I had a little Siamese cat that a huge crow that lived in a big redwood near my house would mess with sometimes. He would sit in his branch and squack down at the cat, and mock swoop it trying to intimidate it. One day he was sitting on the road getting a drink of water and my cat snuck up on him and jumped him. The crow was bigger than her and managed to shrug her off and escape to his tree. Once he realized that this little cat had jumped him he literally wouldn't leave the cat alone. Every time the crow was around and the cat was out in the open the crow would mess with the cat, constantly diving at it and cawing at her. I really didn't know an animal could hold a grudge, but that crow had a serious one that didn't let up until we moved.