I've always wondered this, why do only some rats squeak? Of my three, Ilsa and Rauha seldom make a noise unless they are getting their arses kicked by another rat, but Aino seems to squeak all the time. It's never the 'help me! I am in serious trouble!' squeaks that you get when one rat is really having a go at another, but just little squeaky noises almost seemingly at random. Are some rats simply more vocal than others, or is this some carry over from being a wee kitten?