Wrinkled Hornbill (Rhyticeros corrugatus )

Previously considered in genus Aceros. Has in past been considered conspecific with Writhed and Rufous-headed Hornbills of the Philippines, but there are clear morphological differences and separate south to Sumatra and nearby islands have sometimes been separated as race rugosus on basis of larger size.

Size 67-75 cm. Male 1590 g. Male distinguished from male Wreathed Hornblill by black (not brown) crown and nape, white face and throat but stained with yellow from preen oil, unbarred pouch white (not yellow), bill white but stained yellow with red at the base of upper mandible and brown wrinkle on lower mandible, and high red wrinkled (not wreath, creamy) casque.

Both sexes have blue orbital skin (not red). The female is smaller, black with blue unbarred pouch; from female Wreathed Hornbill by yellow (not creamy) bill and plain casque (no ridges).

Juveniles of both sexes resemble adult male in plumage but bill small, casqueless and pale yellow. The voice is 1-3 coughing notes repeated at intervals, “sok…sok…sok” or “kowwow”, a softer version in flight. Also utters very harsh “pukekkek”.

Ecology and habits

Found in lowland rainforest, especially coastal swamp forest; usually below 30 m elevation but recorded up to 400 m a.s.l. Extends into selectively logged forest, but not secondary forest.

It is not conspicuous and is usually seen more than heard. Feeds in the canopy of large emergent trees, mainly on fruits such as drupes; it is less attracted to figs than some other hornbills.

It also takes some animal items when available. Breeding diet 67% fruit, with Oncosperma horridum (Arecaceae), Litsea and Cinnamomum (Lauraceae), Aglaia (Meliaceae), Gymnacranthera (Myristicaceae) and Syzygium (Myrtaceae) predominant, and 33% animals, mainly insects and land snails but also feeds on reptiles frogs and bird’s eggs.

It searches through the foliage for food or occasionally picks off fruits in flight. Usually lives in pairs but sometimes in small flocks of up to 30 individuals. It move extensively in search of fruiting trees on loud whooshing wing-beats, flying up to 10 km. high above the forest.

It also attends communal roosts; has been know to cross open sea.

Breeding ecology

Eggs are laid in the beginning of the year, Jan-May. Rather aseasonal, in southern Thailand female seals in nest cavity in Feb-Mar and a chick fledges in early Jun. However, there were records form the same area where the females sealed between Jun-Jul and a chick fledged in Oct.

The entire nesting cycle takes 95 days in this area. The nest is a natural cavity in a large forest tree, such as a large Shorea cutisii (Dipterocarpaceae), Artocarpus (Moraceae) or Syzygium (Myrtaceae) near a stream; the female seals the nest entrance with droppings and food remains.

The breeding ecology is little known in the wild; in captivity it lays 2-3 eggs, rarely 4, after a pre-laying period of typically 4-6 days, sometimes longer. Incubation is 29-35 days; the male brings food to the nest and feeds the female by regurgitation.The female leaves the nest together with the chick at fledging. The nesting period tales 65-73 days in captivity but only 35-54 days in the wild; the whole breeding cycle may last up to 124 days.

Wild birds probably feed chicks up to at least 6 months after fledging and stay together in family groups until juveniles become independent and move to own immature flocks.