White-rumped Swallow
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Quick Facts
- Scientific Name: Tachycineta leucorrhoa
- Spanish Name: Golondrina de rabadilla blanca
- Family: Hirundinidae
- Known Nicknames: White-rumped Swallow
- Average Length: 12–13 cm / 4.7–5.1 in
- Average Weight: 12–18 g / 0.42–0.63 oz
- Wingspan: 28–32 cm / 11–12.6 in
- Key Feature: White rump contrasting with dark blue upperparts and white underparts
- Primary Diet: Insectivore
- Range: South America (central and southern Brazil, Paraguay, Bolivia, Uruguay, northern Argentina)
- Habitat: Open and semi-open areas near water (e.g., marshes, grasslands, river edges)
- Social Structure: Colonial to loosely colonial
- Nesting/Breeding: Tree cavities, nest boxes, or holes in buildings
- Conservation Status: Least Concern (LC)
- Population Trend: Stable
The White-rumped Swallow (*Tachycineta leucorrhoa*) is a dazzling aerialist of South America, distinguished by its crisp, monochrome plumage and a striking white patch on its lower back that starkly contrasts with its glossy steel-blue upperparts. Its underparts are pure white, and a subtle white line above the eye gives it a sharp, focused expression. Unlike many swallows, this species is a master of open country, often seen skimming low over grasslands and water bodies in swift, agile flight. A unique behavioral trait is its aggressive defense of nesting cavities, often evicting other birds, and it is one of the few swallows to regularly line its nest with feathers, providing a soft, insulated cradle for its eggs. This combination of vivid contrast, specialized flight, and territorial nesting makes it a standout among its swift kin.
Fun Facts
The White-rumped Swallow is a master of aerial acrobatics, often seen drinking on the wing by skimming its lower beak across the water’s surface without slowing down. Unlike many swallows, it frequently forages alone or in pairs rather than in large flocks, and it has a quirky habit of aggressively chasing off much larger birds like hawks and crows that wander near its nest. When breeding, it will sometimes “parasitize” the mud nests of other swallow species, laying its eggs alongside the host’s clutch rather than building its own. Its scientific name, *leucorrhoa*, means “white rump,” but the bird actually flashes a bright white patch on its lower back that is almost glowingly visible in flight.
Habitats & Distribution
The White-rumped Swallow is found in South America, primarily in southern Brazil, Paraguay, Uruguay, and northern and central Argentina, with its range extending into Bolivia and possibly southeastern Peru. Its habitat consists of open and semi-open landscapes near water, including riverbanks, marshes, flooded grasslands, and the edges of forests. It frequently inhabits agricultural areas, pastures, and urban settings where it can find suitable nesting sites, such as under bridges, in culverts, or in abandoned buildings. The species is generally resident throughout its range, though some southern populations may undertake short-distance seasonal movements.
Behaviours & Reproduction
The White-rumped Swallow is socially monogamous, with pairs forming during the breeding season, though genetic studies of related species suggest occasional extra-pair copulations may occur. They are loosely colonial, often nesting in small, dispersed groups where individuals defend a small territory immediately around the nest cavity. A unique reproductive strategy is their strong reliance on pre-existing cavities, such as abandoned woodpecker holes or crevices in human structures, which they line with grass and feathers; they do not excavate their own nests. Both parents incubate the clutch of 3-6 eggs for about 15 days and feed the altricial young, which fledge after approximately 20-22 days. In some southern populations, they may raise two broods per season, reusing the same nest for subsequent attempts.
Diet
The White-rumped Swallow (Tachycineta leucorrhoa) is an aerial insectivore, meaning it captures all its food on the wing, typically flying low over open fields, marshes, and water bodies. Its diet consists almost exclusively of small flying insects, such as flies, mosquitoes, beetles, bees, wasps, and ants, which it scoops up with its wide, gaping mouth. An interesting fact about its feeding behavior is that it often forages in mixed-species flocks with other swallows and swifts, especially during non-breeding seasons, to exploit dense insect swarms more efficiently. Additionally, unlike some birds that shift to berries or seeds in winter, this swallow remains a strict insectivore year-round, migrating to warmer regions of South America to follow insect abundance. Another notable detail is that it drinks while flying, skimming the surface of ponds or rivers with its lower mandible to scoop up water.
Colors
The White-rumped Swallow has a glossy blue-black head and back, contrasting sharply with a bright white rump patch and entirely white underparts. Its wings and forked tail are dark, with no distinct facial markings or barring. This high-contrast pattern provides no camouflage, serving instead as conspicuous identification in open flight.
Distribution Map
Places linked to this species. A sighting is never guaranteed.
