for human habitation compared to other hornbills. Described as social and noisy, their loud, disjointed “yak-yak-yak” cackling between flock mates comes across as harsh.
Their diet consists primarily of fruit, like figs, rambutans, and palm, as well as insects and small animals, such as reptiles (lizards and frogs), birds, and mammals. They are important forest seed dispersers, consuming fruit seeds too large for smaller birds, resulting in visiting inhabited regions to feed on fruit. Despite being large birds that fly quite awkwardly, their foraging behaviour is quite quiet and involves pairs or small groups.
THREATS
The Oriental pied hornbill is listed by the Red List of threatened animals of Singapore as ‘Critically Endangered’ but ‘Least Concern’ by the IUCN Red List of Threatened Species. Humans are the biggest threat to the hornbill, with humans in Sarawak, Malaysia hunting them for their meat and feathers, regardless that the hornbill is the state bird. However, the Helmeted hornbill (Rhinoplax vigil) is hunted because its bill can be carved in a similar way to ivory. Both the Helmeted hornbill and Rhinoceros hornbill (Buceros rhinoceros) used to be found in Singapore, however, they are now no longer present.
REPRODUCTION
Hornbills are typically monogamous and are dependent on large, tall trees for nest sites, nesting in suitable cavities. As secondary cavity nesters, they take advantage of nest sites already created by other birds and do not normally excavate their own nest sites.
Oriental Pied Hornbill Infanticide & Cannibalism
Malaysia
The Oriental pied hornbill (Anthracoceros albirostris), also known as an Indo-Malayan pied hornbill, is one of the smallest and most common out of the Asian hornbills. Both males and females are similar in coloration, with black-and-white plumage and a whitish-yellow bill and casque, otherwise known as a “helmet”, which is a knob above the bill. The bill is unique as it is made of honeycombed tissue and not solid bone like most birds. The average head-to-tail length of this large bird is 55-60 cm, with a wingspan of 23-36 cm. Males have a larger body size than females, weighing an average of 900g compared to 875g for females, with a larger bill and casque that has fewer black marks, and bright red eyes.
HABITAT & DIET
The Oriental pied hornbill is a large canopy-dwelling bird found throughout Southeast Asia and in the Indian Subcontinent. In the genus, it has the largest distribution, inhabiting tropical and subtropical moist lowland and secondary forests, as well as woodlands and plantations. They can be located outside primary rainforests but are also occasionally found in large city parks and open forests and forest edges due to their higher tolerance
The female will enter the selected cavity and seal herself inside using a mixture of saliva and earth, like mud, droppings, and tree bark, that the male has gathered. Leaving just a narrow slit, the male can provide foraged food through the gap and the female can then feed her nestlings. This is believed to help protect them from predators. Breeding season for hornbills occurs between January and June, with the Oriental pied hornbill usually beginning breeding in February when the onset of rain occurs. This differs based on geographical location, and when there is a peak abundance of fruit. The female and chicks will remain inside the nest for several months until the chicks are ready to fledge. Studies show that the Oriental pied hornbill can return, over subsequent nesting seasons, to their previous nest.
"An unusual discovery revealed the Oriental pied hornbill carries out infanticide followed by cannibalism"
INFANTICIDE-CANNIBALISM
Infanticide has been documented in the Barn Swallow and Guira Cuckoo alongside other species, and siblicide has been reported amongst chicks in species like the Madagascar Fish Eagle. Siblicide can either be obligatory, where a sibling almost certainly gets killed, or facultative, where siblicide is based on environmental conditions and, thus, may or may not occur. Obligatory siblicidal species normally involves a dominant aggressive chick reducing the brood size to one, compared to facultative siblicide where brood reduction is likely related to food resources, for example, for the raptor Osprey. Dietary factors are also a likely explanation for cannibalism in the common pheasant.
An unusual discovery revealed the Oriental pied hornbill carries out infanticide followed by cannibalism. The Singapore Hornbill Project took place on Pulau Ubin, an island north-east of Singapore in the Straits of Johor, located in mixed secondary forest with old fruit plantations of mainly durian. The Oriental pied hornbills on the island started breeding after originally visiting from Malaysia. The four nest sites were 0.6–2.7 km apart, with tree cavities 7-12.1m high. Here they placed video cameras in unoccupied nest cavities in forests of the island for two months from December to January.
In the wild, observations have indicated that the largest clutch size of Oriental pied hornbills is three eggs, however, in captivity, four eggs have been documented. After continuous monitoring of nests in the wild, four-egg clutches may not be unusual which is also supported by other studies and where the observed unexplained loss of chicks occurred. It is believed that the female Oriental pied hornbill commits infanticide of the youngest chick and feeds the individual to the three other chicks to increase their chances of survival. This is interesting due to the presence of a constant food supply and high feeding rates occurring; thus, lack of food does not explain this behaviour. It is suggested that the Oriental pied hornbill has evolved the infanticide and cannibalism behaviour as it benefits the female to lay more eggs than the number of chicks that can be raised effectively. This behaviour reduces the brood size, allowing investment of resources only to the healthiest chicks, whilst ‘recycling’ the weakest and youngest chick between its siblings.