can a runner or swedish cross with a muscovy?

[spish]

i let all my ducks free range together...its mainly muscovies (26) but i have out there also a runner drake and a crested black swedish drake. these two hang round together 24/7 but im wondering will i need to pen these too up come spring to stop them fertilising the scovies eggs? or is that cross not possible and i can let them roam with the scovy ladies without fear of crosses?

 

[Oregon Blues]

Yes, they can cross breed. Resulting offspring should be sterile. The crosses are raised commercially, so it can't be difficult or rare to get a cross.

 

[Bleenie]

I currently have a crested swedish/muscovy mix in a group that a friend gave to me. He/she has a mohawk & a small crest, white adorable but I still wont be keeping her.