My wife and I enjoyed a day trip to the farmlands east of Ellensburg this
past Saturday. The legendary winter fogs had lifted, and it was a nice,
sunny day.

We noticed what appeared to be a strong correlation between bird abundance
and hoar frost. The frost, which I understand is caused by fog freezing on
trees and other objects, was quite heavy around Ellensburg and for about two
miles to the east; beyond that point there was little or no hoar frost.

In those areas with heavy frost (and presumably recent heavy fog) birds were
very scarce; only an occasional flock of starlings or blackbirds. We
checked out some very nice habitat in the frost areas and found almost no
birds. But beyond the frost areas there were reasonably good numbers of
birds, including hawks, falcons, eagles, owls, goldfinches, and most of the
other regular winter species.

Question: Do birds tend to avoid foggy and/or hoar frost areas? I've not
heard any discussion on this topic.

Dave Nunnallee
dnun461 at ecy.wa.gov
Bellevue, WA