(1) Swifts are small birds that migrate in large flocks every fall from Canada to Central and South America. (2) Each flock stops in familiar places along the way to rest before it continues its journey. (3) In our town, a flock have return for years to the tall chimney of an old, empty building. (4) The swifts spend about a month sleeping inside the chimney at night and feasting on flying insects all day. (5) By sunset every evening, the large flock gathers in the sky above the chimney. (6) Then the whole group begins to swirl and gradually lowers into the chimney. (7) By this time, a crowd of people will has gathered to watch the swifts’ evening show. (8) Before the swifts claimed the chimney, the old building has been scheduled to be torn down. (9) Then a group of townspeople worked to protect it. (10) Now it provides a safe, dependable stop for the returning swifts.