Wren (Troglodytes troglodytes)

Description

Wren fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Wren description

The tiny, secretive and cryptically coloured wren (Troglodytes troglodytes) is a highly active woodland bird with a remarkably powerful voice. It has a dumpy, almost rotund body, a fine, pointed bill and very short, rounded wings. The tail is short and stubby, and is characteristically held cocked upright ^{(2) (4) (5) (6) (7)}.

The plumage of the wren is largely dark reddish-brown, with fine dark barring on the wings, tail and flanks. There is a thin, pale line above the eye, and the chin and throat are a slightly paler buffy-brown ^{(3) (4) (5) (7)}. The wren has relatively long, pale brown legs, and its beak is also pale brown ^{(3) (4) (6)}. Male and female wrens are similar in appearance, while the juvenile is darker, with less distinct barring on the flanks and indistinct mottling on the breast ^{(2) (3)}. This species is distinguished from the similar house wren (Troglodytes aedon) by its smaller size, shorter tail and darker colouration ^{(2) (3) (4) (7)}.

One of the most distinctive features of the wren is its song, which is given almost year-round by the male and consists of a complex, continuous stream of warbles and trills ^{(2) (3) (4) (5) (7)}. This song is astonishingly loud for such a small bird - per unit weight, the winter wren sings at ten times the power of a crowing rooster ^{(2) (4)}. The wren also calls with various sharp, dry notes, and may give a harsh ‘churr’ in alarm ^{(2) (3) (4) (5) (7)}.

Around 35 to 44 different subspecies of wren have been described, which differ in size, overall colouration and the extent of barring on the plumage ^{(2) (3) (4)}. A further subspecies from Daito Island in Japan, Troglodytes troglodytes orii, is extinct ⁽³⁾.

Scientists have proposed that the wren may be distinct enough from other wren species to be placed within its own genus ^{(3) (4) (8)}. More recently, genetic evidence has suggested that the wren is in fact more than one distinct species ⁽⁹⁾. Differences in the songs and calls of wrens in different regions have led some scientists to split it into three species: Troglodytes troglodytes in Europe and Asia, Troglodytes hiemalis in eastern North America, and Troglodytes pacificus (Pacific wren) in western North America ^{(3) (4) (10)}.

Also known as

common wren, Eurasian wren, European wren, Holarctic wren, Pacific wren, winter wren.

Synonyms

Motacilla troglodytes, Nannus troglodytes, Troglodytes hiemalis, Troglodytes pacificus.

Size

Length: 8 - 12 cm ⁽²⁾

Wingspan: 12 - 16 cm ⁽²⁾

Weight

6 - 12 g ⁽³⁾

Wren biology

The wren typically forages on the ground or in low vegetation, creeping around the forest floor in short, rapid hops which can make it appear more like a mouse than a bird ^{(4) (5) (7)}. It generally flies only short distances, with very rapid wing beats, and often bobs the head and body up and down when perched ^{(4) (7)}. The diet of the wren consists mainly of invertebrates, including insects, insect larvae, spiders, millipedes and sometimes snails ^{(2) (3) (4) (6)}. It has been known to take vertebrate prey, such as small fish, tadpoles and young frogs, and also eats some plant food, including berries, seeds and even seaweed ^{(3) (4)}. The wren searches methodically for food amongst vegetation, dead wood, roots and other nooks and crannies, and will also snatch insects from the air or even immerse its head in water in search of aquatic prey ^{(2) (3) (4)}.

The breeding season of the wren usually begins in March or April in Western Europe, but is slightly later in Central Europe, Russia and northern North America ⁽³⁾. Male wrens are highly territorial throughout the year ⁽⁴⁾. The males may mate with several females in some areas, although monogamy is more common in North America ^{(3) (4)}. The wren frequently builds its nest in a hole or crevice, such as an old woodpecker hole, a natural tree cavity, a rock crevice, or a hole in a bank, or it may create a free-hanging structure on a branch, log, root mass, building, or underneath a bank of moss ^{(2) (3) (4) (5)}. This species has also been known to nest in unusual locations such as the pocket of a hanging coat or in a bundle of rope ^{(3) (4)}.

The nest of the wren is built by the male, and typically consists of a dome of grass, moss, twigs, bark, rootlets, feathers and hair, usually lined with feathers and with an entrance hole at the side ^{(2) (3) (4) (8)}. The scientific name of this species, troglodytes, means “cave dweller”, alluding to its habit of building enclosed nests, and probably also in reference to its rather skulking and secretive behaviour ⁽⁸⁾. Each male constructs several different nests, and the female then selects one to use for breeding. It is the female that adds the nest lining. The nest site may be reused over a number of years, and the wren will also use surplus nests for roosting ^{(2) (3) (4) (8)}. In cold weather, many individuals may roost in the same nest ^{(2) (4) (8)}, with a record of 31 wrens packing into one nest box in western Washington, USA ⁽²⁾.

The wren lays between one and nine eggs, which are white with reddish-brown spotting ^{(2) (3) (4)}. Only the female incubates, and the eggs hatch after about 16 days. The young wrens are fed by both adults and leave the nest after 14 to 19 days, after which they are fed for a further 9 to 18 days before becoming independent. The breeding pair may go on to raise a second or even a third brood in the same season ^{(3) (4)}. The oldest wren has been recorded living to over six years of age ⁽⁴⁾.

Wren range

The wren is widely distributed across North America, Europe, North Africa and Asia. Its breeding range extends from the Aleutian Islands and Alaska, across Canada, and south along the eastern and western coasts of the United States, as far as Mexico. It also breeds from Iceland, the Faroe Islands and the British Isles, across Europe to Russia and Siberia, and south to North Africa, the Middle East and southern Asia ^{(3) (4) (11)}. The wren is the only wren species found outside of the Americas ^{(2) (4) (8)}.

In most southern regions and on some islands, including Britain and Ireland, the wren does not usually migrate. However, many northern populations migrate southwards in winter, while others move to lower altitudes ^{(2) (3) (4)}. This species is also known as the winter wren, as its winter range reaches further north than any other wren species ⁽⁷⁾.

Wren habitat

In North America, the wren generally breeds in moist conifer forests, particularly favouring areas with fallen logs and other dead wood, and commonly being found near streams, swamps or lakes. It also sometimes inhabits deciduous forest, cliff faces, treeless islands, heaths and riparian woodland, as well as gardens ^{(2) (3) (4) (7)}.

The wren is found in a wider range of habitats outside of the Americas, including various types of woodland, farmland, moorland, heaths, and urban parks and gardens ^{(3) (4) (5) (6)}. As in North America, it is usually associated with relatively damp areas ⁽³⁾. The wren has been recorded at elevations of up to 4,575 metres in the Himalayas ⁽³⁾.

Wren status

The wren is classified as Least Concern (LC) on the IUCN Red List ⁽¹⁾.

Wren threats

The wren has an extensive range and a large global population, which is estimated at tens or even hundreds of millions of birds ⁽¹¹⁾. Its population is thought to be stable or increasing across much of its range ^{(2) (11)}. This small bird can be hit heavily by cold winters ^{(4) (6)}, but its populations are usually quick to recover ^{(3) (8)}.

Although the wren is not globally threatened, there is some concern that the species is being negatively affected by the loss and fragmentation of old-growth coniferous forests in western North America ^{(2) (4)}. In contrast, wrens in Europe often adapt well to highly modified environments, inhabiting gardens and frequently nesting in buildings ⁽⁴⁾. The wren is one of the most common breeding birds in Britain ^{(3) (6)}.

Wren conservation

There are not known to be any specific conservation efforts currently targeted at this common wren. Perhaps the most important conservation measure for the wren would be to clarify its taxonomy, to determine how many subspecies or even distinct species it represents ⁽⁴⁾. Some populations may be small and need particular conservation attention, such as the subspecies Troglodytes troglodytes mosukei, of the Izu Islands, Japan, which is listed as Endangered on the Japanese Red List ^{(3) (12)}.

In North America, the wren may benefit from forest management practices that maintain continuous areas of unlogged, mature forest and which retain fallen logs and root masses, to provide optimum habitat for this diminutive bird ⁽⁴⁾.

ARKive is supported by OTEP, a joint programme of funding from the UK FCO and DFID which provides support to address priority environmental issues in the Overseas Territories, and Defra

Find out more

Find out more about the wren and its conservation:

• BirdLife International - Winter wren:
  http://www.birdlife.org/datazone/speciesfactsheet.php?id=6968
• The Cornell Lab of Ornithology: All About Birds - Winter wren:
  http://www.allaboutbirds.org/guide/Winter_Wren/id
• BBC Nature - Wren:
  http://www.bbc.co.uk/nature/life/Winter_Wren

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Glossary

Cryptic colouration

Colouration that makes animals difficult to detect against their background, so serving to reduce predation. The colouration may provide camouflage against a background or break up the outline of the body, or both.

Deciduous forest

Forest consisting mainly of deciduous trees, which shed their leaves at the end of the growing season.

Genus

A category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.

Incubate

To keep eggs warm so that development is possible.

Invertebrates

Animals with no backbone, such as insects, crustaceans, worms, molluscs, spiders, cnidarians (jellyfish, corals, sea anemones) and echinoderms.

Larvae

Stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.

Monogamous

Having only one mate during a breeding season, or throughout the breeding life of a pair.

Riparian

Relating to the banks of watercourses.

Subspecies

A population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.

Taxonomy

The science of classifying organisms, grouping together animals which share common features and are thought to have a common ancestor.

Territorial

Describes an animal, a pair of animals or a colony that occupies and defends an area.

Vertebrates

Animals with a backbone, including mammals, birds, reptiles, amphibians and fish.

References

1. IUCN Red List (March, 2011)
   http://www.iucnredlist.org/
2. The Cornell Lab of Ornithology: All About Birds - Winter wren (March, 2011)
   http://www.allaboutbirds.org/guide/Winter_Wren/id
3. del Hoyo, J., Elliott, A. and Christie, D. (2005) Handbook of the Birds of the World. Volume 10: Cuckoo-Shrikes to Thrushes. Lynx Edicions, Barcelona.
4. Hejl, S.J., Holmes, J.A. and Kroodsma, D.E. (2002) Winter wren (Troglodytes hiemalis). In: Poole, A. (Ed.) The Birds of North America Online. Cornell Lab of Ornithology, Ithaca. Available at:
   http://bna.birds.cornell.edu/bna/species/623/
5. Peterson, R.T., Mountfort, G. and Hollom, P.A.D. (1993) Collins Field Guide: Birds of Britain and Europe. HarperCollins Publishers, London.
6. RSPB - Wren (March, 2011)
   http://www.rspb.org.uk/wildlife/birdguide/name/w/wren/index.aspx
7. Dunne, P. (2006) Pete Dunne’s Essential Field Guide Companion: A Comprehensive Resource for Identifying North American Birds. Houghton Mifflin Company, New York.
8. Perrins, C. (2009) The Encyclopedia of Birds. Oxford University Press, Oxford.
9. Drovetski, S.V., Zink, R.M., Rohwer, S., Fadeev, I.V., Nesterov, E.V., Karagodin, I., Koblik, E.A. and Red’kin, Y.A. (2004) Complex biogeographic history of a Holarctic passerine. Proceedings of the Royal Society B - Biological Sciences, 271: 545-551.
10. Toews, D.P.L. and Irwin, D.E. (2008) Cryptic speciation in a Holarctic passerine revealed by genetic and bioacoustic analyses. Molecular Ecology, 17: 2691-2705.
11. BirdLife International (March, 2011)
    http://www.birdlife.org/datazone/speciesfactsheet.php?id=6968
12. Red List of Threatened Birds of Japan (March, 2011)
    http://www.biodic.go.jp/english/rdb/rdb_f.html