Cane toads in Australia: a short history

HOW CANE TOADS GOT TO AUSTRALIA:

* Cane toads were deliberately brought into Australia in 1935 by entomologist Reginald Mungomery resulting in one of the worst examples of biological control gone wrong.

* Mungomery, who worked for Queensland's Bureau of Sugar Experiment Stations, travelled to Hawaii and caught 102 toads.

* The amphibians, which are native to South and Central America, were introduced to Hawaii to suppress beetles and other pests in sugar cane fields. The idea was to do the same in Australia.

* Mungomery collected 51 females and 51 males, packed them into two small cases with some moist wood shavings and put them on a boat to Australia.

* When the cases were unsealed in far north Queensland three weeks later, just one had died.

* The toads were put into a specially built enclosure on the Meringa experimental farm, one of the bureau's outposts near Gordonvale, south of Cairns.

* One week later, the females began laying eggs and three days after that the first hatchlings appeared.

* In August 1935, 2400 captive-bred toads were released into the Little Mulgrave River and other sites around Gordonvale, laying the foundations for an ecological disaster.

HOW CANE TOADS TOOK HOLD IN AUSTRALIA:

* Estimates vary, but those 2400 toads have since given rise to a deadly carpet of invaders that spread through Queensland and into the Northern Territory, Western Australia, and northern NSW.

* How many there are is anyone's guess, but estimates range from at least hundreds of millions up to billions.

* Female cane toads can lay two clutches of up to 35,000 eggs every single year. Not all survive, but even a fraction equals meteoric population growth.

WHY TOADS ARE A DISASTER FOR NATIVE SPECIES:

* Cane toads are toxic at every stage of life - as eggs, tadpoles, toadlets and adult toads.

* They have been linked to the decline and extinction of several native predator species in the NT and Queensland, including the northern quoll.

* Their toxin is strong enough to kill most native animals that normally eat frogs or frog eggs, including birds, other frogs, reptiles and mammals.

* Sadly, the introduction of cane toads failed to control the beetles they were imported to suppress. There was no bump in sugar production after they started to spread.

* In fact, they probably made things harder for farmers by eating or fatally poisoning native animals that dined on agricultural pests and by boosting numbers of crop-eating rodents that also seek out toads for food.