I have a breeding pair of Pekin ducks. I have introduced last month 6 female pekins. for a month now the male only goes after ONE duck in the 6 females and mates with her. He doesn't actually get it done. His penis does not come now, as it did before. These females are 14 weeks old. The one he goes after came with a light colored beak and is the smallest of them. They were gotten from a hatchery. I won't know for a few weeks to make sure they are all female. Any ideas why he only goes after one, while he sticks close to his partner most of the time.