I have often thought about a ratter. Do they leave the birds alone?
		
		
	 
 
For me personally I cannot let my dogs be around the ducks at all.  One dog will ignore them but if one walks up to her  she gets into a defensive posture.   This particualr dog is my hunter/chaser/catcher.
 
My other ratter  has waaaay to strong of a prey drive. She quivers with excitement if she is near the ducks.  This ratter is the catcher/killer.
 
My dogs are adults and were not socialized to be around other animals at all.  From puppyhood they were in environments where the other living creatures they experienced were literally vermin or dangerous wild animals.  I've consulted with dog trainers about my specific needs/ reactions  and I've been advised that if our current system works its probably best to keep them excluded.  But if i wanted to we could work on integrating ducks and dogs.
 
I'm  sure with proper training  especially form puppyhood  that you could successfully have ratters around your ducks. 
 
Decker Rat Terriers, JRTs, feists, doxies, etc.  are recommended breeds but any mix  or breed that has the talent or knack for catching vermin  can work as a ratter.
 
My girls are registered as " terrier mixes"  but we adopted them from a southern state that is known for its Decker rat terrier breeders and Feist breeders.  I think our girls were litter rejects because they didn't have that perfect coloring or perfect size.
 
Even though they're little dogs, I feel safe hiking and being outside with them.  I know to run! if their body language tells me that something on the path ahead of us is scaring them.
 
They bring as much joy to me as my ducks. And to be sure they present their own set of challenges....they cannot be outside alone else they'll excavate out a complete chipmunk burrow,  if we do get a mouse or vole in the house they'll  work for it 24 hours a day with no break until it's been neutralized. No  hole or cave or rotten tree or  rock den is safe from their inspection so I can't  hike for cardio  any more.
 
I would love to hike with my ducks and dogs in our woods because i know they both enjoy their hikes in that environment. For now I'm hiking twice as much.