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Re: mammal mystery



John Bois writes:

>Would that I could spend time in Brazilian thickets.  In the meantime I
>note the relatively few species which live in thickets and are flightless
>(as non-avian dinosaurs were).  The kiwi is an exception-and I needn't
>explain its survival.  Rails are not flightless are they. 

A number of rails ARE flightless, yes.  These include small-island forms
but also some fairly good-sized birds on islands like New Guinea and
Tasmania that certainly have predators capable of eating them.  Also many
of the flighted rails are VERY reluctant to fly and much prefer to escape
on the ground, flying only as a last resort.

 They can fly
>away from a low to the ground predator.  Surely if they were as "good" as
>the others in this niche they would lose their wings.  After all, it is
>expensive to fly (I claim this is demonstrated by the apparent rapidity
>with which flightlessness occurs on predatorless island species).

Remember that some rails are migratory, and probably have retained flight
for that purpose.  They do NOT fly much in their normal round of
activities.  Also, NO known bird (even kiwis) has completely lost all wing
elements as a consequence of flightlessness.

>Further, I say that the four legs are better at getting through what must
>be, in a tangled thicket, a series of hoops.  It means landing on your
>feet instead of your beak.  Otherwise, how to explain the great lack of
>bipeds (without wings, now, since wings provide means
>of escape) in the tangled thickets?

In a tangled thicket wings are a lousy means of escape - much better to
creep away on foot, as most terrestrial birds of such habitats do - and
they are damned good at it.  I really think you should brush up on the
natural history of such birds before making such pronouncements - what you
say about bird locomotion is simply not true.
--
Ronald I. Orenstein                           Phone: (905) 820-7886
International Wildlife Coalition              Fax/Modem: (905) 569-0116
1825 Shady Creek Court                 
Mississauga, Ontario, Canada L5L 3W2          Internet: ornstn@inforamp.net