Белобокий стриж Aeronautes saxatalis

The only swift in U.S. and Canada that is not all-dark; white throat, breast, and patches on sides of rump are unique. Longer tail than Vaux's Swift. Narrower wings and different flight style than swallows. Found most commonly around rocky cliffs in deserts; ventures more extensively during nonbreeding season. Listen for its descending series of harsh, screeching notes.