I left my ducks in their run for the day, and when I returned I found my female pekin (about 15 weeks old) was missing some feathers on the back of her neck (I have attached some photos below), I also have an Indian runner duck who I believe is a drake by his quack, who is only 11 weeks old. I wanted to know if this was a sign of mating or not, and if it was normal or if this is aggressive behaviour. I have separated them for the night aswell. Would really appreciate any advice or input