With fewer natural tree hollows around, you can help native wildlife by installing a nest box. Did you know that Australia has the world's most hollow-dependent wildlife? Tree hollows provide nesting, roosting, and shelter for a wide range of our cherished native creatures, including possums. It takes at least 80 years for trees to begin creating hollows, and over 300 years for a hollow large enough for a brushtail possum to inhabit. However, older trees are becoming more uncommon. Many trees have been cleared to make room for urban development or to be used for firewood, or removed if the potential of falling branches poses a risk to public safety. Possum boxes are significant because they provide possums with a place to reside and a habitat.