Grouse are here year round they dont migrate like other birds, also if you don't see any grouse its just cause they camouflaged to well and you didn't flush em!
Try your luck walking gravel/dirt roads and trails with thick near by brush, they need the gravel to digest food they use rocks to grind food in their gizzard so often times are found right on the road and dont spook till you're close...depending on the WMU im in i will often carry a light .22 cal air pistol (under 500fps) and ive dropped over a half a dozen so far this season with it alone while out for deer and coulda had over a dozen more had i actually had it on me...would also probably work on a rabbit