Now that the days are getting shorter, the length of day is just right for the males to have a surge of hormones, causing them to strut/display. They seek out drumming logs and go for it.
Which makes them easy targets for a few weeks, because they are easy to hear, stay close to their log to defend it, and can be incited to drum by the thump of a single cylinder SXS.
Occasionally one will run right out of the woods ready to kick ass. Like a little Banty rooster. LOL.
Just some grouse trivia mixed with grouse biology.
Beautiful bird by the way.