Northern wren, Wren
The Eurasian wren (Troglodytes troglodytes) is a very small insectivorous bird found in Eurasia and Africa (Maghreb). In Anglophone Europe, it is commonly known simply as the wren. The scientific name is taken from the Greek word "troglodytes", meaning "hole-dweller", and refers to its habit of disappearing into cavities or crevices whilst hunting arthropods or to roost.
The Eurasian wren is a plump, sturdy bird with rounded wings and a short tail, which is usually held cocked up. 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, and the feet have strong claws and a large hind toe. Young birds are less distinctly barred and have mottled underparts.
Eurasian wrens occur in Europe and across the Palearctic including a belt of Asia from northern Iran and Afghanistan across to Japan. They are migratory in only the northern parts of their range. Eurasian wrens live in a great variety of habitats including cultivated or uncultivated areas with bushes and low ground covers; gardens, hedgerows, thickets, plantations, woodland, and reed beds. They inhabit more open locations with clumps of brambles or gorse, rough pasture, moorland, boulder-strewn slopes, rocky coasts, and sea cliffs.
Eurasian wrens are active birds, constantly on the move foraging for insects, in the open or among thick vegetation. They move with quick jerks, probing into crevices, examining old masonry, hopping onto fallen logs, and delving down among them. They sometimes move higher in the canopy, but for the most part stay near the ground, often being flushed from under overhangs on banks. Sometimes they hop up the lower part of tree trunks. They may also flit away their tiny round wings whirring as they fly. Eurasian wrens are birds of the uplands even in winter, vanishing into the heather when snow lies thick above. At night, usually in winter, they often roost, true to their scientific name, in dark retreats, snug holes, and even old nests. In hard weather, they may do so in parties, consisting of either the family or many individuals gathered together for warmth. The most common call of Eurasian wrens is a sharp, repeated 'tic-tic-tic'. When the birds are annoyed or excited, their call runs into an emphatic 'churr'. The song is a gushing burst of sweet music, clear, shrill, and emphatic. The males have remarkably long and complex vocalizations, with a series of tinkling trills one after the other for seconds on end. They have an enormous voice for their size and despite their secretive behavior the males sometimes sing from an exposed low perch. Their 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 season, though most noticeable during spring.
Eurasian wrens are carnivores (insectivores) and insects form the bulk of their diet. Other dietary items include spiders, and some seeds are also taken. The young are largely fed on moth larvae, with caterpillars of the cabbage moth and crane fly larvae.
Eurasian wrens are highly polygynous; a male can have, at any one time, more than one female with an active nest on his territory. An active nest is one in which there are eggs or nestlings. Some males have been recorded with four females breeding on his territory. The male builds several nests in his territory; these are called "cock nests" but are never lined until the female chooses one to use. The number of nests on a territory influences the female's choice of mate; she prefers to choose a male that had constructed numerous nests. Courtship includes display and posturing by the male. He sings with wings and tail half-open, or with them drooping, sometimes with one wing extended, or the wings may be raised and lowered several times in quick succession. The neatly-domed nest has a side entrance and is built of grass, moss, lichen, and dead leaves, whatever is available locally. It is often tucked into a hole in a wall or tree trunk or a crack in a rock, but it is often built in brambles, a bush or a hedge, among ivy on a bank, in thatch, or in abandoned bird's nests. On making her selection, the female wren lines the nest generously with feathers. A clutch of 5-6 eggs is laid from April onwards. These are white with variable amounts of reddish-brown speckles, mostly on the broad end. The female alone incubates the eggs for 14 to 15 days. The chicks hatch blind and helpless and fledge after about 16 days. Pairs usually raise two broods during the breeding season.
There are no major threats to the Eurasian wren at present.
According to the IUCN Red List, the total population size of the Eurasian wren is 10,000,000-500,000,000 mature individuals. In Europe, the breeding population consists of 32,700,000-56,500,000 pairs, which equates to 65,300,000-113,000,000 mature individuals. National population estimates include around 10,000-100,000 breeding pairs in China; around 100-100,000 breeding pairs in Taiwan; possibly around 10,000-100,000 breeding pairs in Korea; around 100-100,000 breeding pairs in Japan and possibly around 10,000-100,000 breeding pairs and around 1,000-10,000 individuals on migration in Russia. Currently, this species is classified as Least Concern (LC) on the IUCN Red List and but its numbers today are decreasing.
