The wild and domestic turkey is instantly recognizable by the striking, unfeathered skin covering its head and neck. These areas display a vibrant palette of red, white, and blue. The bare skin acts as a dynamic visual cue, reflecting the bird’s internal state, health, and social standing within its flock. These anatomical features are directly involved in mate selection and dominance signaling.
The Snood: Identification and Function
The snood is a fleshy, pendulous protuberance that extends from the forehead and hangs over the turkey’s beak. This appendage is erectile, meaning it can rapidly extend or contract, changing from a short, stubby projection to a length of several inches. The snood’s length and color are closely observed by females, known as hens, and signal male quality in sexual selection.
Research indicates that hens prefer males, called toms, that possess longer snoods. A prominent snood signals physical fitness and may indicate resistance to common parasites, such as intestinal coccidia. In interactions between males, a longer snood is also associated with dominance, often causing rival toms to defer. The rapid changes in the snood’s size and color display the bird’s mood and health.
Wattle and Caruncles: Location and Purpose
Complementing the snood are the wattle and caruncles. The wattle is a flap of bare, highly vascularized skin that hangs down from the turkey’s throat and neck. Caruncles are small, bumpy, fleshy nodules that cover the entire head and upper neck, giving the skin a textured, warty appearance.
These features play a dual role, serving both social and physical functions. Since turkeys do not sweat, the extensive, unfeathered surface area of the wattle and caruncles assists in thermoregulation. Blood flow to these areas increases on hot days to dissipate excess heat, helping the large birds manage their body temperature. They also swell and brighten to a deep scarlet color during excitement or aggression, signaling the tom’s readiness to mate or fight.
The Science Behind the Color Changes
The dramatic color shifts in the turkey’s unfeathered skin result from tightly controlled blood flow and structural properties within the skin itself. These appendages are covered with a thin layer of epidermis and contain a dense concentration of capillaries just beneath the surface. The bright red color appears when blood vessels engorge, or vasodilate, bringing oxygenated blood close to the surface of the skin.
When a turkey is calm or frightened, blood retracts from the surface vessels, causing the skin to appear pale, white, or blue. The blue hue is caused by the way light interacts with collagen fibers in the skin when blood flow is restricted, an effect known as structural coloration. The nervous system regulates this process in response to hormones associated with stress, aggression, and courtship. This allows the turkey to communicate its emotional state through rapid changes in color.