I don't know about migrants per se, but Great Horneds certainly wander.
Perhaps much of the wandering is undertaken by immature birds in their
first fall, common in most bird species. If so, the wandering is far
enough to get birds of different subspecies out of range. Robert
Dickerman, who has been studying specimens of GHOWs at museums for years,
says that the literature on subspecies in the group is quite confused
because of this. If you look at specimens only from spring, when most
wanderers presumably have gone home, the geographic variation becomes
clearer.

Some arctic GHOWs (Bubo virginianus subarcticus) move south in fall and
winter to the south of their breeding range; these are certainly migrants
in the same sense that our Snowy Owls are. There are lots of specimens of
these pale birds in museums. We just received a road kill from Skagit
County a few months ago. I've never seen one myself in nature; it would be
a thrill.

The race on the west side of Cascadia is B. v. saturatus, the darkest
subspecies. On the east side is B. v. lagophonus, but specimens of both
seem to turn up in the range of the other, so there really is a lot of
movement. In southeastern Oregon is another, considerably paler,
subspecies, which Dickerman told me hasn't been named. When we first
received specimens from Malheur I thought they were arctic GHOWs, but it
turns out they are the resident pale race, a bit darker than the arctic
birds.

Dennis Paulson, Director phone 206-756-3798
Slater Museum of Natural History fax 206-756-3352
University of Puget Sound e-mail dpaulson at ups.edu
Tacoma, WA 98416
web site: http://www.ups.edu/biology/museum/museum.html