Ducks + chickens
There are a bunch of threads on this.....definitely do a search to get everyones opinion!
In my experience- I separated them as babies....ducks got too messy and it would not be healthy for my 5 chicks. I kept the two brooders next to each other since the ducklings were very attached to the chicks. The ducklings also grew much faster and I ended up moving them to a crate in my basement and they would get booted into a temporary enclosure during the day to lessen the mess. The mess that ducks can make is mind blowing. The chicks were a breeze compared to them.
Once I got a coop, everyone lived together...BUT my ducks do pick on my hens...they eat their feathers. I HATE it. Drives me crazy. It's not an aggressive thing, more a dominance thing because my hens just squat and don't move. So my ducks are getting a new pen built so this isn't an issue next winter. But everyone's experiences are different. I think if maybe I had 2 female ducks instead of a drake and hen, it would be better. I recommend building the biggest coop/run you can if you plan on keeping everyone together.
I have a mixed flock of chickens, ducks, and a goose. Everyone has always gotten along. The chickens were raised in a large brooder with ducks and I've never had an issue with fighting. Good luck!
You just need a plan B in case brooding together doesn't work.
My ducks are semi afraid of the chicken in close quarters (penned they are fine, but they won't share the food house, they run out when she comes in). I wanted to build a coop to combine them, but we ended up doing something different and they are still housed separately at night.