Rainforest Revelations

Barely a day old, and thousands of Golden Orb-weaving Spiderlings were consumed by the Cane Toad (Bufo marinus), in one nocurnal pig-out.  Good news though,  scientists believe that they are winning the war against this dreaded pest, which was introduced into Queensland cane fields in 1935 to get rid of cane beetles.

A female cane toad can lay up to 70,000 eggs each year, in two separate layings.  The introduction of this pest into Australia was a monumental environmental disaster as the cane toads multiplied and spread around the coast, eating whatever frogs eat and the frogs themselves.  Wildlife that ate the newly introduced pests died from the toxin produced by 2 glands at each side of the lower head.

Professor Rick Shine, a biologist at the University of Sydney and the environment category winner in The Australian Innovation Challenge awards last year, achieved complete or near-complete eradication of cane toad tadpoles in a trial of the biological control method on toad-infested ponds near Darwin.  Seems that the cane toad tadpoles are attracted to the adults poison, while frogs’ tadpoles are generally repelled.

At Cooper Creek Wilderness we have noted that Nature has changed to deal with the cane toads, for example the Butcherbird first learned to identify the cane toads and not regard them as frogs, one of their favourite delicacies. Then they had to learn how to eat them whilst avoiding the poison glands.  So, about 10 years ahead of the scientists, the butcherbirds and crows have been flipping the cane toads over and devouring them through the belly.  Even antechinas, a small marsupial carnivore has learned how to chew on the back legs of the cane toad for a tasty meal.  Keelback snakes seems to be immune to the small amounts of toxin in the eggs and in the young cane toads, and they too, are helping to exterminate the pest.

Realistically, Professor Shine believes that it is unlikely that his eradication method will rid Australia of this scourge.  He suggests that he could effectively exterminate the pest from special areas of high biodiversity, but would not be able to cover all the billabongs and waterways in Australia, where these creatures breed.

Co-incidentally, Professor Shine and his team, in winning The Australian Innovation Challenge award, received $70,000.  This is equivalent to receiving $1 for each egg from one productive female cane toad in one year.