The swallow-tailed hummingbird (Eupetomena macroura), sometimes informally called the swallowtail hummingbird, is a large, striking hummingbird native to South America, instantly recognizable by its deeply forked blue-black tail. At roughly 15 to 17 centimeters long, it is one of the bigger hummingbirds on the continent, and its bold temperament matches its size. It thrives across a surprisingly wide range of habitats, from dense Atlantic Forest to city parks in São Paulo, and its behavior holds some genuine surprises, including a dawn singing ritual, a habit of stealing nectar, and at least one documented case of feeding another species’ chicks.
How to Recognize One
The most obvious feature is the tail. While many hummingbird species have modestly notched or rounded tails, the swallow-tailed hummingbird carries a long, deeply forked tail that fans out conspicuously in flight and accounts for a significant portion of its total body length. The tail feathers are dark blue-black with a metallic sheen. The rest of the bird is vivid: males and females both show iridescent blue-green on the throat and upper breast, with a darker head and a greenish back. The belly tends to be darker than in many other hummingbirds, giving the whole bird a deep jewel-toned look rather than the pale-bellied appearance common in smaller species.
Size-wise, it is noticeably bulkier than the tiny hummingbirds most people picture. Its bill is relatively short for a hummingbird, and that detail turns out to matter a great deal for how it feeds. Combined with an aggressive, territorial disposition, this bird tends to dominate flower patches and feeders wherever it occurs, chasing off smaller hummingbirds with dive-bombing flights.
Range and Preferred Habitats
The swallow-tailed hummingbird is found across a broad swath of eastern and central South America, from the Guianas south through Brazil and into parts of Bolivia, Paraguay, and northern Argentina. Within that range, it is not evenly distributed. A large citizen-science study drawing on over 500 breeding records between 1999 and 2021 found that the Atlantic Forest biome held roughly 65% of all documented nests, followed by the Cerrado savanna at about 27%, and the Caatinga dry forest at 8%. The Pampa grasslands and Pantanal wetlands each contributed less than 1% of breeding records.1Ornithology Research. Breeding biology of swallow-tailed hummingbird (Eupetomena macroura) based on citizen science data
That distribution tells a clear story: this is primarily a bird of the Atlantic Forest and its edges, with a secondary stronghold in the open woodlands and gallery forests of the Cerrado. It also does well in degraded and fragmented habitats, which is part of why it has adapted so readily to human landscapes. Unlike more specialized hummingbirds that depend on pristine cloud forests or specific elevational bands, the swallow-tailed hummingbird seems comfortable in second-growth forest, parkland, gardens, and agricultural margins.
A Nectar Thief With a Short Bill
All hummingbirds drink nectar, but not all of them play fair. The swallow-tailed hummingbird is among several short-billed species documented engaging in nectar robbery, a behavior where the bird accesses a flower’s nectar without touching the reproductive parts, so the plant gets no pollination benefit from the visit. Research on Erythrina speciosa flowers in southern Brazil found that the swallow-tailed hummingbird, along with a couple of other short-billed species, approached the flowers from below and inserted their bills into the base of the corolla or calyx. They got the nectar but never contacted the anthers or stigma.2Revista Brasileira de Zoologia. Feeding behavior of hummingbirds and perching birds on Erythrina speciosa Andrews (Fabaceae) flowers in an urban area, Londrina, Paraná, Brazil
From the flower’s perspective, this is freeloading. From the bird’s perspective, it is efficient. Erythrina flowers are tubular and long, designed for pollination by longer-billed visitors. A short-billed hummingbird cannot reach the nectar legitimately by pushing into the top of the flower, so it pierces or bypasses the base instead. The behavior is not unique to this species, but the swallow-tailed hummingbird’s combination of a short bill and an aggressive territorial nature makes it a particularly effective nectar thief. It can monopolize flower patches through sheer intimidation and then extract nectar from flowers it is not even morphologically suited to pollinate.
That said, nectar robbery is not its only feeding strategy. The swallow-tailed hummingbird visits a wide variety of plant species, including many with shorter corollas where it does function as a legitimate pollinator. It also catches small insects in flight, a protein source that supplements the sugar-heavy nectar diet. This dietary flexibility contributes to its success across different environments.
Thriving in Cities
One of the more remarkable things about the swallow-tailed hummingbird is how well it does in urban settings. Research in an urban park in southeastern Brazil found that the species showed considerable plasticity in its feeding behavior, visiting a wide range of both native and ornamental plant species and adjusting its foraging patterns to the resources available.3Brazilian Journal of Biology. Analysis of the feeding habits of the swallow-tailed hummingbird, Eupetomena macroura (Gmelin, 1788), in an urban park in southeastern Brazil That flexibility helps explain why the species persists in cities even as many other hummingbird species decline when their habitats are altered.
If you live in a Brazilian city with even modest green space, this is likely one of the hummingbirds you will see. It visits garden flowers, ornamental plantings, and sugar-water feeders readily. Its large size and aggressive temperament mean it tends to dominate urban feeding stations, pushing smaller species to the margins. For anyone putting out feeders in areas where swallow-tailed hummingbirds are present, the dynamic often plays out predictably: the swallow-tailed hummingbird claims the feeder, patrols it from a nearby perch, and chases away any smaller visitors that approach.
The Dawn Lek
Many hummingbird species are solitary outside of mating, but the swallow-tailed hummingbird has an unusual communal display. Males gather at traditional sites called leks, where they sing in the predawn darkness. A 22-month study documented one such lek covering about 12 hectares, with a total of 26 individual male territories mapped within it. The lek was active year-round, with anywhere from 6 to 15 males singing on a given morning.4BioOne. The Dawn Lek of the Swallow-tailed Hummingbird
On average, males began singing about 27 minutes before sunrise and kept at it for about 17 minutes. During that window, individual males spent between 72% and 100% of the time inside their own small territories within the lek. The singing is not especially melodic by songbird standards, consisting of high-pitched, repetitive chips and buzzes, but it serves as an advertisement to females and a way for males to assert territorial claims relative to their neighbors.
Lekking is well known in some other bird families, such as manakins and grouse, but it is comparatively rare among hummingbirds. Most hummingbird species attract mates through individual displays, often involving elaborate aerial acrobatics. The fact that the swallow-tailed hummingbird gathers in groups to sing in the near-darkness before dawn is a behavioral quirk that sets it apart from most of its relatives. Researchers have speculated that the lek system may be related to the species’ relatively high local densities and its use of open or edge habitats where sound carries well, but the evolutionary drivers of lekking in this lineage are not fully settled.
Breeding and an Odd Case of Cross-Species Parenting
Like most hummingbirds, the female swallow-tailed hummingbird handles nest building, incubation, and chick-rearing alone. The nest is a small, compact cup made of plant fibers, spider silk, and lichens, typically attached to a thin branch or sometimes to human-made structures like wires and clotheslines. Breeding records from citizen-science data confirm that nesting occurs across most of the species’ range, with the heaviest concentration in the Atlantic Forest and its margins.5Ornithology Research. Breeding biology of swallow-tailed hummingbird (Eupetomena macroura) based on citizen science data
One particularly striking observation came from an urban area in São Paulo, where researchers documented a swallow-tailed hummingbird caring for the chicks of a completely different species, the glittering-bellied emerald (Chlorostilbon lucidus). The swallow-tailed hummingbird was first seen carrying nesting material to the emerald’s nest before the eggs hatched. After the two chicks emerged, it was recorded feeding them on at least ten separate occasions.6Springer / Ornithology Research. Shared maternity: interspecific alloparental care by the Swallow-tailed Hummingbird in a nest of the Glittering-bellied Emerald (Aves, Trochilidae)
This kind of cross-species parenting, known as interspecific alloparental care, is uncommon in birds generally and quite rare among hummingbirds. The researchers who documented the case noted that both species nested in close proximity in the same urban environment, which may have increased the likelihood of such an unusual interaction. Whether the swallow-tailed hummingbird had lost its own nest and redirected its parental drive, or whether some other behavioral mechanism was at play, remains an open question. It is a single documented case, not a known pattern, but it hints at a flexibility in parental behavior that goes beyond what most people expect from hummingbirds.
Pollination Ecology
Despite its nectar-thieving habits at certain flower types, the swallow-tailed hummingbird still plays a legitimate role as a pollinator for many of the plants it visits. In tropical ecosystems broadly, hummingbirds function as key pollinators thanks to their specialized bill shapes and their habit of visiting many flowers in succession, transferring pollen as they go.7Biotropica. Methodological Effects on Plant–Hummingbird Networks: A Comparison of Pollen Load and Focal Observation Approaches in Colombian Andean Ecosystems The plants that benefit most from hummingbird pollination tend to be those that cannot self-fertilize, because hummingbirds are efficient at moving pollen between individual plants. Research suggests that hummingbird pollination may outperform bee pollination in these self-incompatible plant populations, leading to less wasted pollen and higher outcrossing rates.8PubMed Central. Influence of plant reproductive systems on the evolution of hummingbird pollination
For the swallow-tailed hummingbird specifically, its role in pollination networks is complicated by its short bill and aggressive temperament. It can monopolize floral resources without always performing the pollination service that longer-billed, gentler species provide. But at flowers with shorter corollas that match its bill length, it can be an effective pollinator. The overall ecological picture is one of a species that wears two hats: a pollination mutualist at some flowers and a nectar parasite at others, with the balance depending on which plants are blooming and what competitors are present.
Energy Management and Torpor
Hummingbirds as a family have extraordinary metabolic demands. Their flight muscles make up roughly 25% to 30% of body mass, packed with an unusually high density of mitochondria, giving them one of the highest mass-specific mechanical power outputs among vertebrates.9ScienceDirect. Locomotion and thermogenesis in hummingbirds Maintaining that level of output requires a constant supply of fuel, which is why hummingbirds feed so frequently during the day.
At night, when feeding stops and ambient temperatures can drop substantially, hummingbirds face a crisis: their tiny bodies lose heat rapidly, and burning fuel all night to stay warm would exhaust their energy reserves. The solution is torpor, a state of dramatically reduced body temperature and metabolic rate that conserves energy through the night. Research on hummingbirds has shown that lowering room temperature to around 12 to 14 degrees Celsius triggers cycles of torpor and rewarming. During torpor, levels of a specific uncoupling protein in the flight muscles and heart rise by 1.5 to over 3 times their normal amounts, which appears to be involved in the rapid heat generation that allows the bird to rewarm itself before dawn.10PubMed. Cloning and functional characterization of an uncoupling protein homolog in hummingbirds
Torpor is not unique to the swallow-tailed hummingbird. It is a widespread survival strategy across the hummingbird family. But the physiology is worth noting because it underscores just how much energy management governs every aspect of a hummingbird’s life. The aggressive territoriality, the nectar thieving, the willingness to exploit urban gardens: all of these behavioral traits make more sense when you consider that the bird is constantly walking a metabolic tightrope. Every calorie matters, and behaviors that secure reliable access to nectar are under intense evolutionary pressure.
Why It Gets Confused With Other Species
Birdwatchers new to South American hummingbirds sometimes mistake the swallow-tailed hummingbird for the fork-tailed woodnymph (Thalurania furcata) or the violet-capped woodnymph (Thalurania glaucopis), both of which share iridescent blue-green plumage and forked tails. The distinction is usually clear in the field, though. The swallow-tailed hummingbird is substantially larger, its tail fork is deeper and more dramatic, and its overall coloring runs darker, with less contrast between the breast and belly. It also behaves differently: the woodnymphs tend to be mid-story forest birds that forage in the understory, while the swallow-tailed hummingbird frequently perches in exposed positions and makes conspicuous territorial flights in open areas.
The informal name “swallowtail hummingbird,” which drops the “ed” from “swallow-tailed,” appears frequently in casual usage and online searches but is not the standard common name in ornithological literature. The species is listed as Eupetomena macroura in taxonomic references, placed in the family Trochilidae. Some recent molecular work has suggested shuffling it into or near the genus Aphantochroa, but for practical purposes the name Eupetomena macroura is what you will encounter in field guides and databases. It has no recognized subspecies that birders need to worry about distinguishing in the field, though geographic variation in plumage brightness and tail length has been noted across its range.
Conservation Outlook
The swallow-tailed hummingbird is not considered threatened. It is listed as Least Concern by the IUCN, and its population appears stable across most of its range. Its adaptability to disturbed and urban habitats gives it a resilience that many more specialized hummingbird species lack. While deforestation in the Atlantic Forest and Cerrado continues to be a serious conservation issue for biodiversity overall, the swallow-tailed hummingbird is one of the species that can tolerate and even benefit from the mosaic of forest fragments, agricultural edges, and urban green spaces that replace intact forest.
That said, its success in degraded habitats should not be mistaken for evidence that habitat loss is harmless. The species’ dominance at feeders and flower patches in fragmented landscapes may come partly at the expense of smaller, less aggressive hummingbird species that cannot compete with it. In other words, the swallow-tailed hummingbird’s expansion into disturbed areas might itself be a symptom of ecological simplification, where a few generalist winners replace a more diverse community of specialists. For birdwatchers and conservationists in South America, the presence of this bold, adaptable species is a pleasure, but the absence of the shyer species it outcompetes can tell a more sobering story about what has been lost.