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Re: Thread of Ptero size thread

Dilettante hummingbird watcher--speedy dashes to run off other hummingbirds
who dare trespass on their bee balm (type of flower) territory. They seem to
stake a claim to 40 foot cubed area (est) and patrol it with a vengeance.
Too fast for me to tell if they are changing their flight aspect (word?).
Scott Perry
----- Original Message ----- 
From: "don ohmes" <d_ohmes@yahoo.com>
To: <dinosaur@usc.edu>
Sent: Sunday, December 17, 2006 3:00 PM
Subject: Thread of Ptero size thread

> Lots of stuff in the ptero size thread I'd like to get into further; I may
recompile later in the week. But for right now, and feel free to take your
> "Interesting, I did not realize they shifted to a standard kinematic;
> that would seem difficult.  If you have a reference, I'd be very
> interested in reading it.  In any case, the flapping-style hummingbird
> would be proportionately more affected because of small size.  Since
> hummingbirds cannot adjust planform, it would also be more constrained
> in that regard."  --MH
> OK. This is personal observation, and I have no written reference.
Watching hummingbirds over the years I seen them fly (or thought I've seen)
what appears to be forward flight fairly frequently. I see this as they move
from active foraging to perch, as they do periodically during the day,
presumably to rest. Looked a lot like burst-flapping to me, complete w/
characteristic non-hovering sound pattern. This is usually a short distance
so you have to watch closely. I grant you I wasn't paying attention in the
sense of taking observations; I just like to watch them hover, and am always
disappointed when they stop. That said--
> It follows from what you say that 1) they _hover_ when migrating across
the Gulf of Mexico, 2) they use less energy hovering than level flap-flying
(if they can), and 3) the hovering failure density is indeed lower than
their flapping failure density. Can you confirm? Got refs /obs on migration
flight style?
> Also any hummingbird watchers out there?
> Personally, I would have thought that 1) the (minimum) size constraint in
hummingbirds would be from thermal relations rather than flight, 2) although
their maximum size is currently constrained by hovering, they would
essentially be unconstrained in the sense of evolutionary potential relative
to flapping flight; indeed free to evolve to whatever max bird size
potential is, if they shift gears to soaring flight.
> Don