Why is some mice droppings RED?

Mouse droppings are typically dark brown or black in color, but they can sometimes appear red if the mice have consumed food or water containing red pigment. This is most common in mice that have been feeding on pet food, birdseed, or other food items that contain red dye. The red pigment passes through the mouse's digestive system and into its droppings, giving them a red color.

In some cases, red mouse droppings can also be a sign of internal bleeding. This can occur if the mice have been injured or have a disease or condition that is causing them to bleed internally. If you notice that your mouse droppings are red and you are concerned that it may be a sign of internal bleeding, it is important to take the mouse to a veterinarian for diagnosis and treatment.