> 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 :)

Sooo....one human culture's influence may have slowed Wesward movement,
while another speeds it back up...?

Steve Mansfield steve at nwnet.net
NorthWestNet Network Engineer 425-649-7467