Cavity selection for roosting, and roosting ecology of forest‐dwelling Australian Owlet‐nightjars (Aegotheles cristatus)

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Abstract
We compared a variety of attributes of tree cavities used for roosting by radio‐tagged Australian Owlet‐nightjars Aegotheles cristatus with randomly chosen prospective cavities to test which features are important for the species. Owlet‐nightjars preferentially roosted in tree cavities closer to the ground, in trees with a significantly greater number of cavities and significantly closer to another tree with a cavity than expected by chance. There was also a significant interaction between cavity height and number of cavities in the tree. Tree size, decay stage and tree species were not statistically important cues used for making site choices. The requirements for Owlet‐nightjars differ from those of most other Australian birds that use tree holes and also from most insectivorous bats. Telemetry data indicate that Owlet‐nightjars move ∼300 m between roost sites every 9 days on average. Individual birds used 2‐6 different cavities during the 1–4‐month period over which they were followed. The reasons for the relatively low levels of site fidelity are unknown.