I've shot grouse with a couple of short tail feathers before, often the two middle feathers. The one I shot today, however, is the funkiest looking fan I've taken in 25 years of grouse hunting. It almost looks like two different fans. Even the colors and markings are different. We almost didn't get this bird since it hung up in a popple after I shot it. I walked over to where I thought it landed, didn't see it on the ground and finally noticed Fergus looking up into the trees. The grouse was lodged in the V of a branch about 15 feet up in the air. One shake of the popple, and it dropped to the ground, almost bonking Fergus in the head.
Other hunters have told me that tail deformities such as this are from a predator (fox, coyote, wolf) snapping at a bird and getting a mouth full of feathers instead of a meal. Then as they're growing back, they look like this. That just an old hunter's tale?