Around 42% of Australian mammals, 28% of Australian reptiles and 17% of Australian birds make use of tree hollows. Many of our listed ‘threatened’ species must have tree hollows for their survival. The loss of hollow bearing trees from Victorian native forests is listed as a Potentially Threatening Process under the Flora and Fauna Guarantee Act 1988. The continuing net loss of hollow-bearing trees in native forests and woodlands due to firewood harvesting practices has been nominated and recommended for listing as a Key Threatening Process under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999.
Hollow logs on the ground are equally important for ground-dwelling animals such as the Echidna and many lizards and reptiles. Wombats and Bandicoots will occasionally use a hollow log for refuge.
It can take hundreds of years for a tree to form a medium hollow suitable for a bird or possum. Hollows develop in Australian trees largely as a result of natural branch shedding and damage by wind, lightning, fungi and wood-boring insects, particularly termites. Fire can accelerate this damage, but it can also accelerate the deterioration and collapse of existing hollow trees.
Some tree species readily produce hollows such as Red Gums, Mountain Grey Gums and Manna Gums.
The loss of hollow-bearing trees occurs primarily as a result of clearing for agriculture and urban development. A large, isolated old tree in a paddock may represent an important remnant of a native forest and is most likely providing habitat for numerous mammals, reptiles, birds and insects.