The House Wren is one of the best known song birds in North America. It is moderately small: 11 to 13 cm long, 10 to 12 g. From a distance appears fairly uniform brownish gray, without obvious field marks. The northern House Wren: head, nape and back are near uniform shade of brown-darker and more rufescent in eastern populations, paler and grayer in western populations. Has only a pale, often indistinct superciliary line and no striping on crown. Throat and chest uniformly light gray, sometimes with buffy or brownish tings. Some black, dark brown and buffy barring on flanks (usually becoming indistinct forward of legs), tail, and wings and, in western individuals, on scapulars and back. Sexes identical in plumage. No seasonal changes in plumage (Johnson 1998).
For a comprehensive review of the conservation status, habitat use, and ecology of this and other Montana bird species, please see Marks et al. 2016, Birds of Montana.
Western Hemisphere Range
In the Bozeman area, normal migration periods are May 17 to 25 and August 20 to September 5.
Has an affinity for open, shrubby woodlands, mimicked so well by small town and suburban backyards and city parks; has a preference for human-made "bird houses". Nests readily in small woodlots and at forest edges. In the East, known to occur primarily at or near edges of deciduous forests and in open woodlands. In western plains, found exclusively in wooded areas around water, or farmyards or residential areas with trees and shrubs. In western foothills and mountains, found in deciduous or mixed deciduous-coniferous woodlands in canyons or riparian areas, and at edges or in clear-cut or thinned areas of denser montane coniferous forests (Johnson 1998).
Feeds primarily on small, terrestrial invertebrates (Johnson 1998).
Nests naturally in preformed tree cavities, especially old woodpecker holes, but readily uses nest boxes. Eggs are short, rounded ovate to oval in shape. Smooth and glossy; their ground color white to pinkish white to slightly grayish, marked lightly to quite extensively. Clutch size at most locations usually ranges from low of 4 to high of 7 or 8 (Johnson 1998). Near Fortine, egg dates are from May and June. Young in the nest were seen June 7 to 30, with young in second nests as late as August 20. Statewide, nests are from mid-May through July.