The tree swallow gets its name from its habit of nesting in tree cavities and its aerial ability to “swallow” insects while in flight. This small songbird has adapted to live closely alongside humans, nesting in man-made birdhouses and structures. Its name is a descriptive and apt title for a bird that truly links the forest to the skies.
Quick Facts on the Tree Swallow
Here are some key facts about the tree swallow:
- Scientific Name: Tachycineta bicolor
- Average Length: 5.1-5.9 inches
- Average Weight: 0.7 ounces
- Wingspan: 11.8-13.4 inches
- Average Lifespan: 2-8 years
- Conservation Status: Least Concern
The tree swallow is a small-sized bird with long, pointed wings and a short, forked tail. Adults have iridescent blue-green plumage on their back and wings, and clean white underparts. Females may have slightly duller plumage than males. The tree swallow gets its scientific name Tachycineta bicolor from these two distinctive colors on its body.
Tree Swallow Identification
The tree swallow is most likely to be confused with the violet-green swallow and the purple martin. Here are some tips for identification:
- Forked tail distinguishes it from purple martin
- Dark blue-green sheen on upperparts unlike violet-green swallow
- Nests in tree cavities unlike cliff swallow which nests on cliffs
- Smaller size than northern rough-winged swallow
The white underparts, contrasting with the dark iridescent upperparts, make the tree swallow one of the most beautiful and recognizable North American swallows during flight. In bright sunlight, it can appear to flash different shades of blue and green.
Tree Swallow Habitat
The tree swallow inhabits open areas across much of North America near water sources such as lakes, rivers, wetlands, and coastlines. Typical habitats include:
- Parks and recreational areas
- Orchards and agricultural fields
- Golf courses and suburban backyards
- Marshes and shorelines
Tree swallows nest in abandoned woodpecker cavities in dead trees. They also readily take advantage of nest boxes put up by humans. Unlike other swallows, they are not colonial nesters but prefer spacing their nest sites apart.
Tree Swallow Diet
The tree swallow is an aerial insectivore, which means it catches insects while in flight. Its diet mainly consists of:
- Flies
- Bees
- Wasps
- Flying ants
- Beetles
- Moths
It catches insects in open areas, fields, near water, and in the air. It never eats food from the ground. The tree swallow drinks by skimming the surface of water bodies.
Tree Swallow Behavior
Some interesting behaviors and traits of the tree swallow include:
- Strongly territorial around nest sites
- Forms pair bonds that may last multiple seasons
- Male performs dramatic aerial displays during courtship
- Females build nests out of grasses and feathers
- Produces one brood per mating season
- Often reuses the same nest site across years
- Very vocal with twittering calls
- Migratory – winters in southeastern U.S., Caribbean, and Central America
Tree Swallow Nesting
Tree swallows show high nest site fidelity. A mated pair returns to the same cavity or nest box year after year. The female builds the nest out of grasses and feathers, taking 10-14 days on average. The nest cup is lined with more feathers.
The female lays between 4-7 white eggs and incubates them for 13-16 days. The chicks hatch altricial, meaning naked and helpless. Both parents feed the nestlings, which fledge around 18-24 days after hatching.
Tree swallows readily use nest boxes put up especially for them. Ideal nest box dimensions are around 6 inches wide x 8 inches deep x 8 inches high, with a 1.5 inch diameter entrance hole. They should be located in open habitat near water.
Threats and Conservation
The tree swallow has a large range and healthy overall population. They face no major threats at a species level. However, local populations may be affected by:
- Habitat degradation from human activity
- Competition for nest sites with non-native species
- Decline in flying insects from pesticide use
Providing nest boxes, preserving dead trees with natural cavities, and protecting wetlands helps support tree swallow populations. Tree swallows are a protected species under the Migratory Bird Treaty Act.
Fun Facts
- Female tree swallows prefer males with darker ventral plumage, which may indicate better health and breeding conditions.
- Parents will eject baby swallows from the nest before they are ready to encourage them to fly.
- Also called the white-bellied swallow.
- Male and female take turns incubating the eggs.
- Spends most of its time flying – eats, drinks, and even mates on the wing!
Why “Tree Swallow”?
So why is this graceful, aerial insect-eater called the tree swallow? There are a few main reasons behind this name:
- Nests in tree cavities – Unlike other swallows that nest on cliffs or human structures, the tree swallow nests in abandoned woodpecker holes and natural tree cavities.
- Dependence on trees – It relies on dead trees to provide nesting sites. Living trees provide perches and habitat. Tree swallows are more associated with wooded areas than other swallow species.
- Forages over trees – The tree swallow frequently hawks for insects over treetops, especially near water sources like wooded lakes.
- Original naming – Early European settlers named it the tree swallow in comparison to barn swallow, bank swallow, and cliff swallow. This name emphasized its forest connections.
In essence, the tree swallow gets its wonderfully descriptive name from its strong links to trees for nesting and feeding. No other North American swallow is more specialized for utilizing forest habitats.
Other Names & Confusion With Other Species
The tree swallow also goes by other colloquial names including:
- White-bellied swallow
- Winter swallow
It is sometimes confused with the violet-green swallow or purple martin due to similar plumage. The tree swallow can be distinguished by its habitat preferences, smaller size, and calls.
Appearance & Size Relative to Other Swallows
Species | Length | Main Colors |
---|---|---|
Tree Swallow | 5.1-5.9 in | Iridescent blue-green back, white underparts |
Northern Rough-winged Swallow | 5.5-6.3 in | Brown back, lighter underparts with brown wash |
Bank Swallow | 4.7-5.1 in | Gray-brown back, white underparts with dark breast band |
Cliff Swallow | 5.5-6.3 in | Blue-black back and cap, pale orange forehead, buff underparts |
Barn Swallow | 5.9-7.5 in | Iridescent blue-black back and cap, rusty underparts |
Purple Martin | 7-8.3 in | Entirely iridescent blue-black |
As this table shows, the tree swallow is a mid-sized swallow species. It is larger than the bank and rough-winged swallow but smaller than the purple martin. Its blue-green plumage is also unique among its relatives.
Tree Swallow vs. Violet-green Swallow
The tree swallow is most often confused with the very similarly plumaged violet-green swallow. Here is a quick comparison:
Trait | Tree Swallow | Violet-green Swallow |
---|---|---|
Color | Blue-green iridescence | More purple-green iridescence |
Range | Widespread across North America | Primarily western North America |
Habitat | Open wooded areas near water | Coniferous forests and mountain meadows |
Nest sites | Tree cavities | Cliffs, crevices |
The tree swallow has more blue-green iridescence compared to the purple-tinged violet-green swallow. It is also found in habitats more associated with water and deciduous trees.
Conclusion
With its deeply forked tail, dazzling flashes of blue-green plumage, and aerial mastery, the tree swallow is aptly named for its strong dependence on trees as nesting sites and foraging perches. No other North American swallow is more closely associated with wooded habitats near water, especially those provided by humans. The tree swallow’s graceful beauty and adaptability have made it a familiar sight from backyards to protected wetlands across the continent.