>Hi Tweets
>
>Just one of those idle queries:
>
>if the southbound migration begins about June 21 and is better than 75% over
>by September 21, why do we call it the 'fall' migration?
>
>Michael Price

Here's one of those idle answers: because in the Line Islands, in mid
Pacific, the peak of shorebird migration falls on September 21. All
ornithological terms are supposed to come from as close to the
International Date Line as possible, according to my careful research.

Or, and I seem to remember reading about this somewhere, it may be that the
terms "spring" and "fall" originated from the concept that birds sprang
northward with great vigor before the breeding season, but afterward were
sufficiently drained that they merely fell back toward the Equator. I
think a combination of gravity and the Coriolis force came into play here.

Alternatively, we could just call it "northbound" and "southbound"
migration, but then the Chileans and Australians would get hopelessly
confused.

Or "prebreeding"and "postbreeding" migration, and then its direction or its
season wouldn't matter one whit (speaking of Swainson's Thrushes).

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