We rescued 2 ducks who were about 3 days old back in March, so they are about 7 months old now. They have turned out to be a Blue Swedish and a Magpie, both drakes. Since they are our only pets (and our first-ever ducks) we spend a lot of time with them and take them on weekend excursions to mountain streams and lakes where they follow us in our kayaks. When they are out of their pen they stick very close to us and follow us wherever we go. But lately the Blue Swedish is getting aggressive. If you walk away from him, he grabs your pant leg - hard. If we reach for anything on the ground anywhere near him, he'll bite - hard. We've tried "punishing" him by either holding him down, lifting him high into the air, or grabbing his bill and holding it shut, anything that makes us seem dominant. But he treats this like it's a game and comes back for more! Is there anything I can do, or do I need to just be content that this is typical drake behavior? We can't have females where we live.