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From: stpeters@dawn.crd.ge.com (Dick St.Peters)
Newsgroups: rec.birds
Subject: Re: Crossbill movements
Message-ID: <13392@crdgw1.crd.ge.com>
Date: 3 Nov 90 21:56:52 GMT
References: <9011010807.AA24286@utis15.cs.utwente.nl>
Sender: news@crdgw1.crd.ge.com
Reply-To: stpeters@dawn.crd.ge.com (Dick St.Peters)
Organization: GE Corporate R&D, Schenectady, NY
Lines: 17
Disclaimer: GE would charge for its opinions.  These are mine.

In article <9011010807.AA24286@utis15.cs.utwente.nl> deby@cs.utwente.nl (Rolf de By) writes:
>As I have always understood it, Crossbills start moving due to food (i.e., 
>spruce) shortages. I know little of trees in general, but to me it seems
>unlikely that all spruce forests in the northern hemisphere suffer from
>a bad year. Anyone?

Spruce are especially vulnerable to either acid rain or some common
form of air pollution - I can't remember which (same thing anyway,
really).  They've been taking ill and dying all over this neck of the
woods (upstate NY, New England), and I've heard the same about
Canadian spruce forests.  I haven't heard anything about this last
year being especially bad; all recent years have been bad.

Spruce and sugar maples seem to be among the first to go.
--
Dick St.Peters, GE Corporate R&D, Schenectady, NY
stpeters@dawn.crd.ge.com	uunet!dawn.crd.ge.com!stpeters