Four issues influencing the management of hollow-using bats of the Pilliga forests of inland New South Wales

Abstract

Four issues influencing the management of hollow-dependent bats are examined for the Pilliga forests of inland NSW. These are: 1) 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.

A burning question: what are the risks and benefits of mammalian torpor during and after fires?

“…However, with over 1300 species of bats worldwide, responses to fire are likely highly variable and dependent on niche occupation and life history of the species in question. Fire can be beneficial to bats because it can create or widen tree hollows ( Lunney et al , 1988 ), but may also destroy hollows ( Parnaby et al , 2010 , 2011 ). A reduction in spatial complexity and clutter following fire also permits less manoeuvrable bats (generally larger-bodied bats) to access habitats which previously were too spatially complex for foraging and roosting ( Betts, 2009 ; Inkster-Draper et al , 2013 ).…”

Bat activity before and after a severe wildfire in Pilliga forests: Resilience influenced by fire extent and landscape mobility?

“…Additionally, wildfire and light prescribed fires result in the collapse of tree hollows (Parnaby et al . , ; Lindenmayer et al . ), which are used as roosts by many insectivorous bat species, although fires can also increase basal injuries and hollows (Munks et al .…”

Interspecific differences and commonalities in maternity roosting by tree cavity-roosting bats over a maternity season in a timber production landscape

“…In Australia, silvicultural practices range from clear-cut methods to less intensive group or selective tree harvesting [ 14 ]. Knowledge about the ecological implications of different silvicultural practices and mitigation measures is essential for the conservation of cavity-using wildlife including bats [ 13 , 14 , 16 ] so the need for adequate cavity-bearing tree retention in commercial forests is critical (e.g., [ 14 , 17 – 19 ]).…”