Territory Stories

Vertebrate monitoring and resampling in Kakadu National Park : Year 3, 2003-04



Vertebrate monitoring and resampling in Kakadu National Park : Year 3, 2003-04


Watson, Michelle; Woinarski, John Casimir Zichy; Northern Territory. Department of Infrastructure, Planning and Environment


E-Publications; E-Books; PublicationNT




Date:2004-05; Made available via the Publications (Legal Deposit) Act 2004 (NT)

Table of contents

Summary -- 1. Introduction -- 2. Continuation of a monitoring program that will contribute to the assessment of impacts of cane toads -- 3. Baseline survey of vertebrates at fire monitoring plots -- 4. Investigation of change in vertebrate (especially mammal) species composition at sites sampled in historic surveys -- a. Jabiluka -- b. Kapalga -- 5. Survey of threatened plants -- 6. Investigation of census and trapping methods for feral cats and dingoes -- 7. Training of Parks Australia staff in fauna survey through a field-based camp -- 8. Compilation of data bases and GIS layers showing existing and current fauna records -- Appendix A. Schedule for consultancy RS19 Vertebrate monitoring and resampling in Kakadu National Park.




Animals -- Northern Territory -- Kakadu National Park

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Northern Territory Government

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v, 57 pages : col. maps ; 30 cm.

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Attribution International 4.0 (CC BY 4.0)

Copyright owner

Northern Territory Government



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24 Discussion The re-sampling of a set of sites on the Jabiluka lease in the north of Kakadu National Park has provided results that contrast with mammal re-sampling carried out elsewhere in the Park, e.g. Kapalga (Braithwaite and Muller 1997 Woinarski et al. 2001), Little Nourlangie Rock (Woinarski et al. 2002), Stage 3 (Mary River District) (Woinarski et al. 2002) and Stage 1 and 2 (2003 report). The results of the Jabiluka re-survey do not show evidence of the major decline of native mammals recorded at Kapalga (Woinarski et al. 2001). In fact, three of the species (northern quoll, northern brown bandicoot and pale field-rat) that had decreased at Kapalga have increased at the Jabiluka sites. Notwithstanding these increases, some other mammal species showed significant or near-significant decline at Jabiluka. These (probable) decreasers included the Northern Brushtail Possum and Arnhem Rock-rat, two species that have been reported to have declined elsewhere in Kakadu National Park and the Top End generally. Indeed, although the Northern Brushtail Possum was recorded at too few sites to permit detailed modelling, at one site alone there was an order of magnitude decline in the number of possums recorded in the two survey periods: a clear indication of at least local changes in that species. Like the recent re-sampling of Stage 1 and 2 (2003 report) and Stage 3 (Woinarski et al. 2002), the results from the Jabiluka re-sample are noisy, with some sites showing dramatic increases in native mammal abundance while others have shown dramatic declines. At a number of sites, these changes have been driven by major local changes in the abundance of one or two species (e.g. increases in Northern Brown Bandicoots and Pale Field-rats at Site 16 and decline of Northern Brushtail Possums at Site 11). The causes of such dramatic changes remain unclear. As discussed below, investigation of fire regimes at the survey sites provides some insights into factors that may be contributing to these localised changes but a substantial proportion of the observed variation remains unexplained. Investigation into relationships between changes in the mammal fauna at Jabiluka and fire history parameters showed significant relationships for some species. However, some care needs to be taken during the interpretation of these results. There is a high level of imprecision associated with ascribing fire attributes at the site level, particularly when the size of the sample site is equivalent to the pixel size of the satellite imagery being used (as is the case for the Landsat MSS imagery used to generate fire history data prior to 1996) (Russell-Smith et al. 1997). This error is magnified over multiple years, such that the description of a 20 year fire history (as is being used here) will undoubtedly lack precision. In addition, there is also some error associated with the identification of burnt sites from satellite imagery, such that some sites may be incorrectly scored as burnt or unburnt (Russell-Smith et al. 1997). Notwithstanding these issues, the results of the analysis showed some quite significant relationships between the change in abundance of some species and fire history parameters. Some of the models that contained multiple fire terms were a little confusing, possibly a result of the correlation between fire variables. The model for the Arnhem Rock-rat, which suggested a positive relationship with recent fire frequency contrasts with results of similar analyses of data collected for this species in other parts of the park (Begg et al. 1981 Woinarski et al. 2002 Watson and Woinarski 2003) and in

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