In the core of their range, grasshopper sparrows are dependent upon large areas of grassland where they avoid trees and shrubs.

The primary male song, a high trill preceded by a stereotyped series of short chips, is reminiscent of the sounds of grasshoppers[4] and is the origin of this species' name.

Grasshopper sparrows are in steep decline across their range, even in the core of the breeding distribution in the tallgrass prairies of the central Great Plains.

The grasshopper sparrow was described in 1713 by English parson and naturalist John Ray based on a specimen collected in Jamaica.

[6][7] When the German naturalist Johann Friedrich Gmelin revised and expanded Carl Linnaeus's Systema Naturae in 1789 he included the grasshopper sparrow.

[12] Their breeding habitat is open fields and prairie grasslands across southern Canada, the United States, Mexico and Central America, the Caribbean.

In the central USA, birds are quick to locate newly available habitat, and can be attracted to sites by playing conspecific song.

The reasons for this clumping are elusive; aggregation is not related to group defense against predators or brood parasite, cooperative care, extra-pair matings, or kin selection.

[15] Grasshopper sparrows avoid woody vegetation, and in the wetter parts of their range, prefer fields that are burned every 2–3 years (which reduces encroachment of trees and shrubs) and seek out areas that are moderately grazed by cattle or bison.

The birds breeding in most of the eastern US and southern Canada (A. s. pratensis) migrate latitudinally up to several thousand kms each year,[16] spending winters along the Gulf of Mexico and the Caribbean.

[17] The birds breeding through most of the Western part of their North American range (A. s. perpallidus) winter from Texas west to California, and south into the highland desert grasslands of northern and central Mexico.

Data from light level geolocators indicate that males are present on the breeding grounds from April to October,[17] consistent with birds completing their annual molt prior to migration.

[19] However, relatively few movement tracks for this species exist so far, potentially due to the sparrows' secretive behavior during most of the year other than the breeding season.

[21] In Oklahoma, grasshopper sparrows are one of the species most frequently found dead after colliding with windows, despite rarely being detected in migration.

[33] Grasshopper sparrows build inconspicuous, dome-shaped nests on the ground, typically very well hidden amongst grasses and forbs.

[14] Nestlings are fed an arthropod rich diet, particularly prey ~15–40 mm long, and preferentially select acridid grasshoppers, spiders, and small beetles.

The rate of brood parasitism by brown-headed cowbirds varies across the grasshopper sparrow's range and depends on habitat characteristics such as the amount of woody vegetation and whether the land is grazed.

[4] Male grasshopper sparrows sing "alternate", warble", or "sustained", songs during the breeding season to establish and maintain pair bonds.

[45] The song consists of a 5–15 second series of short notes varying slightly in pitch,[46] and the entire sequence may be repeated two to four times.

The global population of grasshopper sparrows in 2016 was estimated to be around 31,000,000 by the PIF North America Landbird Conservation Plan.

[47] The leading cause of population decline across its range is linked to habitat loss and management, particularly conversion of grasslands to intensive agriculture and encroachment of shrubs and trees.

[49] The majority of the former breeding range of grasshopper sparrows in North America has been converted to intensive agriculture[50] or encroached by shrubs and trees.

[51] Likewise, these birds are experiencing a loss of wintering habitats, particularly within the Chihuahuan grasslands, due to similar impacts (conversion to agriculture and woody encroachment).

[52] Because grasshopper sparrows require areas of dense dead grass for nesting, sparse vegetation for foraging, and little to no woody plants, they are vulnerable to management practices such as high-intensity grazing accompanied by annual burning, fire suppression leading to woody encroachment, and haying that can destroy nests if it occurs during the breeding season.

Ideal grazing intensities and fire frequencies vary across their range depending on climate, but areas with moderate grazing by cattle or bison, prescribed burning every 2–3 years, and removal of woody plants tend to support the highest densities of grasshopper sparrows in the Southern great plains.