| Because they use energy and water so efficiently, Little Pocket Mice can inhabit some of the driest and least vegetated parts of North America. They are abundant in deserts of the southwestern United States and northwestern Mexico, and readily inhabit coastal sage, shrub-steppe, and open grasslands in those regions. This Mouse is able to get by on the water generated through its normal metabolic processes. Its urine and feces are so concentrated, and evaporation is so reduced, that it never requires a drink. When given the choice, Little Pocket Mice invariably select the warmest available environment (below about 30° C). During the summer they inhabit the shallow, warmer parts of the burrow system. When it is cold, the Mice move deeper into the burrow where temperatures are warmest. They typically remain underground for months every year, frequently in a state of torpor, their metabolism and body temperatures lowered, waking occasionally to feed on the seeds they have stored.
Coues, E., 1875. Proceedings of the Academy of Natural Sciences of Philadelphia, 27:305.
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