Bank Swallows (Riparia riparia) are a species of declining aerial insectivores that nest and breed primarily along rivers and streams across Canada. The causes of this decline are complex, with factors such as prey loss, large-scale ecosystem modifications, and environmental contaminants cited as potential drivers. One of the largest breeding populations of Bank Swallows in British Columbia is found along the Peace River in the province’s northeastern region. This same river is also the location of the Site C dam, a decade-long construction project with the potential to introduce pollutants into the environment and alter aquatic ecosystems, thus
potentially reducing the availability of aquatic emergent insects. Such changes can potentially contribute to two major drivers of Bank Swallow decline. This thesis assessed dam construction effects on Bank Swallows by evaluating diet quality and trace element concentrations of nesting adults and juveniles upstream and
downstream from dam construction activities. By analyzing long-chain polyunsaturated fatty acids Eicosapentaenoic acid (EPA), Docosahexaenoic acid (DHA), Arachidonic acid (ARA), Alpha-linolenic acid (ALA), and Linoleic acid (LA) in Bank Swallow blood plasma, I found that juveniles consumed higher-quality diets than their adult counterparts. Juveniles also had consistent high-quality diets, whereas adult Bank Swallows appeared to consume higher quality diets downstream from the construction. Significant differences were also found based on year, with 2021 exhibiting a lower quality diet overall than 2023. Analysis of Bank Swallow feathers revealed potentially harmful concentrations of lead and chromium in juveniles, indicating potential environmental contamination near the construction site. All other trace elements tested were under harmful thresholds. Together, these findings provide preliminary evidence that dam construction may negatively impact the health of nesting Bank Swallows, despite standard environmental mitigation efforts. As this data was collected during the construction phase before the reservoir was completed, further environmental impacts are expected in the coming years. Continued monitoring of diet quality and trace elements, particularly of methylmercury concentrations in the tissues of this at-risk species is strongly recommended.
