Long-tailed Sylph (male)

Quick Facts

• Scientific Name: Aglaiocercus kingii
• Spanish Name: Silfo colilargo
• Family: Trochilidae
• Known Nicknames: Long-tailed Sylph
• Average Length: 16–19 cm / 6.3–7.5 in
• Average Weight: 5–6 g / 0.18–0.21 oz
• Wingspan: 10–12 cm / 4–4.7 in
• Key Feature: Exceptionally long, iridescent blue-green, deeply forked tail
• Primary Diet: Nectarivore (Nectar and small insects)
• Range: Andes Mountains of South America (Venezuela, Colombia, Ecuador, Peru, and Bolivia)
• Habitat: Humid montane forests, forest edges, and secondary growth
• Social Structure: Solitary and territorial
• Nesting/Breeding: Bulky, dome-shaped nests made of moss and fibers in trees or shrubs
• Conservation Status: Least Concern (LC)
• Population Trend: Stable

The male Long-tailed Sylph (*Aglaiocercus kingii*) is a breathtaking inhabitant of the high-altitude Andean cloud forests, best known for its extraordinary, deeply forked tail that can measure up to five inches long—nearly double the length of its body. This iridescent masterpiece shimmers in brilliant shades of sapphire blue and emerald green, trailing behind the bird like a delicate ribbon as it navigates the dense foliage. Complementing this dramatic feature, the male possesses a glittering green crown and a luminous violet-blue throat patch set against a backdrop of rich, dark green plumage. While its oversized tail might seem cumbersome, the male is a master of aerial maneuverability, utilizing its vibrant colors and sweeping tail feathers in elaborate, high-speed courtship displays to attract mates, making it one of the most visually stunning and agile members of the hummingbird family.

Fun Facts

The male Long-tailed Sylph possesses a spectacular iridescent tail that can reach over five inches in length, often doubling the bird’s total size. This shimmering train is a classic example of an evolutionary handicap; it is so aerodynamically cumbersome that males must possess superior strength and stamina just to fly, serving as a literal "fitness test" for female observers. To navigate thick Andean forests with such an unwieldy ornament, they have developed specialized flight muscles that allow them to perform tight maneuvers despite the drag. These birds are also methodical "trap-liners," memorizing specific circuits of flowering plants and aggressively defending these high-energy routes from much larger competitors.

Habitats & Distribution

This hummingbird is native to the Andes Mountains, extending from northern Venezuela and Colombia through Ecuador and Peru, reaching as far south as Bolivia. It primarily occupies humid montane forests, cloud forests, and forest edges, typically at elevations between 900 and 3,000 meters. While it favors dense, moist environments, it is also frequently sighted in clearings, secondary growth, and gardens where nectar sources are plentiful. Within these high-altitude landscapes, the species inhabits the canopy and sub-canopy layers but often ventures to lower flowering shrubs to feed. Its distribution is closely tied to the subtropical and temperate zones of the Andean slopes, where consistent rainfall and mist support the rich epiphytic growth and floral diversity essential for its survival.

Behaviours & Reproduction

Males are highly territorial and solitary, aggressively defending nectar-rich feeding territories from both rivals and other hummingbird species. Their defining characteristic is an exceptionally long, iridescent tail, which serves as a primary tool for sexual selection. Although this ornament impairs aerodynamic efficiency and increases vulnerability to predators, it functions as an honest signal of genetic fitness; only the strongest males can survive and maneuver effectively with such a burden. During courtship, males perform dramatic aerial displays, darting and hovering to showcase the length and shimmer of their feathers to attract potential mates. The species follows a polygynous mating system where males mate with multiple females and provide no parental care. After courtship, the social bond dissolves, and the female is solely responsible for selecting a nesting site, constructing the moss-lined cup, and raising the chicks. This reproductive strategy allows the male to devote his energy entirely to territorial defense and seeking further mating opportunities, while the female relies on camouflage and secluded nesting locations to ensure the survival of the brood.

Diet

The Long-tailed Sylph primarily sustains itself on a diet of nectar collected from a variety of flowering plants, particularly those in the Ericaceae and Bromeliaceae families. While nectar provides the necessary carbohydrates for its high-energy lifestyle, this hummingbird also hunts small insects and spiders to obtain essential proteins and minerals, often catching them in mid-air or gleaning them from foliage. An interesting aspect of their feeding behavior is nectar robbing, where the bird pierces the base of long, tubular flowers to access nectar that its relatively short bill cannot reach through the natural opening. Additionally, despite the male's remarkably long tail, which can be over three times the length of its body and pose a challenge for aerial maneuverability, it remains a highly efficient forager, often defending lucrative feeding territories or following established routes known as traplining to visit specific nectar-rich blooms throughout the Andean cloud forests.

Colors

The male Long-tailed Sylph is characterized by shimmering emerald-green plumage and a brilliant iridescent violet or blue-green throat patch. Its most distinctive feature is an exceptionally long, deeply forked tail that glitters with metallic sapphire and teal hues. This vibrant iridescence serves both as a dramatic courtship display and as a form of camouflage, allowing the bird to blend into the dappled sunlight and shadows of its high-altitude cloud forest habitat.

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