Many species of birds throughout the world use tree hollows for nesting and protection. Birds build nests in a cavity in a hollow tree to avoid ground predators.
Only old, mature trees have hollows. Openings range from as small as 2 centimetres (almost one inch) to as large as 75 centimetres (29 inches). The depth ranges from 10 centimetres (4 inches) to several metres.
Medium-sized hollows are useful for parrots and larger-sized hollows are useful for owls.
Some birds like hollow cavities in tree trunks (called knot holes), while other birds like sloping hollow spouts, or hollows in fallen logs or tree stumps.
Birds renovate the hollow cavity with their beaks, teeth, or claws, to make it suitable for a nest.
Some birds that use hollow tree cavities as nests include barbets, cockatoos, ducks, hornbills, kingfishers, owls, parrots, rosellas, trogons, and woodpeckers.
Photographer: Martina Nicolls
Martina Nicolls: SIMILAR BUT DIFFERENT IN THE ANIMAL KINGDOM