Page:Natural History of the Ground Squirrels of California.djvu/81

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The burrow system above described belonged to just one squirrel, an adult female, which was found to contain five embryos, the only exact evidence we have as to the number of young to a litter. This was at 8,700 feet altitude, on Snow Flat, Yosemite Park, on June 28. Half-grown young were common on Tuolumne Meadows, 8,600 feet, July 16. Young two-thirds grown have been taken at Independence Lake, Nevada County, 7,000 feet altitude, as early as July 13. Three third-grown young were seen, and one of them photographed (fig. 22), at 6,800 feet altitude near Williams Butte, Mono County, June 28. There is thus probably some variation in time of appearance of the young, with altitude, the animals at the highest levels being born latest in the season. The young are out quite generally by the 15th of July. Only one litter