The Chimney Swift is often described as a "cigar with wings" — a small, sooty, blunt-bodied bird with long, curved, blade-like wings that it beats in a distinctive stiff, twinkling flutter as it careens across the sky. It is almost never seen perched; swifts spend nearly their entire lives on the wing, feeding, drinking, bathing, and even mating in flight, clinging only to vertical surfaces when they finally stop. High overhead their chattering, chittering calls give away flocks wheeling after insects.
True to its name, this swift nests and roosts inside chimneys, having largely abandoned the hollow trees its ancestors used before European settlement. In late summer, migrating swifts gather at large chimneys in spectacular numbers, pouring in at dusk in a swirling tornado of birds. That dependence on old masonry chimneys has become a problem: as chimneys are capped or torn down, Chimney Swifts have declined and are now considered Vulnerable.
An exclusive aerial insectivore, capturing flying insects and drifting spiders entirely on the wing — flies, ants, beetles, aphids, and mosquitoes. A single swift can eat thousands of insects a day, and it never forages on the ground or from vegetation.
In late summer those are almost certainly Chimney Swifts gathering to roost. Large flocks circle a chimney at dusk and then funnel inside in a dramatic swirling column, sometimes numbering in the thousands.
Chimney Swifts originally nested and roosted in large hollow trees. As those disappeared, they adapted to masonry chimneys, which mimic the vertical, sheltered surfaces they cling to. The loss of open, uncapped chimneys now threatens them.
Essentially never. Their tiny feet can only cling to vertical surfaces, so they perch inside chimneys and hollow structures. Otherwise they stay airborne, even bathing and drinking in flight.
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