Artificial tree hollow creation for cavity-using wildlife - Trialling an alternative method to that of nest boxes

- A novel technique of artificial hollow provision is described.
- Uptake of mechanically created hollows was fast and by several species.
- The technique has the potential to become an additional management tool.
- Further research is required to advance this technique.

Tree hollow scarcity is a threat to cavity-dependent vertebrate wildlife world-wide across many landscapes. Currently, only nest boxes are commonly used to mitigate or offset lost cavity-bearing trees, with a number of shortfalls reported using this technique. There is a need to trial alternative techniques to improve artificial cavity provisions. This preliminary study investigated the use of carving hollows directly into tree trunks using chainsaws. Sixteen hollows of two simple cavity types were created in a timber production forest in south-eastern Australia. One cavity type comprised a basal entrance (38 mm in diameter) which provided a space above the entrance, intended for bats, and the other cavity type provided a space below a 38 mm or 76 mm entrance, intended for marsupials and birds. Five species used the hollows over a 15-month cavity monitoring period; feathertail glider (Acrobates pygmaeus) (in 75% of the hollows), brown antechinus (Antechinus stuartii) (75%), sugar glider (Petaurus breviceps) (63%), long-eared bat (Nyctophilus sp.) (50%) and white-throated treecreeper (Cormobates leucophaea) (25%). Camera monitoring revealed hollow inspection after only one day post hollow creation by white-throated treecreepers and feathertail gliders, and nest building by white-throated treecreepers after three days. No hollow host tree failure occurred for either of the two hollow wall widths trialled over two years of monitoring tree stability. Wound-wood formed and partly enclosed the hollows' faceplates over time, improving the sturdiness of the hollow and likely resulted in hollows closely resembling natural cavities. Mechanically created tree hollows have a broad application potential across many landscapes with the prospect to overcome some of the reported drawbacks of nest boxes. More research is required to document long-term performance and effectiveness of this technique.