My cat Smokey was terrified of the chickens from the moment we brought them home.
Literally a quivering mess. I thought I had traumatized him permanently.
(Funny. He is not my cat at all. He is my boyfriend's, but you'd never know it these days.)
He has warmed up to the chickens & would really like to be one. Especially at treat time.
They keep him in line, though. He has come flying around the house with four hens on his tail more times than I can count. He'll walk by & give one a sniff, or try to lie down in the middle of the area they are foraging. Once one hen goes to run him off, the rest follow. Funniest thing ever.
The other night the bully cat who beats up my Smokey was casing the yard. He has a little bell to warn us all he is coming. Suddenly the ducks got very upright & charged him. They ran him off at a waddle run that I wish I had a video camera for. They must have learned that from the chickens.