What other pets should be avoided if you have a cat?

I have a comic from the newspaper that I kept: A parot is sitting in a large hoop-type perch and is looking down at the cat. There is a large bend in the side of the hoop, and the parot is saying to the cat, "This demonstration of beak strength is brought to you by Acme Cat Prosthetics."

Just because they don't hunt prey to eat doesn't mean they're defenceless! If a cat tangled with a parot, I'm not sure who would get the worst of it!