Mice are one of the many many mobs added in Mo'creatures. Mice come in 3 different colors, brown, grey and white.
Attacked Mice will flee, but they are not targeted by any animal other than Kitties, so this rarely happens unless triggered by the player.
Mice can be useful to the player if long grass is scarce, for seeds. Birds also serve this purpose.
Mice can also be picked up by their tail bythe mouse with your mouse to move from one place to another.