There are some dogs that just love killing chickens though. It's like it is in their blood. They may be the gentlests of beasts but when they see "chicken".....I had one like that. He didn't specialize though. He liked rabbits, kittens, and hamsters too but chickens were his favorite. (notice the emphasize on had and were:')
Well, it is in their blood... Whether bird dog, hound or shepherd, prey drive is bred into most of our pets, it was their reason for being. Some can be got over it, but only if they are started early or unusually untantalized by chickens. I'd say it would be the unusual dog who would ~not~ be a chicken killer if given the free opportunity.
My friends Bob and Kay had an early bit of marital tension when she moved in with ducks and geese and he had bird dogs. He wasn't about to punish his dogs for killing birds. And seeing how much prey drive Gidget has, I wouldn't try to get birds here. It's just a losing battle.