The turkey vulture is the most widespread of the New World vultures. One of three species in the genus Cathartes of the family Cathartidae, the turkey vulture ranges from southern Canada to the southernmost tip of South America. Turkey Vultures lack the vocal organs to make proper songs. Most of their vocalizations come down to a form of low, guttural hiss made when they are irritated or vying for a better spot on a carcass. They also may give a low, nasal whine while in flight. Here is a link so you can listen to them hiss.

P.S.- sorry about the missed daily bird-posts it will not happen for a while