Cedar Waxwing - Bombycilla cedrorum
I was looking for this bird all summer, and only caught a glimpse of a couple. All of a sudden, during the last week of September, there were dozens of Waxwings clustered in the Mountain Ash/Rowan trees, enjoying the ripe berries. Now they're gone again, somewhere south of here. According to Peterson, they winter in the eastern U.S.