
Photo: Christoph Moning · CC BY 4.0
Apus cooki
Rare visitor: recorded only occasionally in this country
Size
Small swift
Cook's swift is a small bird, superficially similar to a house martin but completely unrelated to those passerines, since swifts are in the order Apodiformes; the resemblance is due to convergent evolution. Like other swifts it has very short legs, used only for clinging to vertical surfaces (Wikipedia, general species account).
The cached account gives nothing further, so this entry is limited to identification.