Some of you native Washingtonians may want to elaborate a little more, but on pg. 19 of the regs under "Protected Wildlife", it states that it is illegal to hunt, kill, possess, or control protected wildlife. Washington ground, red, Douglas, northern flying, and western gray squirrels are all on the list. Unless you are able to positively distinguish between whatever tree rats are running around these parts, I'd say don't hunt them. Besides, the ones I've come across aren't big enough to make into a decent mess of squirrel dumplings unless they are in a park.