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Re: Point of brooding is...



>I am not arguing for or against his position.  Remiges may or may not have
>evolved to enhance the retention of heat which, as you say, is delivered
>by a sometimes naked brood patch.  But feathers are not necessary for
>brooding--except in extreme environments, eg., Antarctica.  And, inasmuch
>as there may be a cost associated with their possession--enrgy to grow
>them, parasites living in them, excess baggage for speedy running, one
>would think there would be easier ways in equable climates to maintain a
>constant microenvironment.

Agreed.

>What I was arguing was your statement that if they were advantageous to
>brooding, then other non-flying egglaying animals would grow them.  I
>don't think you can say that unless the animals in question are warm
>blooded, since the presumed advantage would be to retain heat.  And with
>few exceptions, birds are it.  I was amused at the prospect of feathered
>turtles.  And so I asked which animals you meant?

Well, that was not precisely my point, though I had forgotten about the
monotremes.  My point was that if remiges were so essential to brooding
flightless birds would retain them.  Among the large open-country ratites,
for example, I would have expected to see large wing feathers retained by
rheas and emus as well as by ostriches; their nesting behaviour has many
similarities.  However, they have been lost or all but lost in these birds,
and the ostrich, which does retain them, uses them in display (whatever the
actual reason for their retention may have been).

--
Ronald I. Orenstein                           Phone: (905) 820-7886
International Wildlife Coalition              Fax/Modem: (905) 569-0116
1825 Shady Creek Court                 
Mississauga, Ontario, Canada L5L 3W2          mailto:ornstn@home.com