UBC Theses and Dissertations
Incorporating visual and auditory perception into understanding grizzly bear behavioural responses to roads in Alberta, Canada Parsons, Bethany
Anthropogenic disturbances, including roads, are known to influence animal habitat selection and mortality. However, little is known about the role of sensory perception in animal responses to disturbance. The goal of this thesis was to investigate the effect of visual and auditory perception around roads on grizzly bears (Ursus arctos) in Alberta, Canada. As an apex predator, the greatest threat to grizzly bear populations in my study area is human-caused mortality near roads, yet grizzly bear behavioural responses to roads are not fully understood. In this thesis, detailed topographic and land cover data from airborne Light Detection and Ranging (lidar) and Landsat imagery were used to estimate visibility and audibility around roads. Using a modified semivariogram approach with data on step lengths from GPS-collared grizzly bears, I found that grizzly bears responded to roads at slightly further distances when roads were perceptible (80 m) than when roads were imperceptible (60 m). I extended the analysis of grizzly bear response by modelling habitat selection as a function of road perception and other environmental variables using integrated step selection analysis. I also assessed mortality risk in visible areas by comparing habitat selection between grizzly bears that died and grizzly bears that survived. Grizzly bears were less likely (p < 0.05) to select visible areas when moving slowly or resting, suggesting that road visibility is perceived as a risk. However, bears were more likely (p < 0.05) to select visible areas when moving quickly, which may indicate that grizzly bears use roads as travel conduits. Results suggested no difference in selection for visible areas between grizzly bears that survived and grizzly bears that died. However, an exploratory analysis showed that grizzly bear mortalities commonly occurred in visible areas. From a management context, maintaining 20 m wide vegetative buffers along roadsides may decrease visibility, allowing grizzly bears to use travel corridors associated with roadways and access cut blocks for forage while reducing human-induced risk. Collectively these findings highlight the importance of sensory perception in understanding animal behaviour.
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