The changing natural world at our doorsteps | Illustration and text by Patterson Clark
June 15, 2010
Chimney swifts in decline
On almost any summer day in the city, you can look up into the blue and watch the aerial acrobatics of the birds some call "flying cigars."
The small, sooty-brown birds spend most of their daylight hours in the air. With short tails and long, slender wings they make speedy twists and turns to pick off flying insects.
Swifts that are raising a brood will make regular pit stops to refuel their chicks. Baby swifts sit in a half-saucer-shaped nest of sticks glued with their parents' sticky saliva to the inside wall of a chimney, air shaft or unused smokestack.
In early autumn, huge flocks gather to make a 3,000-mile trip to wintering grounds in northwestern South America.
Before European colonists razed the forests of eastern North America, the birds relied on large, hollow trees for nesting sites. As those disappeared, swifts gradually moved into the region's increasing number of chimneys. Consequently, chimney swift population densities are now highest in cities.
Since 1966, the U.S. population of chimney swifts has fallen 53 percent, and continues to drop at an increasing rate.
Several factors may be contributing to the decline: logging and fires in the upper Amazon River watershed, reduction of insect numbers by pesticides, the cleaning of chimneys during breeding season and, most important, the capping or loss of traditional chimneys and air shafts.
People who want to attract swifts without using a chimney can build a chimney swift tower in their yard. For instructions, visit www.chimneyswifts.org.
Sources: Committee on the Status of Endangered Wildlife in Canada; Driftwood Wildlife Association.