Mike Patterson wrote:

>From this I can tell you that most migrants migrate in flocks the evidence
>beint that I catch birds in waves. I can go one step further many of these
>flocks are same sex waves. Wilsons Warbler for example show a two week
>difference in male arrivalsbefore female.
>I have seen same species flocks of the following:
>
(etc.)
>
>I don't think this should be a particularly surprising revelation. The
>neotropical migrants of this group feed in substatial bird parties on their
>tropical wintering grounds. They would have similar tastes in stopover
>sites and benefit from the safety in numbers advantage of flocking.


I may not have made it clear that I was writing about *nocturnal*
migration, not just the moving through the landscape that birds do while
they forage and that is often in the direction of their normal migration.
It makes all the sense in the world for birds to flock (lots of literature
on that), but it's hard for me to imagine a tight little flock of one
species of warbler moving through the sky at 1,000 meters or so. I was
wondering if Yellow-rumps, which so obviously flock when on the ground, do
so when in the sky. We have no idea, but I'll bet some of the raw data
from TV-tower mortality might shed some light.

Dennis Paulson, Director phone: (206) 756-3798
Slater Museum of Natural History fax: (206) 756-3352
University of Puget Sound e-mail: dpaulson at ups.edu
Tacoma, WA 98416