The issue

The 2019/2020 bushfires has resulted in significant losses of old growth forest and habitat structure and complexity in the Upper Shoalhaven Region. Over 300 of our native species in Australia use tree hollows. Of these, 114 or 15% of our native bird species use tree hollows, the majority for nesting purposes. Some bird species, including Masked Owls, Sooty Owls, Australian Owlet-Nightjars and White-Throated Treecreepers also roost in tree hollows year-round. Native mammals are also heavily dependent on tree hollows, for sleeping during the day or to raise offspring. Of Australian native mammals, 83 species or 31% use tree hollows. These include bats, possums, gliders, and ground-dwelling mammals that climb such as quolls, native rats, dunnarts, phascogales, cuscus, numbats and antechinus. Different species have their own hollow specifications, and will not for example make nests in hollows they consider to be unsuitable. Hollows generally need to be within reach on foot or by wing, of food or water sources to be of use. Many animals will also only choose hollows that are sufficiently small to prevent a predator or more dominant tree hollow competitor from entering.

Studies have found that hollow using species are initially absent from badly burnt ecosystems (0-15yrs), and when they do return, are in very small numbers compared to pre-fire populations - studied from memory out to 50 years. Tree hollows take decades  (tiny) to hundreds (large) of years to form. So there is a very big need for artificial tree hollows to be added to the huge areas of bushfire-affected ecosystems