A common sight at Faville Grove throughout the summer are the foraging flocks of Tree Swallows maneuvering above ponds, wetlands, and prairies to catch the aerial insects that comprise much of their diet. A sleek and impressively designed bird, it’s no surprise that Tree Swallow exhibits such grace and skill in flight. Even their colors seem to emphasize their cool prowess, as the gleaming blue of their backs stands out from afar as they sit atop their nest boxes or cut through the air.
A Tree Swallow poking a head out of a nest cavity in a tree (photo by Courtney Celley/USFWS).
A common inhabitant of nest boxes and tree cavities, Tree Swallows are also known to fiercely defend their nests. They’ll readily squat in bluebird houses, and can often be seen fending off House Sparrows, starlings, and other birds that wish to take advantage of these real estate opportunities. In areas without such nice bespoke homes, Tree Swallows have to compete for tree cavities, better earning their namesake in doing so. They demonstrate high nest fidelity as well, preferring to take up in the same spots yearly.
Tree Swallows often make an early return to Wisconsin, given their shorter migration than many other migratory species. Their breeding territory includes much of the northern US and Canada, and migratory grounds center around the very southern portions of the US and much of Mexico. Unlike many other primarily insectivorous birds, they supplement their migratory diet with various berries, which provides resilience in times of lesser insect abundance. Their early migration may also have to do with the rush to secure nesting sites, as competition can be fierce. Spring cold snaps can be a very precarious time for early returns, and they’ll often form communal roosts in nest boxes, or huddle close together on branches to make it through.
Written by Tucker Sanborn, Faville Grove Sanctuary land steward
Cover photo by Arlene Koziol. A flock of Tree Swallows are perched in the branches of a tree.
