Linked from
The 10 pages that link to Tree hollow, each with the reason it gives.
Nest boxCompared with: It is the natural cavity most commonly imitated by a nest box.
Tree squirrelRelated: Some tree squirrels nest in cavities instead of constructing exposed dreys.
HylonomusRelated: Hylonomus remains accumulated in hollow stumps that were buried by sediment.
PollardingRelated: Old pollard heads can develop cavities that shelter wildlife.
River red gumRelated: Old river red gums develop hollows used by birds, mammals, and reptiles.
Carpenter antRelated: Tree hollows can provide protected nest sites for carpenter ant colonies.
Gouldian finchRelated: Gouldian finches nest in hollows, often in eucalypts.
Owlet-nightjarRelated: Owlet-nightjars commonly roost and nest in cavities.