The Eurasian wren (Troglodytes troglodytes) is a very small insectivorous bird and the only member of the wren family found in the Old World, specifically in Eurasia and Africa (Maghreb). In Anglophone Europe, it is commonly known simply as the wren. It has a very short tail which is often held erect, a short neck and a relatively long thin bill. It is russet brown above, paler buff-brown below, overall finely barred darker, and has a cream buff supercilium. The sexes are alike.
The Eurasian wren occurs in Europe and across the Palearctic, including a belt of Asia from northern Iran and Afghanistan across to Japan. It is migratory in the northern (particularly northeastern), parts of its range, and sedentary in the west and south of its range. It is also highly polygynous, an unusual mating system for passerines. The species was formerly lumped together with winter wren (Troglodytes hiemalis) of eastern North America and Pacific wren (Troglodytes pacificus) of western North America under the merged name of northern wren.
The scientific name is taken from the Greek word "troglodytes" (from τρώγλη "hole", and δῠ́ειν , "creep"), meaning "hole-dweller", and refers to its habit of disappearing into cavities or crevices whilst hunting arthropods or to roost. The taxonomy of the genus Troglodytes is currently unresolved, as recent molecular studies have suggested that the genera Cistothorus and Thryorchilus are within the clade currently defined by Troglodytes.
Taxonomy The Eurasian wren was described by the Swedish naturalist Carl Linnaeus in 1758 in the tenth edition of his Systema Naturae under the binomial name Motacilla troglodytes. The specific epithet is from the Ancient Greek meaning "cave-dweller". In 1555 the German naturalist Conrad Gessner had used the Latin name Passer troglodyte for the Eurasian wren in his Historiae animalium. The species is now placed in the genus Troglodytes that was introduced by the French ornithologist Louis Pierre Vieillot in 1809. Dated 1807 on title page but not published until 1809.
The Eurasian wren was formerly considered conspecific with two North American species, the winter wren (Troglodytes hiemalis) and the Pacific wren (Troglodytes pacificus). Some ornithologists place the Eurasian wren, the winter wren and the Pacific wren in a separate genus Nannus that was described by the Swedish naturalist Gustaf Johan Billberg in 1828 with the Eurasian wren as the type species.
It was estimated that Troglodytes pacificus and Troglodytes troglodytes last shared a common ancestor approximately 4.3 million years ago, long before the glacial cycles of the Pleistocene, thought to have promoted speciation in many avian lineages inhabiting the boreal forest of North America.
Subspecies Currently, 28 subspecies of this taxonomically complex bird are accepted: Troglodytes troglodytes islandicus Hartert, EJO, 1907. Iceland. Troglodytes troglodytes borealis Fischer, JCH, 1861. Faroe Islands. Troglodytes troglodytes zetlandicus Hartert, EJO, 1910. Scotland (Shetland). Troglodytes troglodytes fridariensis Williamson, K, 1951. Scotland (Fair Isle). Troglodytes troglodytes hirtensis Seebohm, H, 1884. Scotland (St Kilda). Troglodytes troglodytes hebridensis Meinertzhagen, R, 1924. Scotland (Outer Hebrides). Troglodytes troglodytes indigenus Clancey, PA, 1937. Ireland, Inner Hebrides, Orkney, Great Britain mainland. Troglodytes troglodytes troglodytes (Linnaeus, C, 1758). Continental Europe and Turkey. Troglodytes troglodytes kabylorum Hartert, EJO, 1910. Northwestern Africa (Morocco to Tunisia), Southern Iberian Peninsula, Balearic Islands (but see below). Troglodytes troglodytes koenigi Schiebel, G, 1910. Corsica and Sardinia. Troglodytes troglodytes juniperi Hartert, EJO, 1922. Northern Libya (Cyrenaica). Troglodytes troglodytes cypriotes (Bate, DMA, 1903). Crete, Rhodes, Cyprus, Near East. Troglodytes troglodytes hyrcanus Zarudny, NA; Loudon, HGG, 1905. Crimean Peninsula to Caucasus Mountains, northern Iraq, Iran. Troglodytes troglodytes tianschanicus Sharpe, RB, 1882. Mountains of Central Asia from Tien Shan (possibly from Altai) south to Pamir and northeastern Afghanistan. Troglodytes troglodytes subpallidus Zarudny, NA; Loudon, HGG, 1905. Himalayas of Afghanistan. Troglodytes troglodytes magrathi (Whitehead, CHT, 1907). Mountains on borders of Pakistan and Afghanistan. Troglodytes troglodytes neglectus Brooks, WE, 1872. Western Himalaya (Gilgit to western Nepal). Troglodytes troglodytes nipalensis Blyth, E, 1845. Central and eastern Himalaya from central Nepal to northeastern Assam and southern Tibet. Troglodytes troglodytes idius (Richmond, CW, 1907). Northern China (southern Hebei to Shandong). Troglodytes troglodytes szetschuanus Hartert, EJO, 1910. Southwestern China (southern Shaanxi and Sichuan eastward to Hupei). Troglodytes troglodytes talifuensis (Sharpe, RB, 1902). Western China (southern Sichuan to western Yunnan) and northeastern Myanmar. Troglodytes troglodytes dauricus Dybowski, BT; Taczanowski, W, 1884. Eastern Siberia to Sakhalin, Manchuria, and Korea. Troglodytes troglodytes pallescens (Ridgway, R, 1883). Kamchatka Peninsula and Komandorskiye Islands. Troglodytes troglodytes kurilensis Stejneger, LH, 1889. Northern Kuril Islands (Shasukotan and Ushichi). Troglodytes troglodytes fumigatus Temminck, CJ, 1835. Japan, southern Kuril Islands. Troglodytes troglodytes mosukei Momiyama, T, 1923. Eastern Japan (Izu Islands and Daito Islands). Troglodytes troglodytes ogawae Hartert, EJO, 1910. Southern Japan (Tanegashima and Yakushima). Troglodytes troglodytes taivanus Hartert, EJO, 1910. Taiwan.
Only limited genetic studies have been carried out to date, but show the subspecies may need further revision. Most notably, the northwest African population (T. t. kabylorum sensu stricto) and the Cyrenaican population (T. t. juniperi) are genetically highly distinct and may not even belong in T. troglodytes at all, being sister to the rest of T. troglodytes plus T. hiemalis (winter wren, of eastern North America). Conversely, the Iberian Peninsula birds currently included in T. t. kabylorum are very close to nominate T. t. troglodytes.
In Scotland, in addition to the typical bird T. t. indigenus widespread in Britain and Ireland, there are four distinct insular subspecies; one, T. t. hirtensis, is confined to the island of St Kilda; another, T. t. zetlandicus, to Shetland; the third, T. t. fridariensis, to Fair Isle; and the fourth, T. t. hebridensis, to the Outer Hebrides. The St Kilda wren is greyer above, whiter beneath, with more abundant bars on the back; the Shetland wren and Fair Isle wren are darker. Other isolated northwestern European island subspecies include T. t. islandicus on Iceland and T. t. borealis on the Faroe Islands. Not all of these are accepted by all authors though; Shirihai & Svensson (2019) merged T. t. indigenus, T. t. zetlandicus, T. t. fridariensis, and T. t. hebridensis into a broader concept of a widespread oceanic climate subspecies T. t. borealis and retaining only the highly isolated T. t. hirtensis as distinct; they also included southeast English birds in nominate T. t. troglodytes.
An additional disputed subspecies T. t. ,Yamashina, Yoshimaro (1938): A new subspecies of Troglodytes troglodytes from the Borodino Islands. Tori 10: 227–228. the Daito wren, became extinct around 1940, if it was ever a valid taxon and not merely a vagrant of another subspecies; in an analysis of Eurasian wren subspecies, the ornithologist Charles Vaurie concuded it was a synonym of T. t. mosukei.Vaurie, Charles (1955): Systematic notes on Palearctic birds. No. 16, Troglodytinae, Cinclidae, and Prunellidae. American Museum Novitates 1751: 1-25. PDF fulltext
Description
The Eurasian wren is a plump, sturdy bird with rounded wings and a short tail, which is usually held cocked up. It is in length and has a wingspan of . It weighs around . It is rufous brown above, greyer beneath, and indistinctly barred with darker brown and grey, even on the wings and tail. The bill is dark brown and the legs are pale brown, the feet having strong claws and a large hind toe. Young birds are less distinctly barred and have mottled underparts. The plumage is subject to considerable variation, and where populations have been isolated, the variation has become fixed in one minor form or another.
Vocal behaviour
The most common call is a sharp, repeated "tic-tic-tic", similar but faster and with less isolated notes compared to that of a robin. When the bird is annoyed or excited, its call runs into an emphatic , not unlike clockwork running down. The song is a gushing burst of sweet music, clear, shrill and emphatic. The male has a remarkably long and complex song, with a series of tinkling trills one after the other for several seconds. The bird has an enormous voice for its size, ten times louder, weight for weight, than a cockerel. The song begins with a few preliminary notes, then runs into a trill, slightly ascending, and ends in full clear notes or another trill. The song may be heard at any time of year, though it is most noticeable during spring. Despite its generally mouse-like behaviour, the male may sing from an exposed low perch as its whole body quivers from the effort. Its song may sometimes be confused with that of the dunnock, which has a warble that is shorter and weaker. The wren's song also incorporates repeated trill sounds while the dunnock's does not.del Hoyo, J. Elliott, A. & Christie, D. (2005) Handbook of the Birds of the World. Volume 10: Cuckoo-shrikes to Thrushes. Lynx Edicions. .
Distribution and habitat
This small, stump-tailed wren is almost as familiar in Europe as the robin. It is mouse-like, easily lost sight of when it is hunting for food, but is found everywhere from the sea coast to the tops of the highest moors.
The Eurasian wren is a Palearctic species. The nominate subspecies breeds in Europe as far north as 67°N in Norway and 64°N in Sweden, Finland and Russia.Peterson, R.; Mountfort, G.; Hollom, P.A.D. 1965. A Field Guild to the Birds of Britain and Europe. Collins Its southern limit is northern Spain, southern France, Italy, Sicily and southern Russia. It also breeds in Western Asia as far east as Syria. It is replaced by other subspecies in Iceland, the Faroe Islands, Shetland, the Hebrides, and St Kilda, and further south in northwestern Africa, Spain and Portugal, the Balearic Islands, Corsica, Sardinia, Crete and Cyprus. Other subspecies also occur in southern Russia and eastern Asia to Japan.
It occupies a great variety of habitats, typically any kind of cultivated or uncultivated area with bushes and low ground cover; gardens, hedgerows, thickets, plantations, woodland and reed beds. It inhabits more open locations with clumps of brambles or gorse, rough pasture, moorland, boulder-strewn slopes, rocky coasts and sea cliffs.
Behaviour and ecology
The Eurasian wren is an ever-active bird, constantly on the move foraging for insects, in the open or among thick vegetation. It moves with quick jerks, probing into crevices, examining old masonry, hopping onto fallen logs and delving down among them. It sometimes moves higher in the canopy, but for the most part stays near the ground, often being flushed from under overhangs on banks. Sometimes it hops up the lower part of tree trunks. Occasionally it flits away, its short flights swift and direct but not usually sustained, its tiny round wings whirring as it flies. On migration, it is however capable of lengthy sustained flight; ringing recoveries of English-ringed birds in Sweden and a German-ringed bird in England, and the regular arrival of presumed Norwegian birds on the east coast of Britain north to Shetland in autumn, shows they can readily cross the over-500 km wide North Sea. The longest distance ringing recovery is of 1,524 km from Rossitten Bird Observatory in Kaliningrad, Russia, to Bosham in West Sussex, England.