Large blackbird with thick triangular bill. Dark blackish plumage, fading to paler reddish-brown at rear. At a distance, appears all black. Striking yellow tail and pale blue eye. Separated from other oropendolas by combination of large size and dark color. Often found in loose flocks anywhere with some trees, including forests, edges, and even disturbed open habitats. Oropendolas are colonial nesters that build hanging woven nests. Listen for bizarre gurgling noises.