White-necked Jacobin (male)

Quick Facts

• Scientific Name: Florisuga mellivora
• Spanish Name: Jacobino nuquiblanco
• Family: Trochilidae
• Known Nicknames: Jacobin, Great Jacobin
• Average Length: 11–12 cm / 4.3–4.7 in
• Average Weight: 6–9 g / 0.21–0.32 oz
• Wingspan: 14–16 cm / 5.5–6.3 in
• Key Feature: Deep blue head and neck with a prominent white crescent on the nape and white outer tail feathers
• Primary Diet: Nectarivore (Nectar and small insects/spiders)
• Range: Southern Mexico to Peru, Bolivia, and Southern Brazil; also Trinidad and Tobago
• Habitat: Canopy and edges of humid lowland forests, second growth, and plantations
• Social Structure: Solitary and territorial
• Nesting/Breeding: Shallow cup nest made of plant fibers and spider silk, typically on a large leaf
• Statut de conservation : Préoccupation mineure (LC)
• Population Trend: Decreasing

The White-necked Jacobin (*Florisuga mellivora*) is a large, striking hummingbird of the Neotropics, instantly recognizable for its bold, contrasting plumage and energetic presence. Adult males are true jewels of the forest, sporting a deep indigo-blue head and chest, a shimmering forest-green back, and a brilliant white belly, all anchored by a signature snowy-white crescent on the nape of the neck. Their most dramatic feature is a broad, pure-white tail that they frequently flare during territorial displays or while hovering at nectar-rich flowers. Uniquely, this species is famous for a rare biological phenomenon called androchromatism, where many females evolve to mimic the vibrant blue-and-white plumage of males to avoid social aggression and gain better access to food. Whether they are darting through the canopy to hawk for insects or defending a favorite feeder, these agile birds are as socially complex as they are visually spectacular.

Faits amusants

One of the most remarkable traits of the White-necked Jacobin is that approximately 20% of females exhibit "androchromatism," possessing the vibrant blue and white plumage typically reserved for males. This clever disguise allows these females to avoid social aggression and enjoy more peaceful access to nectar sources by blending in with the more dominant males. Beyond their deceptive looks, these hummingbirds are aerial acrobats known for "hawking," where they snatch small insects mid-air with lightning speed. During territorial or courtship displays, they frequently flare their expansive white tail feathers into a dramatic, fan-like shape, creating a striking visual contrast against the forest canopy.

Habitats et répartition

Its geographical range extends from southern Mexico and Central America through much of northern and central South America, reaching as far south as Bolivia and southern Brazil, and includes the islands of Trinidad and Tobago. Within this vast territory, it primarily inhabits humid lowland tropical forests and tall secondary growth, though it is frequently found in semi-open environments such as forest edges, clearings, and shaded plantations of coffee or cacao. While predominantly a canopy-dwelling bird of the forest interior, it readily adapts to human-altered landscapes including suburban gardens and parks where flowering plants are abundant. It is most common at elevations below 900 meters, though it occasionally ranges into foothills and lower montane regions up to 1,500 meters. Its presence is closely tied to the availability of nectar-rich floral resources and insects found within these diverse tropical and subtropical ecosystems.

Comportements & Reproduction

These birds exhibit high levels of territoriality and aggression, particularly around food sources. They are known for their rapid flight patterns and generally solitary nature outside of the breeding season. A striking feature of their social structure is female-limited polymorphism, where a significant portion of adult females retain male-like plumage. This unique strategy allows these "androchromic" females to mimic males, thereby reducing social harassment and physical aggression from dominant males, which facilitates better access to high-quality nectar sources. Their mating system is polygynous, with males playing no role in nest construction or parental care. During the breeding season, males may congregate in small groups called leks to perform competitive aerial displays to attract mates. Once mating occurs, the female independently builds a small, cup-shaped nest made of plant fibers and spider silk, typically situated on a large, sturdy leaf. She usually lays two white eggs and handles all incubation and feeding of the chicks until they reach independence.

Alimentation

The White-necked Jacobin primarily sustains itself on energy-rich nectar gathered from a variety of flowering plants, including heliconias and ginger lilies, while supplementing its diet with small insects and spiders for essential protein. This hummingbird employs both "traplining" strategies, where it follows a regular route to visit specific flowers, and territorial defense of high-quality food sources. A fascinating aspect of its feeding ecology involves female-limited polymorphism; females that possess male-like plumage, known as andromorphs, often gain a competitive advantage at feeding sites. These male-mimicking females experience less social harassment from territorial males, allowing them to spend more time feeding on high-energy nectar compared to their more traditionally colored counterparts. Additionally, these birds are skilled aerial hunters, frequently "hawking" insects mid-air or gleaning them directly from leaves and spider webs to balance their nutritional intake.

Couleurs

Male White-necked Jacobins feature a deep blue head and breast, a brilliant white nape and belly, and an iridescent green back. Females typically exhibit a camouflaging green-and-white scaled pattern on their underparts, though some mimic the male’s bold coloration. This species is defined by its namesake white "collar" and high-contrast, flashing white tail feathers.

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