{{Short description|Species of bird}} {{speciesbox | image = Hylia prasina prasina 307043187.jpg | image_caption = | status = LC | status_system = IUCN3.1 | status_ref = <ref name="iucn status 13 November 2021">{{cite iucn |author=BirdLife International |date=2018 |title=''Hylia prasina'' |volume=2018 |article-number=e.T22715182A131970716 |doi=10.2305/IUCN.UK.2018-2.RLTS.T22715182A131970716.en |access-date=13 November 2021}}</ref> | genus = Hylia | parent_authority = Cassin, 1859 | species = prasina | authority = (Cassin, 1855) | synonyms = | range_map = 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.<ref name=IOC9.2>{{cite journal |editor-last1=Gill |editor-first=Frank B. |editor-first2=David B. |editor-last2=Donsker |year=2019 |title=Bushtits, leaf warblers, reed warblers |website=IOC World Bird List |version=9.2 |doi=10.14344/IOC.ML.9.2 |url=https://www.worldbirdnames.org/Family/Acrocephalidae |access-date=1 September 2019 |doi-access=free |archive-date=1 September 2019 |archive-url=https://web.archive.org/web/20190901144930/https://www.worldbirdnames.org/Family/Acrocephalidae }}</ref><ref name="OliverosField2019">{{cite journal|last1=Oliveros|first1=Carl H.|last2=Field|first2=Daniel J.|last3=Ksepka|first3=Daniel T.|last4=Barker|first4=F. Keith|last5=Aleixo|first5=Alexandre|last6=Andersen|first6=Michael J.|last7=Alström|first7=Per|last8=Benz|first8=Brett W.|last9=Braun|first9=Edward L.|last10=Braun|first10=Michael J.|last11=Bravo|first11=Gustavo A.|last12=Brumfield|first12=Robb T.|last13=Chesser|first13=R. Terry|last14=Claramunt|first14=Santiago|last15=Cracraft|first15=Joel|last16=Cuervo|first16=Andrés M.|last17=Derryberry|first17=Elizabeth P.|last18=Glenn|first18=Travis C.|last19=Harvey|first19=Michael G.|last20=Hosner|first20=Peter A.|last21=Joseph|first21=Leo|last22=Kimball|first22=Rebecca T.|last23=Mack|first23=Andrew L.|last24=Miskelly|first24=Colin M.|last25=Peterson|first25=A. Townsend|last26=Robbins|first26=Mark B.|last27=Sheldon|first27=Frederick H.|last28=Silveira|first28=Luís Fábio|last29=Smith|first29=Brian Tilston|last30=White|first30=Noor D.|last31=Moyle|first31=Robert G.|last32=Faircloth|first32=Brant C.|title=Earth history and the passerine superradiation|journal=Proceedings of the National Academy of Sciences|volume=116|issue=16|year=2019|pages=7916–7925|issn=0027-8424|doi=10.1073/pnas.1813206116|pmid=30936315|pmc=6475423|doi-access=free}}</ref>
==Taxonomy== ''Hylia prasina'' is a monotypic songbird that has proven difficult to place within the phylogenetic tree.<ref name="fregin">{{cite journal|last1=Fregin|first1=Silke|last2=Haase|first2=Martin|last3=Olsson|first3=Urban|last4=Alström|first4=Per |year=2012 |title=New insights into family relationships within the avian superfamily Sylvioidea (Passeriformes) based on seven molecular markers |journal=BMC Evolutionary Biology |volume=12 |issue=1 |page=157 |doi=10.1186/1471-2148-12-157 |pmid=22920688 |pmc=3462691 |doi-access=free }}</ref><ref name="sefc"/> 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.<ref name="fregin"/>
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.<ref name="fregin"/>
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.<ref name="sefc"/> The relationship between the genera ''Hylia'' and ''Phylloscopus'' (leaf warblers) has been examined but seems to have low empirical support.<ref>{{cite journal|url=http://www.nrm.se/download/18.7d9d550411abf68c801800015111|last1=Johansson|first1=Ulf S.|first2=Jon|last2=Fjeldså|first3=Rauri CK|last3=Bowie|title=Phylogenetic relationships within Passerida (Aves: Passeriformes): a review and a new molecular phylogeny based on three nuclear intron markers|journal=Molecular Phylogenetics and Evolution|volume=48|issue=3|year=2008|pages=858–876|doi=10.1016/j.ympev.2008.05.029|pmid=18619860|access-date=2016-04-12|archive-date=2023-01-22|archive-url=https://web.archive.org/web/20230122152205/https://www.nrm.se/download/18.7d9d550411abf68c801800015111|url-access=subscription}}</ref> A sister relationship between ''Hylia'' and Aegithalidae (long tailed tits) was similarly poorly supported.<ref name="fregin"/> Close relationships with Nectariniidae (sunbirds), Estrildidae (finches) and Meliphagidae (honeyeaters) have also been rejected.<ref name="sefc"/>
The sister relationship between ''Hylia'' and ''Pholidornis'' (tit hylia) is strongly supported, based on mitochondrial data and physiological similarities.<ref name="fregin"/><ref name="sefc"/> 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.<ref name="fregin"/>
==Description== thumb|left|Specimen at Nairobi National Museum The green hylia has dark brown irises, a black bill and olive green feet.<ref name="stone">{{cite journal|jstor=4064201|last=Stone|first=Witmer|title=Zoological Results of the George Vanderbilt African Expedition of 1934. Part VI: Birds|journal=Proceedings of the Academy of Natural Sciences of Philadelphia|volume=88|year=1936|pages=529–598}}</ref> This species is small, weighing approximately 14 g.<ref name="sefc">{{cite journal |last1=Sefc |first1=Kristina M. |last2=Payne |first2=Robert B. |last3=Sorenson |first3=Michael D. |year=2003 |title=Phylogenetic relationships of African sunbird-like warblers: Moho (''Hypergerus atriceps''), Green Hylia (''Hylia prasina'') and Tit-hylia (''Pholidornis rushiae'') |journal=Ostrich: Journal of African Ornithology |volume=74 |issue=1–2 |pages=8–17 |doi=10.2989/00306520309485365 |s2cid=86085338 |url=http://www.lsa.umich.edu/ummz/birds/publications/pdf/RBP.178.pdf |archive-url=https://web.archive.org/web/20151031004759/http://lsa.umich.edu/ummz/birds/publications/pdf/RBP.178.pdf |archive-date=2015-10-31 }}</ref> There is no noticeable difference in colour between the sexes, however males are generally larger.<ref name="serle">{{cite journal|last=Serle|first=William|title=A contribution to the ornithology of the British Cameroons|journal=Ibis|volume=92|issue=3|year=1950|pages=343–376|doi=10.1111/j.1474-919X.1950.tb03000.x}}</ref>
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.<ref name="serle"/><ref name="marks">{{cite journal|url=http://africanbirds.fieldmuseum.org/sites/africanbirds.fieldmuseum.org/files/Marks%202010%20Hylia%20MPE.pdf|last=Marks|first=Ben D.|title=Are lowland rainforests really evolutionary museums? Phylogeography of the green hylia (''Hylia prasina'') in the Afrotropics |journal=Molecular Phylogenetics and Evolution|volume=55|issue=1|year=2010|pages=178–184|doi=10.1016/j.ympev.2009.10.027|pmid=19903532}}</ref>
===Vocalisation=== The green hylia uses several different calls, the most common being clear whistles (''kee kee'') or dry scolding rattles (''trrit trrrit'').<ref name="sefc"/> 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.<ref name="slabbekoorn">{{cite journal|url=http://www.ioe.ucla.edu/perch/resources/slabbekoorn-condor-bird-song-and-sound-2002.pdf|last1=Slabbekoorn|first1=Hans|first2=Jacintha|last2=Ellers|first3=Thomas B.|last3=Smith|title=Birdsong and sound transmissions: the benefits of reverberations|journal=The Condor|volume=104|issue=3|year=2002|pages=564–573|doi=10.1650/0010-5422(2002)104[0564:basttb]2.0.co;2|s2cid=53995725 |access-date=2016-04-12|archive-date=2016-04-24|archive-url=https://web.archive.org/web/20160424185035/http://www.ioe.ucla.edu/perch/resources/slabbekoorn-condor-bird-song-and-sound-2002.pdf}}</ref><ref name="nemeth">{{cite journal|pmid=16454315|last1=Nemeth|first1=E.|last2=Dabelsteen|first2=T.|last3=Pedersen|first3=S. B.|last4=Winkler|first4=H.|year=2006|title=Rainforests as concert halls for birds: Are reverberations improving sound transmission of long song elements|journal=The Journal of the Acoustical Society of America|volume=119|issue=1|pages=620–626|doi=10.1121/1.2139072|bibcode=2006ASAJ..119..620N}}</ref>
When played imitation recordings, males reacted more strongly to longer notes.<ref name="nemeth"/> 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.<ref name="slabbekoorn"/> The elongation of signals with narrow bandwidth has been found to be a beneficial consequence of reverberations on birdsong transmission.<ref name="nemeth"/>
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.<ref name="kirschel">{{cite journal|last1=Kirschel|first1=A. N. G.|last2=Blumstein|first2=D. T.|last3=Cohen|first3=R. E.|last4=Buermann|first4=W.|last5=Smith|first5=T. B.|last6=Slabbekoorn|first6=H. |year=2009 |title=Birdsong tuned to the environment: green hylia song varies with elevation, tree cover, and noise |journal=Behavioral Ecology |volume=20 |issue=5 |pages=1089–1095 |doi=10.1093/beheco/arp101|hdl=10.1093/beheco/arp101|hdl-access=free}}</ref>
==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.<ref name="marks"/>
The green hylia is a common forest generalist, occurring at forest edges and gaps between vegetation as well as forest interiors.<ref name="beier"/><ref name="sande"/> Its preferred habitat is mostly intact, semideciduous moist forest.<ref name="seker2005">{{cite journal|url=https://web.stanford.edu/~cagan/Angola_Sekercioglu&Riley.pdf|last1=Sekercioglu|first1=Çagan H.|first2=Adam|last2=Riley|title=A brief survey of the birds in Kumbira Forest, Gabela, Angola|journal=Ostrich: Journal of African Ornithology |volume=76|issue=3–4|year=2005|pages=111–117|doi=10.2989/00306520509485483|s2cid=83595052}}</ref> 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''.<ref name="sande"/><ref name="blankespoor"/> Liana and ''Scleria'' species provide suitable habitat as they tangle amongst other vegetation, providing nesting materials and a supply of food.<ref name="blankespoor"/> 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.<ref name="ferger">{{cite journal|pmid=22898920|last1=Ferger|first1=Stefan W.|first2=Katrin|last2=Böhning-Gaese|first3=Wolfgang|last3=Wilcke|first4=Yvonne|last4=Oelmann|first5=Matthias|last5=Schleuning|title=Distinct carbon sources indicate strong differentiation between tropical forest and farmland bird communities|journal=Oecologia|volume=171|issue=2|year=2013|pages=473–486|doi=10.1007/s00442-012-2422-9|bibcode=2013Oecol.171..473F|s2cid=13948567|url=https://boris.unibe.ch/39442/ }}</ref>
==Ecology== The green hylia is a foliage-gleaning insectivore of the canopy and forest understory, usually foraging at a height of about 10 metres.<ref name="beier">{{cite journal|last1=Beier|first1=Paul|first2=Maryann|last2=Van Drielen|first3=Bright O.|last3=Kankam|title=Avifaunal collapse in West African forest fragments|journal=Conservation Biology|volume=16|issue=4|year=2002|pages=1097–1111|doi=10.1046/j.1523-1739.2002.01003.x|s2cid=86320607 |doi-access=free}}</ref><ref name="sande">{{cite journal|last=Sande|first=Eric|title=Understorey bird species diversity and abundance in three forest types of Semuliki National Park, Uganda|journal=Ostrich: Journal of African Ornithology |volume=71|issue=1–2|year=2000|pages=64–68|doi=10.1080/00306525.2000.9639870|s2cid=84042763}}</ref><ref name="blankespoor">{{cite journal|last=Blankespoor|first=Gilbert W.|title=Slash-and-burn shifting agriculture and bird communities in Liberia, West Africa|journal=Biological Conservation|volume=57|issue=1|year=1991|pages=41–71|doi=10.1016/0006-3207(91)90107-k}}</ref> Its diet includes insects, ants or butterflies which are accessible in its feeding area, on the underside of leaves or amongst forest litter.<ref name="sefc"/> The species is considered a forest generalist as it is capable of surviving in a wide range of environmental conditions.<ref name="seker2002">{{cite journal|url=https://web.stanford.edu/~cagan/SekerciogluKibaleBioCons2002.pdf|last=Sekercioglu|first=Cagan H.|title=Effects of forestry practices on vegetation structure and bird community of Kibale National Park, Uganda|journal=Biological Conservation|volume=107|issue=2|year=2002|pages=229–240|doi=10.1016/s0006-3207(02)00097-6}}</ref>
The green hylia is usually observed alone or in a mating pair.<ref name="serle"/> Mating pairs roost together in their nest. The eggs are white and otherwise not very distinctive.<ref name="sefc"/> 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.<ref name="serle"/> It differs from that of other sunbirds in that it is positioned in forks of vegetation and not suspended in the air.<ref name="sefc"/>
==Threats== The green hylia is currently classified as Least Concern by the IUCN based on large population numbers and wide distribution.<ref name="iucn status 13 November 2021" /> 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.<ref name="seker2002"/>
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.<ref name="mills">{{cite journal|last=Mills|first=Michael SL|title=Angola's central scarp forests: patterns of bird diversity and conservation threats|journal=Biodiversity and Conservation|volume=9|issue=7|year=2010|pages=1883–1903|doi=10.1007/s10531-010-9810-4|s2cid=26879170}}</ref> 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.<ref>{{cite journal|url=http://userwww.sfsu.edu/sehgal/Publications_files/Walther%20et%20al%20P%20homopolare.pdf|last1=Walther|first1=E. L.|last2=Valkiūnas|first2=G.|last3=González|first3=A. D.|last4=Matta|first4=N. E.|last5=Ricklefs|first5=R. E.|last6=Cornel|first6=A.|last7=Sehgal|first7=R. N.|year=2014|title=Description, molecular characterization, and patterns of distribution of a widespread New World avian malaria parasite (Haemosporida: Plasmodiidae), ''Plasmodium (Novyella) homopolare'' sp. nov.|journal=Parasitology Research|volume=113|issue=9|pages=3319–3332|doi=10.1007/s00436-014-3995-5|pmid=24974962|s2cid=7371305}}</ref>
==References== {{Reflist|30em}}
{{Cettiidae}} {{Passerida|S.|state=collapsed}} {{Taxonbar|from=Q2668148}}
green hylia Category:Old World warblers Category:Birds of the African tropical rainforest Category:Birds of the Gulf of Guinea green hylia Category:Taxonomy articles created by Polbot