Field sparrows are relatively small and slender and have a rounded head. Upperparts are streaked with dark rusty brown and gray, with a gray head, rusty side stripes on the crown, and a rusty eye line and cheek. There is a distinct white eyering, and two whitish wing bars. Adult underparts grayish, with warm buffy or reddish tan sides and flanks. The bill and legs are pink. Immatures are streaked below. Typical song is a long series of down-slurred whistled notes, accelerating like the rhythm of a dropped ball: tew, tew tew-tew, tututututututuuu. Call is a chip or a short trill.
Similar species: To separate the field sparrow from other sparrows with a rusty cap, remember that field sparrows have a distinct white eyering, a pink bill and bright pink legs, a warm (not gray) plain breast, a rusty (not black) eyeline, and gray (not whitish) eyebrow. Compared to American tree sparrows, field sparrows are much smaller and lighter, with a pink (not two-colored) bill and plain breast (lacking a central black spot).
Length: 5¾ inches (tip of bill to tip of tail).
Field sparrows are common nesting birds throughout Missouri, but they retreat to the southernmost counties to ride out the winter.
Habitat and Conservation
Lives in weedy, brushy fields, glades, and overgrown pastures. Field sparrows are generally not found in cultivated fields, but in overgrown ones. Many people first notice this bird when they hear the male's distinctive loud, clear song, usually sung from a prominent place such as the top branches of a small tree or a fence post. In winter, field sparrows often join mixed flocks of sparrows. Scan such groups for smaller, tanner birds staying close to the ground; those could be field sparrows.
Field sparrows forage on or near the ground for insects and small seeds, especially those of grasses and weeds. Like many other birds, in winter they eat mostly plant matter, in this case seeds; in summer they eat a larger percentage of insects, which are plentiful in the warm months and which provide a high-protein diet for their growing young.
Common summer resident; as winter resident, uncommon in the south and rare in the north.
Females build cup nests, mainly from woven grasses, on the ground in grass clumps or in low vegetation or shrubs; they can have up to 5 broods in a season, and as the season progresses and plants grow higher, their nest placement also is increasingly higher, up to 10 feet over the ground. Clutches comprise 1–5 eggs, which are incubated 10–17 days; young stay in the next another 5–8 days. A field sparrow can live to be at least 10 years old.
The famous naturalist Thoreau described the field sparrow's song: It "jingles [its] small change, pure silver, on the counter of the pastures." Nature writing is recognized as a distinct literary genre, embracing scientific facts as well as human elements such as conservation, philosophy, autobiography, spirituality, and art.
Field sparrows are one of the many species parasitized by brown-headed cowbirds, which lay their eggs in the sparrows' nests, to the detriment of the host birds' own young. But in places where this parasitism is common, field sparrows apparently learn to recognize and attack cowbirds.