page_title: House wren
section_title: Reproduction
hierarchical_section_title: House wren / Ecology / Reproduction
caption_attribution_description: English: Illustration of Troglodytes aedon by John James Audubon
context_page_description: The house wren is a very small songbird of the wren family, Troglodytidae. It occurs from Canada to southernmost South America, and is thus the most widely distributed bird in the Americas. It occurs in most suburban areas in its range and it is the single most common wren. Its taxonomy is highly complex and some subspecies groups are often considered separate species.
context_section_description: The nesting habits do not seem to differ significantly between the northern and southern house wrens at least. They usually construct a large cup nest in various sorts of cavities, taking about a week to build. 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. The male wren finds dry sticks, which he adds to the nest. Once he is done, the female inspects at the nest; but if she does not approve of the construction, she will throw any unwanted sticks to the ground. After this process, the female lines the nest. Nest cavities are usually a few meters above ground at most, but occasionally on cliffs as high up as 15 m (49 ft) and more at least in southern populations; they may be natural or man-made, often using bird houses.
  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 that sang 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 its 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 (0.05 oz) each and measuring c.17 and 13.4 mm (0.67 and 0.53 in) at the widest points. Only the female incubates these, for around 12–19 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, which like all passerines hatch almost naked and helpless, take another 15–19 days or so to fledge. They are being fed by both parents, and need plenty of food given their tiny size (see also Bergmann's Rule). As the young near fledging, the parents spend much of their time procuring food for them. Brood loss due to predation was found to be light in the Southern Andean Yungas, with predation of nestling young being almost insignificant. Known predators of house wrens at the nest include cats, rats, opossums, woodpeckers, foxes, raccoons, squirrels, snakes and owls. Adults away from the nests can usually avoid these predators although both small hawks and owls occasionally take free-flying adult wrens.
  Migrant populations are nesting within 6 weeks of returning from winter quarters, leaving theoretically time for a second brood. In the subtropical montane forest of northwestern Argentina and similar habitat, the southern house wren breeds in the rainy summer months from late October to late December.
  In Washington, D.C. area, house wren parents made significantly more feeding trips per hour in suburban backyards compared to rural backyards. Yet rural nestlings grew at a faster rate than their suburban counterparts. In addition, suburban parents spent less time brooding (sitting on the nest) compared to rural parents. Such results suggest that suburban backyard habitats offer house wrens food for nestlings that is inferior in either quality or quantity to what rural habitats offer. Food items may, for example, be smaller in suburban habitats, and force adults to make more trips to the box.
  In South Temperate Argentina, southern house wrens dispersed more frequently between-seasons than within a season, with females dispersing more often than males.  Widowed and single males dispersed more frequently than paired males, whilst within-season divorce increased the breeding success of females but not males.
caption: Audubon's illustration of nesting house wrens
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