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Great Basin Spadefoot

Spea intermontana

What do they look like?

Great Basin spadefoot toads are gray, olive, or brown on their backs with darker spots that have light-colored centers. They look similar to many of their relatives. They have gray streaks on their back shaped like an hourglass. They are light gray, white, or cream-colored on their belly. Their skin is smooth compared to a lot of toads, but has small bumps. On each eyelid, there is a dark brown or orange spot. Their eyes are large and golden yellow like a cat, but are on the side of their head. Their nose is turned slightly upwards and they have short, fat bodies with short, fat limbs. They get their name from the hard bit of skin underneath each of their back feet that they use to dig and burrow in the ground. Adults are 32 to 67 mm long and females are just a little bit bigger than males. Tadpoles have large bodies and can be up to 70 mm long. Tadpoles are black, brown, and grey and have with scattered golden specks. When threatened, they sometimes give off toxic chemicals from their skin. These chemicals are probably poisonous or taste bad to predators. (Morey, 2005; "NatureServe", 2009; "Frogs and Toads of Nevada", 2003; Whorley, 2001)

  • Sexual Dimorphism
  • sexes alike
  • female larger
  • Range length
    32 to 67 mm
    1.26 to 2.64 in

Where do they live?

Great Basin spadefoot toads live in the United States and Canada. They are found in northwest Arizona, California (east of the Sierra Nevada mountains), northwestern Colorado, southern Idaho, southwestern Wyoming, Nevada, Utah, and between the Cascade Mountains and Rocky Mountains in Oregon, Washington, and British Columbia. (Whorley, 2001)

What kind of habitat do they need?

Great Basin spadefoot toads live in dry areas with shrubs or sagebrush. They also live in places that are temporary lakes, dry pine forests, or forests at high elevation. They need water for breeding like springs, seasonal pools, ponds, or ditches used to transport water for farming. They bury themselves underground to keep from drying out. This means they need to live in soils they can dig tunnels in. ("Washington Department of Natural Resources", 2005; Morey, 2005; "NatureServe", 2009; Whorley, 2001; Zack and Johnson, 2008)

  • Aquatic Biomes
  • temporary pools
  • Range elevation
    2800 (high) m
    9186.35 (high) ft

How do they grow?

Eggs take 2 to 4 days to hatch. Great Basin spadefoot toads are tadpoles for 30 to 40 days. They sometimes start changing into toads earlier if the pool they are living in starts to dry out. Temperature also changes how quickly they grow. After they transform into toads, they still have a tail. The tail goes away shortly after they leave the pool. They may stay nearby for a few days or weeks. Males are able to have their own young in 1 to 2 years, and females are in about 2 years. ("California Reptiles & Amphibians", 2010; "Washington Department of Natural Resources", 2005; Buchholz and Hayes, 2002; Hall, et al., 1997; Morey, 2005; Stebbins, 1954)

How do they reproduce?

Great Basin spadefoot toads breed for a few days sometime between May and August, when the temperature and amount of water they need is right in their breeding pool. Adults live on land, so they travel to a breeding pool location where there is water. These can be pools of rainwater or melted snow, ponds, ditches used by farmers to transport water, or streams. They only breed in water that moves slowly. They choose places that are wet for at least 40 days, but usually not year-round. They mostly travel to breeding spots at night, which makes them less likely to dry out or get eaten. They travel somewhere between 1 and 5 km to reach breeding sites. ("California Reptiles & Amphibians", 2010; "Washington Department of Natural Resources", 2005; Bragg, 1965; Buseck, et al., 2005; Mayhew, 1968; Morey, 2005; Stebbins, 1954; Whorley, 2001; Zack and Johnson, 2008)

Males arrive at breeding spots first and try to attract females with loud calls that are 1 to 3 notes long. The noises they make sound like ducks snoring, and can be heard from a long ways away. Females are attracted to the chorus, so they come to the breeding pools too. Males compete with each other to find mates. ("Washington Department of Natural Resources", 2005; Buseck, et al., 2005; Morey, 2005; Whorley, 2001)

Females lay somewhere between 300 and 1000 eggs in small clumps of 10 to 40. They attach clumps of eggs to floating sticks, underwater rocks, and underwater plants. Eggs normally hatch in 2 to 4 days, but can take longer if the water is too cold. Males are able to breed 1 to 2 years after they transform into toads, and females 2 years after. ("California Reptiles & Amphibians", 2010; "Washington Department of Natural Resources", 2005; Bragg, 1965; Buseck, et al., 2005; Mayhew, 1968; Morey, 2005; Stebbins, 1954; Whorley, 2001; Zack and Johnson, 2008)

  • How often does reproduction occur?
    Great Basin spadefoot toads breed an average of once yearly if conditions are favorable.
  • Breeding season
    Great Basin spadefoot toads will breed from May through August when conditions are favorable.
  • Range number of offspring
    300 to 1000
  • Range time to hatching
    2 to 4 days
  • Average age at sexual or reproductive maturity (female)
    2 years
  • Range age at sexual or reproductive maturity (male)
    1 to 2 years

After females lay their eggs, parents don't invest any more in caring for their young. Females lay their eggs and stick them on plants underwater. Afterwards, they travel back to the places where they find food. (Buseck, et al., 2005)

  • Parental Investment
  • no parental involvement
  • pre-fertilization
    • provisioning
    • protecting
      • female

How long do they live?

Scientists aren't sure about the lifespan of Great Basin spadefoot toads. However, it is probably similar to other spadefoot toads. Spadefoot toad females live about 13 years and males live about 11 years in the wild. (Morey, 2005)

  • Typical lifespan
    Status: wild
    11 to 13 years

How do they behave?

Great Basin spadefoot toads are mostly active in the early morning and late afternoon from April to October. They are more active after it rains and when it's really humid. This is probably because they are less likely to dry out. They survive in dry places by burrowing underground or by hiding in the burrows of small mammals like rodents. Great Basin spadefoots bury themselves in loose soil by digging into the ground with spades on their back legs. They move their back legs around in a circle and back up into the soil. In the day when they're not active, they hang out in burrows just under the surface. These are usually 35 to 45 cm deep, depending on conditions. They usually burrow deeper if it's drier. When they hibernate in winter, they dig burrows as deep as 1 m. They can stay underground for months, taking in water from the soil around them. They also coat themselves with gel to keep from drying out. ("California Reptiles & Amphibians", 2010; "Washington Department of Natural Resources", 2005; Bragg, 1965; Mayhew, 1968; Morey, 2005; Stebbins, 1954; Zack and Johnson, 2008)

Great Basin spadefoot toads live most of their life on land, and only go back to the water to breed. Males stay in the same spot to attract females, but aren't territorial. Except during the time they breed, they are found by themselves. ("Washington Department of Natural Resources", 2005; Morey, 2005; Whorley, 2001)

Home Range

Scientists don't know the average size of the area where Great Basin spadefoot toads live and travel. Since they dig in the ground, they don't need very much space. They usually don't go more than .8 km away from their breeding sites, but can go up to 5 km away. (Buseck, et al., 2005; Morey, 2005; "NatureServe", 2009)

How do they communicate with each other?

Males attract females to temporary breeding pools by making loud calls while they are partly underwater. The calls are only 1 to 3 notes long, and sound like ducks. Their calls sometimes attract other males that compete for the females. Great Basin spadefoot toads have large eyes, which probably helps them see well at night. They use hearing, sight, touch, and chemicals to understand their environment. ("California Reptiles & Amphibians", 2010; Morey, 2005; Whorley, 2001)

What do they eat?

Adult Great Basin spadefoot toads hunt at night, and they eat mostly insects and other arthropods. They eat beetles, flies, bugs, sawflies, wasps, bees and ants, moths and butterflies, net-winged insects, grasshoppers, crickets, weta, and locusts, caddisflies, springtails, and spiders. Ants and darkling beetles are common where they live, so these are what they eat most often. Great Basin spadefoots toads don't prefer one kind of prey or the other, however. They swallow their prey whole, and avoid eating poisonous bugs like ground beetles. They sometimes eat bits of plants, but it's not one of their most important food sources. (Bragg, 1965; Morey, 2005; "NatureServe", 2009; Zack and Johnson, 2008)

Scientists don't know much about what Great Basin spadefoot toad tadpoles eat. Their relatives spadefoot toads, eat algae, decaying plants, small plants, insects, and larvae of other amphibians. They also eat flesh of dead animals or even each other in breeding pools. Larvae that eat other animals grow faster because of the protein. (Bragg, 1965; Buseck, et al., 2005; Morey, 2005; "NatureServe", 2009)

  • Animal Foods
  • amphibians
  • carrion
  • insects
  • terrestrial non-insect arthropods

What eats them and how do they avoid being eaten?

Adult Great Basin spadefoot toads are eaten by western rattlesnakes, coyotes, and burrowing owls. Tadpoles are eaten by western terrestrial garter snakes and American crows. If breeding pools are flooded by rivers, rainbow trout and brown trout also eat the tadpoles. ("California Reptiles & Amphibians", 2010; Buseck, et al., 2005; Morey, 2005)

Adult Great Basin spadefoot toads give off chemicals from their skin that smell like popcorn or roasted peanuts. They are probably poisonous or at least taste bad. Humans might sneeze, get a runny nose, or feel burning in their eyes or nose. They also escape predators by burrowing into the ground and by having camouflaged skin. Tadpoles don't have defenses against predators aside from their camouflage colors. ("California Reptiles & Amphibians", 2010; Buseck, et al., 2005; Morey, 2005)

  • These animal colors help protect them
  • cryptic

What roles do they have in the ecosystem?

Great Basin spadefoot toads are a stable food source for their predators and impact the animals that they eat. They get lung and bladder parasitessmall intestine parasties, small and large intestine parasites, stomach parasites, and stomach wall parasites. (Buseck, et al., 2005; Goldberg and Bursey, 2002)

Commensal or parasitic species (or larger taxonomic groups) that use this species as a host
  • lung and bladder parasites Polystoma nearcticum
  • intestinal parasites Distoichometra bufonis
  • intestinal parasites Aplectana incerta
  • stomach parasites Physaloptera (larvae)
  • stomach parasites Acuariidea (larvae)

Do they cause problems?

Great Basin spadefoot toads can produce skin chemicals that cause allergic reactions in humans. This might include sneezing, runny nose, or a burning feeling when they touch they eyes or nose.

How do they interact with us?

There are no known positive impacts of Great Basin spadefoot toads on humans.

Are they endangered?

Great Basin spadefoot toads aren't endangered. Farming has reduced the number of them in some places, but ditches and ponds used by farmers to hold water have created habitats in other places. They also have an advantage over some species because they eat a lot of different animals. If some of their food isn't available, they can find other things to eat. (Bradford, et al., 2005; "NatureServe", 2009; Zack and Johnson, 2008)

Some more information...

Another scientific name for Great Basin spadefoot toads is Spea intermontana. ("NatureServe", 2009)

Contributors

Bassel Kadi (author), University of Michigan-Ann Arbor, Phil Myers (editor), University of Michigan-Ann Arbor, Rachelle Sterling (editor), Special Projects, Catherine Kent (editor), Special Projects.

References

2010. "California Reptiles & Amphibians" (On-line). Accessed February 21, 2010 at http://www.californiaherps.com/frogs/pages/s.intermontana.html.

Nevada Department of Wildlife. 2003. "Frogs and Toads of Nevada" (On-line pdf). Nevada Division of Wildlife. Accessed March 21, 2010 at http://www.fws.gov/nevada/nv_species/urban_wildlife/Frogs%20and%20Toads%20of%20NV%20Sheet.pdf.

NatureServe. 2009. "NatureServe" (On-line). Spea Intermontana. Accessed March 21, 2010 at http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Spea+intermontana.

2005. "Washington Department of Natural Resources" (On-line). Accessed February 21, 2010 at http://www1.dnr.wa.gov/nhp/refdesk/herp/html/4spin.html.

Bradford, D., J. Jaeger, S. Shanahan. 2005. Distributional Changes and Population Status of Amphibians in the Eastern Mojave Desert. Western North American Naturalist, 65/4: 462-472.

Bragg, A. 1965. Gnomes of the Night. Philadelphia: Univ. Pennsylvania Press.

Buchholz, D., T. Hayes. 2002. Evolutionary Patterns of Diversity in Spadefoot Toad Metamorphosis. Copeia, 2002/1: 180-189.

Buseck, R., D. Keinath, M. Geraud. 2005. "SPECIES ASSESSMENT FOR GREAT BASIN SPADEFOOT TOAD (SPEA INTERMONTANA) IN WYOMING" (On-line pdf). Accessed April 18, 2010 at http://www.uwyo.edu/wynddsupport/docs/Reports/SpeciesAssessments/Great%20Basin%20Spadefoot%20Toad%20-%20Final%20%28Jan%202005%29.pdf.

Goldberg, S., C. Bursey. 2002. HELMINTHS OF THE PLAINS SPADEFOOT, SPEA BOMBIFRONS,THE WESTERN SPADEFOOT, SPEA HAMMONDII, AND THE GREAT BASIN SPADEFOOT, SPEA INTERMONTANA. Western North American Naturalist, 62/4: 491-495.

Hall, J., J. Larsen, R. Fitzner. 1997. POSTEMBRYONIC ONTOGENY OF THE SPADEFOOT TOAD, SCAPHIOPUS INTERMONTANUS (ANURA: PELOBATIDAE): EXTERNAL MORPHOLOGY. Herpetological Monographs, 11: 124-178.

Mayhew, W. 1968. The biology of desert amphibians and reptiles. New York: Academic Press.

Morey, S. 2005. "AmphibiaWeb" (On-line). Accessed February 21, 2010 at http://amphibiaweb.org/cgi/amphib_query?where-genus=Spea&where-species=intermontana&account=lannoo.

Stebbins, R. 1954. Amphibians and reptiles of western North America. New York: McGraw-Hill.

Whorley, J. 2001. "AmphibiaWeb" (On-line). Accessed February 21, 2010 at http://amphibiaweb.org/cgi/amphib_query?where-genus=Spea&where-species=intermontana&account=amphibiaweb.

Wiens, J., T. Titus. 1991. A Phylogenetic Analysis of Spea (Anura: Pelobatidae). Herpetologica, 47/1: 21-28.

Zack, R., D. Johnson. 2008. FEEDING BY THE GREAT BASIN SPADEFOOT TOAD (SPEA INTERMONTANA [COPE]) (ANURA: PELOBATIDAE). Western North American Naturalist, 68/2: 241-244.

 
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Kadi, B. 2012. "Spea intermontana" (On-line), Animal Diversity Web. Accessed September 23, 2014 at http://www.biokids.umich.edu/accounts/Spea_intermontana/

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