Blue-black Grassquit Volatinia jacarina Scientific name definitions

The Blue-black Grassquit is a common and widespread species occupying a variety of open habitats from weedy fields to second growth throughout much of the neotropics from Mexico south through northern Chile and northern Argentina. Males sing conspicuously from fences and grass stalks, hurtling their entire body into the air with each song. During the nonbreeding season, the species form flocks that can sometimes number a few hundred individuals.

8·7–10·9 cm; 8–12 g. Tiny passerine, having longish conical bill with slightly and evenly curved culmen. Male nominate race has head, neck, upperparts and underparts black with dark blue iridescence (in fresh plumage, often narrow brown tips of feather); flight-feathers and tail matt black (lacking iridescence), upperwing-coverts and tertials iridescent like body; patch of white on axillaries and underwing-coverts and at bases of remiges (normally visible only during display), rest of underwing black; iris brown; upper mandible blackish, lower mandible mostly pale grey to horn-coloured; legs grey to greyish-flesh or plumbeous-horn. Female is warm brown, darker above than below, crown, mantle and back very indistinctly streaked, nape and hindneck unstreaked, rump and uppertail-coverts plain warm brown, lacking contrast with back; wings and tail brown, median and greater upperwing-coverts edged brown or buff-brown, paler tips forming two indistinct wingbars, tertials also edged buffy; outer tail feathers tipped buff when fresh; warm buff below (sometimes a cinnamon wash on breast), breast with loose streaks forming distinct streaked breastband that continues to flanks, contrasting with unstreaked throat and belly. Juvenile resembles female, but with darker wings and tail, and coarser and more extensive streaking on underparts; through first winter young male gains blackish feathers in patchy manner throughout body and head, creating patchy calico pattern of streaky brown and black, which is distinctive. Race splendens has reduced or little white on axillaries; peruviensis is similar to previous, but has more white on axillaries, flight-feathers brownish (instead of blackish), also retains brown immature male plumage for longer time than other races.

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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.

Diet mostly seeds, especially of grasses (in genera Paspalum and Panicum); also a few insects and berries, and Cecropia protein corpuscles. Forages on ground; also picks seeds from grass-heads. In pairs during breeding; at other times in flocks, sometimes large ones, and often associated with other seed-eaters.

Song an emphatic metallic “eee-slick”, or “bzeé-eep”, or buzzy “b-zeer”, often given during flight display just before alighting.

Season Apr–Oct in whole range, also Nov in NC Venezuela; late May or early Jun to late Aug in El Salvador; sometimes two or three broods raised in a year. Monogamous; extra-pair copulations common. Solitary, but nests often close together and territories small (1 Dias, R.I., Kuhlmann, M., Lourenço, L.R. and Macedo, R.H. (2009). Territorial clustering in the Blue-backed Grassquit: reproductive strategy in response to habitat and food requirements? Condor. 111(4): 706–714. Close ). During display, male “jumps” from perch , flapping wings six times or more, exposing white in underwing, and vocalizes just before landing; may jump several times in a minute. Nest built by both sexes, a small, thin-walled cup of fibres and grasses, lined with finer rootlets and spider webs, placed within 1·2 m of ground in grass of low bush. Clutch 3 eggs, sometimes 2, bluish-white with brownish or purplish spots, these concentrated at larger end; no information on incubation period; chicks fed by both parents, nestling period c. 9 days.

Not globally threatened (Least Concern). Generally common to abundant. Often very common, breeding in high densities, at optimum sites. Does well at edges of fields in agricultural areas.