I have a Schnauzer and I have both Ducks and Chickens and soon Quail. My Scruffy kills voles, mice and rats. He will go to ground after Rats anywhere. Hubby had one in the garage and the dog literally tore through the wall to get it and get it he did.
He has full run of the chicken run and the duck run and duck house once the ducklings are 2 weeks old. He goes a little crazy if he smells rats and little duckies need to be old enough to get out of the way. I usually let him in the duck house to check it out when the ducks are out and about. We have had a real problem since my drake passed but now that Scruffy can go into the duck house, everything is back to normal. He killed 3 around the duck house. I wouln't think of going out to houses with out him, he lets me know if anything is around.
I brood chicks in the house (quest bathroom) for the first 10 days - 2 weeks then they go to the brooder house. I take him in and he sits on my lap and just watches them. Once they are outside, he thinks they are his and he protects them. He chases off hawks, regularly. Yes, he is a Schnauzer and will run through a pack of hens to get them to fly around. They just settle and laugh at him. He's about 8 years old now, though.
Don't get a puppy, get an older, more settled dog. And see how it does around your chickens and ducks. Introduce them slowly. On leash at first. I'd get the dog then in a month or so, once settled in, I 'd get some chicks and brood them in the house, so it gets familiar with them. If it calmly watches them. You got yourself a keeper of birds, if not you still have a dog that will go to ground for mole, voles, mice and rats.