Habitat
BREEDING: Shrubs and thickets, often near water; open areas in coniferous or deciduous forests; cutover or burned areas; brushy grasslands; pastures and fields (AOU 1983). Relatively dense grasslands, preferring idle or lightly grazed habitats, particularly native vegetation of mid to tall height with abundant litter, undisturbed cover, and a shrubby component (Salt 1966, Knapton 1978, 1994, Faanes 1983, Renken 1983, Arnold and Higgins 1986, Munson 1992, Madden 1996). Will also use more heavily grazed areas, burned areas with brush thickets not markedly affected by fire, weedy and brushy areas, shelterbelts, pine plantations and other open wooded areas, planted cover [e.g., Conservation Reserve Program (CRP) fields and dense nesting cover (DNC)], pasture, swamps, roadsides, and hayland; woodland edges are often used as singing perches (Peabody 1899; Root 1968; Owens and Myres 1973; Maher 1974, Stewart 1975; Kantrud 1981; Buech 1982; Renken 1983; Johnson and Schwartz 1993a,b; Anstey et al. 1995; Madden 1996; Dale et al. 1997; Davis et al. in press). Although presence of shrubs appears to be the main determinant of habitat suitability (Munson 1992, Knapton 1994), may use habitats without shrubs (Renken 1983, Johnson and Schwartz 1993b). Tall forbs and dense grass may provide adequate song perches and nest substrates in shrubless areas (Renken 1983, Johnson and Schwartz 1993b). Idle areas with only 2-3% shrub cover were utilized in North Dakota (Madden 1996). In Wisconsin, selected territories containing dense stands of woody vegetation; avoided open grasslands (Munson 1992).
Nest in residual vegetation on the ground or low (usually < 30 cm high; up to about 1.5 m) in grass tuft, small trees, or shrubs (Peabody 1899, Walkinshaw 1939, Root 1968, Stewart 1975, Knapton 1978, Terres 1980). In Manitoba, preferred to nest in western snowberry (SYMPHORICARPOS OCCIDENTALIS), which provided better concealment and less light penetration than other shrub species (Knapton 1978). In Saskatchewan, high densities occur in grazed pastures with shrubs (Dale 1983). In central Wisconsin, occupied territories that contained more habitat features with high nest cover value than were generally available (Munson 1992).
Breeding territories are commonly placed adjacent to suitable foraging areas. Prefer to forage in open areas with sparse, short vegetation, such as cropland and pastures (Knapton 1978, 1994, Dale 1983). Will use both native and tame vegetation (Peabody 1899, Walkinshaw 1939, Rand 1948, Fox 1961, Salt 1966, Root 1968, Stewart 1975, Renken 1983, Arnold and Higgins 1986, Munson 1992, Knapton 1994, Davis and Duncan 1995, Prescott and Murphy 1996). In Alberta, abundance was similar on native pasture and tame pasture (Prescott and Murphy 1996). In native pasture, abundance was highest in areas characterized by high cover diversity; in tame pasture, abundance was highest in areas characterized by high herbaceous biomass, moderate height variability, and high forb:grass ratio (Prescott and Murphy 1996). In Saskatchewan, preferred native pastures to tame pastures of crested wheatgrass (AGROPYRON CRISTATUM) or brome grass (BROMUS spp.), possibly because native pastures had more shrubs (primarily western snowberry) > 10 cm high (Anstey et al. 1995, Davis and Duncan 1995). In Manitoba, abundance was positively correlated with introduced vegetation and negatively correlated with native vegetation (Wilson and Belcher 1989). In North Dakota CRP fields, abundance exhibited a positive association with alfalfa (MEDICAGO SATIVA) and sweetclover (MELILOTUS spp.), which may substitute for brushy vegetation (Johnson and Schwartz 1993b). In South Dakota, abundance was greater in habitat patches within larger areas dominated by grassland; patch size was not as important as its landscape context (Bakker et al. 2002).
NON-BREEDING: In migration, in mesquite and other desert shrublands, thickets, weed patches, open woodlands, and parks (Rising 1996). In winter, in arid to semihumid grassland and fields with scattered shrubs (Howell and Webb 1995). Also dry scrub and fencerows (AOU 1983).
Ecology
In Saskatchewan, density was about one pair per ha in unburned prairie (Pylypec 1991). Nesting territories are relatively small, about 0.1 to 0.5 ha (Fox 1961, Salt 1966, Root 1968, Terres 1980). In Manitoba, Knapton (1979) reported smaller territories of about 0.04-0.1 ha. Territory size and arrangement in relation to other territories may depend upon shrub cover; nesting in areas with less dense brush cover may require larger territories (Knapton 1979). Although little area was needed for nesting, sparrows required foraging areas outside of defended nest territories (Knapton 1979, 1994).