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Minister for the Environment and Heritage
Dr David Kemp
20 September 2003
The Federal Minister for the Environment and Heritage, Dr David Kemp, today gave a $200,000 funding boost to fight the cane toad threat.
"The Howard Government is keen to support innovative new projects focused on researching ways to control the cane toad which is threatening Australia's biodiversity," Dr Kemp said.
"This funding follows a review report which found CSIRO's world leading research into finding a biocontrol for cane toads is progressing well and offers good hope for a long-term solution.
"This is encouraging news in the face of what seemed to be the unstoppable march of the cane toad - with no real leads in sight.
"My department will call for expressions of interest for research projects by the end of the year."
The cane toad was originally introduced to Queensland to kill pests in cane fields in the 1930s. Since then, the cane toad has spread south as far as Port Macquarie in NSW, reached Kakadu National Park in 2001 and continues to expand its range southwards and north-west. Current estimates show cane toads are spreading at around 27 kilometres a year.
"The Howard Government has so far invested around $3.5 million into this ground-breaking research," Dr Kemp said. "The project has achieved a world first - successfully inserting cane toad DNA into an amphibian specific virus. By inserting the modified virus into a cane toad tadpole, it is hoped that the immune response will prevent the toad from reaching adulthood and maturing to the reproductive stage.
"At the same time, the Howard Government is funding leading edge research in Kakadu National Park which is gathering real evidence about the impact of cane toads on native species. Although this will not halt the spread of the cane toads, the information gathered from these projects will help land managers protect native species that lie in the path of this feral pest."
Experts and stakeholders, including members of conservation groups and research organisations, will attend a workshop early next year to continue to take this world-leading research forward. Any biocontrol agent that is developed for release will be specific to the cane toad and will not affect other species.
"The CSIRO project will take up to 10 years to develop a biocontrol agent and to be sure that we can release it safely, but it is vital the work continues if we are to protect our native wildlife," Dr Kemp said.
Future release of the biocontrol agent would be controlled by the Office of the Gene Technology Regulator (OGTR), after an extensive program of consultation with community groups.
The report is available from the Department web site at www.deh.gov.au/biodiversity/invasive/pests/canetoad or by contacting the Community Information Unit on 1800 803 772. An information sheet on the cane toad is attached.
Cane toads, introduced into Australia to control beetles that were destroying sugar cane crops, are still spreading across Australia. They failed to control the cane beetles, and became a major pest themselves. Cane toads can harm native wildlife by eating small animals and poisoning larger predators that try to eat them. Household pets are also at risk from poisoning. So far, there is no known way to control cane toads across large areas, but scientists are searching for a biological control agent that is specific to the toads.
The cane toad is a native animal of South and Central America. In the early 1900's they were widely exported in an effort to use them as a biological control against insects infesting sugar cane crops. In 1935, about 100 cane toads were shipped from Hawaii to Gordonvale, in northern Queensland. However, there had not been an adequate assessment of whether the toad would be able to do the job it had been imported for, and after the release it was found that the toad could not control the beetles. Instead, it quickly established itself as another pest animal.
Since then, the range of cane toads has expanded through Australia's northern landscape at 27-50 kilometres a year. Cane toads had reached Brisbane by 1945, Burketown in north-western Queensland by the early 1980s, Iron Range on the Cape York Peninsula by 1983 and the tip of the Cape by 1994. By 1995 they had reached the Roper River, in the Gulf of Carpentaria in the Northern Territory; by March 2001 had reached Kakadu National Park. In 2003, cane toads were established at Yamba and Port Macquarie on the north coast in New South Wales after being introduced at Byron Bay in about 1965.
The cane toad continues to expand its range southwards at about 1.3 kilometres a year, and is also spreading across the tropical north towards Western Australia. They can be accidentally transported to new locations, for example, in pot plants or loads of timber.
The cane toad forages at night in a wide variety of habitats. It is a ground-dwelling predator and eats any prey that it can fit into its mouth, including small lizards, snakes, frogs and their tadpoles, marsupials and mice, snails, and terrestrial and aquatic insects. It even takes food left out for pets. Cane toads can use their keen sense of smell to find food and breeding mates.
Cane toads need constant access to water to survive. Instead of drinking, they absorb water through the skin on their belly - from dew, moist sand or any other moist material, including areas deliberately kept moist with their own urine. If forced to stay in flooded conditions, cane toads can absorb too much water and die. They can also die from water loss during dry conditions. In Australia there are no specific predators or diseases that control cane toads.
Cane toads can breed at any time of year but seem to prefer the weather conditions that occur with the onset of the wet season. They will lay their eggs in temporary or permanent, still or slow-moving waters with the females laying 8000-30 000 eggs at a time. In comparison, native frogs mostly lay fewer than 1000 eggs. Cane toad eggs hatch in two or three days and the tadpole stage lasts between four and eight weeks. In tropical conditions, the toadlets can reach adult size within a year, but may take twice that long in colder climates.
The toad is poisonous in all its life stages, from egg to adult. Adult cane toads produce venom from glands over their upper surface, but especially from bulging glands on their shoulders - these exude the venom when the toad is provoked. While some birds and a few other native predators have learned to avoid the poison gland of adult toads, almost anything that eats the toad rapidly dies from heart failure. The poison is absorbed through body tissues such as those of the eyes, mouth and nose, so that even mouthing the toad can cause death.
The recent arrival of cane toads in Kakadu National Park has been linked to a marked decline in native predators in the park, especially northern quolls (Dasyurus hallucatus) and large goannas. Household pets are also at risk.
Cane toads may also eat native animals, with a heavy impact on some species, particularly those that are already threatened. Adult cane toads may compete with native animals for food (particularly insects) and shelter, for example under rocks and logs. Cane toads may also outcompete native frogs for breeding sites, and their tadpoles may outcompete native tadpoles because they are produced in such large numbers.
Cane toads readily eat faeces and, where human hygiene is poor, the toads have been known to transmit diseases such as salmonella.
It is possible to control cane toad numbers humanely in a small area, such as a local creek or pond. This can be done by collecting the long jelly-like strings of cane toad eggs from the water or by humanely disposing of adult cane toads. Control is best at the egg or adult stages, because cane toad tadpoles can easily be confused with some native tadpoles, which could be accidentally killed. This approach to cane toad control requires ongoing monitoring of the creek or pond. Fine-mesh fencing can also assist in keeping cane toads from ponds that are in need of special protection.
At present there is no broad scale method available to control cane toads in Australia. Researchers are attempting to identify a biological control agent, such as a virus, that is specific to cane toads. They are also looking at the toad's impact on native fauna to try to clarify its significance as a pest and also to aid in diagnosing better ways to manage their impact and spread.