At 07:23 5/05/99 +1000, you wrote:
>OK, we have had descriptions of birds' respiratory system, including one
>sent to me personally by a US correspondent, who very kindly also scanned a
>page from one of those 'basic biology texts' that Philip V* quite rightly
>said we should all have consulted first (:-)).
>
>However there is still a question unanswered: someone has written saying
>more or less that birds breathe many times faster than their wings beat, so
>any vocalisation
>should be independent, but someone else has stated that the wing-beats are
>the mechanism that drives air through the system. Which is correct?
>
>John Leonard
>
>
John
As I understand it, wing beats are not the ONLY mechanism that moves
air through the system.
Birds lack a diaphragm and, at rest, external respiration, (the movement of
air in and out of the air sacs), is produced by movements
of the ribs and sternum using the intercostal muscles, which change the
volume of the thoracic cavity, as in mammals.
In flight, I'm sure that the wing beats would assist in respiration although
not necessarily in a 1:1 ratio. I can't find any good info on how ribs/sternum
and the wings are related in producing air flow.
I suspect we've still a lot to find out in this field
Peter Woodall
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