Tree warbler
Encyclopedia
Tree warblers are medium-sized warbler
s belonging to the genus Hippolais, formerly placed in the "Old World warbler
" family Sylviidae but now separated in the marsh- and tree-warbler family Acrocephalidae
. They are found in Europe
, Africa
and western Asia
.
These warblers are associated with trees, though normally in fairly open woodland rather than tight plantations. Compared with the closely related Acrocephalus
species, Hippolais 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 seed
s. The species breeding in temperate regions are mostly strongly migratory
.
in 1997, 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. 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. 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, 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, 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
and Hadoram Shirihai
, 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 ) and Paddyfield and Booted warblers (e.g. Bradshaw & Steele 1995, Bradshaw & Steele 1997, the latter a response to Lars Svensson
's comments on Bradshaw & Steele 1995).
The species are:
(subgenus Iduna)
(subgenus Hippolais)
Warbler
There are a number of Passeriformes called "warblers". They are not particularly closely related, but share some characteristics, such as being fairly small, vocal and insectivorous....
s belonging to the genus Hippolais, formerly placed in the "Old World warbler
Old World warbler
The "Old World Warblers" is the name used to describe a large group of birds formerly grouped together in the bird family Sylviidae. 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...
" family Sylviidae but now separated in the marsh- and tree-warbler family Acrocephalidae
Acrocephalidae
Acrocephalidae is a family of oscine passerine birds, in the superfamily Sylvioidea....
. They are found in Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
and western Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
.
These warblers are associated with trees, though normally in fairly open woodland rather than tight plantations. Compared with the closely related Acrocephalus
Acrocephalus
The Acrocephalus warblers are small, insectivorous passerine birds belonging to the genus Acrocephalus. Formerly in the paraphyletic Old World warbler assemblage, they are now separated as the namesake of the marsh- and tree-warbler family Acrocephalidae...
species, Hippolais 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
Berry
The botanical definition of a berry is a fleshy fruit produced from a single ovary. Grapes are an example. The berry is the most common type of fleshy fruit in which the entire ovary wall ripens into an edible pericarp. They may have one or more carpels with a thin covering and fleshy interiors....
or seed
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
s. The species breeding in temperate regions are mostly strongly migratory
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
.
Taxonomy
Considerable evidence, much of it summarised in Parkin et al. (2004), suggests that the genus Hippolais is paraphyletic with respect to Acrocephalus. DNA studies, e.g. Leisler et al. (1997), interpreted by George SangsterGeorge Sangster
George Sangster is a Dutch ornithologist.He specialises in taxonomy and has written many articles on this subject for the magazines Dutch Birding, British Birds and other publications.He is a member of the Dutch, British and European taxonomic committees....
in 1997, 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. 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. 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, 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, 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
Kenneth Williamson
Kenneth Williamson was a British ornithologist who had a strong association with Scotland and with bird migration.Williamson was born in Bury Lancashire. From 1941-1945 he served with the British occupation of the Faroe Islands in World War II, in 1944 marrying Esther Louise Rein of Tórshavn with...
and Hadoram Shirihai
Hadoram Shirihai
Hadoram Shirihai is an Israeli ornithologist and writer.-Biography:Shirihai grew up in Jerusalem where he became fascinated with birds when he was 13 and spent much time documenting shorebird behaviour, raptor breeding biology and participating in bird migration surveys...
, in discussing the identification of Hippolais and Acrocephalus warblers stressed the similarities between species in the two genera. Colin Bradshaw, in British Birds
British Birds (magazine)
British Birds is a monthly ornithology magazine that was established in 1907. It is now published by BB 2000 Ltd, which is wholly owned by The British Birds Charitable Trust , established for the benefit of British ornithology...
, has written several articles on morphological similarity between cross-generic species-pairs e.g. Eastern Olivaceous and Blyth's Reed warblers (Bradshaw 2000 ) and Paddyfield and Booted warblers (e.g. Bradshaw & Steele 1995, Bradshaw & Steele 1997, the latter a response to Lars Svensson
Lars Svensson (ornithologist)
Lars Svensson is a Swedish ornithologist, who received an honorary degree from the Uppsala University in 2004. He specialises in the identification of passerine birds...
's comments on Bradshaw & Steele 1995).
The species are:
(subgenus Iduna)
- Booted WarblerBooted WarblerThe Booted Warbler is an Old World warbler in the tree warbler group. It was formerly considered to be conspecific with Sykes' Warbler, but the two are now usually both afforded species status...
, Hippolais caligata - Sykes' WarblerSykes' WarblerSykes' Warbler is an Old World warbler in the tree warbler family. It was formerly considered a subspecies of the Booted Warbler, but is now considered a full species. Its breeding range is from northeast Arabia to Afghanistan...
, Hippolais rama - Western Olivaceous WarblerWestern Olivaceous WarblerThe Western Olivaceous Warbler, also known as Isabelline Warbler, is a "warbler", formerly placed in the Old World warblers when these were a paraphyletic wastebin taxon. It is now considered a member of the acrocephaline warblers, Acrocephalidae, in the tree warbler genus Hippolais ...
(or Isabelline Warbler), Hippolais opaca - Eastern Olivaceous WarblerEastern Olivaceous WarblerThe Eastern Olivaceous Warbler is a "warbler", formerly placed in the Old World warblers when these were a paraphyletic wastebin taxon. It is now considered a member of the acrocephaline warbelrs, Acrocephalidae, in the tree warbler genus Hippolais ...
, Hippolais pallida
(subgenus Hippolais)
- Upcher's WarblerUpcher's WarblerThe Upcher's Warbler, , is an Old World warbler in the tree warbler genus Hippolais. It breeds in an area from Turkey south and east to Pakistan...
, Hippolais languida - Olive-tree WarblerOlive-tree WarblerThe Olive-tree Warbler is an Old World warbler in the tree warbler genus Hippolais. It breeds in southeast Europe and the near east. It is migratory, wintering in eastern and southern Africa, from Kenya south to South Africa.This small passerine bird is a species found in open-canopy oakwoods,...
, Hippolais olivetorum - Melodious WarblerMelodious WarblerThe Melodious Warbler is an Old World warbler in the tree warbler genus Hippolais. It breeds in southwest Europe and northwest Africa. It is migratory, wintering in sub-Saharan Africa....
, Hippolais polyglotta - Icterine WarblerIcterine WarblerThe Icterine Warbler is an Old World warbler in the tree warbler genus Hippolais . It breeds in mainland Europe except the southwest, where it is replaced by its western counterpart, Melodious Warbler. It is migratory, wintering in sub-Saharan Africa...
, Hippolais icterina