Order: APODIFORMES
Family: TROCHILIDAE
It is a hummingbird with a short and straight beak. Their colors vary between green, black and white. He likes to frequent the flowers found in the treetops and hunt insects. It is an inhabitant of humid and clear forests.
Description
This species has a marked sexual dimorphism. It has a short, straight, black beak. Its length is approximately 10.2 cm, of which 14 mm belong to its beak. Its weight is more or less 2.6 gr. The head and back are green, with a prominent white band on the rump; the supracaudal coverts are black and coppery green at the tips, with white spots on the flanks. Its legs are black with white pompoms on the thighs. The male has a bright green bib bordered by an iridescent blue pectoral spot; the belly is a little darker in the central part. The wheelhouses are bluish black with white cannons, the three outermost pairs are long and very thin like wires.
The female is smaller and has prominent broad white malar stripes. Ventrally, it is blackish with green spots and a green list on the chest, the throat is especially dark. The flanks with a very conspicuous white spot. The tail is forked with the two pointed outer wheelhouses and the white apex. Juveniles present a pattern similar to that of females.
Taxonomy
Closely related to the genus Lophornis.
Similar species
Both sexes are easily distinguished by their conspicuous white band on the rump.
Regional Differences
It is considered a monotypic species.
Distribution
This hummingbird lives from the northwest of Costa Rica and Panama (slopes of the Caribbean) to the west of Ecuador. In Colombia it is distributed from sea level to 100 m high on the western slope of the Western Cordillera.
Habitat
Uncommon species in low and middle elevations, seasonally common in humid forest, edges and clearings. It does not seem to accept highly intervened areas and is fairly common in secondary growth forests. Probably makes seasonal movements migrating altitude and descending by foothills and surrounding lowlands when the rainy season begins.
Nesting / Breeding
Hummingbirds are solitary in all aspects of life other than breeding; and the male’s only involvement in the reproductive process is the actual mating with the female. They neither live nor migrate in flocks; and there is no pair bond for this species. Males court females by flying in a u-shaped pattern in front of them. He will separate from the female immediately after copulation. One male may mate with several females. In all likelihood, the female will also mate with several males. The males do not participate in choosing the nest location, building the nest or raising the chicks.
The female is responsible for building the cup-shaped nest out of plant fibers woven together and green moss on the outside for camouflage in a protected location in a shrub, bush or tree. She lines the nest with soft plant fibers, animal hair and feather down, and strengthens the structure with spider webbing and other sticky material, giving it an elastic quality to allow it to stretch to double its size as the chicks grow and need more room. The nest is typically found on a low, thin horizontal branch.
The average clutch consists of two white eggs, which she incubates alone, while the male defends his territory and the flowers he feeds on. The young are born blind, immobile and without any down.
The female alone protects and feeds the chicks with regurgitated food (mostly partially-digested insects since nectar is an insufficient source of protein for the growing chicks). The female pushes the food down the chicks’ throats with her long bill directly into their stomachs.
As is the case with other hummingbird species, the chicks are brooded only the first week or two, and left alone even on cooler nights after about 12 days – probably due to the small nest size. The chicks leave the nest when they are about 20 days old. Breeding males are often seen perching on a branch giving a dive display.
Diet / Feeding
The Green Thorntail Hummingbirds primarily feed on nectar taken from a variety of brightly colored, scented small flowers of trees, herbs, shrubs and epiphytes. They favor flowers with the highest sugar content (often red-colored and tubular-shaped) and seek out, and aggressively protect, those areas containing flowers with high energy nectar.They use their long, extendible, straw-like tongues to retrieve the nectar while hovering with their tails cocked upward as they are licking at the nectar up to 13 times per second. Sometimes they may be seen hanging on the flower while feeding.
Many native and cultivated plants on whose flowers these birds feed heavily rely on them for pollination. The mostly tubular-shaped flowers actually exclude most bees and butterflies from feeding on them and, subsequently, from pollinating the plants.
They may also visit local hummingbird feeders for some sugar water, or drink out of bird baths or water fountains where they will either hover and sip water as it runs over the edge; or they will perch on the edge and drink – like all the other birds; however, they only remain still for a short moment.
They also take some small spiders and insects – important sources of protein particularly needed during the breeding season to ensure the proper development of their young. Insects are often caught in flight (hawking); snatched off leaves or branches, or are taken from spider webs. A nesting female can capture up to 2,000 insects a day.
Males establish feeding territories, where they aggressively chase away other males as well as large insects – such as bumblebees and hawk moths – that want to feed in their territory. They use aerial flights and intimidating displays to defend their territories.
Behaviour
It is observed on the tops of emerging trees in good bloom. It catches insects (Diptera and Hymenoptera) in flight and spiders on the underside of large leaves mainly in the upper layers of the forest. It holds its characteristically raised tail almost at a right angle while hovering very quietly, achieving great stability.
Calls / Vocalization
The Green Thorntail is usually silent, but a quiet chip may occasionally be heard.
Conservation status
It us considered as a Least Concern.
References
Hilty, S. L. and W. L. Brown. 2001. Guide to the Birds of Colombia. Princetn. Univ. Press, Princeton, NJ
Remsen, J. V., Jr., C. D. Cadena, A. Jaramillo, M. Nores, J. F. Pacheco, J. Pérez-Emán, M. B. Robbins, F. G. Stiles, D. F. Stotz, and K. J. Zimmer. Version 9 February 2011. A classification of the bird species of South America. American Ornithologists’ Union.
The Internet Bird Collection – IBC. The Green Thorntail (Discosura conversii). On line available at: http://ibc.lynxeds.com/species/green-thorntail-discosura-conversii
http://www.museum.lsu.edu/~Remsen/SACCBaseline.html
BirdLife International (2011) Species factsheet: Discosura conversii. Downloaded from http://www.birdlife.org on 05/25/2011
Species Research by Sibylle Johnson from the web site: https://www.beautyofbirds.com/greenthorntailhummingbirds.html
