Long Point Bird Observatory, situated on a 40-kilometre sandspit near Lake Erie in southwestern Ontario and recognized as a UNESCO Biosphere Reserve, is home to diverse wildlife and holds the distinction of being the oldest continuously operating bird sanctuary in North America.
Recent findings revealed in a study published in the Proceedings of the National Academy of Sciences indicate that tree swallows at Long Point have exhibited a decrease in egg production and a reduction in body size since monitoring began in 1969. The research, conducted by the University of Michigan and Birds Canada using historical data from the observatory, also highlighted a significant decline of 43% in aerial insectivores, such as tree swallows, along with a more than 60% decrease in insect populations since 1977.
Lead author Charlotte Probst, a PhD student at the University of Michigan, emphasized the importance of tree swallows as a “model organism” due to their ease of study through nest box monitoring. The study revealed a timing mismatch between the emergence of insects and the breeding patterns of the swallows, attributed to climate change causing earlier warm temperatures. This phenological mismatch poses challenges for the birds in synchronizing their migration and breeding with peak food availability.
Matthew Fuirst, a research ecologist at Birds Canada and co-author of the study, highlighted the adverse effects of low insect abundance on the condition and size of both nestlings and adult swallows. The study pointed out a widening gap in the timing mismatch, increasing by over three days per decade since 1977, as observed in historical data.
In parallel research, Hadil Elsayed, a PhD candidate at York University, noted a shift in insect emergence due to rising temperatures, leading to a decline in insect populations. Elsayed’s findings indicated changes in heat accumulation patterns affecting insect growth, with insects appearing two weeks earlier than in the 1990s.
While addressing climate change is a global imperative, Probst, Fuirst, and Elsayed emphasized local actions to combat insect declines, such as planting native wildflowers, reducing pesticide use, and preserving habitats for insects. Their recommendations underscore the interconnectedness of ecosystems and the cascading impacts of changes within specific species groups on the broader food chain.