Size: Common swifts are 16–17 cm long with a wingspan of 38–40 cm.

Vocalisations: Their call is a loud scream in two different tone pitches, the higher of which issues from the female. They often form "screaming parties" during summer evenings, when 10–20 swifts will gather in flight around their nesting area, calling out and being answered by nesting swifts.

Habitat: Swifts usually nest in buildings but they can also be found nesting in holes in trees, cliffs and crevices, and even in nestboxes. They may nest in former woodpecker tree burrows found in ancient forests.

Behaviour: Swifts build their nests of air-borne material caught in flight, bonded with their saliva, in suitable buildings hollows, such as under tiles, in gaps beneath window sills, and most typically under eaves and within gables. Swifts form pairs that may couple for years, and often return to the same nesting site and partner year after year. Except when nesting, swifts spend their lives in the air, living on the insects caught in flight; they drink, feed, and often mate and sleep on the wing. Some individuals go 10 months without landing. Common swift food revolves around a range of aerial critters, including airborne spiders and flies. Common swifts are migratory.

Interesting facts: Swifts have very short legs which they use primarily for clinging to vertical surfaces. They never settle voluntarily on the ground, where they would be vulnerable to accidents and predation, and non-breeding individuals may spend up to ten months in continuous flight. Their maximum horizontal flying speed is 111.6 km/h.

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