Hello Dan - I did a search at the Birder's Dashboard for Washington
(choosing the whole state and then "look for a species") for sightings
of White-tailed Ptarmigan during the last 30 days.

It shows three sightings reported to eBird: One at Mt Rainier - Paradise
(Alan Knue), one at Mt Rainier - Sunrise (Chris Warlow), and one at
Snoqualmie Mountain (Adrian Lee).

The Dashboard does not go back beyond 30 days, but you could go directly
to ebird.org and look for earlier sightings.

The Dashboard is at: http://birdingwashington.info/dashboard/wa/

Jane Hadley
Seattle, Wa