Tree Swallow Breeding Biology and the Phenology of Aquatic Emergent Prey in Artificial and Natural Wetlands

Over the past 80-100 years, aerial insectivore populations have declined across North America. Climate change and agricultural intensification are hypothesized to be responsible for the declines by negatively affecting their main food source, aerial insects. Some management strategies in agroecosystems have focused on creating aquatic habitats (e.g. prairie ponds and artificial wetlands) to mitigate nutrient runoff, but their use by avian species has not been well studied. Tree swallows (Tachycineta bicolor) are aquatic aerial specialists and forage over aquatic habitats on emergent adult aquatic insects such as Dipteran and Ephemoptera. Subsequently, their breeding success could be negatively affected by having reduced insect abundances, having implications for future population dynamics. This study investigated whether artificial wetlands in agroecosystems from corn cultures in northeast Pennsylvania and current climate conditions are creating ecological traps for reproducing populations of Tree swallows. I investigated whether trophic mismatch between emerging aquatic Diptera prey and reproductive biology existed. I evaluated aquatic insect emergence from artificial and natural wetlands surrounded by intensive crop cultures as potential prey availability to Tree swallows in northeast Pennsylvania. I predicted the Diptera prey abundance will be similar in the natural versus artificial wetland because of the agriculture land surrounded by it. To do this, I used emergence traps to assess abundance of aquatic Diptera emergence in different wetland types (artificial and natural) utilized by breeding Tree swallow breeding pairs. The wetland sites were selected based on surrounding agroecosystems of intensive cultures.