What is a pika?

The American pika (Ochotona princeps) is a charismatic and conspicuous inhabitant of many western mountain landscapes. Pikas are in the rabbit order (Lagomorpha), have short rounded ears and lack a visible tail. They are small, their body size is usually between 6-8 inches and they weigh between 4-6 ounces. Typical pika habitat includes high elevation talus, boulder fields and lower elevation lava flows. The abundant crevices and cavities found in these areas provide adequate cover. Pikas live in colonies, have small home ranges and are territorial. They are herbivores, grazing during summer and gathering grass and flowers for their haypiles to eat during the winter. There are 30 species worldwide, but only 2 species in North America, the American pika (Ochotona princeps) present in the western United States, and the Collared pika (Ochotona collaris) that lives in the northern areas into Canada and Alaska.

Why are pikas at risk as the climate changes?

Pika distribution in North America

Research suggests that American pikas are vulnerable to climate change. Pikas are temperature sensitive. They have a high body temperature of 40.1°C, and the upper lethal temperature is 43.1°C. Hot summers may prevent pikas from foraging and finding enough food. Additionally, snowpack decline may pose the threat of hypothermia, as less insulation is found during the winter.
Pikas live in alpine and sub-alpine ecosystems and also on lava flows. Even though these areas tend to experience the least amount of disturbance (because of their isolation), climate change can still have an effect on this species, and a population loss can occur without noticeable changes in habitat. Climate change may not only lead to thermal stress but also to alteration of plant and animal communities. This may allow diseases to threaten pika populations, reduce available food supplies, or enable predators such as weasels to have more access into subsurface crevices where pikas escape.

Lava and cave sites at Craters of the of the Moon National Monument and Preserve, ID

Studying pika can help us understand how the effects of climate change are affecting their survival. For example, recent range shifts in pikas appear to be controlled by temperature and precipitation, the two major determinants of range in most species. Research has found that recent pika extinctions occurred mainly at lower elevations, and in sites with warmer temperatures, as well as at talus areas that have exhibited reduction in snow cover and more frequent periods of extreme cold during the winter.

In regard to precipitation, evidence shows that historical pika populations in the southern Rocky Mountains have persisted in all but the driest sites. Additionally, there are other studies that suggest that pikas are more common in sites with an adequate supply of perennial forbs (herbaceous flowering plants) rather than grasses and sedges.

Pika habitat at Crater Lake National Park, OR

Pika may also serve as a model to learn more about species response to climate change. Pikas are known to use areas below the talus surface, where they can find microclimates to persist where surface conditions may be too harsh. In this respect, pikas can help us learn more about species behavioral adaptations.

Fortunately, pikas are relatively convenient to survey. They leave conspicuous signs of their presence, such as hay piles, and occur almost exclusively in barren rock, such is found in mountain talus fields and in lava beds. Therefore, potential habitat patches are easily identifiable.

References:

Beever, E. A., C. Ray, P. W. Mote, and J. L. Wilkening. 2010. Testing alternative models of climate-mediated extirpation. Ecological Applications 20:164-178.

Beever, E. A., P. E. Brussard, and J. Berger. 2003. Patterns of apparent extirpation among isolated populations of pikas (Ochotona princeps) in the Great Basin. Journal of Mammalogy 84:37-54.

Smith, A.T. and M. L. Weston. 1990. Ochotona princeps. Mammalian Species 352:1-8.