Natural resource management advisory series : note 1 : Trees with hollows

Abstract

Tree hollows, which are cavities formed in the trunks or branches of live and dead trees, represent critical habitat features in Australian forest ecosystems. This advisory note examines the ecological significance, formation processes, and conservation implications of hollow-bearing trees in North East New South Wales. Typically developing in mature to over-mature trees aged 100-150 years or older, these hollows provide essential shelter, roosting, and nesting sites for approximately 70 hollow-dependent species, including 20 bat species, 12 arboreal mammals, 26 bird species, and 14 reptile species. The document highlights how anthropogenic activities, particularly timber harvesting and land clearing of mature trees, significantly reduce hollow availability across the landscape, potentially leading to local extinctions of hollow-dependent fauna. Management recommendations include the protection of existing hollow-bearing trees, including dead standing trees, and the retention of recruitment trees to ensure future hollow availability. While artificial nest boxes are discussed as a supplementary conservation measure, they are not considered an adequate replacement for natural tree hollows. This advisory note emphasizes the fundamental role of hollow-bearing trees in maintaining biodiversity and provides practical guidance for their conservation in agricultural and forest management contexts.