Conservation of vertebrate fauna using hollows in forests of south-west Western Australia: strategic risk assessment in relation to ecology, policy, planning, and operations management

Abstract

Forty-two vertebrate species use hollows in live standing trees in the forests of south-west Westem Australia. We determined the reliance of each of these species on hollows in standing trees, assessed the relative frequency of occurrence of suitable hollows (based on the size of hollow and hollow entry), and further categorized species by the size of their home range and their current dependence on publicly-owned forest. No species was identified as being at high or immediate risk of decline. Eight species (6 bird, 2 mammal) were identified as excellent candidates for monitoring, with one species (Trichosurus vulpecula) most likely to provide the earliest indication of any critical reduction in the long-term supply of large hollows at small spatial scales. Past impacts of Aborigines and Europeans on populations of the larger species are likely to have been substantial, as these were hunted for food and trapped for fur. Hollow-using species are considered at present to be adequately safeguarded by: extensive areas of forest reserved from logging; science-based prescriptions mandating the retention of trees in Jarrah Eucalyptus marginata forest available for timber harvesting; a forest-wide baiting program to reduce predation by the introduced Red fox Vulpes vulpes; and a 70 year tradition of adaptive forest management. The recovery of populations of medium-sized mammal species following control of foxes will provide an opportunity to re-assess the adequacy of current hollow-management strategies. Future research should include modelling of stand structure, determining the home range of priority species, and assessing the extent of overlap of home ranges. Monitoring of indicator hollow-using species should take place at landscape scales.