How do we protect against domestic cats?

[Brick Chick]

Ok, so I will hang up cds to scare away hawks. What about neighborhood cats? I have two bantam (small) chickens and two ducks in my backyard. I don't have them in a pen because I like the idea of allowing them to run around in the whole backyard. I live in a neighborhood and I know some of my neighbors have cats. Any advice to protect my chickies and duckies from them? The ducks are pretty much full size and the chickens are about the size of two of my fists put together.
Thank you!

 

[nzpouter]

either keep your chickens in a cage or trap the cats.