Thanks for remembering my previous posting Michael, I enjoyed your report!
I've changed the subject line in case I cause the thread to travel away from
the Grey Butcherbird.
Although I still have Grey Butcherbirds in my garden regularly (usually
lurking in the same tree) I've never heard mimicry again - but then I'm
often not here. Craig Morley reminded me that he published a similar
observation of a Grey Butcherbird in Eastern Park, Geelong, in the Geelong
Naturalist.
It is a puzzle to me - and, I find, to real ornithologists - why they do it.
When I was a beginner birdwatcher in Sydney I remember Alec Chisholm
collecting mimicry records; he maintained that the Chestnut-rumped Heathwren
was the best. There is a good discussion in J.D.Macdonald's Birds for
beginners: how birds live and behave (Reed,1980) including a paragraph
entitled "Mimicry perhaps functionless". He does not mention a theory I
have read somewhere else that predators mimic little birds so the little
birds will come up to see what is happening and the predator can grab them,
or they will lead the predator to their nest. We know this is not true of
our Grey Butcherbirds as ours mimic big birds.
Near Helidon (Southeast Queensland) yesterday 1 April we heard an
Olive-backed Oriole mimicking small birds - Weebill, Speckled Warbler,
Silvereye, White-browed Scrubwren, fairy-wren. It did not mimic any of the
numerous big birds also in the area. Orioles do take nestlings (HANZAB);
Red-backed Fairy-Wrens close by appeared to be taking food to a nest and
were certainly very nervous but we thought this was because of us.
After my March 2007 posting someone wrote who was studying Pied Butcherbird
vocalizations. Sorry I've lost your name but maybe by now you have a theory?
Margaret Cameron
2 Cintra Street
Eastern Heights, Qld
Australia 4305
07 3282 9151
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