^ Geographic Range
Nearctic: American pikas are found in mountain habitats from central British Columbia to South-Central California and east to Colorado.
^ Physical Characteristics
Mass: 121 to 176 g
Ochotona princeps is a moderate sized pika with buffy (as opposed to white in O. collaris) underparts. As in other pikas, the ears are short, the tail is not readily visible, and the body is egg-shaped. Measurements: Body length: 162-216mm; Hind foot: 25-35mm.
^ Natural History
- Pikas utilize two distinct foraging styles: open foraging (feeding) and food collection and caching (haying). During the summer, they cache vegetation in haypiles. Haypiles are composed of tall grasses and forbes and may be cached on open surfaces or under rocks. These haypiles are used to supplement their diet during especially harsh winters. Pikas collect as much vegetation as possible during the haying season, but haypiles are insufficient to sustain them through the winter. Pikas must therefore continue to feed during the winter. Pikas generally feed on short alpine grasses during the summer and on cushion plants and lichens that are accessed by underground tunnels during the winter.
- Adult females have two litters per year and have a postpartum estrous. First litters are usually conceived about one month before snowmelt so that lactating females can feed on the spring emergence of alpine grass. There is a much lower rate of weaning second litters than first litters (<10% of weaned juveniles are second litter), apparently due to the high energetic cost to the female of weaning.
Average litter size ranges from 2.3 to 3.7. Young are completely dependent on their mother for at least 18 days, but exhibit a remarkable rate of growth and reach adult size after only 3 months. Weaning generally occurs at 3-4 weeks after birth, and after 4 weeks, siblings are intolerant of each other and of their mother.
- American pikas are active outside their dens about 30% of daylight hours. Much of this time is devoted to feeding, haying, surveilance and territory defense. Adults establish and defend independent territories and territories of males tend to be adjacent to females. Pikas use two characteristic vocalizations, the short call and the song. The short call is given as an alarm call to alert others of avain predators and as a territory defense call. The song is given primarily by males during the breeding season, but both males and females may sing during the autumn.
- American pikas are found in areas of broken rock and talus, which are surrounded by suitable vegetation. They are most often found at the interface between meadow habitat and open rocky terrain.
A few isolated populations in the Great Basin are threatened, but most populations are abundant.
^ Economic Benefits for Humans
- Pikas are important in maintaining the diversity and abundance of alpine meadow plant species. Plant diversity increases in areas where pikas are actively haying large grasses and forbs.
- None known.
^ Other Comments
Smith, A.T. and M. L. Weston (1990) Ochotona princeps. Mammalian Species 352:1-8. American Society of Mammalogists.
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^ Image Sources
Reference written by Sharon Jansa
Page last updated 1/18/96