I have noticed a difference in the guarding styles.
Females are the workers, they are constantly on guard, ready to go, first to the fence and the alpha female does not leave the fence. She does not allow lower females on the fence with her.
The males tend to get more rest, letting the alert of the female notify them of trouble. Then they get up to go to the 'danger'. The alpha female will let the male on the front line with her, but not other females.
My observations anyway.