A bird well known to locals, the Blue-black Grassquit has become increasingly unusual in Rio de Janeiro. Measuring about 11 centimeters, the male of the species has an unmistakable black plumage in the reproductive period, presenting shades in metallic blue, when in good light. Outside the reproductive period, the male starts to have brownish plumes in the head, back and chest. The female is brownish, with small streaks on the chest and belly, which are lighter. He usually walks in mixed flocks, together with other birds, in search of grass seeds and insects on the ground. It can be seen occasionally in the grassy areas of the Campus.