Green hylia

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Green hylia
Green Hylia specimen RWD.jpg
Specimen at Nairobi National Museum
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Hyliidae
Genus: Hylia
Cassin, 1859
Species:
H. prasina
Binomial name
Hylia prasina
(Cassin, 1855)
Hylia prasina distribution map.png

The green hylia (Hylia prasina) is a monotypic genus widespread in tropical Africa, where it mostly inhabits the understory and mid-stratum of moist forest. It is a canopy insectivore which had been tentatively placed within the family of Cettiidae warblers, but in 2019 its assignment to a new family, the Hyliidae, was strongly supported. [2] [3]

Contents

Taxonomy

Hylia prasina is a monotypic songbird that has proven difficult to place within the phylogenetic tree. [4] [5] Connections between Hylia and other genera have been attempted by comparing DNA sequences, physical similarities and even behavioural characteristics. None of these links have been sufficiently proven to allow definite classification of the green hylia. [4]

The green hylia belongs to the order Passeriformes and the superfamily Sylvioidea, however the classification at family level is under dispute. The species is often attributed to the family Cettiidae (bush warblers) along with Scotocerca , Erythrocercus , Tesia , Cettia and Abroscopus . Investigation into indels does not support a strong relationship between Hylia and the Cettiidae. [4]

Anatomically, the green hylia has similarities to sunbirds and warblers. Characteristics shared with sunbirds include a long hyloid with flattened epibranchial horns, a brush-tipped tongue and membrane-covered nostrils. Similarities to some warblers include very comparable colouring. [5] The relationship between the genera Hylia and Phylloscopus (leaf warblers) has been examined but seems to have low empirical support. [6] A sister relationship between Hylia and Aegithalidae (long tailed tits) was similarly poorly supported. [4] Close relationships with Nectariniidae (sunbirds), Estrildidae (finches) and Meliphagidae (honeyeaters) have also been rejected. [5]

The sister relationship between Hylia and Pholidornis (tit hylia) is strongly supported, based on mitochondrial data and physiological similarities. [4] [5] It has been suggested that both genera should be placed in a new family ‘Hyliidae’, pending further confirmation. It is likely that the green hylia, along with other closely related species, have an uncertain position in the phylogenetic tree as a result of rapid radiation of the families within the Sylvioidea. [4]

Description

The green hylia has dark brown irises, a black bill and olive green feet. [7] This species is small, weighing approximately 14 g. [5] There is no noticeable difference in colour between the genders, however males are generally larger. [8]

There are two subspecies, H. p. prasina and H. p. poensis, which differ in the colouring under the throat. H. p. prasina has an olive green chin and throat and olive-grey underbelly while H. p. poensis has a white-grey throat and underbelly. [8] [9]

Vocalisation

The green hylia uses several different calls, the most common being clear whistles (kee kee) or dry scolding rattles (trrit trrrit). [5] It is known for its recognisable, pure, two-note song. Alarm calls used to warn of nearby predators are short as this makes it difficult for predators to locate exactly where the call is coming from. [10] [11]

When played imitation recordings, males reacted more strongly to longer notes. [11] Analyses of green hylia songs indicated that a build-up of reverberations at the same frequency will lead to longer and louder note tails. This means that dense vegetation can alter birdsong transmissions to allow for a longer and louder signal, using the same amount of energy for vocalisation. The strengthening of the green hylia's song could be beneficial to the species for defending territory or attracting mates. [10] The elongation of signals with narrow bandwidth has been found to be a beneficial consequence of reverberations on birdsong transmission. [11]

Song characteristics will vary depending on habitat structure and ambient noise. Since the species uses narrow bandwidth songs they must adjust their frequency relative to influences such as insect vocalisations in order to be heard. Green hylias were found to sing at a lower frequencies when at higher elevations, cooler temperatures and lower tree coverage. When insect sounds are at a low frequency, the songs are found to be even lower. This behaviour has been interpreted as behavioural plasticity (auditory feedback in each specific environment to determine the clearest frequency), determination by genetic components, or a combination of both. [12]

Habitat and distribution

The green hylia occurs in a wide range throughout most of tropical Africa. The subspecies H. p. poensis can only be found on islands in the Gulf of Guinea. H. p. prasina is much more widely distributed throughout the Guineo-Congolian forest and is found from western Gambia to western Kenya. [9]

The green hylia is a common forest generalist, occurring at forest edges and gaps between vegetation as well as forest interiors. [13] [14] Its preferred habitat is mostly intact, semideciduous moist forest. [15] Green hylia habitat includes plant species such as Elaeis guinensis , Celtis zenkeri , Cola gigantea , Acalypha ornata , Markhamia platycalyx , Coffea canephora , Albizia sp., Fagara macrophylla , Funtumia elastica , Pycnanthes angolensis , Musanga cecropioides and Xylopia aethiopica . [14] [16] Liana and Scleria species provide suitable habitat as they tangle amongst other vegetation, providing nesting materials and a supply of food. [16] Analysis of carbon sources in green hylia food, indicating the origin of the consumed insects, showed that carbon present derived exclusively from C3 plants, which are mostly forest plants, and not C4 plants as might be found in farmland crops, even when these areas border forest habitats. [17]

Ecology

The green hylia is a foliage-gleaning insectivore of the canopy and forest understory, usually foraging at a height of about 10 metres. [13] [14] [16] Its diet includes insects, ants or butterflies which are accessible in its feeding area, on the underside of leaves or amongst forest litter. [5] The species is considered a forest generalist as it is capable of surviving in a wide range of environmental conditions. [18]

The green hylia is usually observed alone or in a mating pair. [8] Mating pairs roost together in their nest. The eggs are white and otherwise not very distinctive. [5] The nest is built a few feet from the ground in a suitable location, such as the vertical forks of young palm trees. The nest is oval and domed in shape with a 20 mm circular opening at the side of the top. Nests are crumbly and friable, the bulk being made up of loose tufts of plant matter which are not fragmented, interwoven or compacted. The outside is covered by a fine layer of fibrous strips topped with the occasional leaf skeleton. The nest measures 150 mm from top to bottom and 90 mm side to side and front to back. [8] It differs from that of other sunbirds in that it is positioned in forks of vegetation and not suspended in the air. [5]

Threats

The green hylia is currently classified as Least Concern by the IUCN based on large population numbers and wide distribution. [1] The species is however likely under pressure from habitat destruction. While the green hylia as a forest generalist is not as sensitive to habitat disruptions as other species, understory and leaf litter clearance does affect its opportunities for foraging and nest building. A significant decline in green hylia population has been observed in plantation areas (as opposed to logged areas) where these habitat components are absent. [18]

The scarp forest habitat of the green hylia is increasingly being cleared for charcoal production and to make way for agriculture. The entire forest understory in certain areas is being cleared through slash and burn techniques to make way for the farming of crops such as bananas, maize or beans. These crops do not support species such as Hylia prasina as they do not possess sufficient understory environments. It is currently unknown how quickly the destruction of these habitats is occurring. While the green hylia has so far not been observed to be affected by this type of habitat clearing, many species with shared habitat requirements are in decline. [19]

Parasites in African habitats may affect the species. Plasmodium parahexamerium was identified as infecting the green hylia in 2009, with as yet unclear ramifications. This parasite was thought to only inhabit New World hosts, thus its appearance in an Old World bird is both interesting and concerning. Despite this, parasites are not known to be a significant threat to the species as a whole. [20]

Related Research Articles

<span class="mw-page-title-main">Passerine</span> Any bird of the order Passeriformes, sometimes known as perching birds

A passerine is any bird of the order Passeriformes, which includes more than half of all bird species. Sometimes known as perching birds, passerines generally have an anisodactyl arrangement of their toes, which facilitates perching.

Old World warblers are a large group of birds formerly grouped together in the bird family Sylviidae. They are not closely related to the New World warblers. The family held over 400 species in over 70 genera, and were the source of much taxonomic confusion. Two families were split out initially, the cisticolas into Cisticolidae and the kinglets into Regulidae. In the past ten years they have been the subject of much research and many species are now placed into other families, including the Acrocephalidae, Cettiidae, Phylloscopidae, and Megaluridae. In addition some species have been moved into existing families or have not yet had their placement fully resolved. A smaller number of warblers, together with some babblers formerly placed in the family Timaliidae and the parrotbills, are retained in a much smaller family Sylviidae.

<span class="mw-page-title-main">Penduline tit</span> Family of birds

The penduline tits constitute the family, Remizidae, of small passerine birds, related to the true tits. All but the verdin make elaborate bag nests hanging from trees, usually over water.

<span class="mw-page-title-main">Cisticolidae</span> Family of birds

The family Cisticolidae is a group of about 160 warblers, small passerine birds found mainly in warmer southern regions of the Old World. They were formerly included within the Old World warbler family Sylviidae.

<i>Cettia</i> Genus of birds

Cettia is a genus of small insectivorous songbirds ("warblers") which make up the core of the newly recognized family Cettiidae. They were formerly placed in the Sylviidae, which at that time was a wastebin taxon for the warbler-like Sylvioidea. The range of this genus extends from Europe to southeast Asia.

<i>Bradypterus</i> Genus of birds

Bradypterus is a genus of small insectivorous songbirds ("warblers") in the newly recognized grass warbler family (Locustellidae). They were formerly placed in the Sylviidae, which at that time was a wastebin taxon for the warbler-like Sylvioidea. The range of this genus extends through the warm regions from Africa around the Indian Ocean and far into Asia.

<span class="mw-page-title-main">Black-throated blue warbler</span> Species of bird

The black-throated blue warbler is a small passerine bird of the New World warbler family. Its breeding ranges are located in the interior of deciduous and mixed coniferous forests in eastern North America. Over the cooler months, it migrates to islands in the Caribbean and Central America. It is very rarely found in western Europe, where it is considered to be a non-indigenous species. The black-throated blue warbler is sexually dimorphic; the adult male has a black face and cheeks, deep blue upperparts and white underparts, while the adult female is olive-brown above and light yellow below.

<span class="mw-page-title-main">Tailorbird</span> Genus of birds

Tailorbirds are small birds, most belonging to the genus Orthotomus. While they were often placed in the Old World warbler family Sylviidae, recent research suggests they more likely belong in the Cisticolidae and they are treated as such in Del Hoyo et al. One former species, the mountain tailorbird, is actually closer to an old world warbler genus Cettia.

<span class="mw-page-title-main">Passerida</span> Clade of birds

Passerida is, under the Sibley-Ahlquist taxonomy, one of two parvorders contained within the suborder Passeri. While more recent research suggests that its sister parvorder, Corvida, is not a monophyletic grouping, the Passerida as a distinct clade are widely accepted.

<span class="mw-page-title-main">Neumann's warbler</span> Species of bird

Neumann's warbler, also known as Neumann's short-tailed warbler, is a species of bird in the family Cettiidae. It is found in Democratic Republic of the Congo, Rwanda, and Uganda. Its natural habitat is subtropical or tropical moist montane forest.

<span class="mw-page-title-main">Chestnut-headed tesia</span> Species of bird

The chestnut-headed tesia is a small insectivorous songbird formerly of the "Old World warbler" family but nowadays placed in the bush warbler family (Cettiidae).

<i>Tesia</i> Genus of birds

The tesias are a genus, Tesia, of Old World warbler. Though once included in the large family Sylviidae, more recent research placed it within a new family, Cettiidae. The four species inhabit undergrowth of montane forest in South and Southeast Asia, where they are resident or short-range migrants. They have longish legs and appear tailless, with (seemingly) only 8 rectrices. Their simple songs are fairly loud, and their nests are typically ball-shaped. Their name is derived from Tisi, the Nepalese name for the grey-bellied tesia.

<span class="mw-page-title-main">Bornean stubtail</span> Species of bird

The Bornean stubtail is a species of bird in the cettiid warbler family Cettiidae. It is endemic to the island of Borneo, where it inhabits forest floors and undergrowth in montane forests at elevations of 750–3,150 m (2,460–10,330 ft). It is a small, short-tailed warbler, measuring 9.5–10 cm (3.7–3.9 in) in length and having an average mass of 10.4 g (0.37 oz). The tops of the head and the upperparts are brown, with whitish underparts that turn grey at the sides of the breast and the flanks. The supercilium is long and buffish-brown, with an equally long dark grey eyestripe and a thin yellow eye-ring. Both sexes are similar.

<span class="mw-page-title-main">Cettiidae</span> Family of birds

Cettiidae is a newly validated family of small insectivorous songbirds ("warblers"), formerly placed in the Old World warbler "wastebin" assemblage. It contains the typical bush warblers (Cettia) and their relatives. As a common name, cettiid warblers is usually used.

<span class="mw-page-title-main">Tit hylia</span> Species of bird

The tit hylia is a species of bird, monotypic within the genus Pholidornis. It is found in rainforests in West and Central Africa. It had been placed in the family Cettiidae, but in 2019 its assignment to a new family, the Hyliidae, was strongly supported.

<span class="mw-page-title-main">Sylvioidea</span> Superfamily of birds

Sylvioidea is a superfamily of passerine birds, one of at least three major clades within the Passerida along with the Muscicapoidea and Passeroidea. It contains about 1300 species including the Old World warblers, Old World babblers, swallows, larks and bulbuls. Members of the clade are found worldwide, but fewer species are present in the Americas.

<span class="mw-page-title-main">Macrosphenidae</span> Family of birds

The African warblers are a newly erected family Macrosphenidae, of African songbirds. Most of the species were formerly placed in the Old World warbler family Sylviidae, although one species, the rockrunner, was placed in the babbler family, Timaliidae. A series of molecular studies of the Old World warblers and other bird families in the superfamily Sylvioidea found that the African warblers were not part of Sylviidae but were instead an early (basal) offshoot of the entire clade Sylvioidea. Some taxonomic authorities place the entire family Hyliidae here.

<i>Horornis</i> Genus of birds

Horornis is a genus of small insectivorous songbirds ("warblers") which make up the core of the newly recognized family Cettiidae. They were formerly placed in the Sylviidae, which at that time was a wastebin taxon for the warbler-like Sylvioidea. The range of this genus occurs from southeast Asia throughout the western Pacific. The most recently described species is the Bougainville bush warbler from Bougainville Island.

<i>Phyllergates</i> Genus of birds

The species of tailorbirds listed below are small birds of the genus Phyllergates . They were previously placed in the Old World warbler family Sylviidae. However, recent research suggests they more likely belong in the Cettiidae.

<span class="mw-page-title-main">Hyliidae</span> Family of birds

Hyliidae is a family of passerine birds which contains just two species, the green hylia and the tit hylia. Physiological similarities and molecular phylogenetic studies strongly support the creation of this family.

References

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  2. ↑ Gill, Frank B.; Donsker, David B., eds. (2019). "Bushtits, leaf warblers, reed warblers". IOC World Bird List. 9.2. doi:10.14344/IOC.ML.9.2 . Retrieved 1 September 2019.
  3. ↑ Oliveros, Carl H.; Field, Daniel J.; Ksepka, Daniel T.; Barker, F. Keith; Aleixo, Alexandre; Andersen, Michael J.; Alström, Per; Benz, Brett W.; Braun, Edward L.; Braun, Michael J.; Bravo, Gustavo A.; Brumfield, Robb T.; Chesser, R. Terry; Claramunt, Santiago; Cracraft, Joel; Cuervo, Andrés M.; Derryberry, Elizabeth P.; Glenn, Travis C.; Harvey, Michael G.; Hosner, Peter A.; Joseph, Leo; Kimball, Rebecca T.; Mack, Andrew L.; Miskelly, Colin M.; Peterson, A. Townsend; Robbins, Mark B.; Sheldon, Frederick H.; Silveira, Luís Fábio; Smith, Brian Tilston; White, Noor D.; Moyle, Robert G.; Faircloth, Brant C. (2019). "Earth history and the passerine superradiation". Proceedings of the National Academy of Sciences. 116 (16): 7916–7925. doi: 10.1073/pnas.1813206116 . ISSN   0027-8424. PMC   6475423 . PMID   30936315.
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  9. 1 2 Marks, Ben D. (2010). "Are lowland rainforests really evolutionary museums? Phylogeography of the green hylia (Hylia prasina) in the Afrotropics" (PDF). Molecular Phylogenetics and Evolution. 55 (1): 178–184. doi:10.1016/j.ympev.2009.10.027. PMID   19903532.
  10. 1 2 Slabbekoorn, Hans; Ellers, Jacintha; Smith, Thomas B. (2002). "Birdsong and sound transmissions: the benefits of reverberations" (PDF). The Condor. 104 (3): 564–573. doi:10.1650/0010-5422(2002)104[0564:basttb]2.0.co;2. S2CID   53995725. Archived from the original (PDF) on 2016-04-24. Retrieved 2016-04-12.
  11. 1 2 3 Nemeth, E.; Dabelsteen, T.; Pedersen, S. B.; Winkler, H. (2006). "Rainforests as concert halls for birds: Are reverberations improving sound transmission of long song elements". The Journal of the Acoustical Society of America. 119 (1): 620–626. Bibcode:2006ASAJ..119..620N. doi:10.1121/1.2139072. PMID   16454315.
  12. ↑ Kirschel, A. N. G.; Blumstein, D. T.; Cohen, R. E.; Buermann, W.; Smith, T. B.; Slabbekoorn, H. (2009). "Birdsong tuned to the environment: green hylia song varies with elevation, tree cover, and noise". Behavioral Ecology. 20 (5): 1089–1095. doi:10.1093/beheco/arp101. hdl: 10.1093/beheco/arp101 .
  13. 1 2 Beier, Paul; Van Drielen, Maryann; Kankam, Bright O. (2002). "Avifaunal collapse in West African forest fragments". Conservation Biology. 16 (4): 1097–1111. doi: 10.1046/j.1523-1739.2002.01003.x . S2CID   86320607.
  14. 1 2 3 Sande, Eric (2000). "Understorey bird species diversity and abundance in three forest types of Semuliki National Park, Uganda". Ostrich: Journal of African Ornithology. 71 (1–2): 64–68. doi:10.1080/00306525.2000.9639870. S2CID   84042763.
  15. ↑ Sekercioglu, Çagan H.; Riley, Adam (2005). "A brief survey of the birds in Kumbira Forest, Gabela, Angola" (PDF). Ostrich: Journal of African Ornithology. 76 (3–4): 111–117. doi:10.2989/00306520509485483. S2CID   83595052.
  16. 1 2 3 Blankespoor, Gilbert W. (1991). "Slash-and-burn shifting agriculture and bird communities in Liberia, West Africa". Biological Conservation. 57 (1): 41–71. doi:10.1016/0006-3207(91)90107-k.
  17. ↑ Ferger, Stefan W.; Böhning-Gaese, Katrin; Wilcke, Wolfgang; Oelmann, Yvonne; Schleuning, Matthias (2013). "Distinct carbon sources indicate strong differentiation between tropical forest and farmland bird communities". Oecologia. 171 (2): 473–486. Bibcode:2013Oecol.171..473F. doi:10.1007/s00442-012-2422-9. PMID   22898920. S2CID   13948567.
  18. 1 2 Sekercioglu, Cagan H. (2002). "Effects of forestry practices on vegetation structure and bird community of Kibale National Park, Uganda" (PDF). Biological Conservation. 107 (2): 229–240. doi:10.1016/s0006-3207(02)00097-6.
  19. ↑ Mills, Michael SL (2010). "Angola's central scarp forests: patterns of bird diversity and conservation threats". Biodiversity and Conservation. 9 (7): 1883–1903. doi:10.1007/s10531-010-9810-4. S2CID   26879170.
  20. ↑ Walther, E. L.; Valkiūnas, G.; González, A. D.; Matta, N. E.; Ricklefs, R. E.; Cornel, A.; Sehgal, R. N. (2014). "Description, molecular characterization, and patterns of distribution of a widespread New World avian malaria parasite (Haemosporida: Plasmodiidae), Plasmodium (Novyella) homopolare sp. nov" (PDF). Parasitology Research. 113 (9): 3319–3332. doi:10.1007/s00436-014-3995-5. PMID   24974962. S2CID   7371305.
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