Do you know the painting "The Scream" ? This tree reminds me of it. The tree hollow ( hole in the trunk ) is a valuable wildlife home that can be used for many Birds and other animals as a shelter and breeding spot. Trees that have hollows are not too common, and good hollows are fought over. Trees with hollows are usually quite old and have been the subject of Bushfires and lightening strikes, or have suffered damage by some means , which is the catalyst for the hollow to start to form.
There is a long list of wildlife that require hollows to breed in they include Bats , Owls, Possums, Gliders, Parrots, Antechinus. Ducks, Rosellas, Kookaburras, Kingfishers, Snakes, Frogs, and numerous types of Reptiles. Where possible, old dead trees should be retained on land as they are also valuable wildlife habitat and can have numerous hollows. 
