Distribution of Nocturnal Forest Birds and Mammals in North-eastern New South Wales: Relationships with Environmental Variables and Management History
Rodney P. KavanaghA, Stephen DebusB, Terry TweedieA, Rick WebsterC
AState Forests of New South Wales, PO Box 100, Beecroft, NSW 2119, Australia.
BDepartment of Zoology, University of New England, Armidale, NSW 2351, Australia.
CEcosurveys Pty Ltd, PO Box 13, Deniliquin, NSW 2710, Australia.
A regional survey of the forests in north-eastern New South Wales recorded eight species of nocturnal forest birds and nine species of arboreal marsupials from 291 sites. These forests are an important source of diversity for nocturnal bird and mammal species compared with the two other regions in south-eastern Australia (south-eastern New South Wales and the Central Highlands of Victoria) where similar studies have been undertaken.
Three major environmental gradients accounting for the distribution of these species in north-eastern New South Wales were identified. The dominant gradient contrasted higher-elevation forests in the western half of the region with lower-elevation forests nearer the coast. The second gradient contrasted wet forest types having a dense mesic understorey with dry forest types having an open or sparse understorey. The third gradient represented logging intensity. Characteristic assemblages of species were associated with each end of these three gradients. A core group of species occurred across a wide range of environmental conditions, including logged and unlogged forest.
Most species occurred with similar frequency in logged and unlogged forest. However, limitations in the design of this study, which reflect regional land-use patterns, restrict the untangling of interactions between forest type, elevation and management history. The more disturbed, lower-elevation forests appeared to be the most species-rich environments but the greatest numbers of animals were recorded in the highland forests of the region. The greater glider (Petauroides volans), whose stronghold is the higher-elevation forests, was identified as the species most sensitive to heavy logging, although numbers of this species weresimilar in selectively logged and unlogged forests.
Many of the species recorded in this study are known to use hollows in large old trees for breeding and diurnal shelter. Management attention needs to be directed towards establishing the threshold levels of retention for hollow-bearing trees and for patches of undisturbed vegetation. The establishment of a comprehensive network of retained undisturbed vegetation along most gully systems in the region would seem to be a prudent course of action to maintain biological diversity. As more of the landscape in theregion becomes altered by intensive logging or clearing for agricultural and urban land uses, it will be necessary to carefully plan and refine management prescriptions to maintain wildlife habitat components.