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Amethyst sunbird

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Amethyst sunbird
Nominate male and female, South Africa
Song recorded in KwaZulu-Natal, South Africa
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Nectariniidae
Genus: Chalcomitra
Species:
C. amethystina
Binomial name
Chalcomitra amethystina
(Shaw, 1812)
Synonyms

Nectarinia amethystina

The amethyst sunbird, also called the black sunbird (Chalcomitra amethystina), is a species of passerine bird in the family Nectariniidae. It is native to the Afrotropics, mostly south of the equator.[2] They are commonly found in well-watered habitats, and undertake seasonal movements to visit flowering woodlands. The demise of some woodlands have impacted their numbers locally, but their range has also expanded along with the spread of wooded gardens.

Habits

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Though mostly found singly or in pairs, larger numbers may concentrate at favourite flowering trees, where they act aggressively towards other sunbird species.[3] The complex song is a loud, sustained twittering.[3] Food includes emergent termites, spiders and nectar.[4] In courtship a male will hop about a branch near a female, drop one wing, then the other, and finally both wings. The wings will then be fluttered and displayed. A responsive female may lower her head, and assume a rigid posture.[5]

Nesting

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Breeding pairs of amethyst sunbird are widely spaced, and the female builds the nest.[6] Favoured trees include exotic eucalypts and pines, and are often close to buildings or human activity.[5] Nests are attached to a drooping branch, below the canopy, or hidden by foliage.[6] Nests are built from fine grass stems, which are bound together with cobwebs.[6] The nest is often decorated with lichens,[3] or other debris. Two speckled eggs are laid, but successive clutches may be raised from the same nest in a single season.[6] Nests are parasitized by green-backed honeybird and Klaas's cuckoo.[2]

Habitat and movements

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Amethyst sunbirds are widespread residents of woodland, mesic savanna, forest edge and suburban gardens.[3] They occur only sparsely in dry savanna[7] or low dry regions, where they keep to riparian woods or concentrations of nectar-bearing plants,[3][7] and are decidedly scarce in the Limpopo valley and mopane regions.[8] A distinct summer influx is notable in the Zambezi valley and Great Zimbabwe woodlands,[7] and they are strictly summer visitors (September/October to April) to the Kalahari sand (or Gusu) woodlands, where they appear in high densities when the Baikiaea trees are in flower.[7] On seaward-facing slopes, they are very common residents up to 1,800 metres,[7] with high reporting rates in afromontane forest and valley bushveld.[8]

Adaptations

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The average hematocrit level for birds is between 30 and 45%; however, the Amethyst Sunbird has an average hematocrit level of 50%.[9] Amethyst sunbirds can be found along an altitudinal gradient in South Africa from the Drakensberg mountain range to the coast of KwaZulu-Natal.[10] During warmer months, the sunbird's hematocrit levels will increase with higher altitudes (where there is also a dramatic drop in temperature) and with lower oxygen concentrations in the atmosphere.[11] Higher hematocrit levels may be attributed to its small body size and can help with oxygen carrying capacity and the metabolic cost of flying.[11]

Subpopulations of Amethyst Sunbirds show variation in their resting metabolic rates, basal metabolic rate, and thermal neutral zones based on the subpopulation's acclimation to different altitudes.[12] Those more acclimated to high altitudes would have lower metabolic rates and a larger thermal neutral zone. Therefore, the Amethyst Sunbird can change its physiology in response to altitude and temperature to achieve a metabolic rate and temperature regulation best suited for its environment.[12]

Status

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On the Mashonaland plateau, race kirkii has declined in favour of scarlet-chested sunbird, after fragmentation of its native miombo woodlands.[8] In South Africa, the range of the nominate race has increased along with the spread of wooded gardens.[2]

Range

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It occurs in Angola, Botswana, Burundi, Republic of the Congo, Democratic Republic of the Congo, Eswatini, Ethiopia, Gabon, Kenya, Malawi, Mozambique, Namibia, Somalia, South Africa, South Sudan, Tanzania, Uganda, Zambia and Zimbabwe.

Races

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Between three[13] and eleven[14] races have been proposed, including:

  • C. a. amethystina
Range: South Africa, southern Botswana, Eswatini
Description: Fairly distinct: bill heavy, females dark from throat to belly, males have tail coverts metallic purple
  • C. a. kirkii Shelley, 1876
Range: Zimbabwe to East Africa
Description: Bill finer than nominate, females much lighter on underside, males with dark brown (not purple) tail coverts
  • C. a. kalckreuthi (Cabanis, 1878)
Range: coastal Tanzania and Kenya
Description: Bill slender, females pale below, unmarked on throat, supercilium long, males may have metallic purple upper tail coverts;[3] often merged with C. a. kirkii
  • C. a. deminuta Cabanis, 1880
Range: West African tropics
  • C. a. doggetti (Sharpe, 1902)
Range: western Kenya
  • C. a. adjuncta (Clancey, 1975)
Range: Eswatini
Description: Similar to nominate, with which it is often merged
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  • C. a. amethystina pair by J. G. Keulemans
    C. a. amethystina pair by J. G. Keulemans
  • C. a. kirkii pair by J. G. Keulemans
    C. a. kirkii pair by J. G. Keulemans
  • Juvenile male of the nominate race
    Juvenile male of the nominate race
  • Juvenile male feeding on mistletoe nectar
    Juvenile male feeding on mistletoe nectar
  • Female specimen, perhaps C. a. kirkii, Kenya
    Female specimen, perhaps C. a. kirkii, Kenya
  • Female in nest suspended from low tree branch
    Female in nest suspended from low tree branch

References

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  1. ^ BirdLife International (2016). "Chalcomitra amethystina". IUCN Red List of Threatened Species. 2016: e.T22717762A94550241. doi:10.2305/IUCN.UK.2016-3.RLTS.T22717762A94550241.en. Retrieved 17 November 2021.
  2. ^ a b c "Chalcomitra amethystina (Amethyst sunbird, Black sunbird)". biodiversityexplorer.org. iziko museums. Retrieved 15 October 2014.
  3. ^ a b c d e f Zimmerman, Dale A.; et al. (1996). Birds of Kenya and Northern Tanzania. Halfway House: Russel Friedman Books. p. 642. ISBN 1-875091-04-1.
  4. ^ "Amethyst Sunbird (Chalcomitra amethystina)". hbw.com. Handbook of the Birds of the World. Retrieved 15 October 2014.
  5. ^ a b Cowles, Raymond B. (January 1936). "Observations on the Amethyst Sunbird, Chalcomitra amethystina amethystina (Shaw)". The Auk. 53 (1): 28–30. doi:10.2307/4077353. JSTOR 4077353.
  6. ^ a b c d Tarboton, Warwick (2000). Field guide to nests & eggs of Southern African birds. Cape Town: Struik. pp. 235–236. ISBN 1-86872-271-6.
  7. ^ a b c d e Irwin, Michael P. Stuart (1981). The birds of Zimbabwe. Salisbury, Zimbabwe: Quest Pub. pp. 375–376. ISBN 0-86925-156-2.
  8. ^ a b c Harisson, J.A.; et al. (1997). The atlas of southern African birds (PDF). Johannesburg: BirdLife SA. pp. 518–520. ISBN 0-620-20730-2.
  9. ^ Marsen, Sky (2009-02-01). "Book review: BARBARA JOHNSTONE, Discourse Analysis, 2nd edn. Oxford: Blackwell, 2008. 312 pp". Discourse Studies. 11 (1): 121–123. doi:10.1177/1461445608101544. ISSN 1461-4456. S2CID 143397992.
  10. ^ Yom-Tov, Yoram (2002-09-01). "Sunbirds: A Guide to the Sunbirds, Flowerpeckers, Spiderhunters, and Sugarbirds of the World. By Robert A Cheke and Clive F Mann; illustrated by Richard Allen". The Quarterly Review of Biology. 77 (3): 340–341. doi:10.1086/345222. ISSN 0033-5770.
  11. ^ a b Lindsay, Claire V.; Downs, Colleen T.; Brown, Mark (2010-10-01). "Seasonal variation in hematocrit levels of Amethyst Sunbirds (Chalcomitra amethystina) over an altitudinal gradient". Journal of Ornithology. 151 (4): 851–855. doi:10.1007/s10336-010-0522-z. ISSN 1439-0361. S2CID 37418670.
  12. ^ a b Lindsay, Claire V.; Downs, Colleen T.; Brown, Mark (2009-02-15). "Physiological variation in amethyst sunbirds (Chalcomitra amethystina) over an altitudinal gradient in winter". Journal of Experimental Biology. 212 (4): 483–493. doi:10.1242/jeb.025262. ISSN 0022-0949. PMID 19181895.
  13. ^ "Amethyst Sunbird (Chalcomitra amethystina)". The Internet Bird Collection. IBC. Retrieved 15 October 2014.
  14. ^ Chittenden, Hugh; Allan, David; Weiersbye, Ingrid (art) (2012). Roberts geographic variation of southern African birds. Cape Town: John Voelcker Bird Book Fund. ISBN 978-1-920602-00-0.
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