Dennis and others,

I would be interested in your opinion on a theory that I have about Snowy Owl irruptions.

I think there may be a very strong correlation between Snowy Owl irruptions and the lows of the solar cycle (which I first got this idea and starting digging into it, I predicted it would be the opposite).

If you consider these days of indisputable Snowy Owl irruptions: 1955, 1966, 1973, 1977, 1984, 1996, 2005

and compare these dates to solar cycle charts like this one:

http://www.spacew.com/swim/bigstorm.html

you will see that major irruptions seem to be corresponding to the lows in these cycles... and I don't see any major irruptions at the highs of the cycle.

This makes some sense to me in terms of the effect solar wind can have on the Earth's electromagnetic fields if the Snowy Owls (and others that irrupt like Great Gray Owls) use this for navigation.

Cindy Ashy

--- On Mon, 12/12/11, Dennis Paulson <dennispaulson at comcast.net> wrote:

From: Dennis Paulson <dennispaulson at comcast.net>
Subject: [Tweeters] Snowy Owl migration
To: "TWEETERS tweeters" <tweeters at u.washington.edu>
Date: Monday, December 12, 2011, 1:57 PM
The way I see it, lemming abundance may influence the owls in two very different ways. First, lemming population crashes may cause the owls to seek new wintering areas, as their food supply is insufficient. But second, lemming population highs may produce very successful breeding, and the large number of offspring may then have to disperse farther to avoid competition with the adults and with each other (there are again too many of them for the current rodent populations). In the first case, the owl populations may be stressed, while in the second case they are doing very well.
Unfortunately, no one has been able to reject either of these hypotheses, and of course something else altogether might be involved, for example, weather patterns.?I can see nothing in the data so far available that points to any effects of global climate disruption (aka global warming) on Snowy Owls. They are able to go wherever there is open country and microtine rodents.