Ed and Tweeters,

There is definitely some evidence that migrating birds are arriving earlier
in the spring. I published a paper which showed that most species of birds
are arriving 2-3 days earlier in the Vancouver area than they did 30 years
ago. Other papers have shown the same thing in other areas.

However, there is no proof that this is due to global warming, especially
since bird migration is supposed to be controlled mostly by photoperiod, not
by temperatures or other climatic factors. A more convincing relationship to
global warming would be if someone showed that the breeding ranges of many
species are shifting farther northward. I think this could be proven, but
I?m not sure that anyone has yet shown it in a published paper.

Wayne C. Weber
Delta, BC
contopus at telus.net




From: tweeters-bounces at mailman1.u.washington.edu
[mailto:tweeters-bounces at mailman1.u.washington.edu] On Behalf Of Ed Swan
Sent: July-19-07 6:31 PM
To: tweeters
Subject: [Tweeters] Is there any data yet on birds and global warming in
North America?

I was wondering if anyone knew of any studies documenting the effects of
global warming on birds in North America, if any, and also anything for
Washington State.? Aren't some species arriving earlier than they used to in
the spring?? And is this global warming or something else?
?
Ed Swan
Vashon Island