The Chestnut-headed Oropendola Psarocolius wagleri is a New World tropical icterid bird. It is a resident breeder in the Caribbean coastal lowlands from southern Mexico to central Costa Rica, both slopes of southern Costa Rica and Panama, and the Pacific lowlands of Colombia and northeastern Ecuador.
The Chestnut-headed Oropendola inhabits forest canopy, edges and old plantations. It is a colonial breeder which builds a hanging woven nest of fibres and vines, 60-100 cm long, high in a tree. There may be 40-50 females and only 4-5 males in a colony. The female lays two dark-marked pale blue eggs which hatch in 17 days and fledge in 30. Botflies are the main cause of nestling mortality, but brood parasitism by Giant Cowbirds also occurs, and the young cowbird will feed on the fly larvae.
The Chestnut-headed Oropendola is a quite common bird in parts of its range, seen in small flocks foraging in trees for large insects, fruit and berries. The male is 35 cm long and weighs 225g; the smaller female is 28 cm long and weighs 125g. The wings are very long.
Adult males are mainly black with a chestnut head and rump and a tail which is bright yellow apart from two dark central feathers. The iris is blue and the long bill is whitish. Females are similar, but smaller and duller than males. Young birds are duller than adults and have brown eyes. The populations south of an area around the border of Honduras and Nicaragua are sometimes separated as a subspecies P. w. ridgwayi, but the separation of this form has been questioned.
The distinctive songs of the male include a gurgle followed by a crash guu-guu-PHRRRRTTT. Both sexes have loud chek and chuk calls.
The scientific name of the species commemorates Johann Georg Wagler, who named the oropendula genus Psarocolius.