Grasshopper sparrow  (Ammodramus savannarum)

The grasshopper sparrow is classified as Least Concern (LC) on the IUCN Red List (1).

A secretive bird of North American grasslands, the grasshopper sparrow (Ammodramus savannarum) is more often heard than seen, as it emits its insect-like melody from dense grasses. The call, for which this species is named, consists of one or two chirps followed by a ‘buzzy’ trill, reminiscent of a grasshopper (2) (3) (4).

The grasshopper sparrow is a small, stocky, flat-headed sparrow with a deep bill and a short tail. The brown upperparts are streaked with chestnut-rust and black, and the black crown in narrowly streaked with buff and divided by a pale buffy-white stripe. The breast is cream-buff above and whitish below, and the back of the neck is greyish, with fine reddish-brown streaks. The edge of the wing is yellow. The juvenile grasshopper sparrow is similar to the adult, but has a band of streaks across the breast (3) (5) (6).

A migratory species, the grasshopper sparrow breeds from southern British Columbia and southern Alberta to southern Maine, southern California, south-central Texas, and central Georgia, and east to North Carolina, Maryland and New Hampshire.

During the winter, it is found from western Oregon, central California, west and southeast Arizona, central Oklahoma, southern Louisiana, southern Mississippi, and southwest Georgia, south to southern Baja California, Mexico and El Salvador (3) (6) (7).

The habitat preferences of the grasshopper sparrow vary greatly across its very large range. It typically breeds in grassland, upland meadows, pastures, hayfields, and old field habitats, favouring open areas of over 100 acres in size. Such habitats usually have short- to medium-height grasses, interspersed with patches of bare ground and a few shrubs (3) (4).

Outside of the breeding season, the grasshopper sparrow is found in similar habitats, in addition to thickets, weedy lawns, vegetated landfills and fence rows (4).

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).

Historically, the grasshopper sparrow was restricted to natural grasslands created by fires or flooding. However, the boom in agriculture in the late 1800s and early 1900s allowed this species to expand its range and increase in number. By the 1950s and 1960s, there was a great decrease in the amount of land devoted to farming or pasture, which, coupled with expanding development, contributed to a decline in this species (4). In fact, grasshopper sparrow populations decreased consistently between 1966 and 2000, at a rate of around four percent of the population per year (6).

Habitat loss remains the greatest threat to the grasshopper sparrow today. In Manitoba, Canada, and some mid-western U.S. states, habitat loss is as high as 99.9 percent, and elsewhere prairie habitat continues to be converted to residential areas and other developments. As the grasshopper sparrow requires fairly large areas of habitat, habitat loss not only fragments its habitat, but reduces the suitability of remaining areas. Mowing hayfields during the breeding season is also a threat to this species, while fire suppression may degrade its habitat by allowing the overgrowth of dense scrub (3) (6).

The grasshopper sparrow is protected in Canada by the Migratory Birds Convention Act, which prevents the hunting or trade of this species, its eggs or its nests (6) (8). It is also afforded some protection in a number of reserves, including the Lakes Wildlife Management Area and the Kissimmee Prairie State Preserve in Florida (9).

A conservation priority for this species is the continued acquisition and restoration of prairie habitats, along with the maintenance of suitable areas of habitat over 100 acres in size. Increasing the connectivity between these habitats would also greatly benefit the grasshopper sparrow. Management of its habitat should aim to limit shrub cover and promote the growth of grasses, potentially by using frequent fire regimes at one to three year intervals (6) (7).

Find out more about the grasshopper sparrow:

• Cornell Lab of Ornithology: All About Birds - Grasshopper sparrow:
  http://www.allaboutbirds.org/guide/Grasshopper_Sparrow/