I thought I would chase up Anthony's suggestion that Casuarinas may differ
from Allocasuarina in that seeds from the cones of the genus Casuarina
drop out every year, while the seeds from Allocasuarina stay in the cone
and drop out after a fire event or the like.
Our botanists here at work couldn't come up with an answer but Matt
Cameron, who is doing his PhD on Glossy Cockatoos in Goonoo State Forest,
was able to help. Who said birdos make lousy botanists?
Apparently, at least one species of Allocasuarina (don't ask me to
remember which one - I'm only a mug botanist) drops it's seed soon after
maturity. Glossies feed on this species but have a small window of
opportunity. Most other species retain there seeds for much longer (as
Anthony suggested). I can't tell you what Casuarinas do.
Glossies have not, as I previously suggested to Judie, been recorded
feeding on River Oak but there is a record of Glossies sitting in this
species but not seen feeding. This could well be coincidence.
It appears that Glossies do tend to feed more or less exclusively on
Allocasuarina, as HANZAB suggests, but Matt Cameron has an interesting
record of Glossies in Belah (Casuarina cristata). They were not seen
feeding however the ground was littered with chewings.
Judie Peet also asked, possibly not on birding-aus, whether other parrots
or cockatoos left chewings could be mistakenly attributed to Glossies. If
you know what you are looking for Glossy chewings are distinctive. Matt
Cameron was of the opinion that if other species decided that they were
onto a good thing there is no reason why they wouldn't create a mat of
chewings similar to Glossies. You would be able to tell the difference by
looking at the chewed cones themselves.
Hope that helps somewhat.
David Geering
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