Climate Stress and the American Pika

Rapid environmental change, including global warming, challenges all residents of changing biomes. Adapting to these changes and coping with environmental stresses is crucial for species survival. Species adapted to extreme environments are often hit hardest by physical and oxidative stress. These species, known as indicator species, provide early signs of significant pressure on their ecosystems.

Enter The American Pika, A Cold-Adapted Specialist

The American Pika, a small relative of rabbits and hares, is a thermally sensitive, cold-adapted specialist. Living in high-altitude environments with cool, moist climates, Pikas have high metabolisms and thick fur that limits heat loss. These adaptations allow them to survive alpine ecosystems without hibernating in winter. However, their cold adaptation comes at a cost.

Pikas have a resting body temperature just a few degrees below their lethal threshold, making them vulnerable to even moderate temperature increases. They seek cooler microclimates on warmer days, but as the planet warms, these cool hiding places are becoming scarce within their traditional ranges. Studies show that the minimum elevation where Pikas are found has risen by roughly 150 meters in the last 100 years, while average temperatures worldwide have risen by approximately 0.75°C during the same period.

The Impact of Environmental Stress on Pikas

A major physiological response to long-term environmental pressure is the activation of the HPA axis, resulting in glucocorticoid release into the bloodstream. Glucocorticoids like cortisol and corticosterone mediate various adaptive responses to stress, including behavioral changes and energy increase via glucogenesis. While beneficial for short-term survival, chronic HPA axis activation can have harmful effects, such as suppressed immune response, reduced growth, protein loss, and decreased cognitive function. For Pikas, already adapting to a changing environment, these additional challenges can be overwhelming.

Measuring Stress in Pikas

To preserve the Pika species in the wild, researchers need to understand not only changes in population, range, and density but also the stress individuals experience due to these changes. Measuring corticosterone in individual animals using Arbor Assays DetectX Corticosterone EIA and CLIA Kits is crucial.

The type of samples used for measuring corticosterone significantly influences results, as the rate of corticosterone deposition varies across sample types. Measuring corticosterone in serum or plasma provides an immediate assessment of stress, as it is released into the blood quickly after a stressful event and may rise and fall within hours. These samples offer a snapshot of individual stress, but timing of sample collection is critical for correlating multiple animals or populations.

Fecal samples provide information on corticosterone levels over the period material passes through the digestive tract, which can range from a few days to a week or more, depending on the species. Fecal samples are non-invasive but can be challenging to assign to individuals in the wild. Collecting various samples can provide reasonably good information on population stress.

Hair samples are emerging as a means of assessing glucocorticoid stress over longer periods. Corticosterone accumulates in hair over its growth period, so hair samples from several individuals can provide information on stress over months or a season. This is especially relevant if compared to populations of Pikas under little to no pressure to establish baseline levels.

Importance of Studying Indicator Species

Studying indicator species like the Pika offers valuable insights into how environments are impacted by stressors like climate change or habitat disruption. These data are crucial for protecting and preserving native species and their habitats for future generations.

Pika Citations for the DetectX Corticosterone EIA Kits

Stress hormone concentration in Rocky Mountain populations of the American pika (Ochotona princeps)   (Oct. 19 2013)

Relating Sub-Surface Ice Features to Physiological Stress in a Climate Sensitive Mammal, the American Pika (Ochotona princeps)   (Mar 24 2015)

Parks, pikas, and physiological stress: Implications for long-term monitoring of an NPS climate-sensitive sentinel species    (Sept. 4 2015)

Characterizing predictors of survival in the American pika (Ochotona princeps)   (Jun. 17 2016)

Individual-based analysis of hair corticosterone reveals factors influencing chronic stress in the American pika   (Apr. 26 2017)