The conservation of arboreal marsupials in the montane ash forests of the central highlands of Victoria, South-east Australia, IV. The presence and abundance of Arboreal marsupials in retained linear habitats (wildlife corridors) within logged forest

Abstract

Arboreal marsupials were censused in 49 retained linear habitats (wildlife corridors) that were excluded from timber harvesting in mountain ash Eucalyptus regnans F. Muell. and alpine ash E. delegatensis R. T. Bak. forests in the Central Highlands of Victoria, south-eastern Australia. The study sites varied in mean width from 30 to 264 m and were bounded by clearfelled and regenerated forests that were aged four years or younger. Of the 402 large trees with hollows that were measured and censused on the 49 study sites, a total of 69 animals was observed from 54 occupied trees, giving one occupied tree per 7·4 trees that were watched. The species of arboreal marsupials recorded during the study included greater glider Petauroides volans Kerr, mountain brushtail possum Trichosurus caninus Ogilby, feather-tail glider Acrobates pygmaeus Shaw, common ringtail possum Pseudocheirus peregrinus Boddaert, yellow-bellied glider Petaurus australis Shaw, sugar glider Petaurus breviceps Waterhouse and Leadbeater's possum Gymnobelideus leadbeateri McCoy. P. volans and T. caninus were the most commonly observed species and accounted for 78% of the animals seen. These species may survive better, at least in the short term, than others in linear strips that are retained after timber harvesting. Colonial and social species of arboreal marsupials that consume widely dispersed food such as saps and gums were uncommon, as predicted by the theory of central place foraging. The presence and abundance of arboreal marsupials in retained linear strips were compared with predictions from models of the habitat requirements of these species developed from sites in contiguous forest. These comparisons revealed that the presence of P. volans, P. breviceps and P. australis in retained linear strips was not significantly different from predictions derived from measures of the suitability of habitat in such areas. T. caninus was recorded at fewer sites than predicted, although the abundance of the species when present was not different from expected values. The endangered G. leadbeateri was recorded only once during the study, despite many sites providing apparently suitable habitat. Retained linear strips supported a significantly lower total abundance of arboreal marsupials than predicted from measures of habitat suitability. A combination of habitat parameters and other measured attributes of retained linear strips such as width and length were used to explain the variation in the presence and abundance of arboreal marsupials. The presence of T. caninus was influenced significantly by the number of trees with hollows and by the length of the site. P. volans was most likely to occur on sites with many trees with hollows, a westerly aspect and where there was no watercourse. Sites with the highest probability of supporting any species of arboreal marsupial occurred in E. regnans forests with numerous trees with hollows and which spanned the topographic sequence (e.g connected a ridge to a gully). The implications of our findings for the use, design and location of strips of retained linear habitat in timber production forests are discussed.