The Turkey Vulture is a scavenger and feeds almost exclusively on carrion. It finds its food using its keen eyes and sense of smell, flying low enough to detect the gasses produced by the beginnings of the process of decay in dead animals. In flight, Turkey Vultures use thermals to move through the air, flapping its wings infrequently. It roosts in large community groups. Lacking a syrinx, the lower larynx or voice organ in birds, situated at or near the junction of the trachea and bronchi and well developed in songbirds, its only vocalizations are grunts or low hisses. Turkey Vultures nest in caves, rock ledges, hollow trees, or thickets. Each year it generally raises two chicks, which it feeds by regurgitation. It has very few natural predators. In the United States, the Turkey Vulture receives legal protection under the Migratory Bird Treaty Act of 1918.