Colorado River toad

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Colorado River toad
Bufo alvarius1.jpg
Scientific classification edit
Kingdom: Animalia
Phylum: Chordata
Class: Amphibia
Order: Anura
Family: Bufonidae
Genus: Incilius
I. alvarius
Binomial name
Incilius alvarius
Girard in Baird, 1859
Bufo alvarius distribution.svg

Ollotis alvaria (Frost, 2006)
Bufo alvarius (Girard, 1859)

The Colorado River toad (Incilius alvarius), also known as the Sonoran Desert toad, is found in northern Mexico and the southwestern United States. Its toxin, as an exudate of glands within the skin, contains 5-MeO-DMT and bufotenin.


The Colorado River toad can grow to about 190 millimetres (7.5 in) long and is the largest toad in the United States apart from the non-native cane toad (Rhinella marina). It has a smooth, leathery skin and is olive green or mottled brown in color. Just behind the large golden eye with horizontal pupil is a bulging kidney-shaped parotoid gland. Below this is a large circular pale green area which is the tympanum or ear drum. By the corner of the mouth there is a white wart and there are white glands on the legs. All these glands produce toxic secretions. Its call is described as, “a weak, low-pitched toot, lasting less than a second.”[2]

Dogs that have attacked toads have been paralyzed or even killed. Raccoons have learned to pull a toad away from a pond by the back leg, turn it on its back and start feeding on its belly, a strategy that keeps the raccoon well away from the poison glands.[3] Unlike other vertebrates, this amphibian obtains water mostly by osmotic absorption across its abdomen. Toads in the family bufonidae have a region of skin known as "the seat patch", which extends from mid abdomen to the hind legs and is specialized for rapid rehydration. Most of the rehydration is done through absorption of water from small pools or wet objects.[4]

Distribution and habitat[edit]

Range of Incilius alvarius in the United States (It also inhabits northwest Mexico)

The Colorado River toad is found in the lower Colorado River and the Gila River catchment areas, in southeastern California, New Mexico, Mexico and much of southern Arizona. It lives in both desert and semi-arid areas throughout its range. It is semiaquatic and is often found in streams, near springs, in canals and drainage ditches, and under water troughs.[3] The Colorado River toad is known to breed in artificial water bodies (e.g., flood control impoundments, reservoirs) and as a result, the distributions and breeding habitats of these species may have been recently altered in south central Arizona.[5] It often makes its home in rodent burrows and is nocturnal.


Colorado River toad is sympatric with the spadefoot toad (Scaphiopus spp.), Great Plains toad (Anaxyrus cognatus), red-spotted toad (Anaxyrus punctatus), and Woodhouse's toad (Anaxyrus woodhousei). Like many other toads, they are active foragers and feed on invertebrates, lizards, small mammals, and amphibians. The most active season for toads is May–September, due to greater rainfalls (needed for breeding purposes). The age of I. alvarius ranges from 2 to 4 years within a population at Adobe Dam in Maricopa County, Arizona; however, other species in the toad family have a longer lifespan of 4 to 5 years.[6] The taxonomic affinities of I. alvarius remain unclear, but immunologically, it is equally close to the boreas and valliceps groups.[7]


The breeding season starts in May, when the rainy season begins, and can last up to August. Normally, 1–3 days after the rain is when toads begin to lay eggs in ponds, slow-moving streams, temporary pools or man-made structures that hold water. Eggs are 1.6 mm in diameter, 5–7 cm apart, and encased in a long single tube of jelly with a loose but distinct outline. The female toad can lay up to 8,000 eggs.[8]

Entheogenic uses[edit]

The toad's primary defense system are glands that produce a poison that may be potent enough to kill a grown dog.[9] These parotoid glands also produce the 5-MeO-DMT[10] and Bufotenin (which is named after the Bufo genus of toads); both of these chemicals belong to the family of hallucinogenic tryptamines. A single deep inhalation of the venom produces strong psychoactive effect within 15 seconds.[11] After inhalation, the user usually experiences a warm sensation, euphoria, and strong visual and auditory hallucinations, due to 5-MeO-DMT's high affinity for the 5-HT2 and 5-HT1A subtypes.[12].

State laws[edit]

The toads received national attention after a story was published in the New York Times Magazine in 1994 about a California teacher who became the first person to be arrested for possessing the venom of the toads.[13][14] The substance concerned, bufotenin, had been outlawed in California in 1970.[15]

Toad at night in Tucson

In November 2007, a man in Kansas City, Missouri was discovered with an I. alvarius toad in his possession, and charged with possession of a controlled substance after they determined he intended to use its secretions for recreational purposes.[16][17] In Arizona, one may legally bag up to 10 toads with a fishing license, but it could constitute a criminal violation if it can be shown that one is in possession of this toad with the intent to smoke its venom.[18]

None of the states in which I. alvarius is (or was) indigenous – California, Arizona, and New Mexico – legally allows a person to remove the toad from the state. For example, the Arizona Game and Fish Department is clear about the law in Arizona: "An individual shall not... export any live wildlife from the state; 3. Transport, possess, offer for sale, sell, sell as live bait, trade, give away, purchase, rent, lease, display, exhibit, propagate... within the state..."[18]

In California, I. alvarius has been designated as "endangered" and possession of this toad is illegal. "It is unlawful to capture, collect, intentionally kill or injure, possess, purchase, propagate, sell, transport, import or export any native reptile or amphibian, or part thereof..."[19]

In New Mexico, this toad is listed as "threatened" and, again, taking I. alvarius is unlawful.[20][21]


  1. ^ "The IUCN Red List of Threatened Species". IUCN Red List of Threatened Species. Retrieved 2018-10-27.
  2. ^ National Audubon Society: Field Guide to Reptiles and Amphibians
  3. ^ a b Badger, David; Netherton, John (1995). Frogs. Shrewsbury, England: Swan Hill Press. pp. 93–94. ISBN 1 85310 740 9.
  4. ^ Zoological Science. Zoological Society of Japan. pp. 664–670.
  5. ^ Gergus, Erik W. A.; Malmos, Keith B.; Sullivan, Brian K. (1999). "Natural hybridization among distantly related toads (Bufo alvarius, Bufo cognatus, Bufo woodhousii) in Central Arizona". Copeia. 1999 (2): 281–286. doi:10.2307/1447473. JSTOR 1447473.
  6. ^ "Lower Colorado River Multi-Species Conservation Program". September 2008: 330–342.
  7. ^ Sullivan, Brian K.; Malmos, Keith B.; Movin, T. (1994). "Call variation in the Colorado River Toad (Bufo alvarius): behavioral and phylogenetic implications". Herpetologica. 50 (2): 146–156. JSTOR 3893021. PMID 3893021.
  8. ^ Behler, J.L. The Audubon Society Field Guide to North American Reptiles and Amphibians. Knopf; 1 edition (November 12, 1979). p. 743. ISBN 0394508246.
  9. ^ Phillips, Steven J.; Wentworth Comus, Patricia, eds. (2000). A Natural History of the Sonoran Desert. University of California Press. p. 537. ISBN 0-520-21980-5.
  10. ^ Erspamer, V.; Vitali, T.; Roseghini, M.; Cei, J.M. (July 1967). "5-Methoxy- and 5-Hydroxyindoles in the skin of Bufo alvarius". Biochemical Pharmacology. 16 (7): 1149–1164. doi:10.1016/0006-2952(67)90147-5.
  11. ^ Weil, Andrew T.; Davis, Wade (January 1994). "Bufo alvarius: a potent hallucinogen of animal origin". Journal of Ethnopharmacology. 41 (1–2): 1–8. doi:10.1016/0378-8741(94)90051-5.
  12. ^ Krebs-Thomson, Kirsten; Ruiz, ErbertM.; Masten, Virginia; Buell, Mahalah; Geyer, MarkA. (December 2006). "The roles of 5-HT1A and 5-HT2 receptors in the effects of 5-MeO-DMT on locomotor activity and prepulse inhibition in rats". Psychopharmacology. 189 (3): 319–329. doi:10.1007/s00213-006-0566-1. ISSN 0033-3158. PMID 17013638.
  13. ^ "Missionary for Toad Venom Is Facing Charges". New York Times. 20 February 1994.
  14. ^ "Couple Avoid Jail In Toad Extract Case". New York Times. 1 May 1994.
  15. ^ Bernheimer, Kate (2007). Brothers & beasts: an anthology of men on fairy tales. Wayne State University Press. pp. 157–159. ISBN 0-8143-3267-6.
  16. ^ "'Toad Smoking' Uses Venom From Angry Amphibian to Get High". FOX News. Kansas City. 3 December 2007.
  17. ^ Shelton, Natalie (7 November 2007). "Drug sweep yields weed, coke, toad". KC Community News. Archived from the original on 14 December 2007.
  18. ^ a b Archived 2008-01-11 at the Wayback Machine
  19. ^ "Title 14. Division 1. Subdivision 1. Chapter 5., § 40(a)".
  20. ^ 19.33.6 NMAC Archived 2016-03-04 at the Wayback Machine.
  21. ^ 19.35.10 NMAC Archived 2012-09-10 at the Wayback Machine.

Further reading[edit]

  • Pauly, G. B., D. M. Hillis, and D. C. Cannatella. (2004) The history of a Nearctic colonization: Molecular phylogenetics and biogeography of the Nearctic toads (Bufo). Evolution 58: 2517–2535.
  • Frost, Darrel R.; Grant, Taran; Faivovich, JuliÁN; Bain, Raoul H.; Haas, Alexander; Haddad, CÉLIO F.B.; De SÁ, Rafael O.; Channing, Alan; Wilkinson, Mark; Donnellan, Stephen C.; Raxworthy, Christopher J.; Campbell, Jonathan A.; Blotto, Boris L.; Moler, Paul; Drewes, Robert C.; Nussbaum, Ronald A.; Lynch, John D.; Green, David M.; Wheeler, Ward C.; et al. (2006). "The Amphibian Tree of Life". Bulletin of the American Museum of Natural History. 297: 1–370. doi:10.1206/0003-0090(2006)297[0001:TATOL]2.0.CO;2.

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