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Cane Toads

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Photograph by Tim Laman
Photo: Close-up of a cane toad in grass

On the front lines of the Australian Outback there is a serious confrontation is about to break out. On one side are the killer cane toads that look just like ones you might find in your back yard but their venom is harmful to humans and lethal to many animals. This near unstoppable army of toads have multiplied and spread across Australia – wiping out much of the native wildlife.

Each cane toad carries enough venom to kill a small child. No wonder the locals aren't fans of this invasive species.

Native to the Americas, the venomous cane toad was brought to Queensland, Australia, in the 1930s in an unsuccessful attempt to reduce destructive beetle populations.



Map: Cane toad range

Cane Toad Range

Fast Facts

Type: Amphibian
Diet: Omnivore
Average life span in the wild: 5 to 10 years
Size: 4 to 6 in (10 to 15 cm)
Weight: 2.9 lbs (1.3 kg)
Group name: Knot or nest
Did you know? An Australian government entomologist named W.W. Froggatt nearly succeeded in halting the release of cane toads in Australia in 1935.

Size relative to a tea cup:
Illustration: Cane toad compared with tea cup

The much maligned venomous cane toads earned their bad reputation shortly after being released into the Australian ecology in 1935 with the hope that they would control the destructive cane beetle population. They turned out to be failures at controlling beetles, but remarkably successful at reproducing and spreading themselves.

About 3,000 cane toads were released in the sugarcane plantations of north Queensland in 1935. They now number well into the millions, and their still expanding range covers thousands of square miles in northeastern Australia. They are considered pests, and government eradication efforts include asking residents to help collect and dispose of them.

Cane toads are large, stocky amphibians with dry, warty skin, and are native to the southern United States, Central America, and tropical South America. Their numbers are manageable in their natural range, but they have thrived in Australia because there are few natural predators, they breed easily, and they have abundant food, including pet food, which they steal from feeding bowls left outside of homes.

Their effects on Australia's ecology include the depletion of native species that die eating cane toads; the poisoning of pets and humans; depletion of native fauna preyed on by cane toads; and reduced prey populations for native insectivores, such as skinks.

Cane toad venom is a mix of toxins that primarily affects the functioning of the heart. It is present throughout their bodies and is secreted as a milky liquid from the parotoid glands located over the toad's shoulders. Envenomation is painful, but rarely deadly to humans, although some people have died from eating cane toads and even their eggs.

Article from National Geographic -- Read More from National Geographic

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