Abstract 233 – Fundamental versus Realized Niche of Grizzly Bear Denning Habitat Across Canadian National Parks; Implications of Anthropogenic Disturbance

Ramona Maraj, Nolan Waters, Emily Gavey, Peter Demontigny, Erin Henderson,
Rachel Stapleton

Expansion of and increase in human modification between 1990 and 2015 resulted in
1.6 million km2 of natural land lost globally. We examined the implications of this on grizzly
bear denning habitat in seven Canadian national parks. We used 417 den locations across seven
western Canadian national parks, ranging through British Columbia, Alberta, the Northwest
Territories and Yukon. Den locations were obtained from aerial sightings, staff or public
sightings, and collared bears. We used MaxEnt to model the influence of 21 covariates on third
order den site selection across the extent of the study area. To model the fundamental niche
for den selection, we considered a model without any anthropogenic influence. We
subsequently considered a realized niche den model that incorporated distance to linear
features and global human modification as explanatory variables. Our fundamental niche model
showed that across grizzly bear range, the visibility of the sky and solar radiation were
important factors that drive den selection. Our models also showed that denning habitat
availability decreases with latitude, until the Arctic coast, where availability becomes
widespread again. Our realized niche model showed that anthropogenic influences were the
most important factor influencing den site selection, with global human modification
contributing almost 50% explanatory power to the model and creating a disproportional loss of
denning habitat across all parks. At current rates of human modifications, availability of denning
habitat may become limiting for bears, even in protected areas.