Nesting Chimney Swifts

South Carolina residents who are hearing strange noises coming from their chimneys can be assured that the visitors are friendly and helpful chimney swifts, the only bird in North America which nests almost exclusively in chimneys.

Most homeowners were unaware that birds were nesting inside their chimneys until the young swifts started their loud food-begging calls at two weeks of age. It takes about 30 days after hatching for the young to leave the nest. Swifts are highly beneficial birds, do not spread vermin, and only use the chimney during the warm months when the fireplace is dormant. Like other birds protected by the Migratory Bird Treaty Act of 1916, chimney swifts are protected from being pursued, captured or killed.

Chimney swift migration occurs in March and April as the birds move northward from wintering groundsChimney swift in Peru, according to Laurel Barnhill, wildlife biologist with the Wildlife Section of the S.C. Department of Natural Resources (DNR). The chimney swift is an aerial acrobat that resembles a small dark swallow (and sometimes is even mistaken for a bat) and spends most its day in flight feeding exclusively on flying insects, many times in groups. Later in the spring it will glue small twigs to the inside of a chimney with its saliva and lay four to five white eggs.

The chimney swift should be familiar to most homeowners because of it chimney-nesting habits, Barnhill said. Before the country was settled, swifts nested in large hollow trees, but as the country was developed, and large trees were cut down, swifts started nesting in chimneys. This adaptation has been so complete that swifts now rarely nest in hollow trees. However, with the increasing popularity of capped chimneys, swifts are finding many of their former chimney homes unavailable to them. This could be disastrous for the long-term population health of chimney swifts, as they will have no place to nest.

There is a distinct advantage to having a nest of swifts in the chimney, according to Barnhill. “Swifts eat annoying insect pests such as mosquitoes, flies, termites and ants, which equates to a third of their weight each day,” she explained. “The swift acts as a highly efficient natural pest-control agent which should be a welcome summer visitor to anyone’s home.” The small, fragile swift nests pose no chimney fire hazard, and the birds- nesting season does not conflict with winter chimney use.