About The Tree Swallow

The six-inch migratory Tree Swallow has an extensive range and can be found across most of northern U.S. and Canada. A graceful flyer, the adult male Tree Swallow has glossy metallic blue upper parts tinged with green and pure white under parts. With a slightly forked tail that is sooty black with a greenish sheen like its wings, the Tree Swallow has light brown legs and feet and dark brown eyes. Its bill is black and the sides of its head are blue-black. In fall and winter, the birds metallic blue upper parts take on a deeper green hue so much so that it looks more green than blue. The female Tree Swallow is duller in color and may have brownish foreheads. The combination of the blue-green upper part and the pure white under part distinguishes the Tree Swallow from the other North American swallows.

The Tree Swallow Nesting Preferences

Unlike other swallows that build their nests in tight colonies, the male Tree Swallow establishes and maintains an area of 15 meters around a suitable nesting hole and defends his territory not just against other swallows but other species of cavity-nesting birds. The ideal habitats for the Tree Swallows nest are large mature or dead trees in wet locations like flooded meadows, marshes, beaver ponds, wetland margins, lakeshores, streams, and open areas near woods. The scarcity of naturally created crevices in which to build nests has forced Tree Swallows to nest in man-made birdhouses and eaves of barns.

The male Tree Swallows arrive at the breeding area a week ahead of the female birds. Once the female arrives, breeding pairs are formed and both birds defend their territory. The female then builds a cup-like nest made of grass and pine needles with the male helping by way of fetching materials for the nest. Both collect feathers to line the nest.

After the nest is made, the female Tree Swallow then lays 4 to 7 white eggs that she incubates for 13 to 16 days. The male protects the nest and continues to bring food. Sometimes during incubation period, both birds temporarily abandon their nest and come back after 3 to 4 days. Nothing bad happens to the eggs except delay their hatching. Once hatched, both male and female take care and feed their young until its time for the young birds to leave the nest.

Tree Swallows raise two broods within a breeding season.

Building a Birdhouse For The Tree Swallow

Tree Swallows are tolerant of people but they prefer to nest in a natural habitat in areas with abundant vegetation and forests that have a dense canopy of trees. These natural sites are quite scarce, however, and man-made nest boxes have had to replace these natural nesting sites.

Tree Swallow houses follow a dimension of 12 ½ high x 6 wide x 8 ½ deep and should be mounted 5 to 15 feet high on a post or tree in open areas. These man-made houses need to be placed 30 to 100 feet apart with the entrance hole facing east.

For Tree Swallows, breeding season normally starts in April.

The Tree Swallow Mating Habits

Once the female birds arrive on the breeding site in mid March or early April, courtship commences. Tree Swallows perch by their nest holes or on the roofs of their nesting boxes while the male attracts the females attention through flutter flight and bowing displays in front of her. Every now and then, one may observe these birds doing the mating ritual of billing or the practice of touching bills with one another. Actual mating occurs a week prior to egg laying. The female Tree Swallow raises two broods in one season and the male can have more than one mate.

The Tree Swallow Feeding Preferences

The Tree Swallows diet consists mostly of insects that it catches on the wing although in winter, the favorite food are bayberries. Tree Swallows leave their breeding sites and form flocks around marshy areas by late July or early August where there is an abundance of winged insects. They migrate southwards by early fall and stick together pretty much during the entire winter. When spring comes, they return in smaller flocks.

Interesting Tree Swallow Facts

Tree Swallows are the only swallows that make the most of their diet of berries and seeds in winter when insects are not available. Favoring bayberries, the Tree Swallows are able to subsist longer during these unkind months and stand bad weather better. Proof of this is the fact that they are the first swallows to reappear in the breeding range come spring. To start their search for suitable nesting areas, the Tree Swallows arrive as early as March when the grounds are still cold and covered with snow.