|
|
|
|
Adult, San Joaquin County |
Adult, San Joaquin County |
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 |
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 |
|
|
|
|
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 |
|
|
|
|
Tadpole, Riverside County |
Tadpole, Riverside County |
Tadpole, Riverside 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 |
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 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 |
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 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 |
|
|
|
|
Breeding pool, Butte County
© Jackson Shedd
|
Habitat, Butte County
© Jackson Shedd
|
Habitat, San Joaquin County |
Breeding pool, San Luis Obispo County, © Andrew Harmer |
|
|
|
|
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. |
Habitat, Ventura County © Jeff Ahrens |
Habitat, Los Angeles County © Jeff Ahrens |
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. |
An adult male calls at night in a shallow creek in San Diego County. © Andrew Borcher |
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.
|
|