As long as the muscovy is not doing any damage to your other ducks you shouldn't worry about it. Of course they can physically mate with your ducks, but I do not believe they can make babies with them (I'm not positive about that, though). Here is an excerpt on muscovies from www.whistleberryfarm.com

"Muscovy ducks merit separate discussion.

First, they are not strictly speaking, a duck. They are distinct from the duck breeds discussed above in that they are not descended from the wild Mallard duck. They originated in South America. They also forage for a much higher proportion of their feed than the average domestic duck. They are calm, quiet and comfortable with being close to humans, as other ducks are not. They can fly, and they sometimes roost on the pasture fence, in the barn rafters, in trees or on my back porch rail."

As far as his behavior goes, he will always be different than the rest of your flock. I think he sounds pretty cute.

thanx
tanya

Oh please give him a chance.... my muscovies are some of my fav ducks... I have Pekins, cayugas, mallards, credteds, blue swedish, runners and most recently I took in a small flock of muscovies that were no longer wanted by their previous owner and they are the darndest ducks, lol.... very independent, very social and very comical..... and yes they CAN mate with other ducks, however, the offspring will be infertile..... so there is no chance of having generation after generation of mixed up ducks, lol... in fact, some of the mixes I have gotten are quite pretty with much less masking and the colors are gorgeous... none of these ducks will lay fertile eggs so the buck stops there... hope this helps....but if he is tame, you will learn to love him...

Muscovy x Mallard (or mallard derived breed) crosses are called "Mule Ducks."

I think he needs to stay with you.

Well we were all ready to accept him into our small flock but he went elsewhere.guess my girls didnt make him feel at home. Do they migrate? Maybe he was just passing through.