Pikas are small, mountain-dwelling mammals belonging to the order Lagomorpha, the same group that includes rabbits and hares. They have compact, egg-shaped bodies and lack a visible tail, setting them apart from their larger relatives. Their small, rounded ears are designed to minimize heat loss in the cold, high-altitude environments they inhabit. These active herbivores are often heard before they are seen, using a sharp, high-pitched call to communicate across the rocky terrain.
Physical Characteristics and Global Range
Pikas are among the smallest lagomorphs, typically measuring 15 to 23 centimeters (6 to 9 inches) in length and weighing 120 to 350 grams (4.2 to 12.3 ounces) depending on the species. Their short limbs are nearly equal in length, unlike the long hind legs of rabbits and hares. Their paws are covered in dense fur for insulation and navigating rocky surfaces. Their grayish-brown fur provides effective camouflage against the rock faces and debris where they live.
The distribution of pikas spans the high-altitude regions of North America and Asia. The two North American species, the American Pika and the Collared Pika, are found primarily in the mountains of the western United States and Canada, including the Rockies and the Sierra Nevadas. The remaining 35 species are native to Asia, with high diversity in China, particularly the Tibetan plateau. Pikas are typically found in alpine environments, residing in piles of broken rock, known as talus fields, which offer numerous crevices for shelter above the tree line.
The Pika’s Unique Lifestyle
Pikas are herbivores that forage on alpine plants, including grasses, flowers, and young stems. Unlike many high-altitude mammals, pikas do not hibernate during the winter, meaning they must remain active and find food year-round. This necessity drives their distinct behavior, known as “haying,” which involves gathering vegetation during the summer and early fall.
During haying, the pika collects mouthfuls of plants and lays them out on rocks in the sun to dry. This process preserves the nutrients and prevents molding. Once dried, they carry these bundles into their sheltered dens to create a winter food cache, or haypile. These stored provisions are the primary source of energy that allows them to survive the long, cold winter under the snow-covered talus.
Pikas rely on a diverse set of vocalizations for communication and territorial defense. Their high-pitched calls, which have earned them the nickname “whistling hares,” serve as an alarm to warn others of predators, such as weasels, coyotes, and hawks. The calls also help rock-dwelling pikas defend their individual territories, which are often marked using scent glands.
Why Pikas Are Sensitive to Warming Climates
The American Pika is highly sensitive to rising temperatures due to physiological adaptations that favor cold environments. Pikas have thick fur and a high metabolic rate, traits advantageous for surviving harsh alpine winters but which increase their risk of overheating in warmer conditions. Their resting body temperature is close to the threshold for suffering heat-related illness.
Pikas can experience heat stress and even death when exposed to temperatures as low as 25°C (77°F). When surface temperatures rise, pikas must retreat into the cooler, shaded microclimates found deep within the rock crevices of the talus. This behavioral thermoregulation, however, limits the amount of time they can spend foraging and gathering the haypiles necessary for winter survival.
As global temperatures increase, pikas are forced to move to higher, cooler elevations, a process that leads to habitat fragmentation. Since pikas already live near the tops of mountains, moving upward eventually becomes impossible, effectively trapping populations on “alpine islands”. Furthermore, the warmer lowlands between peaks act as a barrier, preventing isolated populations from interbreeding and adapting to the changing environment.