Re: Island-dwelling dinosaurs (was Re: Gargantuavis neck vertebra)

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

On Wed, Jun 20th, 2012 at 12:31 PM, Tim Williams <tijawi@gmail.com> wrote:

> However, many island-dwelling birds lost the power of flight because
> of the absence of predators that would otherwise target them.  So it
> was the island habitat that fostered their loss of flight ability.
> Because flight was essentially the only defense they had,
> flightlessness left them highly exposed to the arrival of new
> predators.  The dodo typifies this quite well - iconically, in fact.

It may be that island fauna that evolves in the absence of terrestrial 
predators tend to be 
vulnerable to predation from introduced fauna due to a lack of a fear response 
to predators, rather 
than a lack of volancy specifically. Many volant island birds can be just as 
easy to catch due to 
them having no innate fear of predators.

Any non-volant bird that isn't a strict herbivore will tend to have at least 
enough cursorial 
adaptations to pursue prey (even if their prey are no larger than insects). If 
they live in the 
presence of aerial predators (gulls, skuas, etc) , then I would assume they 
also have the ability to 
conceal themselves in some way to avoid becoming 'sitting ducks'.

Having no instinctual flight response from terrestrial predators (flight as in 
'run away') may be 
more of a factor than a lack of volancy.

-- 
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Dann Pigdon
Spatial Data Analyst               Australian Dinosaurs
Melbourne, Australia               http://home.alphalink.com.au/~dannj
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