27-3-2017 RANCHO NATURALISTA, COSTA RICA - WHITE NECKED JACOBIN (FEMALE) (Florisuga mellivora)

The White-necked Jacobin, scientifically known as Florisuga mellivora, is a medium-sized hummingbird adorned with a striking plumage. The male is particularly distinctive, boasting a dark blue head and chest, contrasted by a pure white belly and tail, the latter tipped with black. A white band graces the nape, setting apart the blue head from the vibrant green back and elongated uppertail coverts. Females exhibit a more variable appearance, often showing green upperparts and a blue-green throat, with white "scales" and a white belly. Their tails are mostly green with a blue terminal band.

Males are unmistakable with their contrasting blue and white plumage. Females and immatures can be more challenging to identify due to their variability, but typically females have less white in the tail and a bronzy hue on the throat and chest.

This species is found in the canopy and edges of humid forests, as well as in semi-open areas like tall secondary forests, gallery forests, and plantations of coffee and cacao. It tends to stay high in the trees but may descend to lower levels at forest edges and clearings.

The White-necked Jacobin ranges from Mexico through Central America and into northern South America, including Brazil, Peru, and Bolivia. It is also present in Trinidad & Tobago. The nominate subspecies, F. m. mellivora, is widespread, while F. m. flabellifera is endemic to the island of Tobago.

This hummingbird's movement patterns are not fully understood, but it seems to shift seasonally in response to flowering patterns. It is known to be aggressive towards conspecifics when feeding but is not typically territorial.

The White-necked Jacobin is not a particularly vocal species. Its song consists of a series of high-pitched notes, while its calls include a short 'tsik', a high-pitched 'sweet', and a descending 'swee-swee-swee-swee' during antagonistic interactions.

Breeding occurs during the dry to early wet seasons, with timing varying across its range. The nest is a shallow cup made of plant down and cobwebs, often situated on a leaf and sheltered by another leaf overhead. Males engage in display flights and chases, while females perform fluttering flights to distract predators.

The diet consists primarily of nectar from flowers of tall trees, epiphytes, shrubs, and Heliconia plants. They are also insectivorous, hawking small insects through various aerial maneuvers.

27-3-2017 RANCHO NATURALISTA - WHITE NECKED JACOBIN (FEMALE) (Florisuga mellivora)

The white-necked jacobin (Florisuga mellivora ) is a medium-size hummingbird that ranges from Mexico south through Central America and northern South America into Brazil, Peru and Bolivia. It is also found in Trinidad & Tobago.

Other common names are great jacobin and collared hummingbird.

The white-necked jacobin is 11 to 12 cm (4.3 to 4.7 in) long. Males weigh 7.4 to 9 g (0.26 to 0.32 oz) and females 6 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. The majority of 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.

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. The nominate has been recorded as a vagrant in Argentina and on the islands of Aruba and Curaçao.

The white-necked jacobin inhabits the canopy and edges of humid forest and also semi-open 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 has also rarely been seen as high as 1,500 m (4,900 ft).

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

The white-necked jacobin 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.