The tree swallow is a migratory passerine bird that breeds in North America and winters in Mexico, Central America, only as far south as Honduras and the Caribbean, farther north than any other American swallows and return to their nesting grounds long before other swallows come back. They can survive the cold snaps and wintry weather of early spring because they will eat plant foods as well as their normal flying insects.

Their bill is short and flat and opens real wide to feed on small, aerial insects that they catch in their mouths during acrobatic twists and turns with their iridescent blue-green feathers flashing in the sunlight.  A spectacle to watch. We can actually watch them off our deck acrobatically catch insects in their wide opened mouths in mid-air.  They feed in open areas full of flying insects, usually foraging no more than 40 feet from the ground from dawn to dusk. Throughout North America they are a familiar sight in summer fields and wetlands.  This morning I saw less than a dozen but I could hear more of them in the nearby trees. They are responsive to climate changes since the 1960s with the warming spring. These birds on average now lay their eggs nine days earlier in the year.

They nest in cavities of trees near water. They will use nest boxes and we have attached a couple to the underside corner of our deck that looks out over the hillside. We also put a couple nest boxes on some nearby trees. There is a declines in cavity-builder populations. Cornell Lab of Ornithology talks about this conservation concern,

“Tree Swallows are common but their populations declined by 1 percent per year between 1966 and 2010, resulting in a cumulative decline of 36 percent, according to the North American Breeding Bird Survey… Tree Swallow numbers are probably most limited by available nest sites, and as people put up more nest boxes their range has been expanding, particularly southward. But boxes account for only a small fraction of Tree Swallow nest sites. Natural cavities, where most Tree Swallows build their nests, have been disappearing for the past 200 years as people clear the land, manage woodlands, cut down older trees, and remove dead trees.”  In spite of all this their numbers are still in a healthy range.

Tree Swallows pair up to breed but are often a bit promiscuous, secretly mating outside the pair. Poor male will have to attends to two mates in separate nest sites helping to feed the little ones. The female lays four to seven white eggs and incubates them by herself. The eggs hatch in about 14 days and fledging in 16–24 days.

If you are lucky you might see these agile fliers do the most amazing things. I remember once being blown away by watching a tree swallow skim it’s bodies against the surface of the water on the lake to bathe. It’s like a quick shower by air, barely touching the surface of the water that sprays a gentle mist into into the air on their feathers. Afterwards they just keep flying ruffling their feathers a bit to shake off any drops of water.