224 A.MMAL LIFE IX THE YOSEMITE 



Lagrange an animal would be started up every hundred yards or so. The 

 rabbits were then common even through the chaparral as far into the hills 

 as Coulterville. In the vicinity of the latter place individuals were come 

 upon wherever there was any grass in the small clearings. Rabbits, like 

 meadow mice, sometimes increase until they overrun the country, then 

 suddenly decrease to a minimum. In earlier years this was true of the 

 jack rabbits in the lower San Joaquin Valley, but since the great rabbit 

 drives of the nineties, when thousands were killed by the ranchers, this 

 great variation in numbers seems not to occur. 



The young of the jack rabbit when bom are far advanced in their 

 development as compared with the young of true rabbits. The body is 

 fully covered with hair and the eyes are open. The body length at birth is 

 about 6 inches and the animal weighs about 2 ounces. Growth is rapid 

 and the young soon take on the rangj' form of the adult. Even in the 

 very young the ears are large (about 2 inches long at birth) and exceed 

 the head in length so that no difficulty is experienced in identifying them 

 as young jack rabbits. In the cottontail the ears are very short at birth, 

 shorter than the head. 



The breeding season of the jack rabbit extends through most of the 

 year, though a somewhat larger percentage of young is produced in the 

 spring than in other seasons. A female (deseriicola) taken at Mono Mills 

 on June 19, 1916, contained 5 embrj^os. The average number in a litter, 

 taking the country at large, is between 4 and 5. 



Sierra White-tailed Jack Rabbit. Lepus townsendii sierrae Merriam 



Field characters. — Form that of Black-tailed Jack Kabbit, but size larger and general 

 build heavier (fig. 34); feet heavily furred; tail large and fluffy. Head and body 19 Vt 

 to 201/2 inches (491--519 mm.), tail S'^j inches (89-92 mm.), hind foot 6% inches 

 (160-164 mm.), ear from crown 6 inches (151 mm.). Body coloration (including cars) 

 pale brown, ticked with black in summer, solidly pure white in winter; tail and feet 

 wholly white at all seasons. Broppinfis: Flattened spheres about V^ inch in diameter. 



Occurrence. — Resident in moderate numbers in high Sierras and at east Itase of 

 mountains. Recorded from Tuolumne Meadows, and near Half Dome, eastward to 

 vicinity of Mono Mills and slopes of Mono Craters. Ranges upward to 12,000 feet on 

 higher peaks. Lives chiefly in open or sparsely wooded situations. Active mostly in late 

 evening. Solitary. 



The Sierra White-tailed Jack Rabbit is known to many persons as the 

 "snowshoe rabbit"; occasionally it is called Sierra Hare. Like many of 

 the other mammals and birds which occur along Ihc crest of the Sierras 

 this hare is a member of a norllicrn grouj) wliicli (iiids conditions suitable 

 for its existence in the boreal region of high altitude on the main Sierra 

 mountain mass and at its colder east bji.se. Locally, even in the midst 

 of its range, this species is much less coninioii tliaii is the Black-tailed Ja»'k 



