Poultry Math - Run size?

So my husband and I have fallen prey to poultry math. It all started when we bought a used 5x10 dog run from a friend. Our dogs just took naps in it and generally seemed to prefer being inside, so we decided to repurpose it. With a little hardware cloth and a roof, I said, wouldn't it make a GREAT chicken run?

He reluctantly agreed and we ordered a mixed bunch of chicks from My Pet Chicken. But alas! We only wanted four, and their minimum number for our area is six! Never fear, we told ourselves. We will just pick four we like and rehome the extras.

Fast forward 5 months. Helen, Penelope, Stella, Gladys, Irene and Page are all still in residence. Our firm resolve to trim down the flock melted as we watched their antics as they battled over lizards and worms in the yard. Sigh.

Now it's the New Year and DH gave in on another request of mine - ducks. Oh boy, but ducks, we find out, need even more space(and of course, WATER)! This is fine, we can build a big run for them and satisfy the ~20ft per bird requirement for the ducks if we only have four or five, and minimum orders on waterfowl are much smaller.

Except we're getting ahead of ourselves, aren't we? We still have 6 chickens in a 50sqft area! Thats about 8.3 sqft per bird. Should we look into getting them a bigger run too? I guess I just don't want to get rid of their run as its been predator proofed and roofed.

Can chickens and ducks forage together? If they are allowed use of our yard (we have since put in a privacy fence around the property so they're safe from neighborhood dogs) will it be sufficient?

 

Yeah, well we were using wood shavings and shoveling them out and replacing them but I have since been told that sand works really well given how wet it is where I live, so we're sanding their run in tonight when I get out of the office. Not sure what kind of upkeep it will require but I don't mind raking sand out if it keeps them drier!

...I think that rhymed.

So far, in regards to the rest of their yard, the worst they've done is poo on some outdoor furniture and tear up a lot of weeds...Minus the poo, they're actually more helpful in the yard than my husband (I have to beg him to break out the weed eater during the winter).

They don't seem to be picking at each other or plucking each other's feathers, or anything like that.