This is a video we took of the these local birds called Swifts. They meet in this chimney every September into October and do this tornado dance into the chimney at sunset and sunrise. It takes the birds about an hour to all make their way into the chimney. The chimney is attached to a school and is no longer used for heating but they left it standing for the Swifts. The school is only a 10min walk from our apt in the NW of Portland.