Ochotona princeps

Pikas are restricted to rocky talus slopes, primarily the talus-meadow interface. Often they occur above treeline up to limit of vegetation but also can be found at lower elevations in rocky areas within forests or near lakes. Occasionally they inhabit mine tailings or even piles of lumber or scrap metal. Nests are hidden in talus.

Adjacent home ranges tend to be occupied by opposite sexes. Population density was 3-10 per ha in favorable habitat in Colorado in mid-August (same as in other regions); population relatively stable due to density-related social behavior (Southwick et al. 1986). Juveniles tend to stay on natal home range or an adjacent one. Adult mortality 37-56% per year.

Pikas are seasonally polyestrus. Gestation lasts approximately 30 days. Adult females produce 1 or 2 litters of usually 2-5 young/litter (average often 3 at high elevations), between May and September; most young come from first litters. In most areas parturition begins in May with a peak in June, occurs as early as March in some low elevation areas (Smith and Weston 1990). In Colorado, pikas initiate 2 litters annually but only one is weaned; births occur late June-early August. Young are dependent on their mother for at least 18 days, weaned as early as 3-4 weeks. Juveniles establish territories and haypiles in the summer of their birth but do not breed until their 2nd summer. Maximum lifespan is about 7 years.