Factors affecting bear and ungulate mortalities along the Canadian Pacific Railroad through Banff and Yoho national parks
Dorsey, Benjamin Paul
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Railroads, roads and associated traffic have been shown to adversely affect ecosystems by killing wildlife and altering the landscape. Relatively little research has been conducted along railroads. Given the probable growth of railroads, it is imperative that we understand the impacts railroads exhibit on wildlife. In this thesis, I reviewed the documented impacts of railroads on wildlife then conducted analyses on data collected along the Canadian Pacific Railroad (CPR) through Banff and Yoho National Parks (~134 km). In the study area, over 1000 train strikes with 26 mammal species have been recorded between 1990 and 2010, which included 579 elk (Cervus elaphus), 185 deer (Odocoileus spp.) and 79 bears (Ursus spp.). The goal of this research was to provide an initial assessment of the factors affecting strikes with ungulates and bears along the CPR. To accomplish these goals, I studied four general factors that have been hypothesized to affect the rate and spatial distribution of strikes. These are: wildlife abundance, anthropogenic foods, and railroad design. I compared strike rates along three mile long rail segments to train spilled grain, train and railroad design variables. I developed an estimate of risk using line transect data so that I could determine if there was evidence for nonconstant strike risk. Statistical models were used to identify which factors best explained strike rates. I detected correlations between the density of train-spilled grain and bear foraging rates but not with bear strikes. I identified locations where corrective measures or mitigation solutions may be needed and identified railroad designs and landscape variables associated with those locations. Hotspots were identified for elk and deer but not bears. Relative abundance was generally correlated with strike rates. High risk locations, where more strikes occurred than were expected, were identified. Train speed limit and right-of-way width was positively associated with strikes for elk and/or deer. For bears, the number of structures (e.g. highway overpasses) and bridges were positively associated with strikes. These results were used to suggest management recommendations including train speed reductions, habitat modifications and railroad design alterations to reduce the risk of strikes.