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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



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

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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 115 described in our previous report (Woinarski et al. 2002). The frog fauna showed some changes, including significant increases for the froglet Crinia bilingua and the introduced cane toad, but significant decreases for Cyclorana australis and Limnodynastes ornatus. Changes in the reptile fauna included a few cases of possible identification mismatches between the sampling periods, but less clearly explained significant increases for three species (Gehyra australis, Cryptoblepharus plagiocephalus and Menetia greyii) and significant decreases for eight species (Diplodactylus stenodactylus, Delma borea, Lophognathus gilberti, Carlia triacantha, Ctenotus decaneurus, Ct. spaldingi, Ct. vertebralis and Glaphyromorphus isolepis). The major changes observed for reptile and frog species were largely unrelated to the invasion of cane toads to a small proportion of the quadrats sampled in 2001. Changes in the bird fauna were clouded by significant inter-observer variability, which provides a timely caveat for protocol in monitoring programs. With the removal of this variability (through stripping of the large data set to only those cases that used the same observer in both time periods), results are substantially clearer. There were major declines from 1988-90 to 2001 for a group of irruptive species (banded honeyeater, bar-breasted honeyeater, varied lorikeet and red-backed button-quail) that were particularly abundant in the first time period. There were also less significant declines for a number of other species, most notably the two trunk-gleaning insectivorous birds (black-tailed treecreeper and varied sittella). In contrast, there were only two species that showed significant increase over this period. These results reveal some of the pitfalls that may compromise a monitoring program. More importantly, they reveal that most fauna populations undergo population fluctuations of varying magnitude, and that it is almost impossible to interpret change from a baseline to a single subsequent re-sampling period. Longer-term trends can be discerned from natural fluctuations only by a series of monitoring periods. Vertebrate sampling at fire monitoring plots During 2002, we provided baseline fauna survey information for 36 of the established KNP Fire Monitoring Plots, increasing the tally of these 135 plots with fauna survey data from 21 (in 2001) to 57 now. The 2002 sampling substantially increased representation across the various districts of the Park, and more equitably across major habitats. Sandstone habitats are still relatively underrepresented, and these are the main priority for sampling in 2003. A composite data base for all sampled plots has been prepared as a CD for all Park Districts. Ongoing priorities This work has considerably extending knowledge of the condition and trend of Kakadus terrestrial vertebrate fauna. Additional activities are proposed under a continuation of this contract to 2003. Priorities for work beyond 2003 include: longer-term monitoring of the impacts of cane toads (and of the change in predator communities that they may engineer); targeted survey to obtain more information on species not well sampled by our conventional sampling protocol (notably including some small dasyurids, raptors, emu and snakes); targeted surveys to more precisely describe the condition and trend of threatened fauna; and