Invasive predators represent the greatest extinction threat to the endangered northern bettong (Bettongia tropica)

Whitehead, Tegan, Vernes, Karl, Goosem, Miriam, and Abell, Sandra E. (2018) Invasive predators represent the greatest extinction threat to the endangered northern bettong (Bettongia tropica). Wildlife Research, 45 (3). pp. 208-219.

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Context: Identification of key threats to endangered species is vital for devising effective management strategies, but may be hindered when relevant data is limited. A population viability approach may overcome this problem.

Aims: We aimed to determine the population viability of endangered northern bettongs (Bettongia tropica) in north-eastern Australia. We also assessed the key threats to the population resilience and how the population viability responds to increases in mortality rates and changes in fire and drought frequency.

Methods: Using population viability analysis (PVA) we modelled survival probability of B. tropica populations under likely scenarios, including: (1) increased predation; (2) changes in drought and fire frequency predicted with anthropogenic climate change; and (3) synergistic effects of predation, fire and drought.

Key results: Population viability models suggest that populations are highly vulnerable to increases in predation by feral cats (Felis catus), and potentially red fox (Vulpes vulpes) should they colonise the area, as juvenile mortality is the main age class driving population viability. If B. tropica become more vulnerable to predators during post-fire vegetation recovery, more frequent fires could exacerbate effects of low-level cat predation. In contrast, it was predicted that populations would be resilient to the greater frequency of droughts expected as a result of climate change, with high probabilities of extinctions only predicted under the unprecedented and unlikely scenario of four drought years in 10. However, since drought and fire are interlinked, the impacts of predation could be more severe with climate change should predation and fire interact to increase B. tropica mortality risk.

Conclusion: Like other Potoroids, B. tropica appear highly vulnerable to predation by introduced mammalian predators such as feral cats.

Implications: Managers need information allowing them to recognise scenarios when populations are most vulnerable to potential threats, such as drought, fire and predation. PVA modelling can assess scenarios and allow pro-active management based on predicted responses rather than requiring collection of extensive field data before management actions. Our analysis suggests that assessing and controlling predator populations and thereby minimising predation, particularly of juveniles, should assist in maintaining stability of populations of the northern bettong.

Item ID: 54585
Item Type: Article (Research - C1)
ISSN: 1448-5494
Keywords: climate change, feral cats, population viability analysis, pro-active management, survival rates
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Copyright Information: © CSIRO 2018
Additional Information:

A version of this publication was included as Chapter 2 of the following PhD thesis: Whitehead, Tegan Carla (2018) Population trends, habitat requirements and conservation recommendations for an endangered marsupial, the northern bettong (Bettongia tropica). PhD thesis, James Cook University, which is available Open Access in ResearchOnline@JCU. Please see the Related URLs for access.

Funders: World Wildlife Fund - Australia (WWF), Queensland Parks and Wildlife Service (QPWS), Department of Environment and Heritage Protection (EHP), James Cook University (JCU)
Projects and Grants: WWF Australian Government's Caring for Our Country grants program
Date Deposited: 18 Jul 2018 07:44
FoR Codes: 41 ENVIRONMENTAL SCIENCES > 4104 Environmental management > 410407 Wildlife and habitat management @ 100%
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