This is the “footless” order of birds. Well, that is at least what Apodiformes means in Greek.
The birds that belong to this order have one thing in common–very short legs and very small feet. They are seldom seen perching long on branches or wires, and have a extremely difficult time walking on the ground–they usually shuffle along branches or wires instead.
There are three families that make up this order, and they are:
The Apodidae (swifts), the Hemiprocnidae (tree swifts), and the Trochilidae (hummingbirds). Of the three families, the Apodidae and Trochilidae are found within North America, and the tree swifts are found in southeast Asia (ranging from India to Indonesia, New Guinea, and the Solomon Islands).
They are the second most diverse group of birds with ~450 species (and ~400 of those species belong to the Trochilidae family), after the Passeriformes order (songbirds).
Between the two families found within North America (Apodidae and Trochilidae) there are 22 species that you can spot somewhere between Alaska down to Mexico. Those species include:
Family Apodidae (swifts)
Family Trochilidae (hummingbirds):
Photography goals for this order include getting a picture of a swift (the chimney swift summers in OK), a tree swift (which means a trip to southwest Asia), and at least one other hummingbird (meaning a trip to another state, or possibly down to Central and/or South America).
References: https://en.wikipedia.org/wiki/treeswift & https://en.wikipedia/org/wiki/apodiformes