Adapted from Jim Conrad's online book A Birding Trip through Mexico, This excerpt from "Nevado de Toluca Volcano" in México state

In the afternoon three black bird-forms come to play in the wind surging through breaks in the volcano's high rim. They don't seem to be searching for food. They just spend an hour zooming toward cliff faces, banking at the last moment, and stalling with cupped wings where mighty blasts of upward streaming wind rises beneath them. What could these Common Ravens be doing but playing with the wind?

Raven and Crow comparison

I know they're ravens and not some kind of crow because of their size and their silhouettes. In the sketch, notice how the tail of the larger raven on the left is "wedge shaped," not squared or broadly rounded like a crow's. Ravens "croak" while crows "caw," though sometimes immature crows also "croak." At this distance, the tail is the thing.

Opposite to the Striped Sparrow, few birds are more widespread and flexible in behavior than ravens. Found throughout the New World and the Old, in both hemispheres, they eat an amazing variety of things but seem to prefer insects. They also eat small mammals, birds, eggs, scorpions, amphibians, and lizards, as well as many kinds of plant material.