He had a tendency to bully her. In a lot of animals a tail up is a sign of dominance. My male Muscovy saw it that way and would pull on her wing feathers. You might be able to see her damaged wing feathers in that photo. She started to drop her tail near him and pop it back up as she walked away. Sometimes she would forget, because she mostly lives in her own world.
My other pekin female I had, died of bumblefoot, but she was a grumpy old lady and put all the ducks, including Muscovy in their place. Even when gimpy no one messed with her.
