Gord Stenhouse, Dario Fernandez-Bellon

Grizzly bears (Ursus arctos) are classed as a species of special concern in Canada and as threatened in Alberta, where the species occurs along the Canadian Rockies and foothills. DNA-based inventories of the Yellowhead Bear Management Area (BMA 3) in 2004 revealed low densities (<5 bears/1000 km2) of grizzly bears. This prompted conservation actions, including a moratorium on hunting, as well as research into demographic status and potential factors limiting these populations. Repeat DNA inventories in BMA 3 in 2004 and 2014 revealed that the population had doubled in the interim ten-year period, scaling to an increase of 7% per year. We hypothesized that these increases were due to improvements in habitat, reduced mortality, and recipients (immigrants) from translocation of bears involved in conflict situations. We used open spatially explicit capture recapture (SECR) models, demographic modelling, as well as modelling of change in habitat to test which mechanisms best explain local patterns of increase. Supported mechanisms included higher survival rates, and transplants of bears into one of the survey areas as well as an increase in higher quality habitat, however, much of the higher quality habitat potentially harbored higher anthropogenic mortality risk. We identified hotspot areas of increase relative to areas of higher habitat value and potential mortality risk. Open SECR models provide a way to obtain survival rate estimates using DNA sampling that were relatively robust to changes in sampling regime during the time period of our study. Our results provide an assessment of the most likely factors influencing increases, as well as potential methodologies that can be used for continued monitoring of these populations.