Crowther M.S.,University of Sydney |
Lunney D.,Office of Environment and Heritage NSW |
Lunney D.,Murdoch University |
Lemon J.,Office of the Environment and Heritage NSW |
And 6 more authors.
Ecography | Year: 2014
The decisions that animals must make to achieve a balance between quantity and quality of resources become more difficult when their habitats are patchy and differ greatly in quality across space and time. Koalas are a prime subject to study this problem because they have a specialised diet of eucalypt leaves and need to balance nutrient and water intake against toxins in the leaves, all of which can change with soil type and climate. Koalas are nocturnal and spend most of the day resting and therefore choose trees for reasons other than feeding, particularly for thermoregulation. We GPS-tracked 40 koalas over 3 yr to determine their shift in tree selection between day and night, and in relation to daily maximum temperature, in a patchy rural landscape in north-western NSW, Australia. The species, degree of shelter, diameter, height and elevation of each visited tree were recorded. We used generalised linear mixed effects models to compare tree use between day and night and maximum daily temperature. Koalas used more feed-trees during the night, and more shelter-trees during the day. They also selected taller trees with more shelter in the day compared with night. As daytime temperatures rose, koalas increasingly selected taller trees at lower elevations. Our results demonstrate that koalas need taller trees, and non-feed species with shadier/denser foliage, to provide shelter from heat. This highlights the need both for the retention of taller, mature trees, such as remnant paddock trees, and the planting of both food and shelter trees to increase habitat area and connectivity across the landscape for arboreal species. Retaining and planting trees that provide optimum habitat will help arboreal folivores cope with the more frequent droughts and heatwaves expected with climate change. © 2013 The Authors.
Parnaby H.,Office of the Environment and Heritage NSW |
Lunney D.,Office of the Environment and Heritage NSW |
Lunney D.,Murdoch University |
Fleming M.,Office of the Environment and Heritage NSW
Australian Zoologist | Year: 2011
Four issues influencing the management of hollow-dependent bats are examined for the Pilliga forests of inland NSW. These are: I) the longevity of eucalypts and implications for the strategies for retaining hollow trees; 2) the condition of the forests and woodlands of the Pilliga at the time of European settlement, focusing on densities of hollow trees; 3) the impact of fire and climate change on loss of tree hollows; and 4) the implications of recent ecological research on perceptions of the vulnerability of hollow-using bats. We argue the need for an urgent reevaluation of these issues. Average tree longevity is likely to be much greater than previously acknowledged, the pre-European Pilliga was a forest with hollow-bearing tree densities approximating those of coastal and montane forests, rather than being an open woodland; and fire will significantly reduce the numbers of hollow trees. Consequently, hollow-using bats in the Pilliga are more vulnerable than previously realised, and densities of hollow-bearing trees need to be quantified across tenures. We suggest that densities of hollow-bearing trees to be retained under current logging prescriptions need to be revised upwards. A cross-tenure approach to management is needed, given that the Pilliga forests are about evenly divided between forest managed by DECCW and by Forests NSW, i.e. the difference between conservation and commercial priorities.We conclude that the protection of remaining hollow-bearing trees is the only effective option for managing the hollow-dependent bats in the Pilliga.We predict that local extinctions of a range of hollow-using bat species will occur without active management and monitoring to protect the remaining hollow-bearing trees, and the intermediate-aged, hollowrecruit trees, from logging and fire.