Tree Swallow

The Tree Swallow is a bird commonly sighted in marshes, meadows, and open fields. After reading this, one might wonder why they’re called Tree Swallows. They’re aptly called the same because they are heavily reliant on tree cavities for nesting. This characteristic of theirs is important enough to earn them their name because it dictates a large part of their behavior.

About Tree Swallows

Tree cavities are not very abundant, and these birds are not particularly the best builders — so they are dependant on woodpeckers to drill them suitable cavities, or they have to search for abandoned tree holes. As a result of the limited availability of nest cavities, Tree Swallows arrive early in Spring to claim tree cavities for nesting. Due to this, breeding also occurs early for these birds.

There is always fierce competition over these nesting cavities. Perhaps as a result of the limited availability of nesting cavities, Tree Swallows very readily accept nest boxes for nesting. As these birds are also tractable, and so easily available to study, they have become a model organism in ecology. By studying these birds, significant advances have been made in the fields of ecotoxicology, history theory, mating systems, and vertebrate physiology. Some impacts of climate change have also been observed by studying these birds. Tree Swallows are easily the most studied birds in North America, but despite this, very little information is available about their migration or their wintering habitats. Tree Swallows living outside of northeastern North America have not been the subject of as much research and study.

If a bird-enthusiast living in their range wishes to be visited by these birds, they can set up a nest box in their yard. This nest box needs to be set up well in time before breeding, as Tree Swallows are early breeders.

● Tree Swallows Photos, Color Pattern, Song
● Tree Swallows Size, Eating behavior, Habitat
● Tree Swallows Range and Migration, Nesting

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Tree Swallow Color Pattern

Tree Swallows gain a very vibrant and beautiful plumage once they reach adulthood. Juveniles look very unlike adults as they have a very dull appearance. Their upperparts are sooty gray with a slight silky shine, and their wings and tails are sooty grays with the presence of a slight greenish iridescence.

Their breasts are incompletely ashy brown, their underparts are dull white and significantly less silky than the underparts of the adults. As juveniles, both sexes look alike but males might possess a slightly glossier plumage.

After the first molt, female Tree Swallows begin to have brown upperparts with a faint greenish iridescence. Some of these feathers might also be greenish-blue like the fully-formed adult’s. The underparts of these birds are white, and they have a faint brown pectoral band. By this time, males look almost similar to their adult plumage, but they might lack the iridescence and the gloss of the adults.

Adult Females have more greenish-blue iridescence on their upperparts, but this iridescence is slightly duller than that of the males. Some females might retain a small number of brown feathers on their forehead for a number of years. If present, this might be the easiest method of identifying her gender. Adult males have much more vibrant plumage.

Description and Identification

Although Tree Swallows are quite distinctive in their appearance, they can sometimes be confused for Violet-green Swallows. In comparison to Tree Swallows, Violet-green Swallows are not as bright, and they have the white eye patch or white rump sides like the Tree Swallows.

Juvenile Tree Swallows are sometimes confused with two species of brown-backed Swallows: Bank Swallows and Northern Rough-winged Swallows. Rough-winged Swallows are almost the same in size and structure but lack the brownish washed throat and breast of juvenile Tree Swallows. Juvenile Tree Swallows are larger than Bank Swallows.

During winters, Tree Swallows are more easily confused with other species of birds. The songs of Tree Swallows are not particularly consistent throughout their range. In this case, a keen eye is much more useful than receptive ears.

Tree Swallow Song

The begging calls of nestlings are extremely variable in the first week after they hatch. Vocalizations of adult Tree Swallows require more comprehensive studies as there is a regional variation in their vocalizations. There have been two studies in Ontario and Colorado, and both of the studies provide different results.

Chatter calls can last 0.05 seconds in both populations. These “shet-shet-shet” calls are usually in quick succession.

“Shriek” calls are a series of low-pitched calls that last for an average of 0.10 seconds. These are alarm calls that members of both sexes make, to raise alarm about potential nest predators or to intimidate nest site competitors. These calls can be directed to offspring, mates, or other conspecifics.

Ticking calls occur in both regions, but they have slight variations in their tone and pitch. They make these calls before or during copulation. Usually, the male hovers around a perched female and begins vocalizing this call before attempting to make sexual contact. This call continues throughout the copulation period.

Chirp calls are contact calls that they make mainly during copulation, but sometimes individual females make these calls when they are just sitting alone. This call might have the possibility of serving a number of purposes, so it needs to be studied in further detail. Tree Swallows make a number of other vocalizations and they have a song that differs according to the geographical range of these birds. The song that the population in Ontario makes comprises of three figures “whine, chirp, and gurgle”. They repeat these three figures endlessly in a variety of patterns.

In Nova Scotia and Colorado, these birds sing two different songs at different times of the day. They sing a shorter song during the day, and a longer one at dawn. The song at dawn also includes other calls these birds make. Males sing both of these songs exclusively. In Ontario, females also sing.

Tree Swallow Size

Tree Swallows are small birds, but medium-sized when compared to other Swallows. Their length ranges from 4.7-5.5 inches, and they have a wingspan between 11.8-13.8 inches. These birds generally weigh between 0.6 and 0.9 ounces.

Tree Swallow Behavior

Tree Swallows are highly gregarious birds that travel in flocks containing over a hundred thousand birds. These birds can also be in such large numbers outside of breeding season. All these Trees Swallows usually group together for roosting during nighttime.

During the breeding season, these social birds are extremely territorial. There are 50-60 feet of the area surrounding their nests that members of both sexes protect aggressively. Competitiveness for nesting sites is the cause for most of the behavior that Tree Swallows make.

Tree Swallows are very agile at flying they glide much more than other Swallows. While bathing they fly towards the water, skim their bodies against the surface of the water, then rise quickly and shake off water droplets.

Interestingly, these birds play with the feathers that they use to line their nests. One bird flies over the nest while holding a feather in its bill, and this can lead to aerial chases or the feather can be dropped to see who will be the first to retrieve it.

Tree Swallows form pair bonds but often mate outside their pairs. Males often visit two separate nest sites. Some individuals might have the same mate for years in a row, but these birds are faithful to the nest sites, and not specifically to their mates.

Often, nests of these birds are predated by birds of other species, and some animals. Common nest predators are black bears, chipmunks, raccoons, minks, weasels, feral cats, deer mice, American Kestrels, Northern Flickers, American Crows, and Common Grackles. Adults are also hunted outside the nest by Great Horned Owls, Black-billed
Magpies, Merlins, Peregrine Falcons, and Sharp-Shinned Hawks. It is common to see Tree Swallows swarming and dive-bombing their predators.

Tree Swallow Diet

The diet of these birds mainly consists of insects. In the absence of an abundance of insects, they feed on plant food and small animals. These aerial foragers mostly feed during the day in areas abundant with flying insects. Often, they do not fly higher than 40 feet while feeding.

Insects commonly consumed by them are damselflies, wasps, beetles, butterflies, stoneflies, mayflies, caddisflies, true bugs, bees, ants, sawflies, dragonflies, and moths. Other than these insects, they also eat mollusks, roundworms, and spiders. The maximum length of prey hunted by them is 2 inches long.

Tree Swallows often forage in large groups in insects swarms. They use their agility and acrobatic ability to successfully chase their prey in the air.

During Spring, these birds include foods such as fish bones, crayfish exoskeletons, eggshells, and clamshells into their diet. These foods are important because they are calcium-rich.

Tree Swallow Habitat

In the past Tree Swallows only live in forested regions as they needed tree cavities for nesting now with the availability of nest boxes they can also be found in open habitats. Most Tree Swallows nest in the same area they nested the previous year. Only about 4% of males and 14% of females find new areas to nest in. New nesting sites are also usually in close proximity to their original breeding grounds.

Areas that Tree Swallows live in are marshes, shorelines, meadows, wooded swamps, beaver ponds, and fields. These birds usually find nesting cavities in dead trees, excavated holes in live trees, and under buildings.

Range and Migration

The breeding range of Tree Swallows covers central and northern North America. The tree lines end at the northernmost end of their range.

Wintering grounds for these birds are located in southern North America. Most populations winter in Florida, and fewer populations winter long on the Caribbean coast.

Tree Swallow Lifecycle

Breeding for Tree Swallows begins between March and May. Most of these birds lay eggs throughout May and June, but egg-laying periods can differ according to the geographical range. In the southern portion of their range, egg-laying begins fairly early.

Tree Swallows sometimes might raise more than one brood. Females lay between 2-8 eggs per clutch which they need to incubate for 11-19 days. These eggs are 0.7-0.8 inches long, and 0.5-0.6 inches wide. Although pale pink at the beginning, soon these eggs become pure white in color.

Parents care for their nestlings for 15-25 days, after which they fledge. Both sexes mature sexually by the time they become one year old.

Adult Tree Swallows have a very conservative survival rate of 40-60%. On average, these birds only survive for about 2.7 years. The oldest Tree Swallow was about 11 years old.

Nesting

The female is the most involved in the nest construction process. She can take up to 2 weeks to complete this process. They collect materials from the ground within 100 feet of the nest site.

This nest is mostly made of grass, but it may also consist of mosses, rootlets, aquatic plants, animal hair, and pine needles. The female uses her body to shape the nest material into a cup. This cup is 1-2 inches deep and has a diameter of 2-3 inches. They also use feathers of many other bird species to line their nests.

Anatomy of a Tree Swallow

Tree Swallows are lean birds that have small legs and feet, long wings, and short bills.

Final Thoughts

Tree Swallows are fascinating birds that are unique in many ways. It’s very interesting how the competitiveness regarding their nesting sites dictates their behavior to such a great extent. An enthusiastic birdwatcher living in their range will definitely enjoy sighting these vibrant birds.

Ornithology

Bird Watching Academy & Camp Subscription Boxes

At the Bird Watching Academy & Camp we help kids, youth, and adults get excited and involved in bird watching. We have several monthly subscription boxes that you can subscribe to. Our monthly subscription boxes help kids, youth, and adults learn about birds, bird watching, and bird conservation.

Bird Watching Binoculars for IdentifyingTree Swallows

The most common types of bird watching binoculars for viewing Tree Swallows are 8×21 binoculars and 10×42 binoculars. Bird Watching Academy & Camp sells really nice 8×21 binoculars and 10×42 binoculars. You can view and purchase them here.

Tree Swallow Stickers

Stickers are a great way for you to display your love for bird watching and the Tree Swallow. We sell a monthly subscription sticker pack. The sticker packs have 12 bird stickers. These sticker packs will help your kids learn new birds every month.

Bird Feeders ForTree Swallows

There are many types of bird feeders. Bird feeders are a great addition to your backyard. Bird feeders will increase the chances of attracting birds drastically. Both kids and adults will have a great time watching birds eat at these bird feeders. There are a wide variety of bird feeders on the market and it is important to find the best fit for you and your backyard.

Bird HousesForTree Swallows

There are many types of bird houses. Building a bird house is always fun but can be frustrating. Getting a bird house for kids to watch birds grow is always fun. If you spend a little extra money on bird houses, it will be well worth every penny and they’ll look great.