In this Tuesday, September 13, 2016 photo,tThe moon is visible in the background as a multitude of migratory Vaux's Swifts flock to roost for the night inside a large, brick chimney at Chapman Elementary School in Portland, Ore. Numbers of Vaux's Swifts are in decline, in part scientists say because of the destruction of the brick chimneys that they use to roost during their annual fall migration. (Photo by Don Ryan/AP Photo)
