The knobbed hornbill is classified in the IUCN Red List as Vulnerable (VU) and in CITES Appendix II. Its national protection is stipulated under Law No. 5 of 1990, Government Regulation No. 7 of 1999, and Regulation of Minister of Environment and Forestry No. 20 of 2018 on Protected Flora and Fauna Species.
A large bird, a male knobbed hornbill’s body length reaches 70-80 cm and weighs 2.36-2.5 kg. Its body and wings are black with metallic green tinge on its back. Tail white, legs black.
Male bird has high, wrinkled casque that is reddish brown in color. Its crown and nape are brick red-brown. The gular pouch under its mandible is deep blue with a dark line coming around below. Male knobbed hornbill’s eyes are reddish orange.
The female has yellow beak with brownish orange folds on the base. Its body and casque are smaller compared to its male counterpart. Casque yellow, head and neck are black. The female’s gular sac has a finer black line. The eyes of a female knobbed hornbill are brownish orange.
The knobbed hornbill’s primary source of food are fruits. Occasionally it will eat animal foods like insects, bird eggs and young chicks. The knobbed hornbill forages in the forest canopy. The species is able to pick fruits while flying and driving away other birds and primates from the fruiting tree.
In general, the knobbed hornbill feeds on mornings and early evenings. In Tangkoko-Batuangus Nature Reserve, the species is more active in the late afternoon-early evenings due to competition with other frugivores, especially the black crested macaque (Macaca nigra).
Knobbed hornbills require large trees to breed and nest at 13-53 m above the ground. They usually nest in tree hollows plastered with mud to protect the egg from predators.
Breeding begins at the end of the rainy season around June-July. The knobbed hornbill lays 2-3 eggs with 32-35 days incubation period. The female may leave the nest after 58 or up to 140 days. From those three eggs, usually only one chick survives.
The decline in knobbed hornbill population is due to a number of factors, including habitat degradation due to logging for construction materials, as well as poaching of the birds by shooting. Its feathers are used as bait for marine fish.
This endemic bird can produce loud calls heard from more than 2 km away. In addition, its feathers and casque is thought to be able to protect the residents of a home from evil spirits or ensure victory, and are also used as head ornaments and drums in the traditional Cakalele dance.
