There is a thread on here about this somewhere, there are a few different squirrels that you can shoot in this state.
http://wdfw.wa.gov/wlm/diversty/soc/wgraysquirrels/8. Protected Wildlife
It is illegal to hunt, kill, possess, or
control protected wildlife. Protected
wildlife are: Cascade golden-mantled
ground, golden mantled ground,
Washington ground, red, Douglas,
northern flying and western gray
squirrels;