Hornbill is a bird species and falls under any of the sixty species of the Old-World tropical birds of order Coraciiformes. The scientific name of hornbill is ‘Bucerotidae’, which means ‘cow horn’ in Greek. They are specifically noted for their characteristic feature of a bony casque which is crowned on their prominent bill. This is found only in a few species. They are found to have a large head that is held by a thin neck. Their wings are broad and their tails are long. The plumage is usually black or brown, having bold white markings. The size of hornbills ranges approximately from 16 inches (i.e., 40 cm) to 63 inches (i.e., 160 cm). The Tockus species is generally smaller in size than that of the great hornbills. Several hornbill species like the Rhinoceros hornbills have the preen gland near the base of their tail. When the beak and the casque rub against this gland, an oily, reddish-orange fluid is secreted which gives the beak and casque a bright, reddish tone. The picture of hornbill bird is shown below.
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The family of Bucerotidae has around 55 living species. Hornbills are found in tropical and sub-tropical Africa, Melanesia, Asia, and parts of the Pacific islands. They are also found in the Solomon Islands and the Philippines. In Africa, around 24 species of hornbill can be found. About 13 of those species are found in grasslands or open woodlands, while others are found in very dry areas or thick forests. One of the hornbill species is found in the open grasslands of Asia, while the rest dwell in the forests there. Indonesia has around 13 hornbill species, with Sumatra accounting for 9 of them, and the rest are found in Sulawesi, Kalimantan, Papua, and Sumba. In Thailand, 9 of these species are found. Even in India and near it, we find 9 species of hornbill birds. In Sri Lanka also, one of the many species of hornbill is found. In the era of Neogene, or the late Miocene, it was found that hornbills inhabited South Europe and North Africa and their remains have been found in Bulgaria and Morocco.
The size, weight, and wingspan of the male hornbills are larger than that of the female ones. The body mass of the males and females differ by 1% to 17%, their bill length varies from 8% to 30% and the wing length differs between the two sexes by 1% to 21%. The black dwarf hornbill is the smallest in the species with a weight of 99.1 g and a length of 32 cm. The southern ground hornbill has an average weight of .77 kg, with a maximum weight of 6.3 kg and a span of around 180 cm across the wings. This is the largest hornbill among all its species. Other species compete for the southern ground hornbill in length at up to 4 ft 3 in. Such species include the Abyssinian ground hornbill, the great hornbill, and the longest of all, the helmeted hornbill which is more than 4 ft 11 in.
The beaks of the hornbill bird are curved downwards. The horn-like casque on the upper of their beak is either filled with some spongy material or is hollow. The purpose of the casque is not known yet. The casque is composed of keratin, the protein by which our hair and nails are made of. In the case of the helmeted hornbill, the casque is not empty. It is filled with hornbill ivory which helps in dramatic aerial combats. The weight of the bill is held by the first two neck vertebrae which are fused. This special adaptation of the neck is found only in these birds. The large bill helps them in fighting, constructing the nest, preening, and catching the prey. These birds are non-nocturnal, that is, they remain active in the daytime. Hornbills have binocular vision but, unlike others, their bill interferes with their visual field. This allows them to see the tip of their bill and helps in handling objects with their bill.
Habitat and Diet
Hornbills make their nests in cavities, especially in that of large trees. Almost in all hornbill species except the two ground hornbills, Bucorvus, the male covers the nest leaving a small hole. Hornbills generally travel in small family groups or pairs. Outside the breeding season, they roam in large flocks. At the roosting sites, large assemblies of hornbills are formed where around 2400 individuals may be found. Hornbills have a short tongue so they cannot swallow their food caught at the beak tip. So, they jerk their head backwards and the food tosses to the throat. They are omnivorous animals, welling on fruits, small animals, and insects. Few species of the omnivore hornbill animals feed only on fruits and are found in forests. The rest of the carnivores are found in the open county. The species found in forests are an important way by which the seeds disperse far from the parent tree. Species that feed on fruits only are less territorial as fruits are distributed patchily, and require to travel long distances. On the other hand, some species defend their territories constantly.
The pairs made by hornbills remain for life and they return every year to nest in the same tree. Before nesting, food is gifted by the male to the female and takes her to the nest site. The nest site is generally made of a cliff face or the side of a tree. The entrance is blocked up by mud and other droppings from inside by the female. The male does the same from the outside. A small hole is kept open which is made to pass in food by the male mate and to pass out droppings from inside the nest. Safety from predators is maintained. The number of eggs laid by hornbills varies from species to species. Larger species lay only two eggs while the smaller species may lay up to eight eggs. The incubation period varies upon species but generally lasts for about 23 days to 4 days. Food is brought by the male to the female and the newborn.
After about six to seven weeks from the time the chicks hatch, the female breaks out of the cover while the newborn may be still walled. Now both the male and the female start feeding the young. The young take about 42 to 137 days to fledge, depending upon the species. The larger species become adults after 3 to 6 years while the smaller species become adults within a year. The total lifespan of a hornbill is about twenty years.
The hornbills are noted by the International Union for Conservation of Nature (IUNC) Red List of Threatened Species so that the majority is not on the verge of getting extinct. Species of hornbills like the bushy-crested hornbill (Anorrhinus galeritus) in South Asia and the crowned hornbill (T. alboterminatus) in southern Africa are extended in huge geographic ranges due to their large populations. However, due to hunting pressure and deforestation, ecologists found that the population of some species is under threat. The IUNC Red List classifies some species to be endangered which include the Narcondam hornbill, the Visayan hornbill (P. panini), a native to Panay Island and its small, neighbour islands, and the Mindoro hornbill (Penelopides mindorensis), which is from Mindoro in the Philippines. Also, the rufous-headed hornbill (Aceros Waldeni), also known as Walden’s hornbill, and the Sulu hornbill (Anthracoceros Montani) are listed to be critically endangered. Both the helmeted hornbill and the great hornbill are protected due to their casque, which is used as carving material like ivory.
Do You Know These Hornbill Facts?
The Rhinoceros Hornbill is the mascot of Sarawak city. But, other hornbills are also found here and for obvious reasons, the nickname ‘the land of hornbills’, is given.
Hornbills are the best friends of monkeys as these birds eat up the insects which annoy the monkeys. In return, the hornbills get warning calls from the monkeys if they see any humans.
The calls made by hornbills are very loud and distinct. The Indian great hornbills make a roaring sound, the Von der Decken’s hornbills make a clucking sound, and the southern ground hornbills make a resounding bass sound.
During the nesting period, the male bird can carry up to sixty fruits in a single go. They also flap their wings on the nest to communicate with the female. The flapping action creates a sound similar to a steam engine.
Besides constructing nests, the hornbills use their beaks to climb trees also.