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White-necked jacobin
White-necked jacobin
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White-necked jacobin
Male F. m. mellivora, Trinidad
Female, Costa Rica
CITES Appendix II[2]
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Clade: Strisores
Order: Apodiformes
Family: Trochilidae
Genus: Florisuga
Species:
F. mellivora
Binomial name
Florisuga mellivora
Synonyms

Trochilus mellivorus Linnaeus, 1758

The white-necked jacobin (Florisuga mellivora) is a medium-sized hummingbird that ranges from Mexico south through Central America and northern South America into Brazil, Peru, and Bolivia. It is also found in Trinidad and Tobago.[3][1] Its other common names include great jacobin and collared hummingbird.[citation needed]

Taxonomy

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In 1743, English naturalist George Edwards included a picture and a description of the white-necked jacobin in his A Natural History of Uncommon Birds. He used the English name "white-belly'd huming bird". Edwards based his etching on a specimen owned by the Duke of Richmond that had been collected in Suriname.[4] When in 1758, Swedish naturalist Carl Linnaeus updated his Systema Naturae for the 10th edition, he placed the white-necked jacobin with the other hummingbirds in the genus Trochilus. Linnaeus included a brief description, coined the binomial name Trochilus mellivorus, and cited Edwards' work.[5] The specific epithet combines the Latin mel and -vorus, meaning "honey eating".[6] The type locality is Suriname.[7] The white-necked jacobin is now placed in the genus Florisuga that was introduced in 1850 by Charles Bonaparte.[8][3]

Subspecies

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Two subspecies are recognised:

Subspecies Male Female
F. m. mellivora

Linnaeus (1758)

F. m. flabellifera

Gould (1846)*

*Sometimes referred to as F. m. tobagensis[3][9]

Description

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The white-necked jacobin is 11 to 12 cm (4.3 to 4.7 in) long. Males weigh 7.4 to 9.0 g (0.26 to 0.32 oz) and females 6.0 to 9.2 g (0.21 to 0.32 oz). The male is unmistakable with its dark blue head and chest and white belly and tail; the tail feathers have black tips. A white band on the nape separates the blue head from the bright green back and long uppertail coverts. Females are highly variable, and may resemble adult or immature males. Most females have green upperparts, a blue-green throat and breast with white "scales", a white belly, and a mostly green tail with a blue end. Immature males vary from female-like, but with more white in the tail, to male-like with more black there. Immature females also vary, but usually have less white in the tail and are somewhat bronzy on the throat and chest.[9]

Distribution and habitat

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Nest, in Colombia

The nominate subspecies of white-necked jacobin, F. m. mellivora, is found from southern Veracruz and northern Oaxaca, Mexico, through southern Belize, northern Guatemala, eastern Honduras and Nicaragua, eastern and western Costa Rica, and Panama into South America. In that continent, it is found in much of Colombia and Ecuador, eastern Peru, northern Bolivia, most of Venezuela, the Guianas, the northwestern half of Brazil, and the island of Trinidad. F. m. flabellifera is found only on the island of Tobago.[3][9] The nominate has been recorded as a vagrant in Argentina and on the islands of Aruba and Curaçao.[10]

The white-necked jacobin inhabits the canopy and edges of humid forest and also semiopen landscapes such as tall secondary forest, gallery forest, and coffee and cacao plantations. It is usually seen high in trees, but comes lower at edges and in clearings. In elevation, it usually ranges from sea level to about 900 m (3,000 ft), but rarely has also been seen as high as 1,500 m (4,900 ft).[9]

Behavior

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Immature male begging for food from its mother

The white-necked jacobin's movement pattern is not well understood. It apparently moves seasonally as flower abundance changes, but details are lacking.[9]

It feeds on nectar at the flowers of tall trees, epiphytes, shrubs, and Heliconia plants. Several may feed in one tree and are aggressive to each other, but they are otherwise seldom territorial. Both sexes hawk small insects, mostly by hovering, darting, or sallying from perches.[9]

This species breeds in the dry to early wet seasons, which vary across their range. The nest is a shallow cup of plant down and cobweb placed on the upper surface of a leaf where another leaf provides a "roof". It is typically 1 to 3 m (3 to 10 ft) above ground and sometimes near a stream. Males display and chase in the canopy and along edges during the breeding season. Females use a fluttering flight to distract predators.[9]

The white-necked jacobin is not highly vocal. Its song is "a long series of high-pitched, single notes, repeated at rate around 0.7–1.0 notes/second 'tseee....tseee....tseee....tseee....'." Calls include "a short 'tsik', a longer, high-pitched 'sweet', and a descending 'swee-swee-swee-swee' in antagonistic interactions."[9]

Status

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The IUCN has assessed the white-necked jacobin as being of least concern. It has an extremely large range, but its population has not been quantified, and its trend is unknown.[1] It is deemed uncommon to common in most of its range. It occurs in many protected areas and appears able to use human-altered landscapes such as tree plantations.[9]

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References

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Further reading

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Revisions and contributorsEdit on WikipediaRead on Wikipedia
from Grokipedia
The White-necked jacobin (Florisuga mellivora) is a medium-sized species in the Trochilidae, characterized by its vibrant , aggressive , and adaptation to a variety of tropical habitats across the Neotropics. Adult males measure 11–12 cm in length and weigh 7.4–9 g, displaying a striking deep blue hood extending to the chest, a prominent white collar on the , glossy upperparts, white underparts, blackish wings, and a mostly white tail with black edges and tips; females are slightly smaller (6–9.2 g) and show more variable , ranging from male-like patterns to blue-green breasts scaled with white and darker tails with white tips. This species inhabits humid lowland forests, including canopies, edges, tall second growth, gallery forests, and human-modified areas such as and cacao plantations, typically from to 900 m (rarely up to 1500 m). Its range spans a vast extent of occurrence covering approximately 11,800,000 km², from southern and (Belize, , El Salvador, , , , ) southward through northern (Bolivia, , , , , , , , ), including the islands of , where it is resident and non-migratory. White-necked jacobins primarily feed on nectar from flowering trees such as and species, supplemented by small arthropods, often foraging aggressively in canopy layers while hovering with a cocked or fanned tail to display white markings. Breeding occurs seasonally from to July (varying by region), with nests constructed in palms or similar vegetation; the species is common in suitable habitats but shows seasonal abundance in some areas. Although the global population is estimated at 5,000,000–50,000,000 mature individuals and considered stable overall, a decreasing trend is suspected due to habitat pressures, leading to its classification as Least Concern on the .

Taxonomy and systematics

Etymology and classification history

The white-necked jacobin was first documented as a new species by English naturalist George Edwards in his 1743 publication A Natural History of Uncommon Birds, volume 2, where he illustrated and described a specimen as the "white-belly'd humming bird" based on material from . In 1758, Swedish botanist formally named the species Trochilus mellivorus in the 10th edition of Systema Naturae, adopting Edwards's description and illustration as the basis for the binomial; the specific epithet mellivorus derives from Latin mellis (genitive of mel, meaning "honey") and vorare ("to devour"), referring to the bird's nectar-feeding habits. The type locality for Trochilus mellivorus was designated as . In 1850, French ornithologist reclassified the species into the newly established genus Florisuga in his Conspectus Generum Avium, separating it from the broad Linnaean genus Trochilus along with the closely related black jacobin (Florisuga fusca); the generic name Florisuga combines Latin flos (or flores, meaning "flower") and sugere ("to suck"), alluding to the hummingbirds' role by extracting from flowers. This generic placement has been widely accepted since, with the current binomial Florisuga mellivora (Linnaeus, 1758) reflecting the combination. The species is now placed within the family Trochilidae (hummingbirds) and the subfamily Florisuginae, which Bonaparte proposed in 1853 to encompass Florisuga and the topaz hummingbirds (Topaza).

Subspecies

The white-necked jacobin (Florisuga mellivora) is divided into two recognized subspecies. The nominate subspecies, F. m. mellivora, originally described by in 1758, occupies the bulk of the species' range, extending from southern (southern and northern ) southward through to , and into northern , including , western , southeastern , northern , , , Trinidad, and Amazonian . The second subspecies, F. m. flabellifera, described by in 1846 and sometimes treated under the synonym tobagensis, is endemic to the island of , where it inhabits similar lowland forest-edge habitats as the nominate form but is distinguished primarily by its larger body size. Historically, taxonomists described numerous additional races across the species' range based on minor plumage and size variations, but modern assessments have lumped most into the nominate subspecies, retaining only the Tobago population as distinct due to its consistent morphological differences; no recent genetic studies have been conducted to further evaluate this differentiation.

Description

Morphology and measurements

The white-necked jacobin (Florisuga mellivora) is a medium-sized with a total body length of 11–12 cm. This compact size facilitates its agile maneuvers in forested environments, where it frequently hovers to feed. In terms of mass, adult males typically weigh 7.4–9.0 g, while females range from 6.0–9.2 g, reflecting slight sexual size dimorphism in which males are marginally heavier on average. The straight, black bill is an adaptation suited to probing shallow corollas. The tail is moderately long and slightly forked in males, consisting of mostly white feathers narrowly edged and tipped in black, which contrasts with the darker tail of females with white tips. Like other hummingbirds, the white-necked jacobin features specialized skeletal and muscular adaptations for hovering flight, including a pronounced keel-shaped that extends ventrally to the large pectoralis muscles responsible for powering rapid beats. This structure, combined with lightweight hollow bones and a ball-and-socket , enables the to sustain high-frequency wing oscillations of up to 50 beats per second during hover-feeding.

Plumage and sexual dimorphism

The adult male white-necked jacobin exhibits striking characterized by a glossy dark blue head and upper breast, a prominent white crescent on the forming a collar, iridescent green upperparts, blackish wings, a white belly, and a mostly white tail narrowly tipped and edged with black. This bold, iridescent patterning serves as a visual cue in social interactions, with the white elements providing high contrast against the dark tones. Adult females display significant polymorphism, with approximately 30% exhibiting male-like (androchromic) featuring shiny blue heads and throats, green backs, white chests, bellies, and neck spots, and tails fringed with a wide black band. The remaining females show a duller heterochromic morph, with entirely green upperparts, mottled gray-and-green throats and chests, and dark green-to-black tail feathers broadly fringed with white, often including a buffy or scaled appearance on the underparts for during nesting. is thus variable, as androchromic females closely resemble males in coloration and patterning, while heterochromic females are more cryptic, with less and bolder scaling on the breast to aid concealment. Juveniles of both sexes initially possess androchromic plumage similar to adult males, including shiny blue heads and throats, green backs, white underparts and neck spots, a buffy malar stripe, and tails with a wide black band, though young individuals often show brownish fringes on feathers and more white in the tail. Age-related changes occur primarily through molting, with a limited preformative molt replacing only a few inner greater coverts while retaining juvenile remiges and rectrices; most females then transition to heterochromic plumage during the second prebasic molt, whereas males attain definitive male plumage by this stage, featuring thinner blue edging on white rectrices. No pronounced seasonal variations in feather quality are reported, though the complete prebasic molts in subsequent cycles maintain the iridescent sheen in adults.

Distribution and habitat

Geographic range

The white-necked jacobin (Florisuga mellivora) occupies a broad range spanning southern southward through and into northern . Its core distribution includes , , , , , , , , , , , , , , , , and northern , extending to . Two subspecies are recognized within this range: the nominate F. m. mellivora, which is widespread across the mainland from southern Mexico (Veracruz and Oaxaca) through Central America to northern South America, including Trinidad; and F. m. flabellifera, which is restricted to the island of Tobago. Vagrant individuals have been recorded outside the core range in Argentina, Aruba, and Curaçao. The is primarily resident across its distribution, though local seasonal movements occur in response to flowering patterns, such as increased abundance in the Colombian Amazon from to October. No significant expansions or contractions of the range have been documented prior to 2000, indicating historical stability.

Habitat preferences and altitudinal distribution

The White-necked Jacobin inhabits a range of tropical environments, with a strong preference for humid lowland forests, including their edges and borders, as well as semi-open areas like gardens and plantations rich in flowering vegetation. It thrives in tall second-growth forests and gallery forests, often in the canopy but descending to and lower strata at clearings and forest margins. This adaptability extends to human-modified landscapes, such as and cacao plantations, where it exploits resources from cultivated plants. The species' altitudinal distribution spans from to about 900 m, though it occasionally occurs up to 1,500 m or higher, potentially in response to seasonal resource availability. Within these elevations, it favors moist lowland and montane forests, showing suitability for both natural and degraded habitats like heavily modified former forests. Foraging microhabitats include both canopy layers for high sources and for accessible flowers, enabling efficient resource use across vertical forest strata. Seasonal shifts in use are closely linked to flowering ; for instance, the becomes locally abundant in the Colombian Amazon from July to October during the bloom of Erythrina fusca, but remains rare outside this period in such areas. Its preferences show partial overlap with those of its congener, the Black Jacobin (Florisuga fusca), in southern Brazilian woodlands and forest edges, where both species exploit similar nectar-rich environments.

Behavior and ecology

Foraging behavior and diet

The white-necked jacobin primarily feeds on from a variety of flowering , including trees such as Lisianthus axillaris, Pseudobombax septenatum, , , , Vochysia, and Symphonia; epiphytes like Norantea guianensis and Columnea, as well as bromeliads; shrubs; and herbaceous such as species. It supplements this with small arthropods, predominantly Diptera and (including some ), which constitute a significant portion of its diet, with arthropods found in 83% of examined individuals. Foraging occurs via trap-lining, where individuals follow predictable routes between sources, and aerial hawking, during which the bird pursues and captures flying above , clearings, or from perches in treetops; from foliage is less common. The species is almost exclusively a hawker when targeting arthropods. These hummingbirds defend patches with toward conspecific intruders, though they rarely establish strict territories. To meet high metabolic demands, white-necked jacobins forage frequently throughout the day, with similar species estimated to visit 1,000–2,000 flowers daily. Feeding intensifies seasonally at abundant blooms, such as Erythrina fusca from July to October in the Colombian Amazon. As a generalist , the white-necked jacobin facilitates transfer across diverse tropical plants, including effective of Hamelia patens shrubs.

Reproduction and breeding

The breeding season of the White-necked jacobin (Florisuga mellivora) aligns with the dry to early wet periods, varying regionally across its range: from January to June (or extending to July) in and , February to May in northwestern , June and November in eastern , March in southern , and December to March in Amazonian , with an isolated July record of a female carrying an egg. Courtship behaviors involve male-plumaged individuals pursuing potential mates through chases and aerial displays in the forest canopy and edges, often incorporating vocalizations and flashes of their iridescent blue to attract s, without the formation of leks. Nests are constructed solely by the as shallow cup-shaped structures, typically measuring 40 mm in height, 75 mm in external diameter, and 27 mm in internal diameter, using plant down, lichens, and cobwebs for binding; they are placed 1–3 m above the ground on horizontal branches or broad leaves of palms such as Geonoma or Asterogyne. The alone incubates the clutch of two immaculate white eggs for 15–19 days until . Chicks after 20–23 days in the nest, during which the provides all brooding and feeding by regurgitation, while performing distraction displays—erratic rising and falling flights up to 3 m high—to deter predators from the site. Nestlings exhibit a defensive behavior resembling poisonous caterpillars, wiggling their bodies and displaying fecal matter to ward off predators, as observed in in 2024 and reported in 2025.

Vocalizations and social displays

The white-necked jacobin (Florisuga mellivora) is generally rather silent, with vocalizations primarily consisting of a delivered by males from exposed perches and a variety of calls used in different contexts. The comprises a long series of high-pitched, single notes repeated at a rate of approximately 0.7–1 note per second, rendered as "tseee....tseee....tseee....tseee....", often described as twittering phrases that function in territory advertisement. Calls include a short, sharp "tsik" note, sometimes doubled as "tsi-sik", which serves as an or contact call, as well as a longer, high-pitched "" utterance. In antagonistic situations, such as territorial disputes, birds produce a descending series of notes like "swee-swee-swee-swee". These vocalizations feature high frequencies well-suited to transmission through dense forest environments, where the species commonly occurs. Social displays emphasize visual and aerial signals, particularly among male-plumaged individuals, which are aggressive at flowering resources but infrequently maintain strict territories. Territorial interactions often involve rapid chases through the canopy or along edges, where androchrome (male-like) birds initiate pursuits more frequently than duller heterochrome females, at ratios exceeding 1.45 chases initiated per chase received. Dive-bombs, performed as high-speed aerial displays, are used in both territorial defense and , showcasing the bird's agile flight. During aggressive encounters, such as pecking or slamming at intruders, individuals fan their tails to reveal the striking white collar and underparts, enhancing visual intimidation. White-necked jacobins typically solitarily or in small, loose groups at flowers, with lek-like gatherings being rare or absent.

Conservation

The white-necked jacobin (Florisuga mellivora) is classified as Least Concern on the , with the most recent assessment conducted in 2021. This status reflects its extremely large geographic range and presumed large , which do not meet the thresholds for higher risk categories under IUCN criteria. As of 2025, the status remains unchanged. Global population estimates for mature individuals range from 5,000,000 to 50,000,000, based on 2019 data from Partners in Flight, though the quality of this estimate is considered poor due to limited direct surveys. The species is generally described as uncommon to common across its range, with higher abundances noted in areas of dense flowering vegetation. Population trends are suspected to be undergoing a moderate decline overall, according to Partners in Flight 2019 analysis, potentially linked to localized reductions in deforested regions. No global-scale threats suggest imminent decline. Abundance is primarily influenced by the availability of nectar-rich flowers, as the species relies on seasonal blooming patterns of trees, epiphytes, and shrubs for foraging. Habitat connectivity also plays a key role, enabling traplining behavior where individuals follow circuits between dispersed flower patches in fragmented landscapes. Regional surveys, including those from eBird and Partners in Flight, underscore that connected habitats support higher local densities compared to isolated patches.

Threats and conservation measures

The white-necked jacobin (Florisuga mellivora) primarily faces threats from habitat loss driven by and across its extensive Neotropical range, which fragments forests and reduces available sources and nesting sites. in agricultural landscapes further endangers the by diminishing populations, a key protein source for hummingbirds despite their nectar-based diet. poses an additional risk by potentially disrupting flower , leading to mismatches between blooming periods and the bird's foraging needs in tropical habitats. Secondary threats include competition for resources at artificial nectar feeders, where the species' territorial behavior may exacerbate conflicts with other hummingbirds in human-modified areas. Conservation measures for the white-necked jacobin, classified as Least Concern with a stable but decreasing population trend, emphasize habitat protection through designated areas across its range. The species occurs regularly in protected sites such as in , Los Katíos and Amacayacu National Parks in , Guatopo and Sierra Nevada National Parks in , Asa Wright Nature Centre in Trinidad, and Serra dos Carajás National Park in , which safeguard forest edges and essential to its . Its inclusion in Appendix II regulates international trade to prevent , though trade levels remain low. Ongoing research priorities include to assess connectivity in fragmented landscapes, to understand nectar resource dynamics, and long-term monitoring to track trends amid environmental pressures, as no systematic programs currently exist. Human interactions provide mixed outcomes: backyard gardens with native flowering plants support local populations by supplementing , but altered habitats introduce risks from that compete for resources or alter food webs.

References

  1. https://www.[jstor](/page/JSTOR).org/stable/1369527
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