Range Breeds from northeastern British Columbia, northern Alberta, and central Saskatchewan east to New Brunswick, south through southern British Columbia to northern Baja California, and across the southern United States from California to South Carolina. Winters across the United States from California to Florida; occasionally further north. Resident in southern California and much of Arizona.

Status On the coast, uncommon to fairly common migrant and summer visitant on southeastern Vancouver Island in the Georgia Depression Ecoprovince; rare to uncommon migrant and summer visitant on the Fraser Lowland of the Georgia Depression, accidental there in winter; casual on the Southern Mainland Coast and accidental on the Northern Mainland Coast of the Coast and Mountains Ecoprovince. In the interior, fairly common migrant and summer visitant in the Southern Interior Ecoprovince; uncommon to fairly common in the southern portions of the Southern Interior Mountains and Boreal Plains ecoprovinces; very rare in the southern Central Interior, the Sub-Boreal Interior, and Taiga Plains ecoprovinces. Breeds.

Status Change No change.

Nonbreeding The House Wren has a widespread distribution during spring and summer across extreme southern British Columbia from the south and east coast of Vancouver Island north to Campbell River, east through the lower Fraser River valley to Manning Park and north to the Nicola valley; through the Okanagan valley, north to Adams Lake and Clearwater (Dickinson 1953); and through southern portions of the west and east Kootenay. In the Central Interior, there are fewer than 20 records, all from the area between 100 Mile House, Williams Lake, and Riske Creek. A specimen from the Kispiox valley is the only record from the Northern Main land Coast of the Coast and Mountains Ecoprovince (Swarth 1924; Brooks and Swarth 1925). In the Sub-Boreal Interior, there are 4 known localities where this wren has occurred: Chetwynd, Prince George (Godfrey 1986), Quesnel, and Smithers. The House Wren also occurs regularly in the Peace Lowland, and locally but fairly regularly in the Fort Nelson area. On the coast, it occurs mainly at elevations from sea level to about 300 m, but there is 1 record at about 1,400 m. In the interior, it has been found up to 1,200 m.  The House Wren is a bird of drier habitats. In the southern interior, it is most abundant in deciduous groves within ponderosa pine forests (Cannings et al. 1987), but also occurs in relatively open stands of trembling aspen, as it does in the northeast. On Vancouver Island and the Gulf Islands, it is most numerous along the edges of dry forests featuring arbutus, Carry oak, and Douglas-fir, particularly in brushy areas at the forest edge or along sun-baked rocky bluffs that border the sea. Specific habitats include hedgerows, bramble tangles, thickets of Scotch broom and gorse, open brushy areas along roads and powerline rights-of-way, and thickets around ponds and seashore. Throughout its range, it occurs frequently in orchards, gardens, and abandoned homesteads. On the coast, spring migration begins slowly in early April, rarely in late March, and peaks in May. East of the coastal mountain ranges, the House Wren arrives after the first week of April and numbers continue to increase into May and June. In the Peace Lowland, spring migrants arrive in May and numbers peak in late May and early June. The northeastern population is continuous with that of western Alberta (Semenchuk 1992), and reaches that area via a migration route east of the Rocky Mountains. West of the Rocky Mountains, the House Wren migrates through intermountain valleys. In the Peace Lowland, the southward migration occurs mainly in August, and most birds have gone by mid-September. In the Southern Interior, the autumn movement can be detected as early as late July but most birds leave in August, with few reported in September and only casual occurrences thereafter. On the coast, the autumn migration is more protracted, occurring in August and September, with only a few individuals left in October and November. There is only 1 convincing late winter record for the House Wren in British Columbia: a specimen from Chilliwack (see also REMARKS). Root (1988) states that the House Wren winters along the Pacific coast mostly where the average January minimum temperature does not drop below -1°C. Our data suggest that even the relatively mild winters on the coast of British Columbia are not suitable for this wren. On the coast, the House Wren has been recorded regularly from 27 March to 28 October; in the interior, it has been recorded from 13 April to 6 October.

Breeding Nests Eggs Nest Success The House Wren breeds throughout most of its summer range, from southeastern Vancouver Island across the extreme southern portions of the province to the foothills of the Rocky Mountains. A disjunct population breeds in the Peace River region and at Fort Nelson. There are many nesting records from the valleys of the Thompson, Okanagan, and Similkameen rivers; in the Columbia River valley near Revelstoke, and the southern west Kootenay; and near Cranbrook. The northernmost breeding records west of the Rocky Mountains are near 100 Mile House, Williams Lake, Quesnel, and Prince George. The highest numbers in summer occur in the Southern Interior, especially in the Okanagan valley. House Wrens are also locally common breeders on southeastern Vancouver Island, the Gulf Islands, and the Peace Lowland. On the lower Fraser River delta, within a few kilometres of the sea, there are many records of House Wrens in spring and summer, but few nesting records. Beyond the centre of its range, the House Wren may breed irregularly. In the Prince George area, this wren seemed to disappear in the 1970s, but had returned to breed by 1993 (J. Bowling pers. comm.). In the Arrow Lakes valley north of Castlegar, House Wrens were not recorded from 1975 to 1990, but several singing males were found in the early 1990s (G.S. Davidson pers. comm.). An analysis of Breeding Bird Surveys for the period 196S through 1993 shows that the number of birds on interior routes has increased at an average annual rate of 4%. Data for coastal routes were insufficient for analysis. In the interior, breeding has been recorded at elevations from 270 m to about 1,150 m; on the coast, from near sea level to 390 m. Most House Wren nests were reported from human-altered habitats (79%; n = 832) and forests (12%), but this summary is biased by the predominance of nests studied at 1 rural residence in the Okanagan valley. Deciduous and mixed woodlands were preferred to coniferous forest. Specific nesting habitats included brushy backyards or farmyards (59G/70; n = S12), pasture and open rangeland (13%), woodlands (11%), orchards (8%), and riparian situations (6%). Other sites included overgrown fields with brambles, fence rows, and railway rights-of-way. In the interior, the House Wren has been recorded breeding from 26 April (calculated) to 28 August; on the coast, it has been recorded from 25 April (calculated) to 12 August.

Nests:  Most nests were found in nest boxes (84%; n = 942), cavities such as abandoned woodpecker nests or natural cavities left by the rotting of branches (13%), and crevices (2%). House Wrens often used nest boxes set out for bluebirds or swallows. Specific sites for non-nest box nests (n = 130) included deciduous trees (58%), stumps (16%), coniferous trees (13%), and buildings (12%). The heights for 139 nests in natural cavities ranged from 0.9 to 15 m, with 55% between 1.8 and 4.5 m. Nest materials included mainly twigs (99%; n = 813), feathers (65%), grass (24%), hair (3%), moss, and occasionally spider webs, rootlets, mud, rope, and leaves. Nests varied in size, as materials usually filled the available space in cavities. The lining of the nest cup usually included fine grass, animal hair, feathers, plant fibres, leaves, plant stalks, pine needles, and other fine materials. Eggs: Dates for 707 clutches ranged from 28 April to 24 August, with 52% recorded between 1 June and 29 June. Calculated dates suggest that nests can have eggs as early as 25 April. Sizes of 684 clutches ranged from 1 to 9 eggs (1E-17, 2E12, 3E-25, 4E-53, 5E-123, 6E-167, 7E-220, SE-59, 9E-S), with 57% having 6 or 7 eggs. In 3 nests, the incubation period was between 14 and 15 days. In Ontario, Peck and James (1987) give a range of 10 to 19 days, with an average of 12 to 14 days. Cannings et al. (1987) note that clutch size in the Okanagan valley declines through the summer; 146 clutches started before 15 June had a mean clutch size of 6.4 eggs, while 71 clutches initiated later than that had a mean clutch size of 5.2 eggs. About half of the nesting females in the Okanagan valley attempt to produce 2 broods each breeding season. Nest Success: Of 535 nests found with eggs and followed to a known fate, 449 produced at least 1 fledgling, for a success rate of 84%; coastal nest success was 100% (n = 2); interior nest success was 84% (n = 533). Finch (1989) showed that the nesting success of House Wrens was greater when nests were placed in open habitats. Belles-Isles and Picman (1986b) demonstrated the same results and suggested that greater nesting success in sparser vegetation resulted from a more effective defence of nests against other marauding House Wrens in such sites. Young: Dates for 683 broods ranged from 15 May to 28 August, with 51% recorded between 18 June and 17 July. Sizes of 598 broods ranged from 1 to 11 young (1Y-9, 2Y-7, 3Y-25, 4Y-51, 5Y-132, 6Y-153, 7Y-175, SY-43,9Y-3), with 55% having 6 or 7 young. In 13 nests, the nestling period ranged from 14 to 22 days, with a median of 16 days. Brown-headed Cowbird Parasitism: Cowbird parasitism was not found in British Columbia in 802 nests recorded with eggs or young. In Ohio, Murphy (1984) reported 2 cases of cowbird parasitism in a sample of over 900 House Wren nests. In Ontario, Peck and James (1987) found 4 nests parasitized in a sample of 1,120 nests. Friedmann and Kiff (1985) list only 9 records for North America.

Remarks Three subspecies of House Wren occur in North America; the one occurring in British Columbia is T. a. parkmanii (Godfrey 1986). All winter records of the House Wren must be carefully documented. We have a number of winter reports of this wren on file, including published Christmas Bird Counts from both the coast and the interior - Campbell River, Comox, Ladner, Nanaimo (including the all-time Canadian high count of 4 birds on 30 Dec 1979 [Anderson l9S0]), Vancouver, Victoria, and Shuswap Lake Provincial Park (Appendix 2). All lack adequate details, and we have excluded them from this account. In addition, 10 House Wrens recorded on the Telkwa High Road Breeding Bird Survey on 23 June 1974 are also without documentation and have not been considered here. The House Wren is notorious as a nest predator. Territorial House Wrens are known to destroy nests of other species and other House Wrens, whether or not they are within its nesting territory. The behaviour includes removing the soft nest lining, killing small nestlings, and pecking holes in eggs (Hill 1869; Sherman 1925; Creaser 1925; Kendeigh 1941; Belles Isles and Picman 1986a). Experiments indicate that this behaviour has the effect of making preferred nesting sites available for their own use (Pribil and Picman 1991).Kennedy and White (1992) discuss nest box selection by the House Wren, and conclude that boxes with wide, slot shaped entrances were more likely to contain a nest with eggs, apparently because the male could more readily carry twigs through slots than holes. McCabe (1961, 1965) and Lumsden (1986) provide additional information on the use and selection of nest boxes by House Wrens.