Evaluation of habitat recovery for Hollow Dependent Fauna – regional scale solutions for long-term resilience: Report for North Coast Regional Landcare Network, Gulbali Institute report number 2

Hollow-bearing trees are particularly important for Australian fauna, including many threatened species, which nest or shelter in hollows. After the 2019-2020 bushfire disaster, Landcare-led Bushfire Recovery in north-eastern New South Wales (funded by the Australian Government) focussed on providing and monitoring hollows for native wildlife. North Coast Regional Landcare Network took a regional landscape approach to the recovery effort in response to the scale of the 2019- 2020 bushfire events. The regional Landcare network represented an extensive, united community with a common purpose. Harnessing this common motivation offered an opportunity to develop a landscape scale monitoring program through the development of an innovative collective approach to monitoring.
As well as installing nestboxes and hollows throughout the region, the Network engaged Charles Sturt University ecologists based at Port Macquarie to work with the individual Landcare groups to: develop agreed upon fit-for-purpose monitoring guidelines; collate a regional dataset that could provide insight into the use of artificial hollows on a regional rather than local scale; evaluate the effectiveness of the nestboxes and hollows installed; and, develop guidelines for future programs (Leck and Knight, 2022).
Landcare provided details of 1194 artificial hollows installed: 285 HollowHogs and 909 externally mounted boxes. By the time data was submitted to CSU, 71% of the hollows had been monitored once within the monitoring period. Many of the externally mounted boxes were already established prior to this project, whilst the HollowHogs installation was largely funded by this program. For this reason, a higher proportion of the externally mounted boxes had been monitored with 79 % monitored, as compared with only 45% of the HollowHogs. Overall, 31 % of the monitored hollows were showed evidence of occupancy by vertebrate fauna. Gliders and Brush-tailed possums were the most common native vertebrate fauna found to be using the artificial hollows. Other vertebrates included bushrats, antechinus, microbats, amphibians, a green tree snake, owls, owlet nightjars and rosellas.
There were limitations to the analysis able to be undertaken, as while a template for data collection had been decided upon by the group, not all data fields were collected by most groups. Initial analysis showed no significant difference for total occupancy related to the severity of the fire, the distance to the burn area or the size of the patch that the artificial hollow was installed in. The strongest indicator of use was the number of days since the hollows had been installed, as the longer they had been in place, the more likely they were to be occupied.
Two criticisms often levelled at nest box programs, that the boxes only provide homes for common and aggressive natives, such as Brush-tailed possums or non-native pest species, were not found to be true in this program. Forty of the hollows monitored were found to be providing homes for native gliders (Sugar, Squirrel, Feathertail and other), and only 27 occupied by Brush-tailed possums. Only one hollow was occupied by a confirmed Indian Myna, and four by European Honey Bees. This may be attributed to the increase in knowledge and utilisation of detailed designs suitable for native species, the habitat surrounding the artificial hollows (including the availability of natural hollows), as well as better understanding of maintenance needs. Long-term monitoring and evaluation of artificial hollow use is essential to adaptive management.
This evaluation has shown that the remarkable effort of Landcare facilitators, Landcarers, arborists, inventers, knowledgeable advisors, landholders and ecologists has provided potential breeding sites and shelters for at least fifteen different species of native vertebrate fauna post-fire across the landscape of north-eastern New South Wales, with very infrequent use by invasive species. Like many collaborative ventures, developing a collective approach to evaluating artificial habitat use after fire was complicated. Challenges included the sheer numbers of participants, varying amounts of knowledge, interruptions from extreme events and the global pandemic, and the complexity of ecology research per se. A main finding was that it takes time for new artificial hollows to be used, and most were not used immediately after the fire. This finding reveals how important it is to plan for artificial habitat type and placement pre-fires, so that where possible some hollows remain available. It also emphasises the need for thinking innovatively about how to respond to wildlife disasters.