The girls are now 5 month old. When the comb reaches a bright red or pink color, the pullet is probably ready to begin laying eggs. Betsy offered us this accidental pose (you can see her here trying to determine if the camera is edible).
The primary function is to help keep a chicken cool in hot weather, the blood circulates in dense networks of tiny blood vessels and capillaries from the chicken’s comb to its wattles. This gives the comb its deep red color and allows the blood to be cooled by the air before traveling to other parts of the bird’s body.
The secondary function of the comb is to help a chicken attract a mate.