Bearded dragons, particularly males, are territorial. A male will display a dark beard to indicate his authority over smaller males and females in his territory. He may accomplish this with head-bobbing, which also is a dominance indicator. A black beard serves as a warning to other males to keep away from this dragon’s female. Females do not generally exhibit black beards for territorial display.
The beards of male bearded dragons are generally larger and darker than females' beards. During the breeding season male dragons will blacken their beards during courtship. A male will start to beard up when he spots a female nearby and may accompany this with slapping a hand on the ground and bobbing his head in a jerky manner. This indicates to the female that he is aroused. If she is ready to mate, she will respond with a particular arm-waving gesture.