I have scan the graph presented in:

KERLINGER, P, M.R.Lein and B.J. SEVICK. 1985. Distribution and
population fluctuations of wintering Snowy Owls (Nyctea scandiaca)
in North America. Can J. Zool. 63:1829-1834.

Which discusses Snowy Owls on Christmas Bird Counts throughout
North America as well as an abstract of the article on the
Snowy Owl trend page at:
http://home.pacifier.com/~mpatters/cbc/snow.html

--
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