How does Miguel save Esperanza from bandits as kids?

In Chapter Four, we learn that when Esperanza was younger, bandits had come into the house at el Rancho de las Rosas to steal all of the family’s silver. Miguel warned Esperanza and Hortensia just before the bandits arrived, so they could all hide under the bed together. Esperanza accidentally made a sound, but in a moment of clarity, Miguel released a field mouse from his pocket. He had intended to scare Esperanza with the mouse but instead it surprised the bandits and they left.