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 for 9th Assembly 2001 - 2005; Tabled papers; ParliamentNT
Tabled by Delia Lawrie
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Professor Grigg Written Submissions Cane Toad Inquiry Report Volume 2 94 3. More broadly, I urge the committee to recommend as a matter of urgency the initiation of well resourced research programmes into Impacts, Containment, and Control. Some government officials in recent years have been downplaying the likelihood of deleterious effects, which has made it too easy for earlier governments to look away. Data now accumulating suggests that some deleterious effects are certain and, because the native fauna of northern Australia is such a nationally significant asset, whatever can be done to protect it, should be done. Thank you for your consideration, Yours faithfully, Gordon Grigg IMPACT OF CANE TOADS ON NATIVE FROGS, ROPER RIVER VALLEY & KAKADU NATIONAL PARK Gordon Grigg1, Andrew Taylor2 and Hamish McCallum3 EXECUTIVE SUMMARY Since 1996 in the Roper River Valley and since 1998 in Kakadu National Park, we have been monitoring the calling activity of native frogs at 16 sites using automatic recording systems based on technology similar to voice recognition which was developed specially for this study. All our data for Kakadu is, until the 2002-03 wet season (not yet downloaded), baseline data, before the arrival of toads. In the RRV we have some pre-toad data and much post-toad data. The results from the RRV are provocative. The number of frog species calling per station declined markedly between the beginning of the study in 1997-98 and 2001 2002. This pattern was consistent at each of the 10 stations and suggests that toads may well have a detrimental effect on frogs. However, because of confounding variables and gaps in the data, combined with the short period before toads arrived, we cannot be sure. We certainly cannot say that there is no effect. The weight of our evidence is that, during the five years of our study, there has been a decrease in frog calling activity at our sites (both in terms of species present and days each species calls). The data from the Kakadu study will be very important because they will provide an independent replicate study, against a longer pre-toad base-line. Brief synopsis of study and results to date, May 2003. We have been monitoring the calling activity of native frogs in two study areas with the aim of making comparisons before and after the arrival of Cane Toads. The areas are along the Roper valley Highway east of Mataranka, where we monitor at 1 0 sites at known wetland habitats Table 1), and within Kakadu National Park where we monitor at six sites (Table 2). The six Kakadu sites are replicated pairs in each of three habitats, savannah woodland, rocky stream and floodplain. 1 Department of Zoology & Entomology, University of Queensland 2 School of Computer Science and Engineering, University of New South Wales 3 Department of Zoology & Entomology, University of Queensland