The house wren (Troglodytes aedon) is a very small bird of the wren family, Troglodytidae. It occurs from Canada to southernmost South America and is thus the most widely distributed native bird in the Americas. It occurs in most suburban areas in its range and it is the single most common wren.
Adults are 11 to 15 cm long including wingspan and weigh about 10 to 12 g. The subspecies vary greatly, with upper parts ranging from dull greyish-brown to rich rufescent-brown, and the underparts ranging from brown, over buff, and pale grey, to pure white.
All subspecies have blackish barring to the wings and tail, and some also to the flanks. All subspecies show a faint eye-ring and eyebrow and have a long, thin bill with a blackish upper mandible, and a black-tipped yellowish or pale grey lower mandible. The legs are pinkish or grey. The short tail is typically held cocked.
This bird's rich bubbly song is commonly heard during the nesting season but rarely afterward. There is marked geographical variation in the song, though somewhat more gradual than in the bird's outward appearance that can strikingly differ, e.g., on neighboring islands in the Caribbean. Birds from far north and south of the species' range nonetheless have songs that differ markedly. In North America, the house wren is thought to achieve the highest density in floodplain forests in the western Great Plains where it uses woodpecker holes as nesting sites.
In South and Central America, it can be found in virtually any habitat and is, as indicated by its common name, often associated with humans. North American birds migrate to the southern United States and Mexico for winter. Most return to the breeding grounds in late April to May and leave for winter quarters again around September to early October. These birds forage actively in vegetation. They mainly eat insects such as butterfly larvae, beetles, and bugs, also spiders and snails. Southern house wrens rarely attend mixed-species feeding flocks.
The nest is made from small dry sticks and is usually lined with a variety of different materials. These include feather, hair, wool, spider cocoons, strips of bark, rootlets, moss, and trash. Nest cavities are usually a few meters above ground at most, but occasionally on cliffs as high up as 49 ft and more at least in southern populations. House wrens are feisty and pugnacious animals considering their tiny size. They are known to occasionally destroy the eggs of other birds nesting in their territory by puncturing the eggshell.
Females thatsang more songs to conspecifics that were simulated by playback lost fewer eggs to ovicide by other wrens. Female bird song in this species is, therefore, thought to have a function in competition and is not only displayed by males. They are also known to fill up other birds' nests within their territory with sticks to make them unusable.
Depending on the exact population, the house wrens' clutch is usually between two and eight red-blotched cream-white eggs, weighing about 1.4 g each and measuring 17 and 13.4 mm at the widest points. Only the female incubates these, for around 13–19 days, and she will every now and then leave the nest for various reasons. While she is on the nest, the male provisions her with food. The young, who like all passerines hatch almost naked and helpless, take another 15–19 days.
