Casqued Cacique Cacicus oseryi Scientific name definitions

The Casqued Oropendola is a relatively small, stocky oropendola restricted to the lowlands of extreme western Amazonia, where it is largely confined to eastern Ecuador and eastern Peru, and is only found within reasonably dense forest. It seems to be largely dependent on seasonally flooded forests, at least for nesting, but the birds certainly range into terra firme forests in order to forage. The body and wings are largely chestnut-colored, but the breast and neck sides are olive-yellow, and the throat is slightly grayish. Both the primaries and the rectrices show prominent yellow edges. Both sexes of Casqued Oropendola possess whitish irides and a prominent pale casque to the bill. The species’ loud, sometimes even raucous calls often provide the first clue as to the Casqued Oropendola’s presence.

Male average 37 cm, 187·7 g; female average 29 cm, 101·4 g. Plumage is mostly rich chestnut , darkest on foreface, with greyish-olive throat and yellowish-olive upper breast and side of neck; upperwing chestnut, yellow edges of flight-feathers; tail dusky olive, outer feathers bright yellow; iris light blue, rarely pale yellowish-grey; bill variable, sometimes upper mandible dark grey, lower mandible yellow-green with dark grey tip, casque dull yellowish-grey to olivaceous grey, sometimes ivory-coloured with or without greenish tinge and with dark grey towards tip, sometimes entirely dark grey (variation in casque and bill colours perhaps related to age); legs black. Sexes similar but female much smaller, with smaller casque. Juvenile has dark eyes.

W Amazonia from E Ecuador (Sucumbíos) and extreme SE Colombia (Leticia, in Amazonas) S to E Peru, W Brazil (W Amazonas, Acre) and N Bolivia.

Diet probably arthropods, small vertebrates and nectar. Stomach contents include unidentified red berries. In Brazil seen to feed on fruits of a Coussapoa species (Moraceae) and in Peru on <em>Cecropia</em> fruits . Reported as flocking with Cacicus cela. Roosts communally with other oropendolas and caciques.

Song variable, one type a “klow klow shrr-weo”, with tonal quality of Cacicus haemorrhous; nesting colonies very noisy.

Season Sept–Nov in Peru. Polygynous, but detailed studies of breeding lacking. Colonies of 14–25 nests, located along small rivers; breeding activities highly synchronized, e.g. all nests in colony of 19 nests were built in about a week; sometimes nests with Cacicus latirostris. Nest built by female, a purse, open at top, woven from diverse brownish plant fibres, in shape resembling that of colonial Cacicus species; all known colonies in Peru and Brazil were in isolated Cecropia trees. Incubation of eggs by female; male parental role is mostly that of nest-guarding and defence of colony against monkeys, toucans (Ramphastidae) and other predators. No other information.