thumb|247x247px|American pika carrying [[forget-me-not flowers and grass to store for winter food in Cawridge, Alberta, Canada]]
The American pika (Ochotona princeps) is a small, herbivorous mammal of the family Ochotonidae, closely related to rabbits and hares (order Lagomorpha). It is native to the mountainous regions of western North America, typically inhabiting rocky slopes and talus fields at or above the tree line. Unlike most mammals of similar size, the American pika is diurnal, being active primarily during the day. It employs two distinct foraging strategies: directly consuming vegetation or gathering and storing plant materials in "haypiles" to sustain itself through the winter months, a behavior known as haying.
Pikas are vocal animals, using a variety of calls and songs both to warn of approaching predators and during the breeding season. Predators of the American pika include eagles, hawks, coyotes, bobcats, foxes, and weasels.
Recent studies suggest that populations in the southwestern United States are declining due to habitat loss and global warming. Despite these regional declines, the American pika is overall assessed as a species of Least Concern by the IUCN and remains common in the northwestern United States and Canada.
Subsequent taxonomic revisions placed the American pika in the genus Ochotona, which is now recognized as the sole genus comprising all pikas. This genus is distinct within the family Ochotonidae, which itself is part of the order Lagomorpha, alongside rabbits and hares. The genus name Ochotona is derived from the Mongolian word for pika, reflecting the species' native range across North America and parts of Asia.
Over time, several subspecies of the American pika have been identified, primarily based on geographic distribution and minor morphological differences. However, taxonomic opinions on these subspecies vary, and ongoing genetic studies continue to refine the understanding of intraspecific variation within Ochotona princeps.
thumb|Lepus (Lagomys) princeps illustration from Richardson's original description in Fauna Boreali-Americana
Description
American pikas, historically known as "little chief hares", are small, rounded mammals with compact, ovate bodies adapted for life in cold alpine environments. Adults typically measure from 16.2 (6.4in) to 21.6cm (8.5in) in length, with hind feet ranging from 2.5cm (0.98in) to 3.5cm (1.38in). They usually weigh between 121 and 176g (4.3–6.2oz), though body size varies among populations and regions. In populations exhibiting sexual dimorphism, males tend to be slightly larger than females. It is well adapted to high-elevation habitats, because its dense fur covering the entire body to provide insulation against cold temperatures.
The skull of the American pika is slightly rounded, with a broad and flat preorbital region that distinguishes it from related species. The zygomatic arches are well developed to anchor large masseter muscles. And the maxillae contain a single large fenestration, helping for chewing coarse plant material. Of the approximately 30 existing species of pika, it is one of only two native to North America, the other being the collared pika (O. collaris). The collared pika occurs farther north, and its distribution is separated from that of the American pika by a gap of about across British Columbia and Alberta.
American pikas primarily inhabit scree and talus fields, often surrounded by alpine vegetation, and are also found in piles of broken rock. They occasionally occupy man-made substrates such as mine tailings or piles of scrap lumber. Pikas typically establish dens and nests below rock surfaces, usually within spaces in diameter, but they often perch on larger, more prominent rocks. They are commonly found near or above the tree line in cool, moist microhabitats such as high peaks or along watercourses. Although pikas do not dig extensive burrows, they may enlarge existing crevices in the talus to create shelter.
American pikas use two foraging strategies: direct consumption of food (feeding) and caching vegetation in "haypiles" for winter use (haying). The timing of haying is influenced by weather patterns, particularly the amount of snow and timing of snowmelt from the previous winter.
When haying, pikas harvest plants in a deliberate sequence corresponding to seasonal plant growth (phenology).
Life history
thumb|247x247px|The American pika's [[camouflage|cryptic coloration helps it blend into its environment in the Sierra Nevada.]]
The American pika is diurnal. The total area used by an individual pika is called its home range, approximately 55% of which is defended as territory against intruders. Territory size varies between , depending on rock formation, distance to vegetation, and vegetation quality. Rising temperatures are thought to drive American pikas to higher elevations Pikas can die within six hours if exposed to temperatures above without access to cool refuges. At lower elevations and during the midday heat, they retreat into cooler scree openings to avoid lethal temperatures.
Studies indicate that some populations are declining, with global warming identified as a major factor. A 2003 study published in the Journal of Mammalogy found that nine of 25 sampled populations in the Great Basin had been extirpated, prompting further research on the species' vulnerability.
In 2010, the U.S. government reviewed but ultimately declined to list the American pika under the Endangered Species Act. The IUCN Red List currently classifies the American pika as a species of least concern.
Recent research has documented widespread extirpations and range contractions at lower elevations, where conditions are warmer and drier. These changes have been attributed to factors such as rising summer and winter temperatures and altered precipitation patterns. For example, a 2021 study reported upslope range retractions in 44 of 64 surveyed watersheds in the Northern Rockies, with average shifts of .
A 2015 analysis of historical pika records across California found that both temperature and habitat configuration strongly influence where the species can persist. Surveys of 67 previously occupied sites showed that pikas were no longer present at about 15% of those locations.