Plains and wood bison fecal samples, diet content, and diet quality

Understanding ecological niche is critical to the management and
conservation of any species or population. For herbivores, dietary niche
is critical for understanding habitat suitability, carrying capacity, and
population and community viability. In closely related species with
similar morphologies, dietary niches can diverge depending on
environmental and seasonal factors. Elk Island National Park in Alberta,
Canada, contains populations of both American bison (Bison bison)
subspecies—plains bison (B. b. bison) and wood bison (B. b. athabascae)—in
similar but separate habitats located at the historical confluence of the
subspecies’ distributions. Using generalized additive models and
nutritional geometry, we compared the subspecies’ dietary niches in terms
of content and quality continuously for one year (Dec 2020 – Nov 2021).
Both subspecies consumed primarily graminoids during winter, spring, and
fall and incorporated a variety of forbs and woody plants during summer.
Plains bison diets contained more upland grasses and digestible organic
matter in their diet and less wetland graminoids (e.g., sedges) throughout
the year. We also found differing dietary niches between the subspecies
during the spring and summer months. Our unique, continuous analysis of
annual diet content and quality can deliver insight into the similarities
and differences between subspecies’ dietary niches that should help
improve management decisions, such as better matching between source
populations and release areas for future translocations.