I would keep good sized pigeons with chickens (like homer size or bigger), but I would avoid putting doves or the smaller breeds of pigeons in with a lot of chickens. Especially if the chickens are standard sized. I have kept a trio of D'uccles in a pen with a couple doves. But the cage is very tall, and I have food for the doves up on a platform where the chickens can't get to it. So the doves can eat and sleep up above the chickens. The only time the doves have to come down on the floor is to occassionally pick at the ground and drink. The one thing most birds tend to pick fights over the most, is a place to roost, and food.