Thank you all for your detailed and considered opinions on this observation.
Some comments:
. initially I did think the birds were probably listening for what dangers (reptilian, mammalian or avian) may be laying inside the nest box. However, I began to doubt this theory when I noticed how frequently the male head pressed the awning strut where he perches near the nest box.
. I searched through 'Australian Parrots' by Forshaw and Cooper but could find no reference to such behaviour.
. the nesting pair aggressively defend the nest area by chasing off, and attacking, other Eastern Rosellas which venture into our back yard to assess the nesting potential. They ignore other curious birds including the resident Kookaburra and Pied Currawongs.
. the rosellas certainly do have mite infestations. After 3 fledglings left the box last year I climbed up to open the box for inspection and was immediately covered with a swarm of tiny, biting mites. These parasites obviously breed up during incubation. They were not obvious after only 1 fledgling left the box the previous year.
If I can get some useful photographs of this behaviour I will attach them to a future email.
Again, thank you all for your interest and suggestions.
Geoff
