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Tree Swallow Nesting, Mating, Feeding Habits

The Tree Swallow is one of the first of our swallows to arrive in early spring.

Leaving its wintering grounds along the seacoast from the Carolinas to California as they begin their courtship, mating, and nesting habits.

Description What they Look Like

Tree Swallows are 5 to 6 inches long. The Male has iridescent blue upperparts and bright white underparts.

In fall, the upper parts may appear greenish. The female has duller, brownish upperparts and grayish under parts.

Tree Swallow on top of Bird house

Tree Swallow

The female has an immature plumage in the 1st year (sometimes 2nd year).

This allows her to approach breeding adult birds and their nest without being chased from the pair's nesting site.

If anything happens to the breeding female and she dies, the younger female Tree Swallow can replace her. This helps ensure a successful breeding season.

Tree Swallow Call

Mating Habits

Soon after arriving on their breeding grounds in mid-March to mid-April, courtship begins.

The birds perch near their nest holes or on top of nesting boxes. Flutter-flight and bowing displays from the male are done in front of the females.

Occasionally, one may see these birds billing. This is the practice of a mating pair touching bills with one another.

Actual mating occurs about a week before egg-laying begins.

Tree Swallow Nesting Habits

Tree Swallows prefer open areas near water in dead trees at the water's edge for nesting.

Tree Swallow at Birdhouse

Tree Swallows are cavity-nesting birds and make ideal candidates for man-made birdhouses.

Competition from House Wrens and House Sparrows makes it even more important to place and monitor birdhouses for these graceful flyers.

Woodpecker holes are in short supply by the time these swallows arrive and nest sites are fiercely defended.

Tree Swallows sometimes arrive before Purple Martins, and may compete for the same nesting cavities.

If you're a Purple Martin landlord, try to provide a separate nesting cavity for these birds. They seem to prefer south-facing nest boxes.

Keep your Purple Martin housing closed until the Tree Swallows select other housing that you've placed for them.

You'll notice a slotted opening on the birdhouse built for this bird. This makes the house a little more resistant to House Sparrows.

The territory that they defend is only the area of the nest itself.

tree swallow perched on reed

Tree Swallow Perched on Reed

If predators or human visitors approach the nest while the birds are around, the birds may swoop toward the intruder and turn at the last minute. Sometimes, just narrowly missing the intruder.

The nest is built primarily by the female, although the male does some gathering of materials.

The nest is cup-shaped, made of grasses for a foundation, and lined with feathers.

The nest-building process can take as long as a month but is generally completed in 2 to 3 weeks.

Egg laying begins early in May when the female begins laying 4 to 7 white eggs. Incubation is by the female and takes 13 to 14 days, but can go longer.

Sometimes, the nest may be abandoned for a few days during egg laying even during incubation times.

During this time, you'll see no activity around the nesting site. Within 3 to 4 days, the birds return with eggs still viable.

This leave-of-absence does not affect the success of the young birds hatching, only delaying the event.

Tree Swallow Nesting Stats
Eggs 4 - 7
Incubation 13 - 14 days
Nestling Phase 18 - 20 days
Broods 1 - 2

After hatching, both males and females provide food for their nestlings.

The young birds will leave the nest on average about 18 to 20 days after hatching. But can be in 15 to 25 days.

One brood is raised each season. Renesting may happen if the early nest fails or is abandoned.

In some extreme western or southern populations, Tree Swallows may raise a second clutch. This is not a common event.

Feeding Habits - What Tree Swallows Eat

The diet of Tree Swallows consists mainly of insects caught on the wing. In winter, bayberries are a favorite food to eat.

Insects are caught on the wing and flying over water is a favorite hunting area. Do not feed on the ground or in trees.

By late July or early August, the Tree Swallows leave their breeding grounds and form flocks, around marshy areas where there are plenty of flying insects to eat.

In early fall, the swallows will begin migrating southward. Migrating birds may winter in Florida, Cuba, and South America.

During winter, they feed in large flocks but when Spring returns, these large flocks break up into smaller flocks and migrate back to their breeding territories.

You may also like reading about The Habits of Barn Swallows