Rhinoceros Hornbill

About the rhinoceros hornbill

The rhinoceros hornbill is a large species of forest hornbill found in lowland and montane tropical and subtropical forest, including mountain rainforest up to 1,400 meters, across the Malay Peninsula from southern Thailand and on the islands of Singapore, Borneo, Sumatra, and Java. It measures 80 to 90 cm (31 to 35 in) long, with males weighing about 2,465 to 2,960 g (87 to 104 oz) and females somewhat lighter at 2,040 to 2,330 g (72 to 82 oz). Its plumage is predominantly black, with white legs and vent and a white tail crossed by a black band.

The bird's namesake feature is its huge bill and casque, colored orange and red from preen oil the bird rubs on from a gland above its tail, and shaped in a way that recalls a rhinoceros's horn — the origin of its species name. The genus name, Buceros, comes from the Ancient Greek for "ox" and "horn." Carl Linnaeus formally described the species in 1758, placing it with the great hornbill in the genus Buceros. The sexes can also be told apart by eye color: males have red eyes with black rims, while females have white eyes rimmed in red. Three subspecies are recognized, distributed across Borneo, the southern Malay Peninsula and Sumatra, and Java.

The rhinoceros hornbill holds official status in Malaysia, where it is both the national bird and the state bird of Sarawak, protected under Sarawak's 1998 Wild Life Protection Ordinance as a "totally protected animal." In captivity, it can live up to 35 years.

The bird carries cultural weight well beyond its official status. Some Dayak peoples, especially Ibanic groups, regard it as the chief of worldly birds, and its statue is used to welcome Sengalang Burong, the god of the augural birds, to feasts and celebrations. It is sometimes mistakenly thought to represent a war god in these traditions — that role instead belongs to the brahminy kite. The rhinoceros hornbill also appears on the reverse of the 5 Malaysian ringgit bill.

Behavior and diet

The rhinoceros hornbill's diet is dominated by fruit, though it will also take insects, small reptiles, rodents, and smaller birds when it can catch them.

Its breeding behavior depends on close cooperation between the pair, since the female must rely on the male to provide for her throughout incubation and chick-rearing. Nests are built inside tree trunks. After the female lays her eggs, she remains sealed inside the cavity with them and, later, the chicks, while the male collects mud to help wall up the entrance alongside food and feces, leaving only a small hole through which he passes food to the female and chicks and through which the female defecates. Once the chicks are fully feathered and ready to leave, the parents chip away the dried mud seal to let them out. Interbreeding between the rhinoceros hornbill and the great hornbill has been recorded, with chicks successfully raised.

Range and habitat

The rhinoceros hornbill is found across the Malay Peninsula from southern Thailand, and on the islands of Singapore, Borneo, Sumatra, and Java, in lowland and montane tropical and subtropical forest, including mountain rainforest up to 1,400 meters in elevation. Its three recognized subspecies correspond to distinct parts of this range: Buceros rhinoceros borneoensis, described in 1845, occupies Borneo; the nominate subspecies, Buceros rhinoceros rhinoceros, described by Linnaeus in 1758, occupies the southern Malay Peninsula and Sumatra; and Buceros rhinoceros silvestris, described in 1816, is found on Java.

Conservation status

The rhinoceros hornbill is listed as Vulnerable, having been uplisted from Near Threatened on the IUCN Red List in 2018. Its main threats are the loss of the rainforest habitat it depends on, along with hunting for its meat, skull, and feathers. Habitat destruction compounds the hunting pressure by removing the large trees the species needs for breeding, which in turn makes remaining birds easier for poachers to locate. Confusion with the more heavily targeted helmeted hornbill also puts rhinoceros hornbills at risk of being shot by poachers seeking that other species.