Research project title
Hollow futures? Declining arboreal mammals and tree hollow availability in tropical northern Australia.
The broad aim of Dr Cara Penton’s thesis was to determine whether tree hollows could be a limiting resource for arboreal mammals in the tropical savannas of Melville Island, northern Australia. Cara's study represents the first targeted research on tree hollow availability and the arboreal community dynamics of the northern Australian mammals the brush-tailed rabbit-rat (Conilurus penicillatus), black-footed tree-rat (Mesembriomys gouldii), and northern brushtail possum (Trichosurus vulpecula arnhemensis), and their use of tree hollows. She found that arboreal mammals most commonly selected large eucalypt (Eucalyptus and Corymbia spp.) trees (diameter at breast height >30 cm) and dead trees as denning sites, and these trees are relatively uncommon. Interestingly, Cara also found arboreal mammals overlapped in their den use with all taxa that frequently utilise hollows >10 cm entrance diameter and commonly share dens intra- and interspecifically.
Although larger hollows can be scarce in tropical savannas populations of arboreal mammals on Melville Island are still significantly impacted by other threats (e.g. feral predators and habitat simplification) and are reliant on the presence of a complex understorey. Due to the open canopy structure of tropical savannas, arboreal mammals spend varying amounts of time foraging and travelling across the savanna floor, thereby exposing themselves to ground-based threats. Her findings highlight the overall importance of large hollows and eucalypts for arboreal mammals and other hollow-dependent fauna. The high degree of larger hollow use and their scarcity in the tropical savanna, coupled with changes in resource availability due to altered fire regimes and invasive species, potentially help explain why arboreal mammals have been susceptible to declines.
Cara’s broad research interests are in conservation biology and management, particularly for threatened species and small mammal populations in Australia. Cara was awarded her PhD in April of 2021 for her thesis investigating the tree hollow availability in tropical savannas and hollow ecology by threatened arboreal mammals on Melville Island. With further interests in understanding how contemporary fire regimes can be best managed at landscape and localised scale for threatened species Cara recently commenced work with Warddeken Land Management an Aboriginal-owned non-for-profit organisation. With traditional owners she is adhering to a two-way approach to carry out ecological monitoring and targeted threatened species research using both Indigenous and western knowledge sets in the Warddeken IPA, western Arnhem Land.