Across the Yass region, large old trees quietly provide some of our most important wildlife habitat. Hollows formed over decades, more over centuries, are essential nesting and shelter sites for birds, bats and mammals. As part of the HumeLink East transmission line project, some of these habitat trees need to be removed where they fall within the transmission line footprint.
To reduce the impact of this unavoidable loss, a comprehensive like-for-like hollow replacement program is underway, ensuring that wildlife continues to have safe places to live, breed and shelter.
Replacing Hollows, Like for Like
Under the guidance and supervision of project ecologists, hollow creation is occurring at a minimum one-to-one replacement, targeting the same species that previously relied on the removed trees. Importantly, at this site 30% of hollows are being installed or created ahead of tree removal, allowing animals the opportunity to relocate immediately rather than waiting until works are complete.
This proactive approach is particularly important for species that are highly dependent on specific hollow sizes and locations.
Recycling Natural Hollows
Large natural hollows removed from habitat trees are being carefully recycled and reinstalled in nearby suitable locations once works commence. This is especially critical for species such as cockatoos and owls, which have very specific nesting requirements that are difficult to replicate artificially.
In some partially cleared areas, trees containing hollows are being retained by removing only the tops of hollow-bearing trees. Where there is no conflict with the transmission lines, this allows valuable habitat to remain in place.
Nest Boxes for a Range of Species
A diverse mix of nest boxes has been installed to support the wide range of wildlife found in this landscape. These include:
- - Tiny microbat homes
- - Nest boxes for small birds
- - Glider and possum boxes
- - Large, over metre-long cockatoo boxes
Each nest box includes starter material, encouraging animals to bring in additional nesting material and establish their new homes more quickly.
Creating Hollows in Living Trees: The Hollow Hog Method
Where suitable large trees already exist nearby, hollows are being created directly into living trees using the Hollow Hog method. This involves carving an internal cavity and installing an appropriately sized entrance. Over time, the living tree naturally grows around the hollow, creating a long-lasting and natural habitat feature.
To be suitable for this method, trees must have a minimum diameter of 400 mm at installation height. Entry sizes vary depending on the target species, ranging from tiny microbat entrances to larger openings suitable for possums and cockatoos, using timber entry face plates.
Thoughtful Placement and Long-Term Monitoring
All hollows and nest boxes are installed with careful consideration of placement, including avoiding north-west to south-facing aspects to reduce heat stress and exposure. An that the number, aspect and location of entrances are well considered for the wildlife intended to use them.
These new homes will be monitored over several years, tracking which species use them and assessing the long-term success of the installations. This monitoring will help inform future habitat replacement projects across the region.
Supporting Wildlife Into the Future
In this area, hollow creation is catering for cockatoos, owls, gliders, bats, small birds, possums and other small marsupials, helping ensure that the region’s wildlife continues to thrive despite necessary infrastructure development.
We look forward to hearing how this major relocation of birds and animals unfolds over the coming years, and to sharing updates as monitoring results emerge.
