Some of the issues with keeping ducks is male ducks

wanting to mate the chickens. This can harm or even kill the chicken so it's something to watch out for.

Can ducks be kept with chickens?

Domestic ducks can peacefully cohabitate with backyard chickens. Duck and chickens basic feed and shelter requirements are very similar, which makes it possible for them to be coop mates, but there are a few considerations that you will need to keep in mind when adding waterfowl to a chicken coop.

What happens when a duck mates with a chicken?

Whichever you believe, the end result is that you will not end up with a hybrid chick or duckling. Most importantly, it's not something you should ever encourage, or even allow if possible. As I explained above, it's very dangerous to let ducks and chickens try to mate, as it can cause serious injuries to the hens.