In response to the posting from BIRDCHAT by Joe Morlan on the speeds at
which birds fly, I agree with him that there has been a lot of
misinformation about bird flight speeds. However, I think he did an
injustice by dismissing swifts as slow fliers. He cited foraging and
migrating flight speeds as 6.5-11m/s or 23-40 km/h (13-24 mph) in the
Common Swift, which is a large species not too different from our Black
Swift. I'm sorry that he wrote no more, as I think anyone who has watched
swifts in flight feels they can fly considerably faster. I have stood on
cliffs and watched White-throated Swifts approaching from a distance that
then passed me at a speed that left me breathless, and I have had similar
experiences with White-throated Needletails in Siberia. Whatever their
speeds, I thought these birds were going far faster than 25 mph; in other
words, I thought they passed through considerably more than 11 meters of
air in a second. However, I had no way to measure the speed, and, as
someone attempting to look at the world from a scientific basis, I know my
'gut feeling' doesn't carry much weight. It is time for someone to clock
those speedy Frenchman Coulee White-throats!

Morlan's eider example tells us that birds with heavier wing loadings
should be high-speed fliers, as they should have to fly faster to stay in
the air, while swifts are so aerodynamic that they can stay aloft at slower
speeds. That doesn't mean that they can't fly fast, however.

Swifts have evolved their long wings for effortless gliding flight, but
when one thinks about swift biology, one realizes that long-distance
*rapid* flying is an adaptation for a swift for which there should have
been strong selection. Black Swifts that nest high in the Cascades forage
over Lake Washington, 50 miles away, on cloudy summer days here, and there
should be a premium on getting down here fast and getting back to the nest
fast, much faster than a four-hour round trip.

Dennis Paulson
dpaulson at ups.edu