It's their hunting instinct [img]smile.gif[/img] . I know someone who puts her cat's bowl of food around corners so the cat can sneak up on it and pounce

. My baby isn't allowed outside so she doesn't get to catch rodents, but she does catch moths that get inside and sometimes little skinks (though I always save them if I catch her in time), and she always plays with them - catches them, then lets them go, catches again and so on until they lie down and don't get up again. Cats are so precious!