By Dr Manuela Fischer, Wildlife Ecologist North-East Region & Johnny Murison, Western Yalanji Aboriginal Corporation
In Far North Queensland, AWC scientists not only undertake monitoring and research on our sanctuaries but also collaborate with National Parks to help monitor and secure populations of endangered mammals. At Mount Lewis National Park, AWC has partnered with the Western Yalanji Aboriginal Corporation (WYAC) and Queensland Parks and Wildlife Services (QPWS) to monitor a small population of the endangered Northern Bettong (Bettongia tropica), a project that is partially funded by the Queensland Government under a Community Sustainability Action Grant.
The Northern Bettong is recognised as one of 20 Australian mammals most at risk of extinction. Once distributed from the Wet Tropics World Heritage Area to central Queensland, the Northern Bettong population collapsed after European colonisation and the marsupials now occur in only two known locations. The larger and better studied of the two populations occurs on the Lamb Range and is considered stable with approximately 730 individuals. The other, much smaller, population occurs on Kuku Yalanji Country at Mount Lewis National Park. Here, information on population size, distribution and habitat use is lacking and key threats are poorly understood.
Beneath the lush and breathtaking country of the Wet Tropics World Heritage Area beats the cultural heart and spirit of the Kuku Yalanji people for whom the region has been home for tens of thousands of years. Over this time, the Area has been actively managed by the Traditional Owners and their culture is built around a deep respect for nature. Since 2017, the Western Yalanji people, one of the Kuku Yalanji tribes, have partnered with AWC to monitor Northern Bettongs on Western Yalanji Country. AWC works hand in hand with WYAC Rangers and QPWS staff to achieve critical conservation goals and to build capacity within the ranger group to manage the project into the future.
Every six months, 98 motion cameras are deployed to gather data on the population size and distribution of the Northern Bettongs across different seasons. The cameras are placed on foot across the steep terrain of the National Park. We work with Western Yalanji Rangers, volunteers and QPWS staff to complete this challenging undertaking. The rangers teach us about traditional bush foods and medicine along the way.
Within the grid of sensor cameras, 50 cage traps are also deployed to capture individuals for a total of eight nights. Northern Bettongs are micro-chipped, and we assess their health and reproductive status. GPS collars are used to monitor spatial and temporal movements in relation to habitat use.
The open grassy understorey of the tall eucalyptus forest which provides crucial habitat for the Northern Bettong are invaded by lantana and degraded by cattle and inappropriate fire regimes. Predation by cats is also a key threat. Hence, AWC staff and WYAC Rangers deploy 60 cameras targeting cattle and cats. In addition, AWC botanists have established long-term vegetation monitoring sites and developed monitoring techniques that are culturally appropriate and applied by rangers.
Capture-recapture analysis shows that approximately 50 Northern Bettongs remain – a worryingly small population. Sensor cameras reveal that Northern Bettongs avoid areas heavily utilised by cattle and some GPS-tracked individuals avoid lantana infested areas. When body condition and reproductive measures are compared to the larger Lamb Range population, a smaller proportion of females at Mount Lewis National Park carry pouch young and the overall body mass index is significantly lower. Given the low number of Northern Bettongs, their poor body condition and low breeding success, we anticipate this population may suffer from inbreeding depression (a consequence of small population size).
We are working with QPWS and WYAC to address key threats. WYAC Rangers have identified changes in current fire management strategies are required to control the invasion of rainforest into sclerophyll forest and, in consultation, QPWS have developed appropriate fire management plans. A cattle fence to stop further incursion of cattle into the National Park has been built and cattle within the park will be removed. In addition, methods to manage areas infested with lantana are being trialled. Supplementation of the smaller population with individuals from the Lamb Range is being considered to enhance genetic diversity and to increase population size. The future conservation of the Northern Bettong in Mount Lewis National Park is going to require extensive ongoing work to address key threats. A collaborative approach is central to success and we look forward to working with WYAC Rangers and QPWS staff to ensure that this small but important population is conserved.
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