Spatial and Temporal Relationships of Adult Male Black Bears to Roads in Northwest Montana, 2003-2004
Chilton-Radandt, Tonya. M.S., Autumn 2006 Spatial and Temporal Relationships of Adult Male Black Bears to Roads in Northwest Montana Chairperson: Dr. Elizabeth Crone Roads have direct and indirect consequences for wildlife. Vehicle collisions are a direct cost of roads on wildlife. Indirectly, roads may increase mortality of game species by increasing hunting pressure along these roads. Adult male black bears (Ursus americanus) are the most desirable age and sex class to many hunters, which may lead to over-harvest of this sex and age class. Road closures (permanently closing or seasonally restricting roads) are used to mitigate impacts of roads on wildlife, including bears. Little is known about how roads affect harvest vulnerability of black bears. I hypothesized that adult male black bears will avoid roads during hunting seasons compared to summer; so road use, and therefore hunting vulnerability, should decrease during hunting times. I used samples of six and ten adult male black bears and evaluated the amount to which these bears avoided roads between seasons. I used ANCOVA to find the effects of season, diel period, and factor interactions on the proportion of bear locations inside a roaded area, the average road density near bear locations, and the average proportion of movements with road crossings. ANCOVA allowed me to account for the confounding of roads and elevation within my study area. Bear distribution proximate to roads differed significantly (p<0.01) between seasons. Specifically, road use - especially of open roads - decreased from nonhunting to hunting seasons for both samples. Bears avoided roads during the fall compared to summer, which may reduce bear vulnerability during the fall hunt. My research neither fully refuted nor supported the question of whether restricting roads appeared to change the effects of season. Although other possible explanations exist, adult male black bears were less likely to be in the roaded area at times when shooting was legal (during the hunting seasons), which is consistent with the idea that they survive to maturity by avoiding the roaded area thus avoiding hunting and traffic.
hunting, North American black bear, ursus americanus, vulnerability
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