Eurasian Wren

A Wren is a tiny brown bird, 9 to 10 cm long and about 10 g, and almost round. It has a short, narrow tail that it often cocks straight up, a fine pointed bill, short rounded wings and fairly long legs, and a pale stripe over the eye.¹ Look too for the fine dark bars on the wings, tail and flanks.²

Close up, the upperparts are a warm brown and the underparts paler, the centre of the belly palest of all. The bill is brown with a paler base, the legs light pinkish-brown and the eye brown. British birds belong to their own subspecies, indigenus, darker, duller and less rufous than Wrens on the Continent.

Adults weighed by BTO ringers average 9.9 g, with males a little heavier than females.³

Males and females look the same. In BTO measurements males have slightly longer wings, 50.3 mm against 47.6 mm on average.

Young Wrens just out of the nest look much like adults, but the breast is softly mottled and the bars on the flanks are fainter.

Some Scottish islands have Wrens of their own subspecies. Shetland Wrens are much darker; Fair Isle has its own form, paler than Shetland's; Outer Hebrides birds are buffier and less barred; and St Kilda Wrens are larger and greyer-brown above, pale and well barred below. The St Kilda Wren was described as a separate species in 1884, which set off a rush of collecting; Birds of the World puts it at 200 to 300 pairs.

Wrens in North America were once counted as the same species. They are now the Winter Wren and the Pacific Wren, which differ mainly in their songs.

Dunnock. A Dunnock also creeps about low down, but it is about the size of a House Sparrow⁴, with a grey head and breast and a streaked brown back.⁵ A Wren is far smaller and rounder, with the tail up and barred, not streaked.

Goldcrest. A Goldcrest is even smaller, about 6 g, and greyish-green, with a yellow stripe on the crown and white wing bars.⁶ A Wren is heavier and brown, with no crown stripe.

For a bird of 10 g the song is astonishingly loud: a fast, complex run of high notes and trills, often ending in a trill.¹ It usually lasts 4 to 6 seconds.⁷ Males sing all year round, from dawn to dusk, and are heard best from March to May. You will often hear one before you see it.

The call is a loud "tic-tic-tic", which the BTO describes as the scolding alarm call. Wrens also give loud churrs.

Song is part of holding a territory: in a playback study, males that had heard a rival sang more before sunrise the next day. Young Wrens start singing in July of the year they hatch.

Listen to British recordings and see them drawn as spectrograms: Wren song and calls.

Almost anywhere with low cover, all year round. In the last national atlas Wrens were found in 98% of the UK's 10-km squares in the breeding season and 97% in winter, missing only from some of the highest ground in Scotland. Densities are higher in Ireland than in Britain, and lower in the uplands.

Broadleaved woodland is their stronghold, but they also live in scrub, farmland hedges, villages, towns and gardens, heaths, moorland, and sea cliffs on islands. Wrens are regular visitors to most gardens, though easy to miss: they forage and hide low in bushes, hedgerows, fallen trees and brush piles.

Listen first: a loud burst of song from a low bush or a scolding "tic-tic-tic" from a hedge often gives a Wren away. Then watch the bottom of the hedge or a log pile for a small brown bird moving like a mouse, tail up.

Not in Britain and Ireland. Our Wrens are largely sedentary: most ringing recoveries are within 50 km, though a few birds have crossed to France.² The longest move on record within Britain and Ireland was 490 km, from Northumberland to Torquay.⁸

Wrens further north and east in Europe do migrate, and they leave most of Scandinavia in winter. A few reach Britain: a young female ringed at Falsterbo in southern Sweden was caught in Northumberland 13 days later, 909 km away.

Mostly insects and spiders. Beetles, bugs, moths and butterflies and their caterpillars, spiders and other small invertebrates make up most of the diet, with some berries and seeds, especially in winter. Wrens forage low down, on or near the ground, picking prey from leaves, twigs, crevices and leaf litter.

They also catch insects in the air, wade into shallow water and will even forage under snow. Now and then they take small fish, tadpoles and young frogs. More detail: What do Wrens eat?

Wrens are not regular feeder birds, and no BTO or RSPB feeding advice names a food for them. The RSPB notes that they sometimes pick up crumbs that have fallen from feeders. They find their food in low, thick cover. More: what Wrens eat.

The male builds several domed nests of moss, leaves and grass, each with an entrance in the side, low down in thick growth, banks, crevices in walls and trees, and sometimes odd places such as the pocket of a hanging coat. The female inspects them, chooses one and lines it with feathers.

In Britain the first eggs are laid on average around 2 May. A clutch is usually 5 or 6 eggs. The female incubates them for 16 to 18 days, and the chicks leave the nest at 14.5 to 18 days. Wrens usually raise two broods a year.³ Some males have two or more females.

More detail: Wren nests, eggs and young.

Wrens are busy, mouse-like birds that creep through thick cover, flicking their wings, bobbing and cocking their tails. They feed alone or in pairs, and a male sings from a raised perch to hold his patch.

On cold nights Wrens huddle together to keep warm, in nest boxes, roosting pouches and other holes. In the BTO's Garden BirdWatch roosting survey up to 51 were found roosting together, near Lyme Regis; the average was about 10 in a nest box and 17 in other cavities.⁹ The RSPB tells of more than 60 once found in a single nest box.

A Wren that survives to breed typically lives about 2 years, and first breeds at a year old. About a third of adults survive from one year to the next, and fewer young birds do.³

The oldest Wren on the BTO's ringing list was ringed as an adult at South Milton Ley in Devon in December 2013 and caught there by a ringer in September 2021, 7 years 9 months 20 days later.¹⁰ The European longevity list of 2023, which gives a minimum age rather than the time since ringing, tops out at 7 years 7 months for a bird from the Channel Islands; it does not include the Devon bird.¹¹

Hard winters hit Wrens hard. Long spells of frost and snow can kill many, young birds most of all, and numbers can fall sharply before recovering quickly. Pet cats are a significant cause of death in some UK cities.²

Wrens seem to adapt to their local winters: they are heavier in colder regions, and northern populations cope with more frost before their numbers fall.¹²

The Wren is on the UK Amber List, moved there from Green in 2021¹³, and is of Least Concern worldwide. It is the UK's most numerous breeding bird: the BTO estimated 11 million territories in 2016, roughly one UK breeding bird in every eight. Numbers more than doubled between 1967 and 2024, up 127%, though they dip after hard winters.³

Recent survey figures agree: UK numbers rose 41% between 1995 and 2024 and 17% between 2014 and 2024. Over the longer period the biggest rise was in Scotland, 82%.¹⁴ A warming climate may have helped. Like all wild birds, Wrens and their nests are protected by law.