Tree Swallow (Tachycineta Bicolor) Nest Success And Nestling Growth Near Oil Sands Mining Operations In Northeastern Alberta, Canada

Industrial development and contaminant exposure may affect reproductive success and food quality for birds. Tree Swallows (Tachycineta bicolor (Vieillot, 1808)) nesting near oil sands development in northern Alberta (Canada) potentially experience elevated environmental stressors that could influence reproduction. We measured reproductive and growth endpoints in Tree Swallows, predicting reduced reproductive success and nestling growth near oil sands operations compared with reference sites. We also identified the invertebrate prey in the stomach contents of nestlings to understand variability in the diet and its potential effect on growth and survival of nestlings. From 2012 to 2015, clutch initiation varied among years but was not influenced by proximity to oil sands operations. Hatching and fledging success decreased in response to increased precipitation, regardless of location. Measurements of nestling growth reflected the variation associated with nestling sex and possibly asynchronous hatching. The composition of the nestling diet was significantly different; birds near oil sands development consumed Odonata, whereas birds at reference sites consumed Ephemeroptera. Nestlings from all sites consumed relatively high quantities of terrestrial insects. Our results demonstrate that factors such as weather conditions, diet, hatching order, and nestling sex are important when interpreting the potential effects of oil sands development on nest success and nestling growth.