The grouse story is the same for a number of states. Here we have far too many aging forests that need to be selective cut to produce understory. With the number of tree huggers in the state that will never happen. If you want to hunt ruffs like we did back in the 60's and 70's you need to visit to UP of Michigan or Wisconsin.
The last grouse I saw in NJ was late 1990s! As a teenager in the early 1980s, we would kick them up in the gap/stokes in the early am walk up to our treestanads in the dark, WOW what a rush when they flushed! !
I hope they rebound.
Also try Maine for them, late fall hunt, nice!