Natural hollows can take over 100 years to form in trees. A hollow large enough for Powerful Owls may naturally take 300 years to form. Many Australian native animals need hollows to reproduce (42% of mammals, 17% of birds, and 28% of reptiles) so there is fierce competition for them.
Manmade “natural” hollows mimic natural hollows – they are concealed, well insulated and they don’t fall apart, unlike regular nest boxes which require maintenance when the bottoms and tops fall off. They are created by skilled arborists. The work is dangerous, carving trees with a chainsaw while hanging from ropes in a tree.
Initially an ecologist will assess the area to determine:
- the fauna active in the area and in need of help,
- the suitable dead trees or stags that are both tall enough and in good enough condition to be modified,
- the trees most suitable for the target species. Birds prefer clear access while mammals prefer vegetation in close proximity.
A skilled arborist will then create the hollow based on the ecologist’s recommendations. The wood is incredibly hard to cut. First, they must take off a thick slice of tree, then carve out the hollow, make a suitable access hole in the cover and finally replace and secure it with screws.
Natural hollows last considerably longer than regular boxes (which are known to lose their bases and tops after a few years of service).
Natural hollows are much better insulated and more inconspicuous to humans and predators alike, so native animals residents are less likely to be disturbed. If you didn’t know they were there, you’re unlikely to notice them.