Re: BEAKS, CASQUES & KINESIS

[Dann Pigdon <dannj@alphalink.com.au>]

Ronald Orenstein wrote:
> 
> Keas are highly opportunistic and adaptable birds.  However, they certainly
> did not evolve their rather unique bill shape to deal with sheep (or
> cars!); before the advent of sheep farmers keas were apparently vegetarian.

I've seen footage of them going down mutton bird (sheer water) burrows to get at
the chicks. It's something of a communal effort. They seem to listen at the
burrow entrance, and if they detect a chick one of them goes in and drags it out
into the open. I believe the footage was part of the "Life of Birds" series. I
wouldn't be surprised if Keas have always taken advantage of the seasonal
abundance of mutton bird chicks.

On Chapel Island, in Bass Strait south of the Australian mainland, a giant
species of tiger snake has also evolved to eat mutton bird chicks. Apparently
they evolved into a larger form than their mainland cousins in order to stuff
themselves full of chicks for about two months of the year, then fast for the
remaining ten months or so.

Then there are the deer that live on islands in the Mediterranean that eat bird
chicks to supplement their diet. I'm beginning to suspect that island dwelling
species of all kinds may occasionally adapt to eating something their relatives
usually wouldn't in order to supplement a diet poor in certain nutrients. Such
adaptive responses were probably also present amongst dinosaur species. It has
been suggested that Muttaburrasaurus may have been partially carnivorous.
Perhaps even ceratopians occasionally took advantage of a carcass - they
certainly had the beaks and dental equipment for it.

-- 
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        Dann Pigdon
        GIS Archaeologist
        Melbourne, Australia

        Australian Dinosaurs:
        http://www.alphalink.com.au/~dannj
        http://www.geocities.com/capecanaveral/4459/
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