The wild turkey is instantly recognizable for its large size and the striking, unfeathered skin of its head and neck. These areas display a remarkable array of fleshy growths that shift dramatically in color and size. This dramatic appearance is a result of specialized anatomy and a dynamic circulatory system that allows the bird to signal its physiological state.
Anatomy: Identifying the Turkey’s Appendages
The “red thing” on a turkey is not a single part but a collective of three distinct, fleshy appendages that adorn the head and neck. The long, pendulous structure that hangs over the beak and forehead is known as the snood. It can be retracted or elongated significantly depending on the turkey’s state.
Below the chin and throat, a flap of skin hangs down, which is called the wattle. Both male and female turkeys possess these structures, though they are far more pronounced in the mature males, known as toms.
The third type of feature consists of small, bumpy protuberances covering the rest of the unfeathered skin on the head and upper neck. These nodules are called caruncles. Collectively, the snood, wattle, and caruncles are highly vascularized tissues that give the turkey its distinctive, brightly colored appearance.
The Biological Functions of the Structures
These specialized appendages serve multiple functions related to the turkey’s social behavior and survival. A primary purpose involves sexual selection, where the size and color of the structures indicate genetic fitness. Female turkeys, or hens, tend to prefer toms with longer snoods and brighter, more voluminous wattles during courtship displays.
These visible features signal health and dominance to potential mates and rivals alike. Research suggests that a longer snood correlates with lower parasite loads and overall better health in male turkeys. The wattle and caruncles also help establish the social hierarchy among toms, with larger, more vibrant structures signaling a higher status.
The extensive surface area of this bare skin is also utilized for thermoregulation. Turkeys do not possess sweat glands, so they must use other methods to dissipate excess body heat. The highly vascularized skin allows blood to circulate close to the surface, releasing heat through convection and radiation to cool the bird’s body.
Why Does the Color Change?
The dramatic color shifts seen in a turkey’s head and neck are a direct result of changes in blood flow to the appendages. The skin is packed with blood vessels that can rapidly expand or constrict, a process known as vasodilation and vasoconstriction. This process controls the amount of blood pooling in the snood, wattle, and caruncles.
When a tom is excited, aggressive, or engaging in courtship, blood rushes into these structures through vasodilation, causing them to engorge and turn a vibrant scarlet red. This influx of oxygenated blood makes the red pigment more visible through the thin skin. Conversely, a reduction in blood flow, often due to fear or stress, causes the structures to become pale white or blue.
The blue appearance is a result of deoxygenated blood pooling close to the surface, which absorbs light differently than oxygenated blood. A very pale or white color can indicate intense fear or illness, as the circulatory system pulls blood away from the skin surface. This dynamic display of color acts as a quick, non-vocal form of communication, instantly signaling the turkey’s mood and overall physiological state to other birds.