Dark colored mice are present in the light sandy desert because they have evolved camouflage or camouflage coloring to blend in with their environment. This adaptation helps them avoid predation and increases their chances of survival in the desert habitat. The dark coloration allows them to blend in with the dark shadows and rocks in the desert, making it harder for predators to spot them. This is an example of natural selection and adaptation, where organisms that are better suited to their environment are more likely to survive and pass on their traits to future generations.