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Ochotona princepsAmerican pika

By Alexandra Peri

Geographic Range

American pikas can be found throughout the mountainous regions of western North America. Their geographic range extends as far south as New Mexico and California, as far north as British Columbia, and as far east as Colorado. (Beever and Smith, 2008; Chapman and Flux, 1991; Fitzgerald, et al., 1994; Mains and Pigott, 2008; Smith and Weston, 1990; Wolf, et al., 2007)

Habitat

American pikas inhabit areas of broken rock and talus fields fringed by alpine meadows. They are most common in cool, moist habitats above tree line. In the northern part of their range, they can be found from sea level to 3,000 meters; however, in the southern part of their range, American pikas are rarely found below 2,500 meters. (Beever and Smith, 2008; Chapman and Flux, 1991; Fitzgerald, et al., 1994)

  • Range elevation
    sea level to 3000 m
    to 9842.52 ft

Physical Description

American pikas are intermediate in size when compared to other ochotonids. Their body mass exhibits a great deal of variation and ranges from 121 to 176 grams. In certain parts of their range, males are larger than females, but only slightly. Their body is ovoid, with short ears, long vibrissae (40-77 mm), short limbs, and no visible tail. Their back paws are digitigrade, have four toes (compared to five on the front), and range from 25 to 35 mm in length. Both sexes have a pseudocloacal openings, which must be everted to expose the penis or clitoris. Females have six mammae which do not enlarge during lactation. American pikas have a high body temperature (average of 40.1°C) and relatively low upper lethal temperature (average of 43.1°C). They have a high metabolic rate (1.53 cm^3 oxygen/hour), and thermoregulation is behavioral rather than physiological. (Chapman and Flux, 1991; Smith and Weston, 1990; Wolf, et al., 2007)

Pelage color of American pikas changes seasonally but maintains an off-white hue on its ventral surface (as opposed to white in Ochotona collaris). On its dorsal surface, pelage ranges from grayish to cinnamon-brown in the summer. In the winter, their dorsal pelage is gray and is twice as long as summer pelage. Their ears are round, covered with dark hair on their internal and external surfaces, and edged in white. Their paws are densely furred, including the soles, with the exception of small black naked pads at the ends of the toes. Their skull is slightly round with a flat, broad interorbital region. Other distinguishing characteristics of the American pika's skull include a slender rostrum, nasals that are widest anteriorly, maxillae with one large fenestration (rather than numerous small fenestrae of Leporidae), an elongated jugal, which forms a prominent projection from the posterior zygomatic arch, and a dental formula of 2/1, 0/0, 3/2, 2/3 totaling 26 teeth. (Chapman and Flux, 1991; Smith and Weston, 1990; Wolf, et al., 2007)

  • Sexual Dimorphism
  • sexes alike
  • male larger
  • Range mass
    121 to 176 g
    4.26 to 6.20 oz
  • Range length
    162 to 216 mm
    6.38 to 8.50 in
  • Average basal metabolic rate
    1.53 cm3.O2/g/hr
  • Average basal metabolic rate
    0.932 W
    AnAge

Reproduction

American pikas are monogamous, and mate pairs are formed with adults from adjacent territories. When more than one potential mate is available, females may exhibit mate choice. (Smith and Weston, 1990)

American pikas typically mate as yearlings. Males are considered sexually active when their testes are 11 mm in length or greater (Smith and Weston, 1990). American pikas are reflex ovulators (i.e., ovulation only occurs after breeding) and are seasonally polyestrus. Each female has 2 litters per year, with an average of 3 young per litter. Breeding commences 1 month before snow-melt and gestation last approximately 30 days. At low elevations, parturition occurs as early as March but occurs from April to June at higher elevations. Pups weigh between 10 and 12 g at birth and are weaned by 28 days old. Lactation significantly reduces a female's fat reserves, and although females exhibit postpartum estrus, they only nurse the second litter if the first does not survive. (Smith and Weston, 1990; Wolf, et al., 2007)

  • Breeding interval
    American pikas breed twice yearly, during the same breeding season.
  • Breeding season
    American pikas breed one month before snow-melt and once again following the birth of their first litter.
  • Range number of offspring
    1 to 6
  • Average number of offspring
    3
  • Average number of offspring
    3
    AnAge
  • Average gestation period
    30 days
  • Average gestation period
    30 days
    AnAge
  • Range weaning age
    18 to 35 days
  • Average weaning age
    28 days
  • Average time to independence
    4 weeks
  • Average age at sexual or reproductive maturity (female)
    347 days
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    347 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    1 years

American pikas are born slightly altrical; they are blind, slightly haired, have fully erupted teeth, and weigh between 10 and 12 grams at birth. For the first 18 days, young are completely dependent on their mothers. Pups open their eyes at 9 days of age. Mothers spend most of their time foraging, but visit the nest once every 2 hours to nurse for an average of 10 minutes. Pups become independent by about 4 weeks old (soon after weening). American pikas exhibit a remarkable growth rates compared to other members of Lagomorpha, and can reach adult size after only 3 months. (Smith and Weston, 1990; Wolf, et al., 2007)

  • Parental Investment
  • altricial
  • female parental care
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • provisioning
      • female
    • protecting
      • female

Lifespan/Longevity

Average annual mortality of American pikas is 37 to 53%, and age-specific mortality is highest for 0 to 1-year-olds and 5 to 7-year-olds. The maximum age of American pikas in the wild and in captivity is 7 years, with an average life expectancy of 3 years in the wild. (Chapman and Flux, 1991; Fitzgerald, et al., 1994)

Behavior

American pikas are diurnal and active above ground for about 30% of daylight hours. During this time, they may survey for predators, feed or cache food, vocalize, or establish and maintain territories. American pikas do not not burrow but seek shelter in talus interstices; however, they do make tunnels through the snow during the winter to access meadows and haypiles. During fall and winter,they spend more time in its den and less time active. (Chapman and Flux, 1991; Fitzgerald, et al., 1994; Kawamichi, 1976; Smith and Weston, 1990; Wolf, et al., 2007)

Territories are held by individuals, as they are asocial. Females disperse farther than males, and once dispersed, males gain territories via competition. A juvenile's chances of survival are contingent upon finding a territory to occupy. Territories are primarily defended via aggression, which includes chasing and fighting. Although aggressive interactions are rare (1 per every 10 hours), they typically occur between members of the same sex and unfamiliar adults. Males are generally dominant to females, and adults are dominant to juveniles. Territorial boundaries tend to overlap. On average, inter-territory distance is smallest between mating individuals and largest between members of the same sex. Territorial overlap of mates is greatest in early to mid-summer and reduced in late summer/early autumn, during which time they actively defend their haypiles. Social cohesion between mate pairs is maintained by exhibiting social tolerance and engaging in short call duets. (Chapman and Flux, 1991; Fitzgerald, et al., 1994; Kawamichi, 1976; Smith and Weston, 1990; Wolf, et al., 2007)

  • Range territory size
    816 to 2182 m^2

Home Range

American pika breeding territories (410 to 710 m^2) make up about 55% of their home range (816 to 2,182 m^2). (Smith and Weston, 1990)

Communication and Perception

American pikas communicate via vocalizations and scent marking, and they can discriminate between individuals through calls and cheek-gland secretions. They make 2 characteristic vocalizations, short calls and long calls. Short calls are used as an alarm when predators are present or as a warning signal to potential intruders (i.e., to defend one's territory). Alarm calls are usually repetitive short calls that change in frequency depending on the type of predator seen (e.g., large vs. small). Long calls are almost exclusively given by adult males and are most common during breeding season, however, both males and females may sing in the autumn. Short call duets are also sung by mating pairs in an effort to maintain social tolerance. (Chapman and Flux, 1991; Fitzgerald, et al., 1994; Smith and Weston, 1990; Wolf, et al., 2007)

American pikas use urine, feces, and cheek marks while scent marking. Cheek markings, produced from apocrine sweat glands, are used to attract potential mates and to demarcate territories. They are spread by both sexes by rubbing their jowls on rocks. During breeding season or upon colonization of a new territory, cheek marking occurs with elevated frequency. Urine and feces are usually placed by haypiles to mark ownership. (Chapman and Flux, 1991; Fitzgerald, et al., 1994; Smith and Weston, 1990; Wolf, et al., 2007)

Food Habits

American pikas are generalized herbivores that select forage by assessing its nutritional value. Preferred plants have higher protein, lipid, and water content and higher caloric value than non-preferred plants. Although certain plant species are avoided due to the presence of toxins, these plants may be cached in haypiles for winter consumption. Some toxins act as natural preservatives that wear off by the time the plant is consumed. Caching, also known as haying, occurs during summer. Haypiles generally consist of forbs and tall grasses, but up to 30 species of plants may be found in a single haypile. Most haypiles are constructed near the talus-meadow interface and serve as territory markers. When winter arrives, haypiles are moved into burrows and used as their main food supply. During winter, American pikas may also feed upon cushion plants and lichens in the subnivean zone to supplement their diet. In the summer, American pikas typically eat short alpine grasses. Forbs and shrubs constitute 78 to 87% of their diet, with alpine avens, clovers, and sedges making up the remaining 22 to 13% of their diet. Occasionally, conifer needles and bark are also eaten. They are not obligate drinkers as water is primarily obtained via ingested plants. (Chapman and Flux, 1991; Fitzgerald, et al., 1994; Smith and Weston, 1990; Wolf, et al., 2007)

American pikas create two types of fecal droppings: a hard brown round pellet and a soft shiny string of material (the caecal pellet). Pikas consume the caecal pellet (which has high energy value and protein content) or store it for later consumption. Only about 68% of the ingested food is assimilated, making the caecal pellets an important part of the American pika's diet. (Chapman and Flux, 1991; Fitzgerald, et al., 1994; Smith and Weston, 1990; Wolf, et al., 2007)

  • Plant Foods
  • leaves
  • wood, bark, or stems
  • flowers
  • Other Foods
  • dung

Predation

American pikas are moderately camouflaged and when a potential predator is detected, they emit an alarm-call informing the rest of the community of its presence. Alarm calls are emitted less frequently for small predators, as small predators may be able to chase them into the talus interstices. Small predators consist of long-tailed weasels (Mustela frenata) and ermines (Mustela erminea). Large predators, such as coyotes (Canis latrans) and American martens (Martes americana), are especially adept at capturing juveniles who are not quick enough to escape. Golden eagles (Aquila chrysaetos) also feed on American pikas, but their impact is minimal. (Fitzgerald, et al., 1994; Mains and Pigott, 2008; Smith and Weston, 1990)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

American pikas are considered allogenic engineers (i.e., altering the environment through their activities). Their large haypiles, containing both plant and fecal matter, are not entirely consumed during the winter, leaving large accumulations of decomposing biomass to act as fertilizer and a potential food source for other animals. As fertilizer, haypiles ultimately increase soil nitrogen, a limiting resource for vegetation at high altitude. Also, American pikas are host to many species of intestinal parasites (Coccidia) and parasitic fleas (Siphonaptera). (Aho, et al., 1998; Bossard, 2006; Lynch, et al., 2007)

Commensal/Parasitic Species
  • Eimeria cryptobarretti
  • Eimeria banffensis
  • Eimeria calentinei
  • Eimeria klondikensis
  • Isospora marquardti
  • Eimeria barretti
  • Eimeria princeps
  • Eimeria worleyi
  • fleas (Siphonaptera)

Economic Importance for Humans: Positive

There are no known positive effects of American pikas on humans.

Economic Importance for Humans: Negative

There are no known negative effects of American pikas on humans.

Conservation Status

Due to its abundance and widespread distribution, the IUCN lists Ochotona princeps as a species of least concern. However, of the thirty six recognized subspecies, seven are listed as vulnerable and one, O. p. schisticeps, is listed as near threatened. The seven vulnerable subspecies (O. p. goldmani, O. p. lasalensis, O. p. nevadensis, O. p. nigrescens, O. p. obscura, O. p. sheltoni, and O. p. tutelata) are all found in the Great Basin and are currently experiencing major threats that have resulted in local extirpations. The greatest threat to American pikas, especially those in the Great Basin, is likely global climate change as they are extremely sensitive to high temperatures. American pikas can die within an hour if ambient temperatures rise above 23°C (75°F). Many populations are expected to migrate north or move to higher elevations. Unfortunately, American pikas are very poor dispersers. (Beever and Smith, 2008; Blakemore, 2007; Wolf, et al., 2007)

Various organizations have suggested placing Ochotona princeps under the protection of the Endangered Species Act. Potential solutions to local population declines may include legislation changes to decrease the amount of global warming stressors, increasing awareness, identification of new protected areas, and re-introductions in areas where they have been extirpated. (Beever and Smith, 2008; Blakemore, 2007; Wolf, et al., 2007)

Contributors

Alexandra Peri (author), University of Michigan-Ann Arbor, Phil Myers (editor, instructor), University of Michigan-Ann Arbor, John Berini (editor), Animal Diversity Web Staff, Catherine Kent (editor), Special Projects.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

coprophage

an animal that mainly eats the dung of other animals

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

diurnal
  1. active during the day, 2. lasting for one day.
duets

to jointly display, usually with sounds in a highly coordinated fashion, at the same time as one other individual of the same species, often a mate

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

fertilization

union of egg and spermatozoan

folivore

an animal that mainly eats leaves.

herbivore

An animal that eats mainly plants or parts of plants.

induced ovulation

ovulation is stimulated by the act of copulation (does not occur spontaneously)

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

keystone species

a species whose presence or absence strongly affects populations of other species in that area such that the extirpation of the keystone species in an area will result in the ultimate extirpation of many more species in that area (Example: sea otter).

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"

tactile

uses touch to communicate

taiga

Coniferous or boreal forest, located in a band across northern North America, Europe, and Asia. This terrestrial biome also occurs at high elevations. Long, cold winters and short, wet summers. Few species of trees are present; these are primarily conifers that grow in dense stands with little undergrowth. Some deciduous trees also may be present.

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tundra

A terrestrial biome with low, shrubby or mat-like vegetation found at extremely high latitudes or elevations, near the limit of plant growth. Soils usually subject to permafrost. Plant diversity is typically low and the growing season is short.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Aho, K., N. Huntly, J. Moen, T. Oksanen. 1998. Pikas (Ochotona princeps: Lagomorpha) as Allogenic Engineers in an Alpine Ecosystem. Oecologia, 114/3: 405-409. Accessed April 07, 2009 at http://www.jstor.org.proxy.lib.umich.edu/stable/4221946?seq=1.

Beever, E., A. Smith. 2008. "Ocotona princeps" (On-line). 2008 IUCN Red List of Threatened Species. Accessed March 18, 2009 at http://www.iucnredlist.org/details/41267.

Blakemore, B. 2007. "

Route to Extinction Goes up Mountains, Scientists Say. Global Warming Is Forcing the American Pika up Mountains and Toward Extinction.
" (On-line). Accessed April 01, 2009 at http://abcnews.go.com/WN/story?id=3155909&page=1.

Bossard, R. 2006. Mammal and Flea Relationships in the Great Basin Desert: From H.J. Egoscue's Collections. Journal of Parasitology, 92/2: 260-266. Accessed April 07, 2009 at http://www.bioone.org.proxy.lib.umich.edu/doi/full/10.1645/GE-3545.1.

Chapman, J., J. Flux. 1991. Rabbits, Hares and Pikas: Status Survey and Conservation Action Plan. United Kingdom: World Conservation Union.

Fitzgerald, J., C. Meaney, D. Armstrong. 1994. Mammals of Colorado. Niwot, Colorado: University Press of Colorado.

Kawamichi, T. 1976. Hay Territory and Dominance Rank of Pikas (Ochotona princeps). Journal of Mammalogy, 57/1: 133-148. Accessed April 07, 2009 at http://www.jstor.org.proxy.lib.umich.edu/stable/1379516?seq=1.

Lynch, A., D. Duszynski, J. Cook. 2007. Species of Coccidia (Apicomplexa: Eimeriidae) Infecting Pikas From Alaska, U.S.A and Northeastern Siberia, Russia. Journal of Parasitology, 93/5: 1230-1234. Accessed April 07, 2009 at http://www.bioone.org.proxy.lib.umich.edu/doi/full/10.1645/GE-1206R.1.

Mains, J., W. Pigott. 2008. "Life of a Pika" (On-line). Tree of Life web project. Accessed March 10, 2009 at http://www.tolweb.org/treehouses/?treehouse_id=4868.

Smith, A., M. Weston. 1990. "Mammalian Species No.352 - Ochotona princeps" (On-line pdf). Accessed March 10, 2009 at http://www.science.smith.edu/departments/Biology/VHAYSSEN/msi/pdf/i0076-3519-352-01-0001.pdf.

Wolf, S., B. Nowicki, K. Siegel. 2007. "Petition to List the American Pika (Ochotona Princeps) as Threatened Under the California Endangered Species Act" (On-line pdf). Accessed March 28, 2009 at http://www.biologicaldiversity.org/species/mammals/American_pika/pdfs/petition_ca-2007.pdf.

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