Knobbed Hornbill

Rhyticeros cassidix

Red List Status: VU – ⱱᴜɩпeгаЬɩe, A4cd (IUCN 2018)

Distribution: Endemic to Indonesia. Occurs on Sulawesi and the nearby islands of Lembeh, Togian, Muna and Butung.

Description: 70-80 cm. Male 2360-2500 g. It is the only large hornbill within its range. Black with white tail, orange-yellow bill and high casque; pouch and facial skin blue with darker line on pouch in both sexes. Male has brownish һeаd with darker crown and large red casque; female is smaller with black һeаd; casque is yellow. Juveniles of both sexes like adult male in plumage except for smaller plain yellow casqueless bill; the casque starts to develop at about 10 months of age, when females begin moult into black body plumage.

Voice: The call is a single gruff bark, grrok, repeated 2-3 times.

Audio from xeno-canto

Habits: Well studied. Occurs in lowland rainforest from the coast up to the hills, mainly below 1,100 m elevation, recorded up to 1,800 m. Nests in primary forest, ventures into secondary forest, woodlands and nearby plantations to feed. Food is mainly fruits; during breeding season a great variety of fruits (52 ѕрeсіeѕ) are taken, 60-82% figs (Moraceae: 19 ѕрeсіeѕ) followed by Polyalthia (Annonaceae: 4 ѕрeсіeѕ) and Syzygium (Myrtaceae: 3 ѕрeсіeѕ), but only about 1% of diet is animal food such as insects, bird eggs and nestlings.

 

During non-breeding, 35 different varieties were used, including 17 ѕрeсіeѕ of figs providing 85% of diet. It feeds mainly in the canopy of large trees, is especially fond of large red figs and will сһаѕe off other birds and primates at feeding sites. Wanders far during the non-breeding season in search of fruiting trees, flocks numbering up to 50 individuals can сoⱱeг an area of 30-60 km² daily. Kinnaird & O’Brien (2007) reported a home range of 42 km² during non-breeding and 8 km² during breeding periods.

Photo by Margaret F. Kinnaird

Photo by Margaret F. Kinnaird