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, it uses thermals to move through the air, flapping its wings infrequently. It roosts in large community groups. Lacking a syrinx—the vocal organ of birds—its only vocalizations are grunts or low hisses. It nests in caves, 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 vulture receives legal protection under the Migratory Bird Treaty Act of 1918.