Sessional Committee on Environment and Sustainable Development Written Submissions Received Volume 2 Issues associated with the progressive entry into the Northern Territory of Cane Toads October 2003
Tabled Paper 1123
Tabled Papers for 9th Assembly 2001 - 2005; Tabled Papers; ParliamentNT
Tabled by Delia Lawrie
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Environment Australia Part I Written Submissions Cane Toad Inquiry Report Volume 2 106 last surveys and again after the arrival of cane toads. In November 2002 a preliminary report on this study provided the first quantitative data available that quoll numbers drop rapidly with the arrival of cane toads. This lent considerable weight to anecdotal evidence from Queensland that quolls disappear abruptly with the arrival of cane toads. As a result, Environment Australia, the NT Parks and Wildlife Commission, the Northern Land Council and Aboriginal traditional owners collaborated to translocate about 60 quolls from the mainland of the NT to islands off Arnhem Land. This initiative is discussed further below. The summary of a report recently received from Ms Watson and Dr Woinarski is at Attachment C. To date, surveys of 110 sites in the southern region of Kakadu have shown substantial declines in numbers of northern quolls where toads have invaded. Less substantial declines were found for a range of other species including the terrestrial gecko Gehyra nana and the pale field rat. Encouragingly, some species including the northern brown bandicoot, dingo, many bird species and most frogs showed no change or a relative increase. Parks Australia also commissioned a more detailed study of northern quolls, which is being conducted by Dr Meri Oakwood. This study has also provided data indicating a dramatic decline in quoll numbers where cane toads have arrived (summary of progress report is at Attachment D) Parks Australia supported a behavioural study of tree goannas, conducted by Dr Sam Sweet, which showed that these two species are unlikely to be seriously affected by cane toads. Parks Australia is supporting a pre & post cane toad study of sand goannas, conducted by Dr Dan Holland. Dr Rod Kennett of EA compiled a reference list of studies conducted and in progress in the Northern Territory that have provided or may provide data on the effects of cane toads on native species. This has been updated for submission to this inquiry (Attachment E). Since cane toads arrived in Kakadu, staff have been collecting specimens for examination of stomach contents, which have comprised a wide variety of invertebrates. Park staff have also recorded observations and/or collected specimens of native animals that have apparently died in attempting to eat cane toads, which have included death adders, goannas and freshwater crocodiles. In summary, there is now scientific as well as anecdotal evidence that cane toads cause substantial declines in northern quoll populations. EA considers that there is a significant risk that quoll species across northern Australia may become locally extinct in areas that cane toads invade. It is likely that cane toads will cause substantial declines in other species including some goanna and snake species. Many other predator, prey, competitor and co-habiting species are also likely to be adversely affected. To date there is insufficient information to quantify the likely extent of declines of any affected species other than northern quolls, or to estimate the potential future recovery of any species. THE CULTURAL, SOCIO-ECONOMIC AND OTHER FACTORS ASSOCIATED WITH THE ENCROACHMENT OF CANE TOADS INTO THE NORTHERN TERRITORY Some of the species most likely to be adversely affected by cane toads are of considerable economic and cultural significance to Aboriginal people in the Northern Territory.