Animal Diversity Web

Ge­o­graphic Range

Great Basin spade­foot toads are found in the United States and Canada. The species oc­curs in north­west Ari­zona, in Cal­i­for­nia east of the Sierra Nevada moun­tain range, north­west­ern Col­orado, lower Idaho, south­west­ern Wyoming, through­out Nevada and Utah, and be­tween the Cas­cade and Rocky Moun­tain ranges in Ore­gon, Wash­ing­ton, and British Co­lum­bia. (Whor­ley, 2001)

• Biogeographic Regions
• nearctic
  • native

Habi­tat

Great Basin spade­foot toads are found in arid re­gions, semi-desert shrub­land, or sage­brush flats, but can also be found in al­kali flats, pin­ion-ju­niper wood­land, pon­derosa pine, and high el­e­va­tion spruce-fir forests at about 2800 m (9200 ft). Great Basin spade­foot toads re­quire tem­po­rary or per­ma­nent water sources for breed­ing, such as slow-flow­ing springs, sea­sonal pools, ir­ri­ga­tion ditches, and ponds. They are able to sur­vive in arid habi­tats by re­main­ing buried un­der­ground, thus their sur­vival re­quires soils that per­mit bur­row­ing. ("Wash­ing­ton De­part­ment of Nat­ural Re­sources", 2005; Morey, 2005; "Na­ture­Serve", 2009; Whor­ley, 2001; Zack and John­son, 2008)

• Habitat Regions
• temperate
• terrestrial

• Terrestrial Biomes
• desert or dune
• chaparral
• forest
• scrub forest
• mountains

• Aquatic Biomes
• temporary pools

• Range elevation

  2800 (high) m

  9186.35 (high) ft

Phys­i­cal De­scrip­tion

Great Basin spade­foot toads usu­ally have a gray, olive, or brown col­ored dor­sal col­oration mot­tled with darker spots with light-col­ored cen­ters. Gray streaks out­line an hour­glass shaped mark­ing on the back. The col­oration is sim­i­lar to that of other species of the gen­era Spea and Scaphio­pus. Ven­tral col­oration is light gray, white, or creamy and with­out mark­ings. The skin is rel­a­tively smooth com­pared to the rough, warty na­ture of true toads (genus Bufo), but still con­tains small bumps. Paro­toid glands seem to be ab­sent. There is a dark brown or or­ange spot pre­sent on each upper eye­lid. Pupils are ver­ti­cal, and the eyes are large, cat­like, golden yel­low, and lo­cated on the side of the head. The nose is slightly up­turned and there is a raised cal­lus be­tween the eyes. The body is short and fat with stubby limbs. Spade­foot toads get their name from the pres­ence of a black, ker­a­tinized spade, or tu­ber­cle, on the un­der­side of each hind foot, which is used for bur­row­ing be­hav­ior. Adult body lengths vary from 32 to 67 mm and fe­males tend to be only slightly larger than males. Tad­poles have large glob­u­lar bod­ies and can reach 70 mm in length. They are col­ored black, brown, and gaey with scat­tered golden specks. When threat­ened, adult Great Basin spade­foot toads can pro­duce nox­ious skin se­cre­tions, which are prob­a­bly poi­so­nous or at least dis­taste­ful to preda­tors. (Morey, 2005; "Na­ture­Serve", 2009; "Frogs and Toads of Nevada", 2003; Whor­ley, 2001)

• Other Physical Features
• ectothermic
• heterothermic
• bilateral symmetry
• poisonous

• Sexual Dimorphism
• sexes alike
• female larger

• Range length

  32 to 67 mm

  1.26 to 2.64 in

De­vel­op­ment

Eggs usu­ally hatch within 2 to 4 days. Tad­poles trans­form in about 30 to 40 days, but the rate of meta­mor­pho­sis can in­crease if the tem­po­rary pools in which the lar­vae are de­vel­op­ing begin to dry out. Growth and dif­fer­en­ti­a­tion rates are also in­flu­enced by tem­per­a­ture, which af­fects thy­roid hor­mone ac­tiv­ity (thy­roid hor­mone is in­volved in meta­mor­pho­sis). It is crit­i­cal that lar­vae de­velop rapidly in species that breed in tem­po­rary pools, such as Spea in­ter­mon­tana, be­cause meta­mor­pho­sis must occur be­fore the water evap­o­rates, as the tad­poles can­not sur­vive out­side of water. Trans­formed ju­ve­niles still have a tail which dis­ap­pears soon after they leave the breed­ing pools, and they may re­main at the breed­ing lo­ca­tion for a pe­riod of sev­eral days to sev­eral weeks be­fore they leave the site. Trans­formed ju­ve­niles de­velop into sex­u­ally ma­ture adults in 1 to 2 years for males, and in about 2 years for fe­males. ("Cal­i­for­nia Rep­tiles & Am­phib­ians", 2010; "Wash­ing­ton De­part­ment of Nat­ural Re­sources", 2005; Buch­holz and Hayes, 2002; Hall, et al., 1997; Morey, 2005; Steb­bins, 1954)

• Development - Life Cycle
• metamorphosis

Re­pro­duc­tion

Great Basin spade­foot toads are ex­plo­sive breed­ers, with all breed­ing com­pleted in a few days. There is no spe­cific or def­i­nite breed­ing sea­son, but all breed­ing takes place from May through Au­gust, when tem­per­a­ture and water avail­abil­ity is fa­vor­able. There is much vari­a­tion in the tim­ing of mat­ing each year due to the na­ture of mat­ing lo­ca­tions. Adults are ter­res­trial, but breed­ing sites are lo­cated around water sources. As a re­sult, adults of the species must mi­grate to the breed­ing sites. These jour­neys typ­i­cally occur at night in order to limit ex­po­sure to dan­gers such as evap­o­ra­tive water loss and pre­da­tion. The fac­tors that stim­u­late mat­ing are not very well un­der­stood. Rain­fall may be one of them, but is not nec­es­sary for it as is the case with other spade­foot toad species. Adults mi­grate any­where from 1 to 5 km to reach breed­ing sites. ("Wash­ing­ton De­part­ment of Nat­ural Re­sources", 2005; Buseck, et al., 2005; Morey, 2005; Whor­ley, 2001)

The breed­ing pools may be per­ma­nent or tem­po­rary sources of water, such as rain-wa­ter pools, snowmelt, ponds, ir­ri­ga­tion ditches, and streams. Breed­ing is more com­mon in ephemeral water sources in areas where it rains enough to cre­ate tem­po­rary pools, and more com­mon in per­ma­nent water sources in areas where it does not rain enough to cre­ate tem­po­rary pools. The water must be still or slow-mov­ing to allow breed­ing. In order to sup­port meta­mor­pho­sis, breed­ing pools must re­main filled for at least 40 days to allow enough time for eggs to hatch and for lar­val trans­for­ma­tion. ("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 mi­grate to breed­ing sites, par­tially sub­merge near the shore, and at­tempt to at­tract fe­males using loud calls 1 to 3 notes in length. The calls, or cho­ruses, are re­ported to be mo­not­o­nous duck-like snor­ing sounds, and may be heard over great dis­tances. The cho­ruses at­tract fe­males, and prob­a­bly other males, to the breed­ing pools. As fe­males ar­rive, males scram­ble and com­pete to find mates. Re­pro­duc­tion in­volves am­plexus, where males em­brace fe­males from be­hind using their fore­limbs. This po­si­tion al­lows males to ex­ter­nally fer­til­ize the fe­male eggs as they emerge from the fe­males' cloa­cae. When mat­ing is com­pleted, the adults quickly bur­row un­der­ground to avoid evap­o­ra­tive water loss. ("Wash­ing­ton De­part­ment of Nat­ural Re­sources", 2005; Buseck, et al., 2005; Morey, 2005; Whor­ley, 2001)

• Mating System
• polygynandrous (promiscuous)

After mat­ing, fe­males lay any­where from 300 to 1000 eggs in small clus­ters of 10 to 40 eggs. They at­tach the egg clus­ters to float­ing sticks, sub­merged rocks, and un­der­wa­ter veg­e­ta­tion. Eggs usu­ally hatch within 2 to 4 days, but may take longer if water tem­per­a­tures are too cold. Their size at sex­ual ma­tu­rity is un­known. Males ma­ture sex­u­ally in the first 1 to 2 years after meta­mor­pho­sis, while fe­males do not sex­u­ally ma­ture until at least the sec­ond year after meta­mor­pho­sis. ("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)

• Key Reproductive Features
• iteroparous
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• fertilization
  • external
• oviparous

• Breeding interval

  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

There is no parental in­volve­ment in the care for young once the eggs are laid. Fe­males lay and at­tach their eggs to veg­e­ta­tion in bod­ies of water, and sub­se­quently mi­grate back to feed­ing habi­tats, along with males, to re­plen­ish their en­ergy re­serves. (Buseck, et al., 2005)

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

Lifes­pan/Longevity

The lifes­pan of Great Basin spade­foot toads is un­known. It is as­sumed to be sim­i­lar to other spade­foot toad species and is there­fore es­ti­mated to be about 13 years for fe­males and 11 years for males in the wild. (Morey, 2005)

• Typical lifespan
  Status: wild

  11 to 13 years

Be­hav­ior

Great Basin spade­foot toads are mostly noc­tur­nal, but are also ac­tive in the early morn­ing and the late af­ter­noon. They tend to be more ac­tive after it rains and dur­ing pe­ri­ods of high hu­mid­ity, prob­a­bly be­cause damp en­vi­ron­ments help pre­vent des­ic­ca­tion. The toads are able to sur­vive in dry and arid cli­mates by bur­row­ing un­der­ground or by using the bur­rows of small mam­mals, such as ro­dents. Great Basin spade­foots are able to bury them­selves in loose soils by using the spades on their hind legs to dig into the ground. They ac­com­plish this by mov­ing their hind legs in a cir­cu­lar fash­ion and back­ing up into the soil. When in­ac­tive dur­ing the day, the toads spend their time in shal­low bur­rows just be­neath the sur­face. The bur­rows are typ­i­cally 35 to 45 cm deep, de­pend­ing on con­di­tions. In gen­eral, the drier it is, the deeper the toads tend to bur­row. When the toads are hi­ber­nat­ing, the bur­rows may be as deep as 1 m. ("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 are ac­tive from the months of April through Oc­to­ber. They hi­ber­nate dur­ing the win­ter by bur­row­ing deep un­der­ground to avoid the cold. Once buried, the toads can re­main un­der­ground for months and can tol­er­ate high lev­els of water loss by ac­cu­mu­lat­ing urea in their body flu­ids. This al­lows the toads to ab­sorb water os­mot­i­cally from their sur­round­ings. The toads may also pro­tect them­selves from dessi­ca­tion by coat­ing them­selves in a gelati­nous sub­stance that helps pre­vent water loss. ("Cal­i­for­nia Rep­tiles & Am­phib­ians", 2010; "Wash­ing­ton De­part­ment of Nat­ural Re­sources", 2005; Morey, 2005; Steb­bins, 1954; Zack and John­son, 2008)

Great Basin spade­foot toads are mostly ter­res­trial, and only re­turn to water to breed. Males tend to main­tain in­di­vid­ual space when cho­rus­ing to at­tract fe­males, but may some­times at­tract other males. They are not ter­ri­to­r­ial, and with the ex­cep­tion of breed­ing pe­ri­ods, tend to be soli­tary crea­tures. ("Wash­ing­ton De­part­ment of Nat­ural Re­sources", 2005; Morey, 2005; Whor­ley, 2001)

• Key Behaviors
• terricolous
• fossorial
• saltatorial
• nocturnal
• crepuscular
• motile
• sedentary
• hibernation
• daily torpor
• solitary

Home Range

Home ranges for Spea in­ter­mon­tana are un­known, but given the species' fos­so­r­ial and rel­a­tively seden­tary lifestyle, it can be sur­mised that with ap­pro­pri­ate liv­ing con­di­tions (e.g. soil suit­able for bur­row­ing, avail­abil­ity of breed­ing sites), in­di­vid­u­als would not need much space to sur­vive. In­di­vid­u­als can­not ven­ture too far from breed­ing sites; typ­i­cally mi­gra­tions tend to be under 0.8 km, but some re­ports have sug­gested that mi­gra­tions could po­ten­tially be up to 5 km. (Buseck, et al., 2005; Morey, 2005; "Na­ture­Serve", 2009)

Com­mu­ni­ca­tion and Per­cep­tion

Males at­tract fe­males to tem­po­rary breed­ing pools with loud calls while they are par­tially sub­merged in the water. These calls may also at­tract other males who will com­pete for the fe­males. The calls are short, be­tween 1 and 3 notes long, and duck-like. Be­cause Spea in­ter­mon­tana is noc­tur­nal, it has large eyes prob­a­bly adapted to see­ing at night. Great Basin spade­foot toads likely per­ceive their en­vi­ron­ment through a min­i­mum of audio, vi­sual, tac­tile and chem­i­cal stim­uli. ("Cal­i­for­nia Rep­tiles & Am­phib­ians", 2010; Morey, 2005; Whor­ley, 2001)

• Communication Channels
• tactile
• acoustic
• chemical

• Perception Channels
• visual
• tactile
• acoustic
• chemical

Food Habits

Adult Great Basin spade­foot toads are in­sec­ti­vores and car­ni­vores who feed pri­mar­ily at night. They are gen­er­al­ists, feed­ing on eas­ily cap­tured ter­res­trial in­sects and other arthro­pods. One study found that adult toads con­sumed at least 56 dif­fer­ent arthro­pod taxa from the or­ders Coleoptera, Diptera, Hemiptera, Hy­menoptera, Lep­i­doptera, Neu­roptera, Or­thoptera, Tri­choptera, Collem­bola, and Araneae. Due to their abun­dance in the na­tive habi­tats of Great Basin spade­foot toads, ants and dark­ling bee­tles are the most com­mon sources of prey. Great Basin spade­foots do not have any par­tic­u­lar pref­er­ence, how­ever, for one prey type over an­other. Toads are lim­ited to eat­ing species small enough for them to swal­low whole, and tend not to eat species that pro­duce nox­ious se­cre­tions, such as cer­tain types of ground bee­tles. While plant mat­ter has been found in the stom­ach con­tents of the toads, veg­e­ta­tion is not a pri­mary source of food for adults of the species. (Bragg, 1965; Morey, 2005; "Na­ture­Serve", 2009; Zack and John­son, 2008)

Lit­tle in­for­ma­tion is avail­able re­gard­ing the feed­ing habits of Great Basin spade­foot toad larva. Tad­poles of spade­foot toads are om­niv­o­rous; they feed on wa­ter-born plant ma­te­r­ial such as algae, or­ganic de­tri­tus, and small plants, as well as in­sects and other am­phib­ian lar­vae. Tad­poles also feed on car­rion and may even be­come can­ni­bal­is­tic, es­pe­cially in breed­ing pools. Car­niv­o­rous lar­vae are able to grow and meta­mor­phose faster due to the higher level of pro­tein in their diet. (Bragg, 1965; Buseck, et al., 2005; Morey, 2005; "Na­ture­Serve", 2009)

• Primary Diet
• carnivore
  • insectivore

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

• Plant Foods
• algae
• phytoplankton

• Other Foods
• detritus

Pre­da­tion

Adult Great Basin spade­foot toads are preyed upon by west­ern rat­tlesnakes, coy­otes, and bur­row­ing owls. Tad­poles are mainly preyed upon by west­ern ter­res­trial garter snakes and Amer­i­can crows. When water lev­els rise high enough to flood breed­ing pools, tad­poles are also preyed upon by rain­bow trout and brown trout. ("Cal­i­for­nia Rep­tiles & Am­phib­ians", 2010; Buseck, et al., 2005; Morey, 2005)

When threat­ened, adult Great Basin spade­foot toads can pro­duce nox­ious skin se­cre­tions, which are re­ported to smell like pop­corn or roasted peanuts. The skin se­cre­tions are prob­a­bly poi­so­nous or at least dis­taste­ful to preda­tors. They may even cause minor al­ler­gic re­ac­tions in hu­mans, symp­toms of which may in­clude sneez­ing and a runny nose, and may also cause a burn­ing sen­sa­tion upon con­tact with the eyes and nose. Bur­row­ing and cam­ou­flaged col­oration may also help adult spade­foots es­cape pre­da­tion. By con­trast, tad­poles are com­par­a­tively help­less and have few de­fenses against pre­da­tion other than cryp­tic col­oration. ("Cal­i­for­nia Rep­tiles & Am­phib­ians", 2010; Buseck, et al., 2005; Morey, 2005)

• Anti-predator Adaptations
• cryptic

• Known Predators

  • western rattlesnakes (Crotalus viridis)
  • coyotes (Canis latrans)
  • burrowing owls (Athene cunicularia)
  • western terrestrial garter snakes (Thamnophis elegans)
  • American crows (Corvus brachyrhynchos)
  • rainbow trout (Oncorhynchus mykiss)
  • brown trout (Salmo trutta)

Ecosys­tem Roles

Great Basin spade­foot toads af­fect pop­u­la­tions of the arthro­pods they prey on. Due to the rel­a­tive sta­bil­ity of their pop­u­la­tions, the species also helps main­tain the pop­u­la­tions of its preda­tors, as the toads are a rel­a­tively con­sis­tent source of food. They have no sym­bi­otic or mu­tu­al­is­tic in­ter­ac­tions with any other species. Par­a­sites that in­fect the species in­clude Poly­stoma nearcticum in the lung and blad­der, Dis­to­i­chome­tra bu­fo­nis in the small in­tes­tine, Aplectana in­certa in the small and large in­tes­tine, species of the gen­era Physa­loptera (lar­vae) in the stom­ach, and Acuari­idea (lar­vae) in cysts on the stom­ach wall. (Buseck, et al., 2005; Gold­berg and Bursey, 2002)

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

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

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

When threat­ened, adult Great Basin spade­foot toads can pro­duce nox­ious skin se­cre­tions which may cause minor al­ler­gic re­ac­tions in hu­mans, symp­toms of which may in­clude sneez­ing and a runny nose, and may also cause a burn­ing sen­sa­tion upon con­tact with the eyes and nose.

Con­ser­va­tion Sta­tus

Total adult pop­u­la­tion size is not knows but ex­ceeds 10,000. The species has no spe­cial con­ser­va­tion sta­tus and pop­u­la­tions seem to be sta­ble. Nat­ural habi­tats have mostly not been sub­ject to threat, though agri­cul­ture has re­duced and threat­ened some pop­u­la­tions. Ir­ri­ga­tion, how­ever, could be cre­at­ing new habi­tats, as it cre­ates stand­ing water sources nec­es­sary for breed­ing in areas pre­vi­ously in­hos­pitable to the toads. Man-made reser­voirs also ac­count for a siz­able num­ber of breed­ing sites. The fact that the toads are gen­er­al­ized in their feed­ing habits is also good news for the sur­vival of the species; the elim­i­na­tion or re­duc­tion of a par­tic­u­lar species of prey will not sig­nif­i­cantly im­pact the avail­abil­ity of food. In gen­eral, Great Basin spade­foot toads have a good chance of sur­vival wher­ever stand­ing water is avail­able and wher­ever soil al­lows for bur­row­ing. (Brad­ford, et al., 2005; "Na­ture­Serve", 2009; Zack and John­son, 2008)

• IUCN Red List

  Least Concern
  More information

• IUCN Red List

  Least Concern
  More information

• US Federal List

  No special status

• CITES

  No special status

Other Com­ments

Spea in­ter­mon­tana may some­times be re­ferred to as Spea in­ter­mon­tana. ("Na­ture­Serve", 2009)

Some stud­ies place Spea in­ter­mon­tana as a sis­ter group to to Spea bomb­ifrons and sug­gest that S. in­ter­mon­tana is in fact pa­ra­phyletic. (Wiens and Titus, 1991)

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.