Abstract 33 – Spatial Behavior of Grizzly Bears in the US Northern Rockies

Sarah Sells, Cecily Costello, Paul Lukacs, Lori Roberts, Milan Vinks

Once-contiguous grizzly bear (Ursus arctos) populations remain largely isolated in the western
US. Research has been needed to understand habitat use and assess potential corridors that
could promote genetic and demographic connectivity among recovery ecosystems. Accordingly,
our objective was to model grizzly bear habitat use, movements, and population connectivity.
We employed GPS data from male and female grizzly bears in Montana’s Northern Continental
Divide Ecosystem (NCDE) and an integrated step selection function approach to test hypotheses
of habitat selection and simulate movements. Results demonstrated highly individualistic
behaviors, with some individuals avoiding and others preferring various features like forest
edge, riparian areas, and secure habitat. Such individualism supported the need for an
individual-based modeling approach to understand and predict grizzly bear behavior.
Simulation of movements using each individual’s model within and near the NCDE produced
habitat maps with high predictive power. Simulated pathways from the NCDE to nearby
recovery areas revealed pathways bears may use under varying levels of exploratory versus
optimal movements. The predicted habitat and pathways identified by our study can be
targeted for proactive conservation efforts such as conservation easements, conflict
prevention, and road mitigations to help recover grizzly bears in western Montana and beyond.