Blue-headed hummingbird

Blue-headed hummingbird
Blue-headed hummingbird in Morne Diablotins National Park, Dominica
CITES Appendix II [2]
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Clade: Strisores
Order: Apodiformes
Family: Trochilidae
Genus: Riccordia
Species:
R. bicolor
Binomial name
Riccordia bicolor
(Gmelin, JF, 1788)
Synonyms

Cyanophaia bicolor[3]

The blue-headed hummingbird (Riccordia bicolor) is a hummingbird of the genus Riccordia. It is exclusively found on the islands of Dominica and Martinique in the Lesser Antilles, in forests along rivers. The males and females have distinct appearances; the female has a white frontside, and her backside and wings are iridescent bronze-green colored. The male is entirely emerald of varying shades, with an especially blue head, as his name suggests. Its behavior is typical of most hummingbirds, mostly feeding off of nectar. It nests from February to May in tree ferns, incubating a clutch of 2 white eggs for 16 to 18 days. It is a near-threatened species, with an estimated mature population of 25 to 150 thousand.

Taxonomy and systematics

The blue-headed hummingbird was formally described in 1788 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae. He placed it with all the other hummingbirds in the genus Trochilus and coined the binomial name Trochilus bicolor.[4] Gmelin based his description on "Le saphir-ésmeraude" that been described in 1779 by the French polymath Georges-Louis Leclerc, Comte de Buffon in his Histoire Naturelle des Oiseaux.[5] Buffon believed his specimen had come from Guadeloupe but this was an error for Dominica.[6]

The blue-headed hummingbird was formerly the only species placed in the genus Cyanophaia.[7] A molecular phylogenetic study published in 2014 found that Cyanophaia was nested within the resurrected genus Riccordia.[8][9] Based on that study and others, the North American Classification Committee of the American Ornithological Society, the International Ornithological Committee (IOC), and the Clements taxonomy merged it into Riccordia.[10][11][12] However, as of 2020 BirdLife International's Handbook of the Birds of the World (HBW) retained it in Cyanophaia.[3]

Genus Riccordia had originally been introduced in 1854 by the German ornithologist Ludwig Reichenbach with the Cuban emerald as the type species.[13] Reichenbach based the genus name on the specific epithet of the type species recordii which had been chosen by Paul Gervais to honour the French surgeon-naturalist Alexandre Ricord (born 1798). The specific name bicolor is Latin meaning "two-colored".[14]

The blue-headed hummingbird is monotypic.[11]

Description

The blue-headed hummingbird is medium-sized hummingbird at 9.4–9.9 cm in length and 3.9–4.7 g in weight.[15] On average, the bill (measuring along the culmen) is 17 mm, each wing is 59 mm long, and the tail is 37.2 mm in length.[16] Its iris is dark brown but may appear black due to lighting, and the skin around its eyes are dark gray.[17] Its legs are slightly larger compared to other hummingbirds but are otherwise typical, small and weak.[18] It is sexually dimorphic; the female is slightly smaller compared to the male, and each gender's plumage is different.[15]

The female blue-headed hummingbird is dichromatic; from behind she is a shiny, bronze-like green that appears indigo from certain angles. Her throat and neck are whitish.[15] Her largest flight feathers (the primaries and secondaries) are black and lose their glossiness with wear. Her tail feathers (rectrices) have a detailed pattern: the center 2 feathers are the same metallic green as her back with darker fringes, but the remaining 4 feathers on both sides are dark green to black and terminate with a white or gray tip that become broader farther from the center, and the outermost 2 feathers on each side are especially broad, resulting in a stepped appearance. The underside of her tail feathers and her belly are gray with green spots on the fringes. The sides of her head and especially the area around her eyes are darker, and the top of her head is markedly more cyan compared to the rest of her body.[19]

The males are strikingly different from the females. He is entirely an iridescent emerald of different shades, except for the feathers around his thighs, which are white to grayish. At certain angles (especially the back of the head, the lower back, the rump, and the breast) his feathers appear especially vivid and blue. His head and throat are a vivid azure, as is his tail feathers and underparts. His largest flight feathers are similar to that of the female but exaggerated, with a slight violet sheen when fresh. The underside of his wing is much duller in comparison, largely colored black, although the feathers nearest to the head (the underwing lesser and median coverts) are a much more vibrant bright green bronze.[19]

Juveniles strongly resemble adults, however, they are generally duller in color, their bills are shorter and not decurved, and they have smaller tail and wing feathers. The juvenile female's upperparts do not look as indigo from some angles, and her tail feathers have much whiter tips. Unlike the adult, who has an entirely black beak, the juvenile male's lower beak is a bright pink that may be tipped black. His tail feathers are also less azure and more of a dusky blue.[20]

Similar species

The blue-headed hummingbird is largely distinct in its range, however, a female blue-headed may look similar to the female Antillean crested hummingbird, which also has a white breast and chin with gray underparts; however it can be distinguished from the blue-crested by its shorter bill and eponymous crest. The male blue-crested hummingbird may look black in poor lighting, making it hard to distingush from the male purple-throated and green-throated caribs, however, unlike the blue-crested hummingbird, the wings of the two caribs are usually much brighter than the rest of the body, their bills are longer with a downwards curve, and they are larger in size.[21]

Distribution and habitat

The blue-headed hummingbird exclusively present on the islands of Dominica and Martinique in central Lesser Antilles,[22] between 500–1,200 meters above sea level,[23] although they are the most numerous between 800–1,000 m. It inhabits undisturbed forests and secondary forest along rivers.[24] It is sedentary, meaning that it does not migrate at all.[25]

Behavior

Little is known of the blue-headed hummingbird's behaviors, but it can be assumed that they are mostly similar to other Lesser Antillean hummingbirds.[26][27][28]

Feeding

Typical of all hummingbirds, the blue-headed hummingbird forages for nectar from a variety of flowering plants and trees. It feeds at all levels of the forest, usually hovering 6 meters above the ground. In addition to nectar it feeds on arthropods captured by hawking from a perch, especially over streams, and also gleans them from leaves.[26]

Breeding

The blue-headed hummingbird breeds from February to May. Its nest is a cup 58 mm tall and 47 mm in diameter, made of assorted plant material, often lined with kapok tree fluff, and usually attached to a nearby twig with cobwebs.[29] It is placed on horizontal twigs or tree fern fronds between 1–4 meters above the ground. Its eggs are small at 13.5 by 8.6 mm in size, and they are white in color.[30] The female incubates the clutch of two eggs for 16 to 18 days; fledging occurs 20 to 23 days after hatch.[27]

Vocalization

The blue-headed hummingbird's calls are similar to those of other small hummingbirds, and include "shrill, metallic notes, rapidly descending in pitch, and a metallic 'click-click-click'."[28]

Conservation and ecology

BirdLife International, which provides the IUCN conservation status for birds, classifies the blue-headed hummingbird as near-threatened due to climate change and the resulting severe weather.[1] The blue-headed hummingbird is common in its habitat, albeit sporadically distributed; estimates for population density have varied greatly. In a 1996 survey of Martinique, it was found to be the 7th most common bird of the entire island with an estimated density of 350–770 per square kilometer. In a 2021 study, the population density was estimated to be 3–4 per square kilometer. This discrepancy may be caused by the 2021 study being exessively cautious, and the 1996 survey is likely the more accurate figure for higher altitudes, and as such the global population is estimated to be 25–150 thousand mature individuals.[31]

The aftermath of Hurricane Maria in 2017 resulted in 18% of tree cover being lost in Dominica, with the a heavy decrease in blue-headed hummingbird abundance, however, on Guadeloupe other hummingbird species have successfully recovered from Hurricane Hugo, which, along with the high frequency of cyclones in the Lesser Antilles, suggests that the blue-headed hummingbird may be naturally resistant to cyclones.[31]

References

Footnotes

  1. ^ a b BirdLife International 2024, Assessment Information.
  2. ^ "Appendices | CITES". cites.org. Retrieved 2022-01-14.
  3. ^ a b 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 MB] retrieved 27 May 2021
  4. ^ Gmelin, Johann Friedrich (1788). Systema naturae per regna tria naturae: secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis (in Latin). Vol. 1, Part 1 (13th ed.). Lipsiae [Leipzig]: Georg. Emanuel. Beer. p. 496.
  5. ^ Buffon, Georges-Louis Leclerc de (1779). "Le saphir-ésmeraude". Histoire Naturelle des Oiseaux (in French). Vol. 6. Paris: De l'Imprimerie Royale. pp. 26–27.
  6. ^ Schuchmann, K.L. (1999). "Blue-headed hummingbird". In del Hoyo, J.; Elliott, A.; Sargatal, J. (eds.). Handbook of the Birds of the World. Vol. 5: Barn-owls to Hummingbirds. Barcelona, Spain: Lynx Edicions. p. 582. ISBN 978-84-87334-25-2.
  7. ^ Peters, James Lee, ed. (1945). Check-List of Birds of the World. Vol. 5. Cambridge, Massachusetts: Harvard University Press. p. 44.
  8. ^ McGuire, J.; Witt, C.; Remsen, J.V.; Corl, A.; Rabosky, D.; Altshuler, D.; Dudley, R. (2014). "Molecular phylogenetics and the diversification of hummingbirds". Current Biology. 24 (8): 910–916. doi:10.1016/j.cub.2014.03.016. PMID 24704078.
  9. ^ Stiles, F.G.; Remsen, J.V. Jr.; Mcguire, J.A. (2017). "The generic classification of the Trochilini (Aves: Trochilidae): Reconciling taxonomy with phylogeny". Zootaxa. 4353 (3): 401–424. doi:10.11646/zootaxa.4353.3.
  10. ^ "Check-list of North and Middle American Birds". American Ornithological Society. June 29, 2021. Retrieved August 9, 2021.
  11. ^ a b Gill, F.; Donsker, D.; Rasmussen, P., eds. (January 2022). "Hummingbirds". IOC World Bird List. v 12.1. Retrieved January 15, 2022.
  12. ^ 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
  13. ^ Reichenbach, Ludwig (1854). "Aufzählung der Colibris Oder Trochilideen in ihrer wahren natürlichen Verwandtschaft, nebst Schlüssel ihrer Synonymik". Journal für Ornithologie (Supplement) (in German). 1: 1–24 [8].
  14. ^ Jobling, James A. (2010). The Helm Dictionary of Scientific Bird Names. London: Christopher Helm. pp. 336, 72. ISBN 978-1-4081-2501-4.
  15. ^ a b c Mlodinow et al. 2026, Field Identification § Identification.
  16. ^ Mlodinow et al. 2026, Plumages, Molts, and Structure § Measurements.
  17. ^ Mlodinow et al. 2026, Plumages, Molts, and Structure § Bare Parts § Iris and Facial Skin.
  18. ^ Mlodinow et al. 2026, Plumages, Molts, and Structure § Bare Parts § Tarsi and Toes.
  19. ^ a b Mlodinow et al. 2026, Plumages, Molts, and Structure § Plumages § Definitive Basic Plumage.
  20. ^ Mlodinow et al. 2026, Plumages, Molts, and Structure § Plumages § Juvenile (First Basic) Plumage.
  21. ^ Mlodinow et al. 2026, Field Identification § Similar Species.
  22. ^ Mlodinow et al. 2026, Distribution.
  23. ^ Mlodinow et al. 2026, Distribution § Elevational Range.
  24. ^ Mlodinow et al. 2026, Habitat § General Habitat.
  25. ^ Mlodinow et al. 2026, Movements and Migration.
  26. ^ a b Mlodinow et al. 2026, Diet and Foraging.
  27. ^ a b Mlodinow et al. 2026, Breeding.
  28. ^ a b Mlodinow et al. 2026, Sounds and Vocal Behavior.
  29. ^ Mlodinow et al. 2026, Breeding § Nest.
  30. ^ Mlodinow et al. 2026, Breeding § Eggs.
  31. ^ a b BirdLife International 2024, Population.

Sources cited

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