Drought, disease or devil declines? Identifying the cause of decline of the eastern quoll, Dasyurus viverrinus : implications for conservation and management
thesisposted on 2023-05-27, 15:12 authored by Fancourt, BA
Diagnosing the cause of a species' decline is one of the most challenging tasks faced by conservation practitioners. A decline in abundance may simply be part of a natural population fluctuation from which the species will recover without management intervention, or it may indicate a more concerning trajectory towards extinction. Different threats and mechanisms can operate at different temporal and spatial scales, in succession or simultaneously. Often, several threats act together to produce synergistic effects that are greater than the sum of the contributions of each threatening process in isolation. Effective conservation strategies require an understanding of the factors that threaten a species and how those factors interact. The eastern quoll (Dasyurus viverrinus) is a medium-sized carnivorous marsupial that is extinct on the Australian mainland and survives only in Tasmania. The species has declined by more than 50% in the 10 years to 2009, with no sign of recovery. The reasons for this precipitous decline are not currently understood. Population eruptions and declines have been anecdotally reported in eastern quolls since the 1800s, suggesting that the species may be sensitive to short-term variations in weather. Additionally, a recent study suggested that the decline of the Tasmanian devil (Sarcophilus harrisii) due to the spread of the Devil Facial Tumour Disease (DFTD) may have released feral cats (Felis catus) from competitive suppression. A subsequent increase in cat sightings might be linked to eastern quoll declines, possibly through mechanisms such as increased predation, competition or exposure to toxoplasmosis, the disease caused by the cat-borne coccidian parasite Toxoplasma gondii.
Rights statementCopyright 2015 the author Chapter 2 appears to be the equivalent of an article finally published as: Fancourt BA, Bateman BL, VanDerWal J, Nicol SC, Hawkins CE, Jones ME and Johnson CN (2015) Testing the role of climate change in species decline: is the eastern quoll a victim of a change in the weather? PLoS ONE 10(6) e0129420 Chapter 3 appears to be the equivalent of an article finally published as: Fancourt BA, Nicol SC, Hawkins CE, Jones ME and Johnson CN (2014) Beyond the disease: is Toxoplasma gondii infection causing population declines in the eastern quoll (Dasyurus viverrinus)? International Journal for Parasitology: Parasites and Wildlife 3(2), 102-112. Chapter 4 appears to be the equivalent of an article finally published as: Fancourt BA and Jackson RB (2014) Regional seroprevalence of Toxoplasma gondii antibodies in feral and stray cats (Felis catus) from Tasmania. Australian Journal of Zoology 62(2), 272-283 Chapter 5 is published as: Fancourt BA, Hawkins CE, Cameron EZ, Jones ME and Nicol SC (2015) Devil declines and catastrophic cascades: is mesopredator release of feral cats inhibiting recovery of the eastern quoll? PLoS ONE 10(3), e0119303. Appendix A appears to be the equivalent of an article finally published as: Fancourt BA (2014) Rapid decline in detections of the Tasmanian bettong (Bettongia gaimardi) following local incursion of feral cats (Felis catus). Australian Mammalogy 36(2), 247-253.