CASSOWARY CRESTS REVISITED

[darren.naish@port.ac.uk]

Lizardlips (??) wrote (unfortunately the text was kind of written 
lengthways across the screen and thus hard to follow.. I know nothing 
about computers and thus don't understand why some texts do this.. 
but anyway)...

> In an earlier posting, Darren Naish commented on the uses of the 
> crest or casque of the cassowary. I would be grateful for any 
> references to the statement that 'cassowaries use their crests 
> as tools when foraging in soil and leaf  litter' or 'as foliage deflectors'.  

Check out general reviews of bird biology: HBW (_The Handbook to 
the Birds of the World, Vol. 1_) is a good place to start, Perrins 
and Middleton is good too. Both refer to observations where 
cassowaries have been seen to use the crest as a digging tool.

Use of crests as foliage deflectors is, as I think I said last time I 
mentioned this, speculative. However, please understand the context. 
One should not imagine an enraged, speeding cassowary ploughing 
headlong through the rainforest, robustly swatting aside all branches 
and other obstacles that invade its path. Those informed in 
dinosaurological matters may have gleaned this impression given what 
has been written (in Norman) about proposed functions of 
lambeosaurine crests. A _Parasaurolophus_ that whacks a branch with 
its crest is probably a _Parasaurolophus_ with a broken crest.

What instead may occur is that, when reaching through foliage to 
pluck fruits or reach objects on the forest floor, the bird pushes 
foliage aside with the crest, much as we would do with one hand when 
reaching a desired object with the other. It is of incidental 
interest that Wellnhofer and Kellner proposed the same behaviour for 
tapejarids, which they interpreted as frugivorous (more recent 
interpretations do not support this theory). 

I think Lizardlips also wrote something about breakage of the crest 
and this being in correlation with a life in captivity. Please 
re-send this bit of the message as it seems to have gotten lost when 
I re-formatted the text. 

However, above all I think display is the primary function of the 
cassowary crest given that it is only fully developed in sexually 
mature birds, plus it differs in morphology between species (e.g. 
_C. bennetti_ has a low, mound-like* crest as opposed to the tall, 
laterally compressed crests of _C. unappendiculatus_ and _C. 
casuarius_). I cannot verify that females have bigger crests.

*A Gauthieresque term

"Reflect on your significance while resting in the shadow of a large 
carnivore"

DARREN NAISH
darren.naish@port.ac.uk