Overview

Comprehensive Description

Description

Spea hammondii, the Western spadefoot toad, is medium-sized with adults reaching up to 65 mm in SVL. The skin is loose with small vertebral tubercles. The head is as wide as the body, having a rounded snout with an upward tilt and large protuberant eyes. The parotoid glands are small and not distinct. Forelimbs and hindlimbs are short and stout, with the foreleg having dorsal tubercles. The feet have well-developed webbing between the toes. The main distinguishing features are the single semicircular black "spade" (keratinized inner metatarsal tubercle) on each heel, and vertical pupils.

The dorsal ground color ranges from light green to gray with scattered darker splotches. A pair of light-colored spots is generally present, one on each side of the anus. Body tubercles can be orange to somewhat red. Usually a pair of light-colored paravertebral stripes is present, extending from behind the eyes. Ventrally, the color is whitish to creamy-yellow.

Hear calls at the Western Sound Archive.

  • Grismer, L. L. (2002). Amphibians and Reptiles of Baja California. University of California Press, Berkeley.
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Distribution

occurs (regularly, as a native taxon) in multiple nations

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National Distribution

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

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Global Range: (250-20,000 square km (about 100-8000 square miles)) 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).

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Range Description

This species occurs in the Central Valley and bordering foothills of California and along the Coast Ranges (south of San Francisco Bay) in the USA, southward into north-western Baja California, Mexico. It is found from near sea level to 1,363m asl (Zeiner et al. (eds.) 1988, cited by Jennings and Hayes 1994), but usually below 910m asl (Stebbins 1985b).
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Distribution and Habitat

Western spadefoot toads occur throughout the Central Valley of California into northwestern Baja California. In Baja, they are found at least as far south as Mesa de San Carlos. They inhabit sandy areas or regions with loose soil, primarily in arroyos, fields, and open plains.

  • Grismer, L. L. (2002). Amphibians and Reptiles of Baja California. University of California Press, Berkeley.
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Physical Description

Size

Length: 6 cm

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Ecology

Habitat

Comments: 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).

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Habitat and Ecology

Habitat and Ecology
It lives in a wide range of habitats, from lowlands to foothills, in grasslands, open chaparral and pine-oak woodlands. It is fossorial, and breeds in temporary rain pools and slow-moving streams (for example, in areas flooded by intermittent streams). It also breeds in stock tanks and other artificial water bodies as long as the surrounding habitat is not developed for human settlement or irrigated agriculture.

Systems
  • Terrestrial
  • Freshwater
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Migration

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Migrates up to at least several hundred meters between nonbreeding and breeding habitats.

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Trophic Strategy

Comments: Adults invertivorous; larvae eat algae, organic debris, plant tissue, etc., sometimes small animals (e.g., crustaceans, tadpoles).

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Population Biology

Number of Occurrences

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 21 - 80

Comments: Jennings and Hayes (1994) mapped several dozen localities with extant populations.

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Global Abundance

10,000 - 1,000,000 individuals

Comments: Total adult population size is unknown; likely at least many thousands.

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General Ecology

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

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Life History and Behavior

Cyclicity

Comments: Inactive underground throughout much of the year. Most active during rains of winter-spring breeding period. Remains below ground during dry/cold weather.

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Reproduction

Breeds January-May. Female lays cylindrical mass of eggs.

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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage: Spea hammondii

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 1
Species With Barcodes: 1
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Conservation

Conservation Status

National NatureServe Conservation Status

United States

Rounded National Status Rank: N3 - Vulnerable

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NatureServe Conservation Status

Rounded Global Status Rank: G3 - Vulnerable

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).

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IUCN Red List Assessment


Red List Category
NT
Near Threatened

Red List Criteria

Version
3.1

Year Assessed
2004

Assessor/s
Georgina Santos-Barrera, Geoffrey Hammerson, Steven Morey

Reviewer/s
Global Amphibian Assessment Coordinating Team (Simon Stuart, Janice Chanson, Neil Cox and Bruce Young)

Contributor/s

Justification
Listed as Near Threatened because this species is probably in significant decline (but probably at a rate of less than 30% over ten years) because of widespread habitat loss through much of its range, thus making the species close to qualifying for Vulnerable.
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Global Short Term Trend: Decline of 10-30%

Comments: Since the 1950s, drastic declines have been noted in the Central Valley and southern Califoria. In southern California, more than 80% of the previously occupied habitat has been developed or converted to incompatible uses; more than 30% in northern and central California (Jennings and Hayes 1994).

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Population

Population
Jennings and Hayes (1994) mapped several dozen localities with extant populations. The total adult population size is unknown but is likely to be at least many thousands. Since the 1950s, substantial declines have been noted in the Central Valley and southern California. In southern California, more than 80% of the previously occupied habitat has been developed or converted to incompatible uses; more than 30% has been similarly affected in northern and central California (Jennings and Hayes 1994). In both the US and Mexican portions of its range, this species is still common where appropriate habitat exists.

Population Trend
Decreasing
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Life History, Abundance, Activity, and Special Behaviors

Outside of the mating season, Spea hammondii spend most of their time underground in their burrows. The Western spadefoots are mostly nocturnal creatures, but can be heard calling during the day following winter and spring rain.

Mating occurs from late December to mid-May. Spadefoot toads are "explosive" breeders, taking rapid advantage of summer rains and ensuing temporary ponds to mate. Their mating call consists of a loud snore lasting 0.5 to 1 second, sounding like w-a-a-a or r-a-a-a-w.

A single female can lay more than 600 eggs, attaching them to vegetation. Development can be extraordinarily rapid, with hatching occurring in as little as five days. Tadpoles are light gray to dark greenish brown in color, with a cream-colored underside and a transparent tail. The larvae have a fast growth rate and can be distinguished by their tendency to hang vertically in the water and gulp air or feed on surface material. Larvae are carnivorous and have been observed preying on other species' tadpoles as well as on conspecific tadpoles. The adult diet consists mostly of arthropods.

  • Grismer, L. L. (2002). Amphibians and Reptiles of Baja California. University of California Press, Berkeley.
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Threats

Degree of Threat: A : Very threatened throughout its range communities directly exploited or their composition and structure irreversibly threatened by man-made forces, including exotic species

Comments: Main threat is development and conversion of habitat to incompatible uses (urbanization, agricultural development) (Davidson et al. 2002). Recruitment may be unsuccessful in pools with introduced fishes (e.g., mosquitofish used for mosquito abatement).

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Major Threats
The main threat to this species is the development and conversion of habitat to incompatible uses such as human settlement and irrigated agriculture, which destroy the terrestrial habitat and change the hydroperiod of temporary pools. Recruitment may be unsuccessful in pools with bullfrogs (Rana catesbeiana) or introduced fish (for example, at least historically, those containing mosquitofish (Gambusia) used for mosquito abatement).
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Management

Global Protection: Few to several (1-12) occurrences appropriately protected and managed

Comments: This species is protected in a few small Nature Conservancy preserves.

Needs: Protect assemblages of rainpool habitat throughout the range.

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Conservation Actions

Conservation Actions
This species is protected in a few small Nature Conservancy preserves, some US Department of Defence, Department of Energy, and Bureau of Land Management lands, some National Monuments, and some National Wildlife Refuges. It also occurs within the University of California's Natural Reserve System. This species is also covered in some US federal Habitat Conservation Plans, but is is not listed by US state or federal agencies.
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Wikipedia

Spea hammondii

The Western Spadefoot Toad (Spea hammondii) is a relatively smooth-skinned species of spadefoot toad. Its eyes are pale gold with vertical pupils. It has a green or grey dorsum often with skin tubercles tipped in orange, and it is a whitish color on the ventrum. It has a wedge-shaped black spade on each hind foot. Adult toads are between 3.8 and 7.5 cm (1.5 and 2.95 inches) long.

Juvenile Western Spadefoot Toads look similar to adults, but have more distinct spotting.

Populations of Spea hammondii are localized, but widespread. It ranges throughout the central valley of California as well as the coast south of San Jose and some parts of the desert. The Western Spadefoot prefers grassland, scrub and chaparral locally but can occur in oak woodlands. It is nocturnal, and activity is limited to the wet season, summer storms, or during evenings with elevated substrate moisture levels. It is easily handled, with less skin secretions than similar toad species. Their secretions smell like peanut butter and may cause sneezing.[1] The Western Spadefoot is experiencing some habitat loss, but is still common in its range and the population declines are very minor even though it is listed as "near threatened" in some counties of CA.

The epithet or specific name, hammondi, is in honor of amateur naturalist General William Alexander Hammond, M.D.

References

  1. ^ Conant, Roger. 1975. A Field Guide to Reptiles and Amphibians of Eastern and Central North America. Houghton Mifflin. Boston.
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Names and Taxonomy

Taxonomy

Comments: Placed in the genus SCAPHIOPUS by some authors. Hall (1998) argued against the recognition of SPEA as a distinct genus, but most authors have accepted the split of SPEA from SCAPHIOPUS.

Wiens and Titus (1991) presented a phylogenetic analysis of the genus (or subgenus) SPEA based on allozymic and morphological data. Regarded as conspecific with S. MULTIPLICATUS until 1976 (Brown 1976); some authors retain MULTIPLICATUS within HAMMONDI (Tanner 1989), but various data support the contention that these are distinct species (see Wiens and Titus 1991).

Garcia-Paris et al. (2003) used mtDNA to examine the phylogentic 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.

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