Miranda’s Daily Blog: Day 22 & 23
Spotted-tailed quolls are a rare and special sight. They are cryptic animals that, “are particularly difficult to detect during surveys” (Nelson et al 2008). That is why it was so exciting to see these ones filmed on our hidden remote sensor cameras, within a few kilometers of The Observer Tree.
On mainland Australia spotted-tail quoll populations have been devastated by land clearing and invasive species such as foxes and dingos. They are listed in the EPBC act as endangered on the mainland and vulnerable in Tasmania. They are also listed in the Tasmanian Threatened Species Protection Act as rare. As with the Tasmanian devil, there is an urgent need for more research on the impact of logging on the species. Shannon Troy, a PhD student currently undertaking such research says “In both a report to the Regional Forest Agreement, and the Spotted-tailed Quoll Draft National Recovery Plan, it has been stated that a lack of understanding of the impacts of silvicultural practices on the species is a significant knowledge gap preventing its effective conservation management.” (Troy 2011)
One thing is known for sure, logging poses a very real threat to the spotted-tail quoll. According to the Australian government’s environment website, “Land clearing: loss and fragmentation of habitat is a primary threat to this largest of Australia’s marsupial carnivores, especially areas of suitable forest with sufficient numbers of den sites and prey.” In the National Recovery Plan for spotted tail quolls, “habitat loss, modification and fragmentation and timber harvesting” are also cited as a major threat to the species” (Long and Nelson 2008).
“Habitat loss resulting from timber harvesting has been implicated in local population declines and extinctions of the endangered mainland spotted-tailed quoll.” suggests Troy (2011). In Tasmania “It is estimated that 50% of the habitat from the species ‘core distribution has been cleared, with approximately half of the remaining habitat having been subjected to logging practices in the last 20 years (Jones & Rose 1996)” (Long and Nelson 2008).
Cool temperate forest and wet sclerophyll are the primary habitat of the quoll (DPIW 2011). Essentially the spotted-tail quoll could be described as a “forest dependent species” (Long and Nelson 2008). It is exactly these types of forests that are most subject to logging in Tasmania, and the type of forest that I am sitting in right now.
“At the stand scale, clearance of mature forest is hypothesised to result in a loss of structural diversity, including a reduced abundance of hollow logs and tree hollows used as den sites by spotted-tailed quolls and their prey, and lowered prey population densities. At the landscape scale, fragmentation of formerly contiguous habitat may result in population isolation and subsequent population decline.” (Troy 2011)
Basically spotted-tail quolls need old growth forests. They rely on hollow logs and hollow tree roots for maternal den sites” (Long and Nelson 2008). Hence their abundance will be influenced by forestry practices, with flow-on effects to resident quoll populations” (Belcher and Darrant 2006, Glen and Dickman 2006a, 2006b cited in Nelson et al 2010). In addition to the need for large patches of forest with suitable dens, they also require a suitable amount of prey (Long and Nelson 2008) medium-sized mammalian prey (Belcher 2000; Belcher & Arrant 2006b; Glen & Dickman 2006a, b).(Long and Nelson 2008). Like the quoll itself, much of their prey also relies on tree hollow for shelter and breeding, “therefore forestry practises can severely impact on prey availability” (Gibbons & Lindenmayer 2002 cited in Long and Nelson 2008).
Hollow trees are a key feature of old forest. The Flora and Fauna Guarantee Act in Victoria has recognised the destruction of hollows as a “threatening process.” It states that the minimum age at which sizable hollows begin to form depends on the tree species; ages of 120 years and up to 300-400 years have been cited.” Once old growth areas are logged in Tasmania they become a managed forest that is felled on rotations of around 80 years – not enough time to provide these crucial tree hollowsLiterature on the relationship between spotted-tail quolls and their habitat also showed that burning after felling was problematic and raised particular concerns about the impact of forestry operations occurring around breeding season (Andrew 2005, Watt 1993 cited in Long and Nelson 2008)
Dr Menna Jones from UTAS has done extensive research on devils and quolls. She states that “quolls live at low density and need a lot of space. Their conservation needs to be addressed at local, landscape and regional scales “(Jones 2011) The females are territorial, defending their home range from other females. This also limits their ability to adapt to degradation of their home ranges” (Nelson et al 2010).
The National Recovery Plan states that “given the threatened status of the Spotted-tailed Quoll, all habitats within its current distribution that are known to be occupied are considered important” (Long and Nelson 2008). As with the Tasmanian devil, it is critical that all possible steps are taken to ensure the survival of this species. With such clear evidence that this species relies on the very trees that are being cut down through industrial scale logging, it is questionable how such practices can be allowed to continue. The loss of either the Tasmanian devil or the spotted-tail quoll would be not only a tragedy for the species itself, but it would also have dramatic impacts on the populations of other predator and prey species, “because as carnivores, they are essential for ecosystem function” (Jones 2011).
It is time to protect the large tracts of intact old forests that are so vital to the survival of this beautiful and important animal.
Shannon Troy: http://www.crcforestry.com.au/view/index.aspx?id=47683
Dr Menna Jones: http://www.zoo.utas.edu.au/hons/mj_proj.htm
Nelson, J., Scroggie, M., Woodford, L. and Robley, A. (2008). Assessing the distribution and status of the Spot-tailed Quoll population of the Otway Ranges, South West Victoria. Unpublished report to the Department of the Environment, Water, Heritage and the Arts. Arthur Rylah Institute for Environmental Research, Department of Sustainability and Environment, Heidelberg, Victoria.
Australian government environment department: http://www.environment.gov.au/biodiversity/threatened/publications/pubs/tiger-spotted-quoll.pdf)
Long, K. and Nelson, J. (2008) National Recovery Plan for the Spotted-tailed Quoll Dasyurus maculatus. Department of Sustainability and Environment, Melbourne.