School of Earth & Environmental Sciences
Nicholson, J, Spot the difference: Using camera-traps to analyse the Spotted-tailed Quoll population in the Illawarra Highlands, NSW Australia, BEnviSci Hons, School of Earth & Environmental Sciences, University of Wollongong, 2018.
The deleterious effects of habitat loss, modification, and fragmentation continue to drive mammal extinctions worldwide. Understanding population-specific responses to changing landscapes are essential for effective conservation management. In southeast Australia, the spotted-tailed quoll is a threatened marsupial carnivore that occupies large home ranges in low-density populations, therefore increasing the possibility of encountering a multitude of threatening processes. Despite their known vulnerability to these threats, the knowledge of size, distribution, and ecology for stronghold populations are often inadequate to apply effective conservation efforts. This study aimed to investigate the population dynamics of spotted-tailed quolls located in Budderoo National Park, Barren Grounds Nature Reserve, and Morton National Park; an area recognised as a stronghold population of the species. To investigate this, a long-term camera trap survey was undertaken continuously over a 24-month period. In addition, two annual periods of live-trapping were also conducted to determine the distribution, abundance, and spatial organisation of the spotted-tailed quoll across the study sites. Camera-trap surveys were conducted from 2016 to 2018 using 29 infrared cameras. This resulted in an overall sampling effort of 18,898 trap nights, during which 699 independent quoll captures were found. Through the use of the individual profiling to distinguish between individuals, 64 quolls were individually identified. Individual identification was used to determine the movements and behaviours of each quoll by analysing their captures.
This study found that the population was primarily located within the Barren Grounds Nature Reserve and the central portion of Budderoo National Park. Across the two year study period there was an observable increase in quoll captures between the two years, ultimately finding a minimum count of 58 quolls in the population. The highest number of captures occurred during the winter months, coinciding with to the breeding season, and summer (introduction of the current year's sub-adult population). For a subset of the population, eight males and six females were analysed for their spatial organisation. Findings showed that the home range and movement of males were significantly larger than that of the females. Generally, females only appeared on two or three cameras occupying an average home range of 132ha, while males appeared on an average of six cameras with a larger average home range of 2350ha. Using the known biology, spatial organisation and movement patterns of these quolls, we attempted to determine the sex of another four individuals. Through the comparison of these individuals to the behaviour of the known population, we estimated the sex of the four individuals to be two males and two females. By following the dispersal pattern of the individuals captured as juveniles, we found that males moved far from their natal site to establish new adult home ranges. In contrast, females typically occupied areas near their natal home range. Daily activity pattern differences between males and females were not significantly different. Nonetheless, it was found that individuals were not entirely nocturnal, and had observable diurnal and crepuscular periods of activity. The seasonal analysis of activity patterns found a significant difference with a substantial nocturnal activity increase during the winter months.
Our study provides ecological insights into the life history and biology of spotted-tailed quolls and reveals the current distribution and abundance of a recognised stronghold population. By understanding the distribution and behaviour of the Illawarra highlands, the local factors that constrain population growth can be identified and assessed. This knowledge is vital in the application of effective conservation management strategies needed to prevent further species decline and ensure the persistence of the spotted-tailed quoll on the Australian mainland.