capable of breeding at any time if conditions are favorable. One pond full of tadpoles was found in San Diego County in August after a heavy rainstorm. (Ervin and Cass 2007 Herp. Rev. 38:2, 196-197)

Breeding typically occurs 1 - 2 days after heavy rains, sometimes as few as one or two nights each year at a particular location. There may be additional breeding during later rains.

Adults emerge from their underground refuges and move to the breeding pool. Pools do not always occur in the same place each year, so the adults may be scattered at a distance from the pool. The loud calls of the first male to enter the pond quickly attract other males and females. During dry years, breeding pools may not form at all and breeding will not take place.

To be suitable for the successful transformation of larvae, temporary breeding pools must last for at least 30 days. If pools dry up before 30 days, larvae will not survive.

Eggs

Females lay 300 - 500 eggs in irregular groups of 10 - 42 eggs, which are attached to underwater vegetation or detritus.
Eggs hatch very quickly, typically in 3 - 4 days, but they may hatch anywhere from a little over half a day to 6 days later.

Tadpoles and Young

Tadpoles transform in 4 - 11 weeks, depending on food availability and the duration of the pool.
Larvae will delay transformation to take advantage of a long-lasting pool with lots of available food.

Newly transformed juveniles leave the breeding pool a few days after metamorphosis, moving at night.
Where they go and how they survive the dry conditions present when they transform when rain is scarce, are not understood.

Habitat

Prefers open areas with sandy or gravelly soils, in a variety of habitats including mixed woodlands, grasslands, coastal sage scrub, chaparral, sandy washes, lowlands, river floodplains, alluvial fans, playas, alkali flats, foothills, and mountains. Rainpools which do not contain bullfrogs, fish, or crayfish are necessary for breeding.

Geographical Range

Endemic to California and northern Baja California. Ranges from near Redding south throughout the Great Valley and its associated foothills, through the South Coast Ranges into coastal southern California south of the Transverse mountains and west of the Peninsular mountains, into northwest Baja California.

The U.S. Fish and Wildlife Service recognizes two geographically and genetically distinct population segments (DPS) of Spea hammondii.
"The northern DPS is found from Shasta County through the Central Valley, and down the coast from Santa Clara County to Santa Barbara County.
The southern DPS is found from Los Angeles County to northwestern Baja California, Mexico.
The Transverse Range separates the northern DPS from the southern DPS."

Red = Approximate Historic Range of Spea hammondii - Western Spadefoot

Elevational Range

From near sea level up to 4,500 ft. (1365 m) in San Diego County mountains.

Notes on Taxonomy

For many years S. hammondii was grouped with spadefoots from Arizona through New Mexico into western Texas and Oklahoma, with the California subspecies called Scaphiopus hammondii hammondii.

Alternate and Previous Names (Synonyms)

Spea hammondii - Western Spadefoot (Stebbins 2003, Stebbins & McGinnis 2012))
Scaphiopus hammondii - Western Spadefoot (Stebbins 1966, 1985)
Scaphiopus hammondii hammondii - Hammond's Spadefoot (Western Spadefoot, Hammond's Spea, Western Spadefoot Toad, New Mexican Spea) (Wright & Wright 1949)
Scaphiopus hammondii - Western Spadefoot Toad (Storer 1925)
Scaphiopus hammondii hammondii - Western Spadefoot - (Spea hammondii; Spea stagnalis) Hammond's Spea, New Mexican Spea, Hammond's Spadefoot
s (Grinnell and Camp 2017)

Conservation Issues (Conservation Status)

This spadefoot has lost an extensive amount of habitat in the central valley due to urban and agricultural development of land that formerly supported the formation of temporary rain pools. It is estimated to be gone from almost 80 percent of its former habitat along the south coast. Formerly present in much of lowland southern California including the Los Angeles coastal plain, but is now absent from the area. Mosquito fish introduced into vernal pools also threaten some populations.

In December 2023 the U.S. Fish and Wildlife Service announced that Spea hammondii is comprised of two geographically and genetically distinct population segments (DPS) and proposed to list both as threatened under the Endangered Species Act.

"The northern DPS is found from Shasta County through the Central Valley, and down the coast from Santa Clara County to Santa Barbara County.
The southern DPS is found from Los Angeles County to northwestern Baja California, Mexico.
The Transverse Range separates the northern DPS from the southern DPS."

Taxonomy
Family	Pelobatidae	Spadefoot Toads and Relatives	Cope, 1865
Genus	Spea	Western Spadefoots	Cope, 1866
Species	hammondii	Western Spadefoot	(Baird, 1859 “1857”)
Original Description
(Baird, 1859) - Rep. Pacif. R.R. Survey, Vol. 10, Williamson's Route, Pt. 4, No. 4, p. 12, pl. 28, fig. 2 ["1857" 1859] from Original Description Citations for the Reptiles and Amphibians of North America © Ellin Beltz
Meaning of the Scientific Name
Spea - speos - Greek for cave, cavern hammondii - honors Hammond, John F. from Scientific and Common Names of the Reptiles and Amphibians of North America - Explained © Ellin Beltz
Related or Similar California Frogs
Scaphiopus couchii Spea intermontana
More Information and References
California Department of Fish and Wildlife AmphibiaWeb Stebbins, Robert C., and McGinnis, Samuel M. Field Guide to Amphibians and Reptiles of California: Revised Edition (California Natural History Guides) University of California Press, 2012. Stebbins, Robert C. California Amphibians and Reptiles. The University of California Press, 1972. Flaxington, William C. Amphibians and Reptiles of California: Field Observations, Distribution, and Natural History. Fieldnotes Press, Anaheim, California, 2021. Samuel M. McGinnis and Robert C. Stebbins. Peterson Field Guide to Western Reptiles & Amphibians. 4th Edition. Houghton Mifflin Harcourt Publishing Company, 2018. Stebbins, Robert C. A Field Guide to Western Reptiles and Amphibians. 3rd Edition. Houghton Mifflin Company, 2003. Behler, John L., and F. Wayne King. The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, 1992. Powell, Robert., Joseph T. Collins, and Errol D. Hooper Jr. A Key to Amphibians and Reptiles of the Continental United States and Canada. The University Press of Kansas, 1998. Bartlett, R. D. & Patricia P. Bartlett. Guide and Reference to the Amphibians of Western North America (North of Mexico) and Hawaii. University Press of Florida, 2009. Elliott, Lang, Carl Gerhardt, and Carlos Davidson. Frogs and Toads of North America, a Comprehensive Guide to their Identification, Behavior, and Calls. Houghton Mifflin Harcourt, 2009. Lannoo, Michael (Editor). Amphibian Declines: The Conservation Status of United States Species. University of California Press, June 2005. Storer, Tracy I. A Synopsis of the Amphibia of California. University of California Press Berkeley, California 1925. Wright, Albert Hazen and Anna Wright. Handbook of Frogs and Toads of the United States and Canada. Cornell University Press, 1949. Storer, Tracy I. Amphibia of California, University of California Press, 1925. Davidson, Carlos. Booklet to the CD Frog and Toad Calls of the Pacific Coast - Vanishing Voices. Cornell Laboratory of Ornithology, 1995. Ervin, Edward L. and Timothy L. Cass. Herpetological Review 38:2, 196-197, 2007 Steven R. Morey - Western Spadefoot section of Amphibian Declines: The Conservation Status of United States Species, UC Press, 2005. Joseph Grinnell and Charles Lewis Camp. A Distributional List of the Amphibians and Reptiles of California. University of California Publications in Zoology Vol. 17, No. 10, pp. 127-208. July 11, 1917.

Conservation Status
The following conservation status listings for this animal are taken from the January 2024 State of California Special Animals List and the January 2024 Federally Listed Endangered and Threatened Animals of California list (unless indicated otherwise below.) Both lists are produced by multiple agencies every year, and sometimes more than once per year, so the conservation status listing information found below might not be from the most recent lists. To make sure you are seeing the most recent listings, go to this California Department of Fish and Wildlife web page where you can search for and download both lists: https://www.wildlife.ca.gov/Data/CNDDB/Plants-and-Animals. A detailed explanation of the meaning of the status listing symbols can be found at the beginning of the two lists. For quick reference, I have included them on my Special Status Information page. If no status is listed here, the animal is not included on either list. This most likely indicates that there are no serious conservation concerns for the animal. To find out more about an animal's status you can also go to the NatureServe and IUCN websites to check their rankings.
Organization	Status Listing	Notes
NatureServe Global Ranking	G2G3	Imperiled
NatureServe State Ranking	S3	Vulnerable
U.S. Endangered Species Act (ESA)	None	USFWS proposed ESA threatened listing 12/23.
California Endangered Species Act (CESA)	None
California Department of Fish and Wildlife	SSC	Species of Special Concern
Bureau of Land Management	S	Sensitive
USDA Forest Service	None
IUCN	NT	Near Threatened

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