There is nothing that says spring to me like the chattering of Chimney Swifts over town. The swifts circle back and forth picking out the best chimneys for roosting and nesting. Before Europeans settled here they likely used giant hollow trees in the forest or shallow caves. But with the loss of big snags in the forest and the construction of chimneys in the towns and cities, Chimney Swifts moved from the country to the city.
Chimney Swifts are perhaps the most aerial of any land bird, only landing when at the nest or roosting at night. They even bathe in flight by skimming the surface with their breast feathers, shaking the water off as they fly upward. They do everything in flight, eating, drinking, preening, and even apparently copulating. They have long sleek wings that are much longer than their bodies to help keep them aloft with less energy.
Swifts don’t perch like similar appearing swallows do. You will never see them sitting on an electric line. They have very short legs and long claws to cling to walls of chimneys and other upright surfaces. The also have tail feathers with long stiff shafts to rest against the wall as they cling, much like woodpeckers.
Recent changes to chimney designs such as narrow flues and liners, spark arresters and covers, or the outright loss of old chimneys have decreased the available nest sites and may be a factor in their declining populations. Populations have dropped by nearly 50% in many places throughout their range. Only one pair of Chimney Swifts will nest in each available chimney.
They are gregarious during the non-breeding season. On migration some old factory stacks may hold thousands of roosting swifts, making these old structures potentially important migratory stop-over sites for the birds on their travels to back and forth to their wintering grounds in South America.
It has been estimated that two parents and their nestlings will consume about 12,000 flying insects everyday. Take a walk around your town some evening after dinner and watch the aerial acrobats at work.