Mountain Ash is a great grouse food however the grouse usually never get a chance to utilize due to songbirds wiping them clean during migration.
At least that is how it works in my corner of lower Michigan. I have one in my front yard that I planted in 2018 or '19 and it gets stripped by bluebirds most frequently but waxwings, jays, and others use it too. Japanese beetles can do a lot of damage if you don't spray regularly.