Human-polar bear interactions on the northern coast of Alaska

Abstract

Polar bears (Ursus maritimus) are sea ice-dependent marine mammals that, due to reductions in sea ice extent in the southern Beaufort Sea, are increasing their time spent on shore. Simultaneously, the anthropogenic footprint on the northern coast of Alaska is growing. As a result, human-polar bear interactions in this region are increasing. These interactions have the potential to be dangerous for humans, harmful to polar bears, and, therefore, require deliberate management. In this thesis, I examined two study systems that lacked the depth of knowledge necessary to craft defensible management plans. My research generated information regarding human-polar bear interactions that could be used to shape policy in the Arctic. In Chapter 1, I explored a dataset that documented human-polar bear interactions at a popular polar bear viewing area in Kaktovik, Alaska. My objectives were to determine what factors influence 1) polar bear displacement (temporary or permanent) from the viewing area and 2) human response (assertive or neutral) to an approaching bear. Using logistic regression, I determined that permanent polar bear displacement was more likely later in the observation season and when the bear's initial reaction to a human approach occurred as a greater distance. I also found that humans were more likely to act assertively towards a bear when food resources (i.e., whale bone pile) in the area were depleted. These behavioral patterns indicate that human and bear tolerance change over time and in relation to resource availability. In Chapter 2, I conducted the first systematic evaluation of polar bear behavioral response to overhead aircraft traffic. I conducted field sampling in a fixed-wing aircraft and observed polar bear response at varying altitudes. My goal was to intentionally elicit a behavioral response that, under the guidelines in the Marine Mammal Protection Act, would be considered biologically significant. My objectives were then to 1) predict when a polar bear would exhibit a biologically significant behavioral response and 2) estimate the probability of an aircraft eliciting a biologically significant response at different altitudes above the animal. Using linear regression and a hierarchical Bayesian approach, I found that bears were most likely to exhibit a biologically significant response when they were active prior to sampling, located on the mainland coast, and the aircraft approach altitude was less than 457m (1500ft). Furthermore, I found that the probability of eliciting a biologically significant behavioral response at a flight altitude of 30m (100ft) was 21.31% for an inactive bear on a barrier island and 61.46% for an active bear on the mainland coast. Together, these research efforts address pressing knowledge gaps related to polar bear behavior on the northern coast of Alaska. Information generated from this project can be used to inform management and reduce disturbance for polar bears in a changing Arctic.