Grassland Sparrow Ammodramus humeralis Scientific name definitions

The Grassland Sparrow looks and acts much like the more northern Grasshopper Sparrow (Ammodramus savannarum) which is likely familiar to North American readers. Grassland Sparrows are large-headed and relatively short-tailed, giving them a unique shape similar to their northern relative. Grassland Sparrows are dull and brownish above, with a pale central crown stripe and a face adorned with yellow supralores, and white crescents above and below the eyes. Their underparts are grayish-white, with warmer colored flanks. It is a well named sparrow as it is found in various types of grassland, but favoring older (old field) type grasslands, rather than heavily grazed areas. They require some taller forbs in the grassland, and use them to sing from, although fence posts are equally useful for this purpose. The Grassland Sparrow is relatively conspicuous early in the breeding season when they are singing from a prominent perch. After breeding, they retreat to the grass and are much more difficult to find. Their song is pleasant but soft, and high pitched with an insect-like quality to it, although the final trill can be sweet and resonating.

13 cm; 13–19 g. A short-tailed and large-headed sparrow with medium-sized bill, relatively long legs and large feet, and short wing, primaries entirely hidden by tertials. Nominate race has distinctive head pattern, having brown crown with neat and well-defined white central crownstripe, greyish-brown face with pale lores, noticeable yellow patch in supraloral area continuing as pale grey supercilium; dark brown postocular stripe broadens as it reaches side of neck; nape and hindneck grey with narrow rusty streaking, back grey and warm brown with darker streaking, rump unstreaked warm brown; tail brown; upper­wing brown, upperwing-coverts with broad blackish centres and pale tips (creating two indistinct wingbars), inner coverts edged cinnamon, outer ones grey or grey-brown, tertials blackish with white fringe, fringe becoming wider and cinnamon towards bases; marginal coverts bright yellow (showing as yellow area at bend of wing on perched bird); throat whitish; breast and flanks warm buff, sometimes obscurely streaked on rear flanks, rest of underparts off-white; iris dark; bill blue-grey to pinkish, dark culmen; legs dull pinkish. Distinguished from A. aurifrons by having shorter bill, pale median crownstripe, yellow on face restricted to supraloral area, and bolder pattern on wing-coverts and tertials. Sexes alike. Juvenile is similar to adult, but paler and duller plumage, less striking facial pattern tending to lack yellow in loral area, and has breastband of narrow streaks. Races vary marginally on size, more distinctly in plumage darkness: xanthornus is darker than nominate, has chestnut edging on upperparts, and deeper and more extensive yellow above eye; tarijensis is larger, similar in plumage to previous, but browner above and buffier below; pallidulus is palest, and less strongly streaked on upperparts than nominate.

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Editor's Note: Additional distribution information for this taxon can be found in the 'Subspecies' article above. In the future we will develop a range-wide distribution article.

Variety of grassland, from tall grassland to savanna, campos and cerrado of Brazil, as well as drier pampas in S Brazil, Uruguay and Argentina; moist grassland, in pampas also those moist enough to have sedges (Cyperus articulatus). Found also in pastures and other agricultural areas with grassy field edge. Absent where overgrazed and grass is too short. To 1300 m.

Resident in much of range; possibly short-distance migrant in C Argentina.

Diet seeds and insects, latter particularly during breeding season. Forages exclusively on ground. Adults specialize on grass seeds, and will use feet to pull down taller grasses, enabling them to feed on them while on ground.

Season Apr–Aug in N and Sept–Feb in S. Cup-shaped nest placed on ground, with runway leading to it through grass; sometimes grass grows over runway, creating loosely covered tunnel. Clutch 3–4 eggs, pale whitish. No other information.

Not globally threatened. Fairly common throughout most of extensive range. Preference for a variety of grassy and open habitats makes this a low-sensitivity species, and forest clearance likely increasing available habitat for it. Occurs in several protected areas.