Tree warbler

{{Automatic taxobox

| name = Tree warblers

| image = Hypolais.jpg

| image_caption = Several Hippolais species

| taxon = Acrocephalidae

}}

Tree warblers are medium-sized warblers in the marsh- and tree-warbler family Acrocephalidae. They are found in Europe, Africa and western Asia.{{cite book|editor1=Del Hoyo, J. |editor2=Elliot, A. |editor3=Christie D.|year=2006|title=Handbook of the Birds of the World. Volume 11: Old World Flycatchers to Old World Warblers|publisher= Lynx Edicions|isbn= 84-96553-06-X}} Until recently, they were all classified in the single genus Hippolais.

These warblers are associated with trees, though normally in fairly open woodland rather than tight plantations. Compared with the closely related Acrocephalus species, tree warblers have squarer tails and broader bill-bases. Most are unstreaked greenish or brownish above and cream or white below. They are insectivorous, but will occasionally take berries or seeds. The species breeding in temperate regions are mostly strongly migratory.{{cite book|last1=Mullarney|first1=K.|last2=Svensson|first2= L.|last3=Zetterström|first3= D.|last4= Grant|first4= P. J. |year=1999|title=Collins Bird Guide|publisher=HarperCollins|isbn= 0-00-219728-6|title-link=Collins Bird Guide}}

Taxonomy

All the tree warblers were formerly placed in the "Old World warbler" family Sylviidae but are now separated in the family Acrocephalidae, along with the marsh warblers, Acrocephalus, and some related species.

Considerable evidence, much of it summarised in Parkin et al. (2004),{{cite journal|last1=Parkin|first1= David T.|first2= Martin|last2= Collinson|first3=Andreas|last3= J. Helbig|first4= Alan G. |last4=Knox|authorlink5=George Sangster|last5=Sangster|first5=George|authorlink6=Lars Svensson (ornithologist)|first6=Lars|last6= Svensson|year=2004|url=http://www.britishbirds.co.uk/search?id=9067|title=Species limits in Acrocephalus and Hippolais warblers from the Western Palearctic|journal=British Birds|volume=97 |issue= 6| pages =276–299}} suggests that the genus Hippolais is paraphyletic with respect to Acrocephalus. DNA studies, e.g. Leisler et al. (1997),{{cite journal|last=Leisler|first= B.|author2=Heidrich, P. |author3=Schulze-Hagen, K. M. |author4= Wink, M. |year=1997|doi=10.1007/BF01651381|title= Taxonomy and phylogeny of reed warblers (genus Acrocephalus) based on mtDNA sequences and morphology|journal=J. Ornithol.|volume=138|pages=469–496|issue=4|bibcode= 1997JOrni.138..469L}} interpreted by George Sangster in 1997,{{cite journal|last=Sangster|first= George|authorlink=George Sangster|year=1997|title= Trends in Systematics – Acrocephalus and Hippolais relationships: shaking the tree |journal=Dutch Birding |volume= 19 |issue= 6 |pages =294–300}} indicated that the olivaceous and booted/Sykes's warbler grouping (the subgenus Iduna) are more closely related to Acrocephalus species than they are to icterine and melodious warblers and as a result the Dutch Committee on Avian Systematics (CSNA) has moved these four species into Acrocephalus.{{cite journal|last1=Sangster|first1= George|authorlink1=George Sangster|first2=Cornelius J. |last2=Hazevoet|authorlink2=Cornelis Hazevoet|first3= Arnoud B. |last3=van den Berg |first4= C. S.|last4= Roselaar |year=1998|title=Dutch avifaunal list: species concepts, taxonomic instability, and taxonomic changes in 1998 |journal=Dutch Birding|volume=20 |issue= 1| pages =22–32}} A subsequent review by the British Ornithologists' Union Records Committee retained the genus Hippolais, for all eight species, but in agreement with Sangster, acknowledged that they fell into two groups.{{cite journal|first1=Alan G. |last1=Knox|first2= Martin|last2= Collinson|first3=Andreas J.|last3= Helbig|first4=David T. |last4=Parkin|authorlink5=George Sangster|first5=George|last5=Sangster|year=2002|title= Taxonomic recommendations for British birds |journal=Ibis|volume= 144 |issue=4|pages= 707–710|doi=10.1046/j.1474-919X.2002.00110.x|doi-access=free}}

The retention of the Iduna grouping within Hippolais was done because it was felt that more evidence was needed for its placement, because of low bootstrap values,{{cite journal|last1=Helbig|first1= A. J.|last2=Seibold|first2= I.|year=1999|title= Molecular phylogeny of Palearctic-African Acrocephalus and Hippolais warblers (Aves: Sylviidae)|doi=10.1006/mpev.1998.0571 |journal=Mol. Phylogenet. Evol.|volume=11|pages=246–260|issue=2|pmid=10191069|bibcode= 1999MolPE..11..246H}} rather than because of a belief that the status quo was correct – no evidence was put forward to refute the DNA findings. Mark Constantine, in The Sound Approach to Birding,{{cite book|last1=Constantine|first1=Mark|last2=The Sound Approach|year=2006|edition=1st.|title=The Sound Approach to birding: a guide to understanding bird sound|location=Dorset, England|publisher=The Sound Approach|isbn=90-810933-1-2|pages=142–148}} illustrated that there is extensive overlap in song types between species from the two genera, and that vocally, no characters existed which enabled species to be sorted into one genus or the other. Kenneth Williamson{{cite book|last=Williamson|first= K.|year=1968|title=Identification for ringers 1. The genera Cettia, Locustella, Acrocephalus and Hippolais}} and Hadoram Shirihai,{{cite book|last1=Harris|first1= A.|authorlink2=H. Shirihai|last2=Shirihai|first2=H.|first3=D.|last3= Christie|title=The Macmillan birder's guide to European and Middle Eastern birds|title-link= The Macmillan birder's guide to European and Middle Eastern birds}} in discussing the identification of Hippolais and Acrocephalus warblers stressed the similarities between species in the two genera. Colin Bradshaw, in British Birds, has written several articles on morphological similarity between cross-generic species-pairs e.g. eastern olivaceous and Blyth's reed warblers (Bradshaw 2000){{cite journal|last=Bradshaw|first=Colin|year=2000|title=Separating Acrocephalus and Hippolais warblers|journal=British Birds|volume=93 |issue=6 |page= 277}} and paddyfield and booted warblers (e.g. Bradshaw & Steele 1995,{{cite journal|last1=Bradshaw|first1= Colin |first2= Jimmy|last2= Steele |year=1995|url=http://www.britishbirds.co.uk/search?id=7885 |title=Mystery photographs 195|journal=British Birds|volume=88|issue=11|pages= 561–564}} Bradshaw & Steele 1997,{{cite journal|last1=Bradshaw|first1= Colin |first2= Jimmy|last2= Steele |year=1997|title=Mystery warblers in Tselinograd|journal=British Birds|volume=90|issue=4 |pages= 155–158}} the latter a response to Lars Svensson's comments{{cite journal|authorlink=Lars Svensson (ornithologist)|last=Svensson, Lars|year=1997|title=Mystery warblers in Tselinograd |journal=British Birds|volume=90|issue=4 |pages= 152–154}} on Bradshaw & Steele 1995).

The species are:{{citation needed|date=April 2013}}

Genus Iduna

Thick-billed warbler, Iduna aedon
Booted warbler, Iduna caligata
Sykes's warbler, Iduna rama
Western olivaceous warbler (or isabelline warbler),The name isabelline warbler was first used in volume 11 of the Handbook of the Birds of the World. Iduna opaca
Eastern olivaceous warbler, Iduna pallida
Mountain yellow warbler, Iduna similis
African yellow warbler, Iduna natalensis

Genus Hippolais

Upcher's warbler, Hippolais languida
Olive-tree warbler, Hippolais olivetorum
Melodious warbler, Hippolais polyglotta
Icterine warbler, Hippolais icterina

Genus Calamonastides

Papyrus yellow warbler, Calamonastides gracilirostris

Tree warbler

Taxonomy

References

Further reading