At 06:07 AM 10/11/97 -0700, you wrote:

>But it really isn't that simple. My understanding is that Blue Jays are
>moving west because of human modification of the Great Plains by planting
>trees for windbreaks and the like. So it is "natural" in the sense that
>they a flying rather than being transported; but they are flying from one
>human-produced patch of landscape to the next and thus leapfrogging across
>what was previously a "natural" barrier.

And, of course, even that "natural" barrier was subjected to periodic burning
by Native Americans :)



- Don Baccus, Portland OR <donb at rational.com>
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