Tree Swallows Enliven the Landscape and Eat Bugs
March is as much winter as spring in Ohio, a yo-yo ride of lamb to lion weather changes. As I write this, a dusting of snow frosts the ground and the air temperature hovers just below the freezing mark. A week ago it was comparatively balmy and our first flowers were poking forth.
March hardly seems the time for insect-eating birds to return.
Yet our third month is when the tree swallows tumble into town. The earliest scouts venture into Ohio by the first week of March, and by month’s end these perky little swallows are far and wide and in big numbers. It’s a bit of a gamble, venturing into a still wintry landscape when your primary fare is insects.
But these shiny blue-green birds are tough customers – far hardier than the other five species of swallows that nest in Ohio. Tree swallows do venture to tropical haunts for the winter, as any self-respecting swallow should. They’re no dummies, and many of our Ohio birds probably winter in Florida – true snowbirds. Tree swallows also range into Mexico and along the Caribbean coast of Central America, all the way to northern South America.
The pull to return to northern breeding grounds is intense, and tree swallows don’t dilly-dally when it comes time to head north. Early birds sometimes appear by February’s end, and there are always sightings by early March, and they’re abundant by April.
Tree swallows subsist primarily on flying insects, which they deftly pluck from the sky. Aerialists supreme, a tree swallow can put the best stunt pilot to shame. Jigging and jagging with impossible speed and agility, no bug that bumbles onto a tree swallow’s radar is safe. They even bathe on the wing, skimming low over water and bumping the surface to create a shower of spray.
Why would an insect-dependent bird return to Ohio so early as to expose itself to the peril of March freezes? Competition for nest sites, mainly. Tree swallows nest in cavities, and suitable holes are in great demand. The early bird truly gets the worm, and the earliest swallows to return can claim the best nest sites. On the downside, these early arrivals may perish in a fierce bout of wintry weather.
Tree swallows have a few tricks that help them to survive inclement conditions, at least for a while. When temperatures nosedive, a swallow can lower its metabolism and greatly reduce energy expenditure – a condition knows as torpor. They are also our only swallow that will eat fruit in a pinch, in addition to various seeds of wetland plants.
These dapper-looking birds, with their two-toned coats of glossy green and white, greatly enrich the landscape. Tree swallows are even a treat for the ears, talking more or less constantly in a language of rich liquid gurgles. If you’ve got the space, you may even be able to offer them homes. Tree swallows take readily to nest boxes, just as Eastern bluebirds do. Having a squadron of voracious insect-eaters working your air space is just another perk of their companionship.
Jim McCormac
Ohio Division of Wildlife
Please credit the Ohio Division of Wildlife for the article and images, unless otherwise noted.
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