Ochotona princeps
American pika

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)

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 (Chapman and Flux, 1991). (Beever and Smith, 2008; Chapman and Flux, 1991; Fitzgerald, et al., 1994)

Ochotona princeps is intermediate in size when compared to other ochotonids. Its body mass exhibits a great deal of variation and ranges from 121 to 176 grams. In certain parts of its range, males are larger than females, but only slightly (Smith and Weston, 1990). The body of O. princeps is ovoid, with short ears, long vibrissae (40-77 mm), short limbs, and no visible tail. Its hind 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. Ochotona princeps has a high body temperature (average of 40.1°C) and relatively low upper lethal temperature (average of 43.1°C). It has 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 (Smith and Weston 1990). 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)

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). (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)

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). (Smith and Weston, 1990; Wolf, et al., 2007)

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)

Ochotona princeps is diurnal and is active above ground for about 30% of daylight hours. During this time, O. princeps may survey for predators, feed or cache food, vocalize, or establish and maintain territories. Ochotona princeps does not burrow but seeks shelter in talus interstices; however, they do make tunnels through the snow during the winter to access meadows and haypiles. During fall and winter, O. princeps spends more time in its den and less time being 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 Ochotona princeps is an asocial species. 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 O. princeps actively defends its haypiles. Social cohesion between mate pairs is maintained by exhibiting social tolerance and engaging in short call duets (Chapman and Flux, 1991). (Chapman and Flux, 1991; Fitzgerald, et al., 1994; Kawamichi, 1976; Smith and Weston, 1990; Wolf, et al., 2007)

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)

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, owever, 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)

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 (Chapman and Flux, 1991). 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 (Fitzgerald, Meaney, and Armstrong, 1994). 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)

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)

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)

There are no known positive effects of Ochotona princeps on humans.

There are no known adverse effects of Ochotona princeps on humans.

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 O. princeps has been extirpated. (Beever and Smith, 2008; Blakemore, 2007; Wolf, et al., 2007)