For Chickens
Got to go with Mink, They can squeeze through the smallest hole and just keep killing till every bird is dead. Plus they like to pile them all up in a corner. I have a totally enclosed chicken coop and run. And still have had 3 huge losses to the Mink.
Dogs would be close second, and are #1 if they are owned by a neighbor who is neglectful and ignorant. Had a couple bad dog experiences, but each time the neighbor has been very sorry and considerate.
Raccoons would be a distant #3, they are crafty and had some bad experiences with. 1 Time they pulled my baby ducks through the cages to get them and all I had left was just heads and feet in the cage. But have to give them some respect as they normally only take what they need and won't clean out your whole flock in a night if they get in.
For Pigeons
- Hawk is #1 since they attack in the day, right in front of you and are protected
- Weasel is #2 basically a smaller version of the mink.