Tree Swallow (Tachycineta bicolor)

Tree Swallow by Jake Zadik

What would summer be without the dizzying acrobatics of swallows in hot pursuit of insects over fields, woods, and waters? These birds winter from the southern United States to Central America, migrating north to breed when temperate conditions generate a ready supply of insect prey. The Tree Swallow is among the earliest of the migrants to arrive, sometimes well before insects are abundant. This handsome species, with iridescent green back and brilliant white underside, set it off from the darker Barn Swallow and larger Purple Martin, prefers open areas, edges, and wetlands where insects flourish. It can also be seen foraging on the ground. This species has declined with the loss of natural habitat and threats from pesticides, which kill off its food source.

To learn more about ID, range, breeding, and voice, visit Cornell’s All About Birds

What Tree Swallows Need How Can We Help
Food and Water: Primarily insectivores, Tree Swallows take their prey, including countless mosquitoes, on the wing over meadows, woodlots, wetlands and open water. During fall migration they may eat small berries, such as bayberry.
  • Support the protection of streams in your area.
  • Install a small pond.
  • Create a meadow patch with a variety of native plants to provide an array of insect prey.
  • Consider planting a bayberry (Myrica cerifera).
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    Breeding: By late April in our area, pairs form and begin nesting. This continues for six weeks or more. They choose cavities like old woodpecker holes or bird boxes in open areas or edges, preferably near water. Broods are five eggs or so (more when food is abundant) are incubated for about two weeks. Both parents make scores of trips every day carrying multiple items to the young until they're able to feed themselves.
  • Leave dead trees standing for Tree Swallows to build nests in. If a dead tree is close enough that it might fall on your or your neighbor's house, cut off the crown of the tree to remove the weight at the top. The more of the trunk you can leave in place, the more habitat it will provide. Even a 12" snag provides habitat.
  • Consider erecting nest boxes. Tree Swallows are not picky--they will nest in almost any cavity or crevice. (Here and here are sites to tell you all about building and siting nest boxes for Tree Swallows.)
  • Ideally, build nest boxes back-to-back, and you may get both Bluebirds and Tree Swallows. These species usually don't tolerate the same species nesting close by, but are often more amicable with one another.
  • To encourage further nesting and safeguard the health of successive broods, clear out fouled nest materials at the end of the season and thoroughly clean the boxes.
    • Shelter: Cavities and nest boxes double as shelter for this species.
  • Preserve snags of dead trees.
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    Other Threats: Tree Swallows will compete with Bluebirds for nest boxes. You should be delighted to have either species nest in your property! Both species face heavy competition from non-native starlings and House Sparrows. Predators like raccoons and snakes are an obstacle to breeding success.
  • Help to fend off the intrusions of sparrows and starlings by monitoring nest boxes and discouraging these species until the boxes are successfully claimed by Tree Swallows or Bluebirds.
  • Add a baffle on the pole and a wire guard on the entrance hole to prevent access by predators.
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