Wild Profile: Meet the tree swallow

Published: May 11, 2021

A male tree swallow perched on a branch against a muted background By Elliotte Rusty Harold/Shutterstock

Did you know that people once thought that the tree swallow hibernated on the moon? Or, in the mud at the bottom of lakes and oceans? Of course, folks had reasons for thinking this. In spring, tree swallows tend to arrive on the scene suddenly, returning from where they actually spent the winter—near the Caribbean Sea—and descending from the sky in swirling flocks. Then, they skim the surface of the lakes, hoping to snatch up emerging insects.

Because a tree swallow’s favourite habitat is near water—wetlands, beaver ponds, rivers, lakes—about 90 per cent of their diet comes from insects that live near water, including midges, gnats, and blackflies. But they can nab practically any bug that flies, thanks to their acrobatic twists and turns in the air.

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Tree swallows nest in early May. Their tiny beaks are too small to dig out a fresh nesting cavity in a prospective tree; they have to rely on natural holes or empty woodpecker homes. Dead trees that have fallen into the water are choice spots—psst, another reason to leave dead wood where it falls—but if a swallow can’t find one, it will resort to a hollow, unanchored floating log. Often, there are too many tree swallows and not enough suitable trees. This means that both males and females will fight each other for a home.

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When you see a tree swallow (you can’t miss the males, with their flashy, blue-green feathers), it’ll probably be flying. They spend more time in the air than any other songbird. And be on the lookout if you’re in a slow-moving boat; tree swallows have been known to almost crash into boaters’ heads while pursuing a meal. Thankfully, they’re pretty good a veering off at the last second. Still. Close call.

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