Colorado River Toad

Location

In the Zoo

Scientific Information

Scientific Name: Incilius alvarius
Class: Amphibia
Order: Anura
Family: Bufonidae
Genus: Incilius

Size

Male

Female

Height:
Length: 3-7 inches 3-7 inches
Weight:
Maturity: One month One month

Lifestyle and Lifespan

Diet: Carnivorous
Activity Timeframe: Nocturnal
Interactivity: Solitary
Sexual Dimorphism: No
Gestation: 2-12 days
Lifespan in the Wild: 10-20 years
Lifespan in Captivity: 9.2 years

Geographic Range

North America; west coast; Colorado, Arizona, New Mexico and California. Especially common in the Sonoran Desert.

Conservation

Status in the Wild:
Threats:

Characteristics

This is the largest western toad at 4-7.5 inches. It is chunky and short-legged, with dark olive-green leathery skin above and a smooth creamy-white underside. Prominent cranial crests, and an enlarged whitish wart near the angle of the jaw. (Both males and females have pale throats.) It's vocal sac is absent or vestigial. It's voice is weak and low-pitched, resembling a ferryboat whistle.

Species Specifics

Physical Characteristics

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Ecology

Habitat

Occurs in a variety of habitats, from creosote bush desert scrub to grasslands up into oak-pine woodlands, thornscrub and tropical deciduous forest in Mexico.

Distribution

Ranges from arid mesquite lowlands and arid grasslands into the groves in mountain canyons. Often found near permanent springs, reservoirs and streams. Ranges include southern Colorado across Arizona to extreme southwestern New Mexico to northwestern Sinaloa, also extreme southeastern California.

Diet

Carnivorous. Insects, spiders, beetles, grasshoppers, lizards, rodents and other toads.

Ecological Web

Secondary consumer. Also controls crop pests, such as snails.

Activity and Behavior

Activity Pattern

Nocturnal. The Colorado River Toad remains underground during the heat of the day. Activity is stimulated by rainfall, but is not dependent on rainfall for breeding. Most active May-July, (living in burrows under the ground during the winter.) Breeding usually occurs in spring and summer. (More aquatic than most toad species.)

Behavior

Social Behavior

Solitary. This toad is a solitary species until the mating season in the summer months, when large groups of toads gather at temporary pools to mate.

Reproductive Behavior

Colorado River Toads appear when the summer showers start and breed in the temporary pools that form after the rains begin. Mating occurs from May to July. Males croak incessantly, but have a relatively weak call, compared to other frogs and toads. The female lays strands of black eggs. There can be as many as 8,000 eggs in a single strand! The tadpoles hatch within 2-12 days. After the breeding season is over, this toad will return to its burrow where it will spend the winter.

Offspring

Born as yellow-brown tadpoles, but quickly grow into toadlets after about one month.

Conservation

Status

Not endangered in most of its range, but near extinction in California. Listed as a species of Least Concern by IUCN. (However, in California the toad is classified as Endangered and in New Mexico it is considered Threatened.)

Historical

Historically its range extended throughout southeastern California, though it has not been seen there since the 1970's.

Current Threats

Our Role

How You Can Help

Fascinating Facts

Largest native toad in the United States!

Also known as the Sonoran Desert Toad. Parotid glands, (located just behind the eyes) and warts secrete a sticky white poison, which in some Bufo species (including this one) can paralyze or kill dogs and other predators. Many animals, however, eat toads with no ill effect. The skin secretion may irritate the eyes or mouths of humans, but handling the toads does not cause warts (contrary to popular belief)!

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 raccoons well away from its poison glands!

This toad's toxin can be smoked, and is a powerful psychoactive. After inhalation, the user usually experiences a warm sensation, euphoria and strong auditory hallucinations. No long-lasting effects have been reported.However, it is illegal to have the poison from the toad, called bufotenin, in your possession in the state of California. (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!)

What is the difference between a toad and a frog? Toads are actually a type of frog, so technically there is no difference between the two. However, when people refer to toads they are generally talking about frogs from the scientific family bufonidae. This family has stubby bodies and short back legs. They typically walk instead of hop. They also prefer dryer climates and have warty dry skin.

It's call is described as a 'weak, low-pitched toot, lasting less than a second.'

References

Badger, David. Frogs. 1997. Barnes & Noble Publishers.

Stebbins, Robert. 1985. Western Reptiles and Amphibians. Houghton Mifflin, Boston, MA. p.68-69.

Brunelle, R. 2001. "Incilius alvarius" (On-line), Animal Diversity Web. Accessed March 02, 2017 at http://animaldiversity.org/accounts/Incilius_alvarius/

Colorado River Toad, Bufo alvaris (On-line), NatureWorks. 2017. New Hampshire Public Television. Accessed March 02, 2017 at http://www.nhptv.org/natureworks/coloradorivertoad.htm

Sonoran Desert Toad (On-line), Arizona-Sonora Desert Museum. Accessed March 02, 2017 at https://www.desertmuseum.org/books/nhsd_desert_toad.php

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