The red-billed emerald (''Chlorostilbon gibsoni'') is a species of

hummingbird Hummingbirds are birds native to the Americas and comprise the biological family Trochilidae. With about 361 species and 113 genera, they occur from Alaska to Tierra del Fuego, but the vast majority of the species are found in the tropics aro ...

in the "emeralds", tribe Trochilini of subfamily Trochilinae. It is found in

Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...

and

Venezuela Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...

.HBW and BirdLife International (2020) ''Handbook of the Birds of the World and BirdLife International digital checklist of the birds of the world'' Version 5. Available at: http://datazone.birdlife.org/userfiles/file/Species/Taxonomy/HBW-BirdLife_Checklist_v5_Dec20.zip xls zipped 1 MBretrieved 27 May 2021

Taxonomy and systematics

The red-billed emerald was originally described as a species and later treated as a subspecies of the blue-tailed emerald (''Chlorostilbon mellisugus''). Since the early 2000s, most taxonomist have again treated it as a species in its own right. It has also at times been considered conspecific with the

western emerald The western emerald (''Chlorostilbon melanorhynchus'') is a species of hummingbird in the "emeralds", tribe Trochilini of subfamily Trochilinae. It is found in Colombia and Ecuador. Taxonomy and systematics The western emerald was originally ...

(''C. melanorhynchus'').Clements, J. F., T. S. Schulenberg, M. J. Iliff, S. M. Billerman, T. A. Fredericks, J. A. Gerbracht, D. Lepage, B. L. Sullivan, and C. L. Wood. 2021. The eBird/Clements checklist of Birds of the World: v2021. Downloaded from https://www.birds.cornell.edu/clementschecklist/download/ Retrieved August 25, 2021 As currently (2020) understood, the red-billed emerald has three subspecies: the nominate ''C. g. gibsoni'', ''C. g. chrysogaster'', and ''C. g. nitens''.

Description

The red-billed emerald is long and weighs about . The males of all three subspecies have a straight bill with a mostly red

mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...

. The females' mandibles are red at the base. The bills are about long. Males of the nominate subspecies have dark bronze-green upperparts and a deeply forked blue-black tail. Their faces and underparts are glittering green to golden green. Nominate females are shining green above and plain gray below with dusky cheeks and a short white line behind the eye. Their central tail feathers are dark blue-green and the rest dark green with dusky ends and narrow gray-white tips.del Hoyo, J., N. Collar, G. M. Kirwan, and P. F. D. Boesman (2020). Red-billed Emerald (''Chlorostilbon gibsoni''), version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.rebeme1.01 retrieved July 31, 2022 Subspecies ''C. g. chrysogaster'' is larger than the other two subspecies. The male is mostly malachite green; its tail is slightly bluer and more deeply forked than the others'. ''C. g. nitens'' is very like the nominate, but with a slight gold sheen and a less deeply forked tail.

Distribution and habitat

The nominate subspecies of red-billed emerald is found in central Colombia's Magdalena River valley. ''C. g. chrysogaster'' is found in northern Colombia between Córdoba and

Norte de Santander North Santander (Spanish: Norte de Santander) () is a department of Northeastern Colombia. It is in the north of the country, bordering Venezuela. Its capital is Cúcuta, one of the country's major cities. North Santander is bordered by Venez ...

departments. ''C. g. nitens'' is found on Colombia's

Guajira Peninsula The Guajira Peninsula ( es, Península de La Guajira, links=no, also spelled ''Goajira'', mainly in colonial period texts, guc, Hikükariby) is a peninsula in northern Colombia and northwestern Venezuela in the Caribbean. It is the northernm ...

and adjoining northwestern Venezuela. The species mostly inhabits dry to arid landscapes including desert scrublands, dry woodland, farmed areas, and parks and gardens. In Colombia it is mostly found at elevations below but does occur as high as in the upper Magdalena valley. In Venezuela it has been recorded up to .

Behavior

Movement

No movements of the red-billed emerald are definitely known, but at least in parts of northern Colombia it appears to make seasonal changes.

Feeding

The red-billed emerald forages for nectar by

trap-lining In ethology and behavioral ecology, trap-lining or traplining is a feeding strategy in which an individual visits food sources on a regular, repeatable sequence, much as trappers check their lines of traps. Traplining is usually seen in species ...

, visiting a circuit of flowering trees, shrubs, and other plants. It usually feeds close to the ground, though sometimes higher, and on small flowers that are less attractive to larger hummingbirds. It is assumed to also feed on small insects.

Breeding

The red-billed emerald's breeding seasons are not well defined but appear to span March to August in Venezuela and include November in at least one part of Colombia. One nest was a downy cup with lichen on its outside attached to a fern frond.

Vocalization

The red-billed emerald's song is "a continuous series of wiry trilled notes, 'wirrr...wirrr...wirrr...'". It also makes "high-pitched penetrating 'tseeee' and a reedy 'tzreee'" calls.

Status

The

IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

has assessed the red-billed emerald as being of Least Concern, though its population size and trend are unknown. It is considered uncommon throughout its range, but is probably not threatened by human actions because its dry habitat is not heavily used.

References

{{Taxonbar, from=Q1273197 red-billed emerald Birds of Colombia Birds of Venezuela red-billed emerald red-billed emerald Taxonomy articles created by Polbot