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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 

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.