Small sparrow; male and female plumages similar. Body length 127 to 147mm; male slightly larger than female. Body mass in summer 11.0 to 15.5 g; female heavier than male. Summer adults have rufous to chestnut brown crown, distinct white superciliary line, black lores and eye-stripe, gray rump, unstreaked gray breast and flanks blending into dull white belly, and black bill (frequently pale brown at base of lower mandible). Female duller than male, with crown frequently finely flecked dark brown (Middleton 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 from May 5 to June 10 and August 20 to September 25. The fall peak is around September 10.
Unlike many sparrows, which are commonly associated with grassland communities, the Chipping Sparrow prefers open woodlands, the borders of natural forest openings, edges of rivers and lakes, and brushy, weedy fields. It has a preference for nesting in open glades of coniferous forests, and for foraging in brushy open areas making it suited to human-modified habitats. A common summer resident in towns and gardens (Middleton 1998).
Feeds primarily on seeds of grasses and various annual plants, infrequently supplementing this diet with small fruits. Adds insects and other invertebrates when breeding (Middleton 1998).
Territory sizes of 1.1 to 1.8 acres in Douglas fir or lodgepole pine forests in western Montana have been recorded.
Nests in a wide variety of trees and shrubs; has a distinct preference for conifers. Nest is a loosely woven cup. Eggs are subelliptical to short subelliptical in shape. Ground color varies from sky blue to pale sky blue, rarely pure white, and are sparsely marked. Clutch size most commonly four (Middleton 1998). Near Fortine, egg dates range from May 26 to July 14. Statewide, nesting is from late May to mid-July.