In domestic chickens, the comb is primarily used for thermoregulation.
A chicken’s comb contains many blood vessels close to the skin. Blood flowing through this exposed structure can release heat, helping the bird regulate body temperature. Combs are often larger and more vivid in adult males, although females also have them.
Comb shape varies among breeds. Single, rose, pea, cushion, and walnut combs are among the recognized forms. Breed standards frequently use comb type as an identifying feature.
A healthy comb is commonly red, but color and texture can change with age, illness, cold conditions, or reproductive status. The comb is not the same structure as the wattles, which hang beneath the beak and also help expose blood vessels for heat exchange.