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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Written Submissions Environment Australia Part I Volume 2 Cane Toad Inquiry Report 113 ATTACHMENT C Vertebrate monitoring and re-sampling in Kakadu National Park, 2002 Project RS10 Report to Parks Australia, March 2003. Michelle Watson and John Woinarski SUMMARY This report provides information on a range of studies undertaken in 2002, that involve aspects of monitoring and re-sampling of the terrestrial vertebrate fauna of Kakadu National Park. Assessment of short-term impacts of cane toads upon the terrestrial vertebrate fauna The terrestrial vertebrate fauna was sampled in 110 quadrats in the Mary River district of KNP in the dry season of 2001. Cane toads were not present in any of these in the dry season of 2001, but colonised parts of the district including 77 of these quadrats in the wet season of 2001/02. We re-sampled all 110 quadrats in the dry season of 2002, and here compare changes in abundance from 2001 to 2002 in the set of toad-invaded quadrats and in the set of 33 quadrats that hadnt yet been reached by toads (control quadrats). This study design allows us to quarantine much of the variation between sampling periods that is unrelated to toad invasion. The resulting data base included records of 122 frog, reptile, bird and mammal species that were recorded from at least 5 quadrats over the sampling period. Of these species, 112 were recorded in toad-invaded quadrats following that invasion. The most marked change in the vertebrate fauna was the highly significant decline of northern quolls in the toad-invaded quadrats. None were caught in quadrats that toads had invaded, whereas 41 individuals had been caught at 17 of these quadrats in the previous year. There were less substantial declines observed for a range of other species including pale field-rat and the terrestrial gecko Gehyra nana. In contrast, some species showed a relative increase in toad-invaded quadrats. These included many bird species, most frogs and the feral pig. There was little or no evidence of decline for some species for which some concerns had previously been raised. These included northern brown bandicoot, dingo, most frog species, blue-winged kookaburra, kingfishers, pheasant coucal, dollarbird, grey shrike-thrush, magpie-lark and butcherbirds. Some caution is required in the interpretation of this study. We obtained insufficient data for some species that may be affected by toads, including some of the small dasyurid species, raptors, goannas and elapid snakes. We analyse results for very many species, so there are likely to be some Type I (false-change) errors. Some factors other than toad impacts may have contributed to the results (e.g. a higher proportion of control sites being burned). Our results consider only short-term impacts. The more important longer-term impacts may be very different, with