Description
Common Swifts are 16–17 cm long with a wingspan of 38–40 cm and entirely blackish-brown except for a small white or pale grey patch on their chins which is not visible from a distance. They have a short forked tail and very long swept-back wings that resemble a crescent or a boomerang.
The call is a loud scream in two different tone pitches, of which the higher one is from the female and the lower one from the male. They often form 'screaming parties' during summer evenings where about 10-20 Swifts will gather and fly around their nesting area, all calling out to each other, and being answered by other Swifts within the nests. Larger "screaming parties" are formed at higher altitudes, especially late in the breeding season. The purpose of these is not known, but it appears to be the case that these parties, or many Swifts in them, will then ascend to sleep on the wing, while still breeding adults tend to spend the night in the nest.
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