Chapman Swifts are a flock of Vaux's Swift

Vaux's Swift

Vaux's Swift is a small swift native to North America and northern South America. It was named for the American scientist William Sansom Vaux.-Description:...

, a small migratory bird, that roost in the chimney at Chapman Elementary School in Portland

Portland, Oregon

Portland is a city located in the Pacific Northwest, near the confluence of the Willamette and Columbia rivers in the U.S. state of Oregon. As of the 2010 Census, it had a population of 583,776, making it the 29th most populous city in the United States...

, Oregon

Oregon

Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...

, U.S. It is North America's largest concentration of Vaux's Swift.

Every evening from mid-August to mid-October, thousands of Swifts gather in the sky over the school shortly before sunset. An estimated count of 1,700 to 35,000 of the birds at varying times has been reported. Shortly after sunset, over a period of 10 to 30 minutes, they fly into the chimney to roost on the c. 1925 brick chimney's interior walls until they depart at sunrise. The school is on the birds' migratory route to wintering in southern Central America and Venezuela.

The birds began roosting here in the early 1980s in response to decreased natural habitat—old growth Douglas-fir and forest snags. Vaux's Swift prefer roosting in a standing hollowed out snag.

To provide a haven for the flock, the school did not use the heating system during the weeks of roosting. Students and teachers wore sweaters and jackets, especially toward the end of September when classroom temperatures could be 50 to 60 °F (10 to 15.6 °C). Around 2003, the Audubon Society of Portland

Audubon Society of Portland

The Audubon Society of Portland is a non-profit environmental organization dedicated to wildlife conservancy in Portland, Oregon, U.S.Founded in 1902 and incorporated in 1909, it is one of the oldest such organizations in the world....

, school fundraisers, and corporate sponsors donated $60,000 to $75,000 for an alternate school heating system which is independent of the brick chimney. The chimney is maintained for the birds.

The flock attracts several predators, such as Peregrine Falcon

Peregrine Falcon

The Peregrine Falcon , also known as the Peregrine, and historically as the Duck Hawk in North America, is a widespread bird of prey in the family Falconidae. A large, crow-sized falcon, it has a blue-gray back, barred white underparts, and a black head and "moustache"...

 and Cooper's Hawk

Cooper's Hawk

Cooper's Hawk is a medium-sized hawk native to the North American continent and found from Canada to Mexico. As in many birds of prey, the male is smaller than the female...

, as well as hundreds to thousands of human spectators.