Troglodytes aedon

This is a moderately small wren that from a distance appears brownish gray, without a strong pattern. The head, nape, and back are brown, darker and more reddish in eastern populations, paler and grayer in western populations. There is a pale, often indistinct line above the eye and no striping on the crown. The throat and chest are light gray, sometimes with a buffy or brownish tinge. The flanks, tail, and wings have black, dark brown, and buffy barring. The sexes are identical in plumage. The plumage does not change in appearance between summer and winter. Length is around 4.75 inches (12 cm). Song is a series of rapid trills and rattles.

House wrens inhabit thickets, shrubbery, and brushy areas in partly open situations, open woodland, farmlands, chaparral, and areas around human habitations; also (south of the United States) humid montane forest, forest edge, clearings, pine-oak associations, and mangroves. This species occurs most often in human-disturbed habitats. It sleeps in all seasons in crannies in buildings, holes in trees, niches in banks, or in similar sites. Nests usually are in cavities (natural, abandoned woodpecker holes, bird boxes, and within various human artifacts).

House wrens commonly reuse nesting cavities in successive years. Prior to reuse, the male usually removes the old nest-lining and sometimes the old sticks as well. Removal of old nest material can significantly reduce the abundance of parasitic mites that may attack the wrens.

See Drilling and Thompson (1988) for intensive study, using 910 nest boxes over several years, of natal and breeding dispersal in Illinois.

Density was 10-18 pairs per 40 ha in northern Arizona pine forest (Brawn and Balda 1988).

Sometimes destroys the clutches of other birds, including conspecifics.

Breeding season is relatively short and strongly seasonal in the north, protracted and variable in the tropics (e.g., see Young, 1994, Condor 96:341-353). Egg laying in the United States begins as early as April in some areas, in May in most regions. Nesting may extend into July or August in some areas. Clutch size averages about 3-4 at low latitudes, about 5-7 at high latitudes (Young, 1994, Auk 111:545-555). Individual females in the north produce 2, sometimes 3, broods per year (3-4 in Costa Rica). Incubation, by the female, lasts 12-15 days. Young are tended by both parents, leave nest at 12-18 days; male may feed fledged young while the female renests. Breeding is most commonly monogamous; males sometimes polygynous.