Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!ucsd!ucbvax!cs.utwente.nl!deby
From: deby@cs.utwente.nl (Rolf de By)
Newsgroups: rec.birds
Subject: Crossbill movements
Message-ID: <9011010807.AA24286@utis15.cs.utwente.nl>
Date: 1 Nov 90 08:07:21 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Lines: 21


I am wondering whether any of you knows some facts about Crossbill movements.
This year, we had quite a large influx of Crossbills from the north here in
Holland, and as I understand also in Denmark and the UK. Even some Parrot
Crossbills have reached Holland, although it's still unclear in what
numbers. Also, as I understand from some of the American Rare Bird postings
some movement of (Red) Crossbills has occurred in the USA. This induces the
question whether Crossbill movements are a global phenomenon.

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?


Rolf A. de By
Vakgroep Informatiesystemen			Tel   : (0)53--893753
Faculteit der Informatica			b.g.g.: (0)53--893690
Universiteit Twente				Fax   : (0)53--339605
Postbus 217, 7500 AE Enschede			Email : deby@cs.utwente.nl
The Netherlands						deby@henut5.bitnet