Grizzly Diet

Significant dietary components of major grizzly bear populations inhabiting North America

Jacqueline Ngo '23

Paulson-Frost Intern

The grizzly bear (Ursus arctos) is a bear species that is found throughout North America, with major populations persisting in Alaska, British Columbia, and the Greater Yellowstone Ecosystem (GYE). These large terrestrial creatures are opportunistic omnivores that feed on a diverse variety of foods. This dietary range can be broken down into six categories: ungulates, small mammals, marine prey, plants, berries, and anthropogenic foods. The environmental differences between grizzly bear habitats influence the dietary habits between major grizzly bear populations, as these changes may affect both the abundance and distribution of the food items and prey that are consumed. By researching the major dietary components of these grizzly bear populations, we are able to enhance the recovery and reintroduction of grizzly bear populations while identifying favorable and non-lethals methods to manage human-bear interactions. We conducted a literature review using previous studies relating to major food items identified via stable isotope analysis (δ13C and δ15N) of grizzly bear hair samples. With this data, we compiled a list of the historical diet of grizzly bears and determined the significant food items of grizzly bear populations residing in Alaska, British Columbia, and GYE. The most frequently detected items for grizzly bears inhabiting areas in the GYE were whitebark pine and various terrestrial prey, particularly elk and ground squirrels. In Alaska, the most consistent food item was salmon as grizzly bears obtained virtually all of their carbon and nitrogen from salmon. Grizzly bears residing in British Columbia tended to feed on vegetation and consumed high amounts of ungulates (elk, caribou, and moose) and salmon. Anthropogenic foods are also a major component of grizzly bear diets, but this category of food has a negative impact on grizzly bear lifestyle.
Read Jacqueline's poster presentation on her research here.
Photo of the Grizzly Bear by: Tsalani Lassiter