Rather large, dark, yellow-tailed bird of humid evergreen forest and edge in tropical lowlands. Where present, colonies of large pendulous nests adorn tall trees. Often in flocks, usually in forest canopy at fruiting trees. Male is much larger than female, but sexes look similar, with a dark, rich brown head and body, blackish upperparts, pale yellowish bill, and bold yellow tail sides. Flight much quicker than larger Montezuma Oropendola, with deep, rather swooping wingbeats that produce a rushing sound.