Sonoran Desert Toad / Colorado River Toad, Bufo alvarius aka Ollotis alvaria - Care Information and Breeding

Sonoran Desert Toad / Colorado River Toad - Bufo alvarius - Care & Breeding
by John P. Clare


Natural History
The Sonoran Desert Toad (or Colorado River Toad), Bufo alvarius (there is a move by some to reclassify this species as Ollotis alvaria), is a remarkable anuran found in extreme south eastern California (though it seems to be extirpated there), the southern half of Arizona, and extreme southwestern New Mexico, in the USA, and also in north western Mexico near those US states. It can reach over 7 inches (18 cm) in length from snout to vent and as such it is one of the largest anurans in the world. Few other toads can match it for size (specimens of Bufo marinus and Bufo guttata have been known to do so).


Male Sonoran Desert Toad, Bufo alvarius. Photo ©John P. Clare / FrogForum.net

These toads live in arid regions and they are quite adept at surviving near-desert conditions. They are even known to "bask". When the first significant rains of a year come to its range, the toads breed explosively, producing many thousands of eggs that hatch in a couple of days and mature into toadlets in a very short period of weeks.


Female Sonoran Desert Toad, Bufo alvarius. Photo ©John P. Clare / FrogForum.net

Controversy and Defence Mechanism
Our members are interested in this toad solely as a pet/captive. Sadly, there is a large amount of controversy surrounding this species and unfortunately the majority of readily accessible information on the Internet about this toad deals with the abuse of this inoffensive animal and the chemicals it produces. This is the archetypal "psychedelic toad" - the species most likely to be used by misguided recreational drug enthusiasts. The chemical compound in question is 5-MeO-DMT (5-methoxy-dimethyltryptamine), a highly potent hallucinogen. The venom is released by the toad from the numerous large glands on its body, which are actually collections of many individual granular poison glands. The toad produces this milky substance when it is physically assailed by a predator. The secretion is actually a cocktail of various chemical compounds which are quite potent - every year in southern Arizona there are cases of dogs becoming seriously ill or dying in short order. Threatened toads will puff up with air and stand as tall as they can, while angling their bodies towards the assailant so that the poison glands are "presented".

The venom of this toad is classed as a Schedule 1 controlled substance under US law and it is illegal to possess the venom. Possession of the toad in and of itself is not a crime in the USA, but of the three states where the toad is found in the wild, only Arizona allows the species to be collected and then only with an Arizona fishing license. However it is against Arizona state law to remove the species from the state, fishing license or no fishing license.


Poison Emission demonstrated by Zookeeper, Bufo alvarius. Photo ©John P. Clare / FrogForum.net

It doesn't take much deduction to realise that most of the Sonoran Desert Toads available in captivity were illegally collected to begin with, or were illegally sent across Arizona state lines. Captive breeding is possible but it's not the easiest species. Most of the toads photographed and depicted on this page are residents of a zoo.

One interesting fact is just how readily the venom shoots out of the glands - in the last photo only the slightest pressure was necessary to project the venom violently up to 15 feet! A single bite by a dog or other predator results in that jet of poison flying into its mouth with generally fatal consequences.

In Captivity / as a Pet
These toads make interesting captives. Adults are very laid back and are quite content to bask under lights in relatively dry terraria. Youngsters are more flighty. They accept a wide range of food, though like other American Bufonids they seem to have a hard time with nightcrawlers, being surprisingly inept at eating them.

They are an attractive species to the pet keeper due to their size and surprisingly calm and bold demeanor (for a toad) in captivity. They seem to tame much more readily than Cane Toads (Bufo marinus) and a full grown adult makes an impressive display animal that usually isn't hiding all the time like most ground dwellings true toads. They are unfussy eaters and an adult Sonoran Desert Toad is quite capable of eating an adult mouse, though these should not consititute a significant part of the toad's diet due to the reports of complications in amphibians fed regularly with mice and rats. Crickets and cockroaches, both captive cultured, are the best staples. Our Basic Toad Care information sheet applies well to this species, although unusually for most amphibians these guys seem to appreciate an incandescent bulb under which to bask (probably for warmth). A good temperature for the hot end of their terrarium is 85-90 degrees Fahrenheit (that's about 32-34 degrees C). This toad is very tolerant of dry conditions, but hides should be provided, along with a water bowl in which the toad can soak, and a sandy or loose substrate is the most natural for this species. Finally, a note on handling - these toads tolerate handling quite well for a large anuran and captive specimens rarely secrete venom under gentle handling. However, as with any amphibian you should wash your hands well after handling the toad and keep handling in general to a minimum just like you should for any frog or toad. Obviously since this toad is a serious poison danger to a playful cat or dog (or child), keep it out of their reach. Getting the venom on your skin is harmless - just don't get it in your mouth or your eyes. It washes off with soap and water.

Breeding
Conditioning for breeding is accomplished by giving a cool dry winter period for a few months (7-15 degrees Celsius, 45-59 F). During the peak of summer, with a peak average temperature about 35 degrees C (95 F), place 1-2 males and a single female in a large rain chamber in the morning (rain on) with several inches of water and some objects that allow the toads to sit out of the water if desired - keeping the rain chamber a little cooler than the terrarium should help.


Spawning Sonoran Desert Toads, Bufo alvarius. Photo ©John P. Clare / FrogForum.net

Timing breeding with a drop in atmospheric pressure can only help (i.e. when there is a rain storm in your area). The male should grasp the female in amplexus within an hour or two. If the pair are still together by the evening, make sure the pair are undisturbed for the night - eggs should be laid during the night.

Raising the Young
Eggs are laid in a jelly enclosed string single file or alternating one to each side (see the photo of the breeding pair with eggs earlier in this article). At 29 degrees C (85 F) the eggs hatch in less than 20 hours. Tadpoles become free swimming and eating within 40 hours (they should still have external gill remnants at this point). Within another 24 hours the external gills are completely absent and the tadpoles breed internally. Growth is very rapid and metamorphosis can take place within 14 days of laying. Tadpoles reach between 4 and 5 cm (2 inches) before metamorphosis, but this species' tadpoles have short tails and wide, bulky bodies. The dorsal spotting of the toadlets (see the photo below this paragraph) is visible on tadpoles even before the front legs appear. Toadlets are usually 1.5-2.5 cm (1 inch) snout-to-vent length after tail resorption but the larger ones seem almost as wide! After the tail is fully resorbed, the toadlets begin to seek food.


1 week old Sonoran Desert Toadlets. Photo ©John P. Clare / FrogForum.net

Offer them small captive-cultured cockroaches and 1/8 inch (0.32 cm) gut-loaded crickets (fruit flies and pinhead crickets are a little small but are eagerly accepted). Fruitflies are not a good growth food so augment them with something more nutritious, such as gut-loaded crickets. Toadlets tend to be jittery and they can move surprisingly fast so don't let them get out. They calm down well after a few weeks of feeding and growing. These toads can reach adult size in less than a year if fed well and kept warm.


The difference of 10 days growth for Toadlets. Photo ©John P. Clare / FrogForum.net

As you can see from the photo above, these toads are capable of a phenomenal growth rate. The toadlet on the left began feeding about 1 day before the photo was taken. The toadlet on the right began feeding 11 days before the photo.


13 day old Sonoran Desert Toadlet. Photo ©John P. Clare / FrogForum.net

This toadlet is the same age and size as the one on the right of the size comparison photo - 13 days out of the water, 11 days eating.

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I want to make clear that the toad emitting venom in the last photo was under minimal stress - it only hunched up like that during the actual emission (I believe to protect its own eyes from the venom) and showed no signs of discomfort before or after the actual emission. This is a long-term captive and tame toad that had little or no fear of humans. Finally, the venom was not collected; this was a demonstration carried out by a zoo official to illustrate the defensive mechanism of this toad species.