The rat’s vibration means that the rat is feeling something too intensely for it to express. It can be a sign of nervousness and can also be a sign of intense excitement or apprehension. Given the intensity of the emotion, the rat is not sure how to react and that is why it will literally quiver or vibrate in your hand. Rats exhibit both forward explorative behaviour and nervous fear, and generally need plenty of reassurance to relax to a state where they can enjoy the experience.
Why do rats occasionally vibrate when we hold them?
