My research relates to climate change and alpine ecosystems, with a particular emphasis on the use of a model species (pikas) to identify, interpret and model climate change impacts in high elevation areas. Pikas are charismatic inhabitants of mountainous or rocky areas throughout the western United States. These cold adapted members of the rabbit family are sensitive to warmer temperatures, and rely on access to cooler micro climates located underneath rocky habitats (e.g. talus). As a result of climate-mediated population extirpations, pikas are widely considered a sentinel species for detecting ecological effects of climate change. I've traveled to lots of different mountainous areas to collect data related to pikas and climate change, including the Rocky Mountains, the Sierra Nevada, numerous mountain ranges in the Great Basin and even India (where non-talus dwelling pikas burrow to escape the heat)! Past research efforts have involved the use of climate and vegetation data to model persistence and occupancy, and details about my current research projects are given below.
Population decline begins with individuals, and assessments related to the physiological condition of individuals can serve as early warning signs of populations in trouble. But many species, such as American pikas, can be difficult to capture and are easily stressed in captivity. I've recently developed non-invasive methods to quantify physiological stress in pikas, by validating the use of stress hormone metabolite (GCM) measurement in pika scat. Baseline measurements of this stress metric can be easily obtained, and can be used to monitor populations and identify factors (climatic or other anthropogenic) causing physiological stress in individuals.
Indicators of watershed health
Pikas appear to be declining in mountainous areas that are losing sub-surface ice features. These features are key to water production and storage, and will likely represent an important component to water resources in a warming climate. Pikas inhabiting talus areas without sub-surface ice features are experiencing higher levels of physiological stress (GCM concentration), and may be more vulnerable to changing climates. Additionally, pika presence may be useful indicators of these features, which can be difficult to identify in alpine ecosystems. Pikas could serve as a sensitive bio-indicator of hydrological change in high elevation watershed areas, and my research is complementing other efforts to understand how landscape change will affect water resource availability.
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Multi-regional assessment of climate mediated stress
Animals can experience higher levels of physiological stress due to changes in environmental conditions, either naturally occurring (fire, flood, etc.) or anthropogenic (habitat degradation, climate change, etc.). And non-invasive measurements of physiological stress can be biased by environmental conditions, since various levels of moisture or temperature can alter GCM concentration in scat. This confounding factor makes it difficult to separate environmental effects on the animal, from those acting on the exposed scat. Using pika scat samples collected from a broad array of habitat types, I am quantifying the impact of environment on GCM concentration. After accounting for the influence of local climatic characteristics, baseline levels of this stress metric are being established for pikas across the western US. In collaboration with the National Park Service, these data can be used to assess vulnerability of wildlife in parks to predicted climate change.
Population Viability in a Changing Climate
In order to better understand wildlife population dynamics, we need data related to key factors affecting patterns and rates of individual survival. Information gleaned from non-invasive sampling techniques provides invaluable insight regarding the current physiological condition of an animal. Given the limited time and resources that characterize many wildlife conservation projects, it is important to identify which physiological metrics are the most informative for a species. We are currently relating survival to several stress metrics and micro-climatic variables. This research is part of a large and collaborative project designed to determine factors affecting local extinctions of pikas throughout the western US. Long-term demographic studies in the Rocky Mountains are providing data on how
changes in climate may affect population density and persistence and individual survival.
changes in climate may affect population density and persistence and individual survival.