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September 13, 2010

Home Above the Hearth

An open chimney can provide valuable habitat for a family of swifts

All Animals magazine, September/October 2010

  • With sticks and saliva, resourceful chimney swifts build homes for their broods. Paul D. and Georgean Z. Kyle/Driftwood Wildlife Association

by Arna Cohen

Anticipating the arrival of houseguests this past spring, Robin and Robert Horne had their chimney cleaned. It’s not something one would ordinarily do for company, but after all, these visitors would be sleeping in the flue.

For the past 10 years, chimney swifts have been making an annual appearance at the couple’s Fort Walton Beach, Fla., home. A flock arrives from South America on April 1, give or take a day or two, and a pair immediately sets up housekeeping, using twigs to build a saucer-shaped nest that they glue to the chimney wall with their saliva.

Once the three to five nestlings hatch, their demands for food can get loud, but only for a few weeks until they fledge, says Robin, who describes the cacophony as “music to our ears.” The youngsters then join their parents in sustained flight, swooping and diving in search of mosquitoes, gnats, termites, biting flies, and other insects; the family consumes thousands a day before they return at dusk to roost.

With a breeding range that includes U.S. states east of the Rockies and parts of southern Canada, swifts have been using chimneys since colonial times, when old growth forests—the site of their preferred nesting spots inside hollow trees—were first cleared for farmland and housing. Small, strong feet enable them to cling effortlessly to the masonry, and bare spines on the tips of their short tail feathers help the birds brace themselves on the vertical surface.

Populations have decreased by more than half over the last four decades, from nearly 7.9 million in 1966 to 3.49 million in 2006, and some experts blame the loss of these manmade habitats as one factor in the decline. Metal liners used in modern flues deprive the birds of a rough surface to cling to, and chimney caps that keep out raccoons and rain deny access to swifts.

Sheltering Swifts

When homeowners aren’t willing to share their chimneys with wildlife such as raccoons, they often have caps installed as an alternative to removing or killing the animals, says The HSUS’s John Griffin. As director of Humane Wildlife Services, a program that implements humane resolutions to wildlife conflicts, Griffin supports chimney caps as a nonlethal way to prevent problems. But for chimney swifts’ sake, he wishes he didn’t have to. “If you can tolerate a raccoon in there, fantastic,” he says, noting that the temporary squatters don’t cause any damage to the structure.

In lieu of a cap, you can guard against water damage to your chimney by installing a cover with open sides that measure at least 12 inches. Metal-lined chimneys, however, should always be capped, as birds and animals can fall to the bottom, unable to climb out.

If your insurance company requires a chimney cap to prevent sparks from setting fire to the roof, check for permission to remove the cap in the spring before the swifts’ breeding season and replace it in the fall after they’ve flown south.

For other considerations when turning the space above your hearth into a chimney swift home, the Driftwood Wildlife Association offers these tips.

• Have the chimney professionally cleaned every spring before the birds arrive to remove creosote residue, which can present a fire hazard as well as prevent the nest from adhering to the chimney wall.

• Have old nests removed during annual cleaning. On the rare occasions when swifts reuse previous years’ nests, the structures can collapse under the weight of a new brood.

• Don’t have chimneys cleaned during the 28–30 days before babies fledge. If forced from the nest too soon, the youngsters will be unable to sustain flight and feed themselves, and their parents will be unable to find them—condemning the babies to a slow death by starvation. You can muffle the noisy demands of hungry nestlings by placing a large piece of foam rubber or non-fiberglass insulation above the closed damper; remove the material before using the fireplace in the fall.

• Delay maintenance on chimneys where swifts have nested or roosted until after Oct. 31; the birds should be safely on their way south by this point.

• The Migratory Bird Treaty Act prohibits the harming of chimney swifts or disturbance of an active nest. Avoid any chimney cleaning service that says it will remove a nest of eggs or chicks. Most reputable companies belong to the National Chimney Sweep Guild, which supports the birds’ protection and conservation.

The Hornes help with conservation efforts by reporting their winged guests’ annual arrival and departure to the Texas-based Driftwood Wildlife Association and participating in counts of swifts gathering en masse ahead of their annual journey to wintering grounds in Peru. On late summer evenings, they sit outside and watch as the birds congregate, swirling above the chimney and zooming down the flue one by one. “They look like little cigars with wings,” Robin says.

The couple counted 99 in August 2004; the number dropped to 68 in 2008 and zero in 2009. A nesting pair is back this year, but the Hornes don’t know why their flue no longer hosts flocks. They’re hoping a freshly cleaned chimney will act as a giant welcome sign—bringing a full house once again.

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