The White-throated Swift is a resident of the Santa Rita Mountains. This is one fast bird, as it has been clocked fleeing from a predator at over 200 mph!
This is a medium-sized swift, with brown and black coloring over most of the body. The throat is white, along with patches on the stomach and edges of the wings. Their gray face has a dark patch under the eye.
This species is very susceptible to the cold, and may die if temperatures drop too low. They have exhibited the ability to drop their internal temperatures to help them survive, but this does not always work.
The White-throated Swift takes advantage of man-made structures for roosting. They often hang out under bridges, overpasses and buildings, ignoring heavy traffic and the presence of people.
If you happened upon a group of swifts, you could say you saw a “box”, “screaming frenzy” or a “swoop” of them. This is one of the few species of birds where you are correct if you said you saw a “flock” of swifts.
Reference: The Nature of Madera Canyon by Douglas W. Moore, Friends of Madera, 1999; whatbird.com