|Geographical Range||Parts of India, China, southeastern Asia, Malaysia and Indonesia|
|Habitat||Evergreen and moist deciduous forests|
|Scientific Name||Buceros bicornis|
|Conservation Status||Near threatened|
The first thing you notice about the great hornbill is the golden-yellow horn (called a casque) on the top of its head. This curious feature serves several functions. It acts as a "resonating chamber" that amplifies the nasal sounds that the birds make. The casque is also an indicator of sexual maturity. Although immature hornbills start developing a casque at six months of age, it takes five years to develop a really prominent structure.
The casque may look heavy and cumbersome, but it's actually very light. It's made up of thin, hollow cells supported by tiny, hollow bones.
The great hornbill is well named; it's the largest member of the hornbill family. It weighs an average of seven pounds and stands two-and-a-half feet tall, with a wingspan at least as wide.
In addition to its large casque, the bird has a huge down-curved bill, a black band across its mostly white tail, and a black patch of feathers around its face. The feathers that appear yellow on the neck, breast, wing, and tail are really white, but are stained with preen-gland oils.
Although male great hornbills are slightly larger than females, there's a sure-fire way to tell the sexes apart. In the female, the iris of the eye is white, while the skin surrounding the eye is pink to red. The iris of the male is red, with black skin surrounding the eye.
Fruit is by far the favorite food of great hornbills, though they've also been observed eating snakes, lizards, small rodents, and large insects. Depending on where the birds live, some populations even develop their own particular preferences: scientists report that figs make up 73% of their diet in India.
Recent research has begun revealing the role that great hornbills play in dispersing the seeds of numerous fruit trees. They deposit the seeds of the fruit they eat in their droppings, thereby transporting the seeds elsewhere and helping the forest renew itself. Their importance in forest regeneration is similar to that of many other fruit-eating animals.
Can You Hear Me Now?
Hornbills don't seem to mind being conspicuous. In fact, they frequently make their presence known with their loud calls -- a very useful means of communication in dense forests. The calls are often uttered back and forth by two birds in "duets".
The hornbills' calls help the birds maintain contact with each other, and are also used by males to claim possession of their territory. Males and females can often be distinguished by differences in pitch.
Hornbills are fairly social birds. Though they don't live in large flocks, they typically form cooperative groups comprised of a dominant breeding pair, immature adults, and juveniles. The birds tend to be monogamous (keep the same mate).
During mating season, male hornbills may become aerial acrobats as they compete for a mate. They sometimes engage in a head-to-head "casque-butting" contest while flying in the air! The prize? The right to mate with a female!
Great hornbills are territorial and usually spend their lives in one area. They keep to a regular schedule of feeding and roosting: they're active during the day, moving about in their small family units.
Just Give Me a Little Privacy!
A female great hornbill typically lays two eggs, though only one chick usually hatches from a clutch. In the wild, the mother lays her eggs in the cavity of a large tree between January and April. Then comes one of the most amazing behaviors in the bird world:
With the male on the outside of the tree hole and the female inside, the pair works together to enclose the female and her eggs inside. They use a combination of dung and food to seal up the cavity entrance, leaving only a small slit. The female stays there until her chick hatches and is nearly ready to leave -- up to four months! This self-imposed isolation keeps her safe from predators as she incubates her young. During this time, the male feeds her through a small slit in the nest opening. (Talk about a trusting mate...)
The female finally breaks her way out of the nest cavity a week or more before her chick is ready to leave the shelter. She does this to help her mate find food to feed their growing baby. With an amazing display of instinct, the baby immediately rebuilds the entrance barrier! Then both parents take turns feeding the baby until it is ready to come out permanently.
Here at the Saint Louis Zoo, the female hornbill doesn't emerge before her chick but stays inside the tree cavity until the baby is ready to emerge. This variation from wild behavior is the result of the plentiful food supply available in captivity -- there's no need for her to join the mate in searching for food for the chick.
Help for Hornbills
Although the species is spread over a wide range, great hornbill populations are declining in many areas due to habitat destruction. The birds are also threatened by hunting and trapping for food, tribal medicinal use, and trade.
Governments and conservation groups are working to help great hornbills. Refuges have been set aside for these birds, as well as for the protection of native fig trees. In Thailand, local people are paid stipends to guard hornbill nests. Zoos across the world, including the Saint Louis Zoo (see side story) are also helping with captive breeding programs.
- The great hornbill has never been seen drinking water.
- Every year, the Saint Louis Zoo sends the molted tail feathers from our great hornbills to Indonesia, where they're used for ceremonial costumes.