Glossy Black Cockatoo musings

To: "Paul Burcher" <>, "Greg & Val Clancy" <>, "Birding Aus" <>
Subject: Glossy Black Cockatoo musings
From: Carol Probets <>
Date: Fri, 4 Apr 2008 15:30:09 +1000
Greg and all,

There was a fairly long discussion around these questions in March 2002 - should be in the Birding-Aus archives. Apparently HANZAB mentions Glossies feeding on the seeds of Swamp Oak (C. glauca) but this seems to be only a rare thing. Looking at measurements of the seed cones, River Oak has the smallest cones, Swamp Oak a little larger, and slightly larger again (but smaller than other Allocasuarinas) is A. diminuta which the Glossies feed on in the Dubbo area. However, the late Judie Peet suggested that it's not the cones that are too small for the glossies, but the seeds. She wrote: "River Oak seeds are really tiny, less than 1/2 the size of A.diminuta seeds which come from a cone of only about 10mm long. Getting at River Oak seeds would be a lot of energy output for little return."

Judie also observed that Dubbo Glossies differ from Glossies in other areas by holding the cones at the stem end when feeding (as opposed to the distal end). She had a theory this habit developed in response to having to feed on the tiny cones of A. diminuta.

One of the main distinguishing features between Casuarina and Allocasuarina is in fact the seeds, which are dull and pale in Cas., black and shiny in Allocas. Red-browed Finches often feed on the seeds of River Oak (Cas. cunninghamiana). I suspect Judie was right about the size of the seeds.



At 7:49 PM +1100 3/4/08, Paul Burcher wrote:

I think the fruits (?and hence the seeds) are too small. Also swamp oaks grow on very poor saline soil so the nutrients are pretty low. Similarly River Oaks grow on recent alluvium which also may be poor. There is some paper somewhere about them choosing those fruits with amongst their locally favoured Allocasuarinas that have a higher nutrient content.


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