Assessing the use of chainsaw-carved artificial hollows by wildlife across fire-affected East Gippsland, Victoria

Natural tree hollows are becoming rarer due to anthropogenic pressures, and their loss cannot be mitigated by natural processes at a rate sufficient to meet the needs of hollow dependent wildlife. Chainsaw hollows provide an alternative form of artificial habitat in lieu of naturally formed tree hollows, and the nature of their construction means they typically benefit hollow-dependent fauna more than more conventional nest boxes. In Australia, the use of chainsaw hollows is relatively new and the factors that influence chainsaw hollow use by wildlife are poorly known. Our study set out to determine the occupancy rates of wildlife using chainsaw hollows in East Gippsland, Victoria, and to determine what factors of chainsaw hollow-bearing trees and surrounding environmental features influenced occupancy rates by wildlife. We monitored 111 chainsaw hollows? nested within clusters in three lowland forest sites? of two different size classes for signs of wildlife occupancy, which were installed five to fourteen months prior to surveying. We performed three repeat observations of hollow occupancy via pole camera and assessed vegetation characteristics in the vicinity of chainsaw hollows. We found that chainsaw hollows of the larger design were not used by any wildlife. Of the 81 smaller hollows, 33% showed signs of wildlife occupancy, with confirmed use by white-throated treecreepers, Krefft? gliders and eastern pygmy possums. No invasive or pest species were observed using the chainsaw hollows. The entrance height of chainsaw hollows and internal volumes were found to positively influence occupancy by wildlife, with species more likely to use hollows installed higher and with larger internal volumes (within the small hollow size class). At a site-scale we observed higher rates of occupancy in sites featuring common food trees for arboreal marsupials and occupancy was highest at sites in areas up to ten years following the last fire. The results of our study show the potential for chainsaw hollows as an alternative to nest boxes to supplement habitat for a range of arboreal species d where natural hollows are not present or low in abundance. Future studies and chainsaw hollow installation projects should carefully consider the physical characteristics and placement of chainsaw hollows, focusing not only on the requirements of target species, but also factors that may influence access by potential predators. Despite their promise, given the knowledge gaps and uncertainties regarding hollow supplementation and the factors influencing both natural and artificial hollow use, we recommend the primary goal for conservation efforts should remain the preservation of remnant forest and mature trees.<p></p>