Every year when I see early arrival of Tree Swallows I wonder why they come so early and why not wait a little longer until the weather warms up and the insects are more abundant. I recently came across a research study conducted in Queen's University. The researchers analyzed data taken from Tree Swallow nest boxes over a period of 42 years (1977-2017). The findings are quire fascinating. The study observed that over the years the Tree Swallows are gradually losing their body mass and they attributed this to climate change that is making our Spring cooler and wetter resulting in fewer flying insects and thus depriving the Swallows of their food sources. Here's the link to the main article.
https://www.queensu.ca/gazette/stories/tree-swallows-expose-state-our-climate
