bio

Tree hollow

A cavity in a trunk or limb where a bird nests, a possum sleeps, a bat roosts. Hollows are not excavated by animals: they are the product of a slow collaboration between wood-decay fungi, insects working the softened tissue, and mechanical injury from wind or lightning — and that collaboration takes a shocking amount of time. Small hollows begin forming at around 100 to 120 years; cavities large enough for a substantial vertebrate need 220 to 500 years or more. In Australian forests over 300 vertebrate species depend on hollows, with no substitute available.