"Merriam's Ground Squirrels live in high desert habitat dominated by big sagebrush, western juniper, and greasewood, and are also found in grasslands and agricultural lands. They eat grasses and forbs. Like other ground squirrels, they are active in the daytime—when they are active at all. They emerge from hibernation in the spring, and disappear underground again in August. One litter is produced each spring. Until recently, Merriam's Ground Squirrel, the Piute Ground Squirrel, and Townsend's Ground Squirrel were all classified as one species, but their chromosome counts are different: Townsend's has 36 chromosomes, Piute 38, and Merriam's 46, enough genetic difference to classify them as three separate species."
Links:Mammal Species of the World
Original description: Merriam, C.H., 1898. Proceedings of the Biological Society of Washington, 12:70.