Why old trees are so important for endangered woodland birds

We're reliant on rot developing within a tree, and that usually involves some sort of injury to the tree, like a branch snapping off, or some fire damage, or something like that. So it takes time for these hollows to form. Young trees just don't have hollows in them.

So for Forty Spotted-Pardalotes, for example, the problem is that there's not a lot of Old Growth Eucalyptus viminalis - White Gum – left around. Most of it is regrowth so there's not a lot of hollows in the sorts of forests that Forty Spotted Pardalotes are foraging in. White gums aren't very tolerant of fire, so when you get a fire go through a forest, it usually kills all of the white gums. So you get a lot of regrowth coming back - with lots of younger trees, but not very many older trees, so not many tree hollows in white gum forests. That is why nest boxes are really important tool for Forty Spotted Pardalotes.