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Which birds belong to the order Apodiformes?

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Illustration of a chestnut-collared swift (Cypseloides rutilus) in flight, showing its dark brown body and wings with a distinctive reddish-brown collar around its neck. — Apodiform Chestnut-collared swift (*Cypseloides rutilus*)

The order Apodiformes comprises two primary groups of birds: swifts and hummingbirds.12

These birds are classified into three families within the order:3

Hemiprocnidae: Known as tree swifts or crested swifts.14
Apodidae: Known as true swifts.14
Trochilidae: Known as hummingbirds.14

While these groups differ significantly in appearance and lifestyle, they are united by their exceptional aerial agility and specific anatomical features, such as their wing structure, where the hand and primary flight feathers constitute a relatively large proportion of the wing. They also share characteristics like weak feet and specific nostril conditions.1432