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 2 116 continuing accumulation of fauna data from the established fire monitoring plots. ATTACHMENT D THE EFFECT OF CANE TOADS ON A MARSUPIAL CARNIVORE, THE NORTHERN QUOLL, DASYURUS HALLUCATUS. Progress Report, February 2003 Meri Oakwood Ecosystem Management University of New England Armidale NSW 2351 SUMMARY Northern quoll populations in Kakadu National Park are considered to be at risk of local extinction with the invasion of the introduced cane toad. In 2001, two study sites were chosen where monitoring of the effect of cane toads on northern quolls could occur: near East Alligator Ranger Station and near Mary River Ranger Station. In December 2001, cane toads were reported approximately 15km from the Mary River Ranger Station site, consequently radio-tracking of northern quolls commenced there in January 2002. Cane toads arrived at this site in very low numbers in March 2002. Between January and June 2002, 40 female quolls were radio-tracked for varying periods of time. Of these, 14 were tracked to the site of their death. An additional two dead quolls were found opportunistically. Thirty one percent of these deaths appeared to have been caused by cane toad poisoning. As the dry season progressed, the toads became cryptic and quoll mortality that appeared to be caused by cane toads ceased (normal mortality still occurred). In consideration of funds available, radio-tracking then ceased, the plan being to recommence in the next wet season. Trapping indicated that the quoll population at Mary River was demonstrating the normal pattern (a slight decline) throughout the dry season up until early October, however the December and January trapping trips revealed that a sudden decline had then occurred. Normally, the wet season is a time of high quoll abundance as the juvenile quolls become independent and enter the trappable population. Examination of rainfall records showed that rain began in the area in the middle of October. It appears likely that with the rain, the cane toads emerged from their refuges and despite their low numbers at the site, were numerous enough to affect the quolls. In contrast, the non toad-affected East Alligator site still has very high quoll abundance, with large numbers of juveniles. These results support the anecdotal evidence from Cape York that quoll populations are severely affected by toads.