One of several alternative theories for Snowy Owl irruptions
suggests that lack of snow may be a cause (suggested on
BIRDCHAT a few weeks ago). I wasn't quite clear on the
mechanisms, but weather conditions in Alaska do not seem
particularly harsh. The following item on CNN.com is
testimony to this.

http://www.cnn.com/2000/US/12/30/tundra.fire.ap/index.html

Large scale weather phenomena were suggested as a likely
cause of owl irruptions by KERLINGER et al. (1985. Distribution
and population fluctuations of wintering Snowy Owls (Nyctea
scandiaca) in North America. Canadian J. Zoo. 63:1829-1834.)
when statistical analysis failed to support the Lemming/Owl
connection.

--
Mike Patterson Alas, to wear the mantle of Galileo,
Astoria, OR it is not enough to be persecuted
celata at pacifier.com by an unkind establishment,
you must also be right.
---Robert Park
http://www.pacifier.com/~mpatters/bird/bird.html