A patch of dark hair on the male turkey's chest?

From Wikipedia:

Males typically have a "beard" consisting of modified feathers that stick out from the breast. Beards average 9 inches (230 mm) in length. In some populations, 10 to 20 percent of females have a beard, usually shorter and thinner than that of the male.

What_is_the_patch_of_dark_hair_on_male_turkey%27s_chest