Do you hear birds in your chimney? They’re probably a family of Chimney Swifts.
As their name indicates, Chimney Swifts like to roost in chimneys. Their feet are specifically adapted to grip rough surfaces, like the bricks in chimney walls or the inside of a hollow tree. Chimney swifts are unable to perch on branches or stand on the ground like other birds. Using their sticky saliva, Chimney Swifts build their nests on the walls of chimneys. Both of the parents, and usually a few other family members, care for the nestlings until they are old enough to fly. That chirping sound you may be hearing in your chimney would be the sound of the baby swifts begging for food.
If you hear these birds in your chimney, it is best to let them be. The babies should fledge in a just a few weeks and then the family will leave.
If you’d rather not have avian visitors in your chimney next year, just put a cap on your chimney once the family has moved out. But Chimney swifts do have their benefits! They can eat thousands of mosquitoes in a single day!
Due to the declining use of chimneys, Chimney swift populations are shrinking. They are considered a Species of Greatest Conservation Need in DC and are listed as Near Threatened on the International Union for Conservation of Nature Red List.