I checked the ground and couldn't find it. Then I decided to really look over the branches. Squirrels are so slippery that it's possible that it could have somehow shot up the trunk around the back side undetected. Failing to spot anything, I was about to hang it up when there it was! A tiny fluff of fur on one of the upper branches. It was the very tip of its tail. The squirrel was laying flat on the branch, out of my line of sight. I walked around the tree with my eye glued to the tail so as not to lose sight of it. All of a sudden it shot up and started to head for the very top of the tree. I let off a round and it dropped like a bean bag. That was one that I never thought I'd see again.
The last squirrel was spotted on the ground, but made it into a dead tree that didn't have many leaves. I lost sight of it but I knew it had to be up there somewhere, likely lying flat on one of the dead branches. That's when I spotted it. The body was fully hidden but I had a clean shot at the head. It would be like hitting a quarter at 30 yards, so I took careful aim and squeezed off the round. It rolled over and hit the ground. That was squirrel number 4, and the end of an amazing few hours.