Subject: Swift Flight
Date: Aug 7 08:16:28 2002
From: Rick Howie - rick.howie at shaw.ca
Good morning Tweeters:
The discussion on swift swifts is quite interesting as usual.
I agree with others that the density of the air is probably not a
significant factor in their flight speed. I have watched swallows at low
elevations demonstrate surprisingly different, or apparently different,
flight speeds under different circumstances.
My thoughts at those times, were that the flight behavior related to the
prey that they were foraging on. On one occasion, I watched a flock of
hundreds of mixed Bank & Rough-winged (mostly Bank) foraging as a tightly
knit flock. They would bank and wheel high over the marsh and then swoop low
over the water, only to turn and streak over the tops of the cattails and
then rise again into a loose group to forage more casually hundreds of feet
in the air. Then they would regroup and scream like a squadron of F-16s to
within metres of the pond as hordes of mosquitoes were hatching.
Flight speeds varied widely during all of these manoeuvers.
I think that swifts have the ability, like all birds, to really turn it on
when they need to, or can enjoy a more leisurely, energy-saving flight
(relatively speaking), when their prey items allow them to do so. Perhaps
too, they get into a fast-paced feeding frenzy when there is a lot of food
around. If prey density is lower, they may move more slowly in an
energy-conserving search mode until they find something to grab.
As appealing as it may be to think that I could run like Carl Lewis at high
altitudes because of the the thin air, I don't think it is going to happen.
But I know that I often walk a little faster up there just because such
places are so exciting to wander in. !
Rick Howie
Kamloops, BC
rick.howie at shaw.ca