Polar bears (Ursus maritimus) are among the most visible symbols of climate change. As sea ice diminishes, they face increasing nutritional, energetic, and physiological stress as they are forced to seek resources on land. These long-term changes pose a significant threat to the animals’ health, reproductive success, and very survival. While individual stress measures have been studied in polar bears, researchers have yet to successfully evaluate these challenges in terms of allostatic load—the cumulative burden of stress on the body.

The newest Cornell K. Lisa Yang Postdoctoral Fellow in Wildlife Health, Dr. Kayla Buhler, aims to change that. Working under the mentorship of Dr. Raina Plowright, Rudolf J. and Katharine L. Steffen Professor of Veterinary Medicine and a Cornell Atkinson Scholar, Buhler aims to establish biomarkers for allostatic load in polar bears that can be used to quantify the impacts of environmental change on their health, with the ultimate goal of improving conservation prospects for the species. By creating a standardized method to measure chronic stress in bear populations, this work will help identify subpopulations at greater risk of infectious diseases and/or reduced fitness, providing policymakers, Indigenous communities, and governments with information that could help guide potential management.

“Allostatic load provides a more complete picture of how ongoing stressors—nutritional, energetic, environmental, and physiological—combine to impact wildlife health,” said Plowright. “Kayla’s project has the potential to transform how we understand and manage the impacts of climate change on polar bears and other vulnerable species."

Buhler brings more than six years of Arctic field experience and a strong background in disease ecology and conservation. For her PhD, she investigated vector-borne pathogens in Arctic wildlife across Canada and Alaska, including rodents, caribou, Arctic foxes, and polar bears. As a postdoctoral researcher at the University of Inland Norway, she collaborated with Sámi communities to identify emerging diseases linked to supplementary feeding in semi-domesticated reindeer. Through this work, she has built a collaborative network among Indigenous communities, government agencies, and academic partners across Canada, Greenland, and Fennoscandia.

Her fellowship project, “Assessment of Allostatic Load in Bears: Implications for Sustainable Conservation of Polar Bears and Management through Indigenous Harvests,” will begin by identifying key biomarkers in a stable population of brown bears before expanding to polar bear populations across the Arctic. Buhler is planning to track how stress responses change in response to environmental variability, such as sea ice extent and seasonal temperatures. Additionally, sampling protocols will be developed in partnership with Indigenous communities across North America to provide opportunities for standardized stress measurements across the polar bears’ circumpolar range.

“How can we measure the true cost of climate change on polar bear health?” Buhler asked as she embarked on developing this project. “By identifying key biomarkers and developing standardized methods, we can move from isolated stress measures to a more holistic understanding of the challenges polar bears face. This work will also strengthen opportunities for collaboration with Indigenous communities, who depend upon the bears and other wildlife, ensuring that knowledge is shared and applied where it is needed most.”

“One Health is integral for polar regions, where the health of people, the health of wildlife, and that of the environment are closely interwoven.”

For Buhler, the project represents the intersection of her core research interests: wildlife health, conservation, and One Health. “One Health is integral for polar regions, where the health of people, the health of wildlife, and that of the environment are closely interwoven,” she said. “This incredible fellowship with the Yang Center for Wildlife Health will allow me to address key conservation concerns in the most rapidly warming region of the world, while reinforcing my commitment to collaboration with and support of Arctic peoples.”