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Re: Altitude effects on hummingbird flight?
----- Original Message ----
From: jrc <email@example.com>
Sent: Thursday, December 21, 2006 11:04:58 AM
Subject: Re: Altitude effects on hummingbird flight?
----- Original Message -----
From: "don ohmes" <firstname.lastname@example.org>
Sent: Thursday, December 21, 2006 9:55 AM
Subject: Altitude effects on hummingbird flight?
> Hummingbirds are the largest observed species using hovering, a
> size-constrained locomotion;
No, a number of other, much larger birds use hovering -- but they do it by
means of a different technique, full momentum reversal (the flutter stroke).
You will see hawks doing it regularly while hunting, and they are for the
most part, larger than hummingbirds.
------------- Not as a primary form of locomotion, they don't. Especially in
still air. If you define "hovering" as "remaining stationary relative to the
ground", yeah, lots of stuff "hovers", especially in moving air. Perhaps I
should have said, "largest observed species using hovering as a primary form of
locomotion...", but as I was discussing evolutionary scenarios, I didn't think
it necessary. IIRC, Pennycuick says pigeons are about maximal for "hovering" in
_still air_, and that is momentary (less than 4 min), not primary. Unless it is
a functional bottleneck relative to ecology, it seems unlikely to control
> if some "un-related" group of similar size
> evolved hovering, it seems to me that a high degree of convergence
> would be expected.
There is another small african species that regularly hovers (I forget its
name), but it doesn't fly backwards and doesn't suppinate the wing to the
extent that hummingbirds do. Other, larger species hover by means of a very
different technique -- no convergence.
------------ No functional equivalence, no convergence. Not a primary form of
locomotion, no equivalence. The African species sounds interesting. On my list
of things to do.
> In either case, I wonder what could have knocked
> them out? Given that hummers occur in Alaska, it astonishes me that
> they never got a foothold in Asia. Anybody know got a clue?
Nope, not a clue. I'd expect 'em to spread as well. They are very good at
what they do.
------------- It all seems downright weird to me.