Had a pair of Barred Owls calling very persistently near mid-day in
that area a few years ago. One was in a tree right by the path going
west out of the clearing about 200 ft. south of your marker, so it was
possible to triangulate on it by walking back and forth. AMAZING how
hard it was to see in the shadow of another branch even though it was
not actually screened by anything, from less than 10 yards away.

Monday morning we did a very short walk near the visitors' center, and
had a few birds, and a chipmunk eating blackberries, along the route
marked here (if it worked). This area is largely surrounded by higher
ground, so it was nearly calm and quiet, except for crows that may
have found a hawk, guessing from their racket. The area north of the
north parking lot is probably a better overall birding area (pond for
ducks, and I've seen woodpeckers and Varied Thrush there) but this
spot seems to worth a look. Maybe it was just a slow day, but there
was no one else around there.
http://maps.google.com/maps/ms?ie=UTF&msa=0&msid=
102518646865414635991.0004734df3153bc862f4e

Mike Wagenbach
Seattle