This week’s featured creature is one that many people have probably seen, but may not have known just what species it was when they saw it.

And to be honest, the tree swallow is much less common than other swallows that we see in Oklahoma — such as cliff and barn swallows (future columns).

Tree swallows inhabit open areas, and are so named due to the fact that they nest in trees cavities.

Tree swallows are among the earliest birds to arrive during spring migration, and the earliest to leave. Some tree swallows will begin heading south in July.

I know when I see them in spring, migration is about to ramp up.

While I don’t know it for sure, I can only imagine that the tree swallow was the inspiration for the naming of the Blue Swallow Motel in Tucumcari, New Mexico, as male tree swallows have blue-green backs.

Appearance

Male tree swallows are dark above and white below. On their backs, heads and portions of their wings, they have an iridescent blue-green coloring which is quite stunning when the sun shines on them.

Females resemble males, but are usually duller. The blue-green coloring above is much more subdued. However, some females can be nearly as colorful as males, according to the Cornell Lab of Ornithology.

Juveniles resemble adults, but lack any blue-green coloring.

Range

Tree swallows are an uncommon summer resident in Oklahoma. Their breeding range covers much of the northern two-thirds of the United States, up into Canada, eh, and Alaska. They winter along the southern border of the United States — including the Gulf Coast — and down to Central America.

Food

Tree swallows eat mostly insects, many of which they catch mid-air as they are great aerialists. Insects include, true flies, caddisflies, dragonflies, damselflies, mayflies, sawflies, wasps, bees, butterflies and moths. According to the Cornell Lab of Ornithology, they also eat some plant material such as berries on rainy days and during the winter.

Habitat

Tree swallows inhabit open and semi-open areas, usually near water. According to the Cornell Lab of Ornithology, they “prefer to live near bodies of water that produce multitudes of flying insects for food.” Those bodies of water include ponds, lakes and marshes.

Nesting

As I mentioned previously, tree swallows nest in tree cavities, usually abandoned woodpecker homes.

Males and females often choose new mates each year, according to the National Audubon Society.

And these birds will readily set up shop in nesting boxes.

Females lay between four and seven eggs, which are incubated for 11 to 20 days, according to the Cornell Lab. Young fledge after 15 to 25 days.

For more information about attracting birds with nest boxes, visit the Cornell Lab’s website, NestWatch, at https://nestwatch.org/.

Odds and ends

• Tree swallows are common but overall populations declined by nearly 50% between 1966 and 2014, according to the North American Breeding Bird Survey. During the same period, however, while the species decreased in the east and west, populations in central North America increased, according to the Cornell Lab.

• The Cornell Lab reports that tree swallows are highly social, forming large migratory and wintering flocks; and pairs often nest close together, particularly where nest boxes are numerous. However, I believe this would occur mostly where the birds are more common. In the Southern Oklahoma/North Texas area, I usually see a nesting pair with no other tree swallows in sight.

Randy Mitchell is a freelance writer and photographer. He has been an avid birdwatcher, nature enthusiast and photographer for more than 40 years. Reach him at rnw@usa.com.

Recommended for you