American Pikas scent-mark with their cheek glands, and also communicate with both long and short vocalizations. Short calls are uttered as alarms and to announce that they are departing or returning from foraging, and males perform a "song" during the breeding season. Males and females maintain individual, same-size territories, usually living next to an individual of the opposite sex. Pikas seem to spend much of the day sitting still, observing their surroundings. Females breed when they are a year old, and have a litter of three after a 30-day gestation period. The young are independent about a month after birth. Predators include coyotes, long-tailed weasels, martens, and ermine.
Adaptation: The shapes of the molar crowns of lagomorphs, such as this American pika, Ochotona princeps, and the Antelope Jackrabbit, Lepus alleni, are fairly simple on the surface but they are also un-rooted, and consequently, ever-growing, an adaptation for an extremely abrasive diet.
Reproduction Comments: Seasonally polyestrus. Gestation lasts approximately 30 days. Produces 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, initiates 2 litters annually but only one is weaned; births late June-early August. Young dependent on mother for at least 18 days, weaned as early as 3-4 weeks. Juveniles establish territories and haypiles in summer of birth, but do not breed until their 2nd summer. Maximum lifespan 7 years.
Ecology Comments: Home range size varies seasonally, largest during spring breeding season; defends haypiles in late summer. May defend territory; home range size about twice as large. Male and female territories average same size. Reported home ranges: 0.3-0.5 ha (Barash 1973); and mean 0.26 ha, range 0.04-0.30 ha (Kawamichi 1976). 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.
Habitat Comments: Restricted to rocky talus slopes, primarily the talus-meadow interface. Often above treeline up to limit of vegetation. Also found at lower elevations in rocky areas within forests or near lakes. Occasionally on mine tailings, or piles of lumber or scrap metal. Does not dig burrows but may enlarge den or nest site under rock.
Food Comments: Feeds primarily on grasses and sedges; also eats some flowering plants and shoots of woody vegetation. In late summer and fall, harvests and stores food (forbs, grasses, marmot pellets) for winter consumption; stored food may be most important when winter is unusually harsh or long (see Smith and Weston 1990). May forage in winter in snow tunnels. Ingests caecal pellets, either directly or after storage.
Length: 22 centimeters
Weight: 128 grams