Steve:
I don't know what the cover is like north of Duluth, but I gather it is similar to the western Upper Peninsula. I use dogs so I can't speak to the success of four wheel hunting, or trying to walk them up.
If I was going to hunt without dogs I would find two tracks, swamp edges or trails to hike. If moving through the cover I would also change directions and stop frequently. Grouse move away from danger on a 45 degree angle, so you need to outflank them so to speak. Stopping will frequently make them nervous, because they no longer know where the danger is.
As the food sources change so do the prime locations for late season grouse. In the U.P. that means the buds of Ironwood trees, aspen buds and what wild strawberry leaves, clover or other ground cover they nibble on. They are an edge bird so hunt edges i.e. two tracks, where young aspen runs up against mature aspen, the swamp edges of aspen stands, aspen stands with fields mixed in. My experience suggests they like mixed cover and by that I mean aspen with lots of balsam mixed in and a thick under story such as hazel. Prime aspen cover is about 12 years of age and many of the trees will be the size of your wrist.
When all is said and done grouse are where you find them. Every time I think I have the game figured out they surface in the most unlikely of spots. When you see a spot that is thicker than the surrounding area that is a likely location for them to seek refuge.
Enjoy your hunt.
