Feathers vs Wingspan (was: postulated bird/pterosaur competition...)

[philidor11@snet.net]

If I understand you correctly, whether the situation arose because 
of the inherent limits of feathers (much as chitin limits the 
size of some insects) or because competition caused birds to 
adapt to the role of small, quick flyers or both, there's a limit 
to how big a bird with a lot of feathers can be.
Assume that there is an ecological niche available for big flyers 
and that many heavy feathers are not required for a very large 
animal to fly; the pterosaurs appear to demonstrate these assertions. 
 Naive question:  wouldn't a bird with fewer feathers be able 
to increase its size, particularly wingspan successfully and 
so move into an available niche?  Are there other adaptations 
in all birds that would prevent them from relying less on feathers 
as a strategy?
Glad I'm asking someone who does know the technical requirements 
for flight strategies.

= = = Original message = = =

I don't see the contradiction.  I think there may well be an 
inate structural
limit for the size/weight ratio of feathers that limits how long 
they can be in
a flying bird.  This would act to limit the bird's wingspan. 
 That has nothing
to do with the seperate issue of comptetion (which I don't feel 
strongly about
anyway).  Even for a smaller bird the size of an eagle, the feathers 
are
reported to weigh about twice as much as the skeleton.  But note 
that in all
fairness, this is an area that I'm not terribly interested in 
and haven't given
much thought.



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