Ever see the Far Side cartoon "What We Say to Cats/What Cats Hear"?

The "what we say to cats" panel shows a person talking to a cat, and in the "speech balloon" of the cartoon is a litany that goes something like "Bad kitty, mustn't climb the drapes, mustn't take fish out of the aquarium, mustn't kill the pretty songbirds" or some such.

The "what cats hear" panel shows the same scene, and in the person's "speech balloon" is... nothing.

A cat will hunt whatever it finds to hunt, indoors or out, regardless of what humans think is proper prey and what we think is not. Also, our definition of proper prey changes with the situation: for the gardener, a cute little bunny or squirrel or bird is a destructive pest that should be kept out of the garden if the crops are to survive to maturity.

The value judgments about which animals are "okay" to kill are made by humans, not by the animals themselves. Try to tell a cat that it's "right" to kill a mouse but "wrong" to kill a rabbit because you don't "need" him to do so. Try to tell a dog that it's "right" to eat the beef-flavored dog food and "wrong" to eat the roast on the table because he doesn't "need" it since he has his dog food.