Description
Measuring 15–18 cm (5.9–7.1 in) in length with a wingspan of 24.75 cm (9.74 in) and ranging from 19.0 to 35.4 g (0.67 to 1.25 oz) in mass, the adult Golden-crowned Sparrow is fairly large for an American sparrow. Like all Zonotrichia sparrows, it has a relatively long, square-tipped tail and a slightly peaked crown. Males and females are similarly plumaged, though males average slightly larger than females. Other than a plain gray nape, the adult's upperparts are grayish-brown, with broad brownish-black streaks on the back and scapulars, and unstreaked rump. Its underparts are gray, slightly paler on the belly and buffier on the flanks. Its wings and tail are brown, and it shows two white wing bars. Its legs are pale brown, and its bill is dark, with the upper mandible darker than the lower. Its iris is brown.
In the breeding season, the Golden-crowned Sparrow has a broad yellow central crown stripe which becomes pale gray towards the back of the head.
Studies show that the Golden-crowned Sparrow's black and gold head stripes are used to signal social status in wintering flocks. Such signals help to reduce the incidence of confrontation between flock mates, thereby reducing such potential costs as injuries or the unnecessary expenditure of energy. The size and color of a bird's crown patches are better predictors of dominance (indicating which bird will avoid confrontation with another) than are the bird's size or sex. Birds with similarly sized gold crown patches are far more likely to engage in agonistic behavior than are those showing differences, and the outcomes of such confrontations can be predicted based on the color of their black stripes. This suggests that social status in this species involves more complexity than a single signal will allow, and that the multiple color patches allow a gradient of interactions between flock mates.
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