We have lots of specimens of all the WA grouse in the Slater Museum, so I
have the good fortunate of being able to see all of them at once any time I
want, unlike a birder in the field. And I enjoy looking at them sufficiently
that I sometimes just browse in the collection.

Your bird is unquestionably a ptarmigan, as several have already said. Being
so far south, it surely must be a White-tailed, but, not only that, the
"cold," almost black and gray, look of it is characteristic, too. The other
two ptarmigan are much warmer brown.

It's easy for a summer ptarmigan to hide all of its white. Only the wings
and tail are white, and the latter is hidden by the long uppertail coverts.

Dennis Paulson
dpaulson at ups.edu