The grasshopper sparrow forages mainly on the ground, where it walks with the body hunched forwards, the head lowered and the wings tightly folded, and occasionally jerks the tail and flicks the head (3). It feeds almost entirely on grasshoppers, which it immobilises by pinching the thorax and gives to the chicks after shaking the legs off (2).
Shortly after arriving at the breeding grounds, the male grasshopper sparrow establishes a territory, by singing from a prominent perch and using flight displays (3). The females arrive around three to five days after the males, and breeding pairs soon form (6).
The female grasshopper sparrow builds the nest, which is a cup of grass stems and blades, well concealed on the ground. The female incubates the clutch of 3 to 6 eggs for 11 to 13 days. The chicks are well feathered by 9 days, when they leave the nest, and are fed by both the male and female for a further 4 to 19 days, before becoming fully independent. The grasshopper sparrow may produce a second brood in the same breeding season, but this clutch tends to be smaller, with usually only two eggs (6).