Do you hear chattering in your chimney? It could be chimney swifts. But no need to worry, these are interesting and beneficial migratory birds who are only temporary houseguests. These grayish/black birds are a protected species whose numbers are declining due to habitat loss. Their first choice is to nest in large hollow trees, but unfortunately those are far and few between these days. So chimney swifts have adapted to use our chimneys to rear their young and they will return to the same chimney year after year. A family of chimney swifts will consume over 12,000 flying/biting insects each day!
These birds arrive in the U.S. in late March and are gone by early November when they migrate all the way to the Amazon Basin of Peru!
Chimney swifts do not perch, instead they hang onto tree bark and masonry with their claws and barbs at the end of their tail feathers. They have very short legs meant for hanging not perching. They eat on the fly, catching flying insects throughout each day.
Chimney swifts prefer masonry chimneys, where they build a very small cup-shaped nest which is adhered to the chimney wall with the parent bird's saliva. If you hear chattering it is most likely the fledgling babies calling to their parents for food. There are usually 3-5 white eggs laid in a nest and both parents tend to the nestbuilding and rearing of young. Their nesting period is May through August, with peak season being July and August in the Northeast. The young leave the nest after about a month and continue to roost in the nest at night for several weeks. At the end of August through September the swifts congregate in large flocks and will begin their fall migration once the first cold front appears.
If you do think you have chimney swifts nesting in your chimney, please leave them be. They will move on in a few weeks long before you need to use your chimney for winter fires. Please DO NOT set a fire in your fireplace, this will burn the birds. Instead wait until all the birds have vacated the chimney (best to wait until November to be certain) and then you can have a chimney sweep remove any nesting material if you desire. These nests do not pose a fire hazard, as they are very small and easily incinerate at the first fire.
If the nest falls or a fledgling falls into your fireplace or on top of your chimney damper, you can take the young and place them in a small wicker basket and place the basket securely (so that it doesn't tip) on the chimney shelf inside the flue or on top of the damper inside the flue. The parents will continue to feed their young in the basket until they are able to fly out of the flue on their own.
You can see and hear chimney swifts coming back to their roosts each night at dusk which is a fascinating sight to see.
If you have questions about chimney swifts or other native wildlife, please call Wildlife in Crisis at 203-544-9913 (hours each day are 9am-5pm). Or you can visit www.wildlifeincrisis.org for many answers to frequently asked questions about wildlife.