Each fall, Chimney Swifts gather in large groups as the prepare to migrate south for the winter. In the Eastern United States (eBird map), you can find these swifts in large flocks from late August through mid September. While the Western US doesn’t have Chimney Swifts, you can see Vaux’s Swifts (eBird map).
Watching these swifts come in to roost is quite the spectacle! They spend a lot of time swirling around in the air before dropping into their roost site. Although there is no listing of all roost sites that you can visit, check with your local Audubon Society to find out where you can observe these birds. Some organizations might even have organized events where you can learn all about the swifts!
If you want to learn more about these awesome birds, click here.