Weird & Wonderful Creatures: Rhinoceros Hornbill

Rhinoceros Hornbill (Buceros rhinoceros) by Mark Louis Benedict. Licensed under CC BY-NC-ND 2.0 via Flickr.

The rhinoceros hornbill (Buceros rhinoceros), the national bird of Malaysia, is noted for the colorful protuberance, known as a casque, sticking out of its head above its beak.

The casque is made of keratin, the same type of protein that makes up human fingernails, and is hollow inside. Scientists believe that it helps to serve as a resonator for the bird's calls, helping them to sound loudly across a large distance. The casque is white when the bird is born, but as it matures over its first six years, the bird's grooming habits will help it gain its brilliant yellow-red hue. Like most birds, the rhinoceros hornbill secretes oil from a gland, the uropygial gland, at the base of its tail that it will spread with its bill and casque to help keep its feathers healthy. In some birds, such as flamingos and hornbills, this oil contains pigments that give the birds their striking colors. Scientists are investigating whether the oil may also have antiparasitic effects in some bird species.

The rhinoceros hornbill is a large bird, growing up to 50 inches in length and 4.5–6.5 pounds in weight, with a wingspan of up to five feet. Its body is black and its tail is white, with a black band across the center of the feathers. Its thighs and stomach are white. Like all hornbills, its top two vertebrae are fused together, an adaptation unusual in birds, but useful for helping to support the additional weight of the casque.

Hornbills primarily eat fruit, but will also consume insects, lizards, snakes, and small mammals. Their eyes—red in males, white in females, as shown above, and protected by eyelash-like feathers—face forward, giving them the advantage of binocular vision (where both eyes look at the same image and develop a three-dimensional picture of it in the brain), however, their beak gets in the way of this vision. Scientists think this allows them to see the tip of their bill and to better manipulate small pieces of food. Their tongues aren't as long as their beaks, so to consume food they've caught, they must toss the food back into their mouths with a jerk of their head.

Hornbills are monogamous, mating for life. When the birds are ready to lay their eggs, the pair finds a narrow crevice high up in a tree. The female enters the hole, which must be sufficiently spacious inside to accomodate a large bird and a couple small chicks, and then the birds work to seal the hole, using fruit, feces, and mud, leaving only a small opening which she will use to empty her nest of excrement and which the male will use to deliver food. The female lays 1–2 eggs, which she'll sit on for 40 days. A month after the young are born, the female will break through the barrier to the outside, and then both parents and young will work to reseal the hole. The parents will continue to deliver food for nearly another two months, before the chicks are ready to leave the nest, and may continue to care for their young for an additional six months outside the nest.

The rhinoceros hornbill lives in in the treetops of large tracts of lowland and hill evergreen forest in southern Thailand, parts of Malaysia and Indonesia, Brunei, and Singapore. Because of their size, the birds cover large distances in their quests to find food and, during the course of their travels, they transport fruit seeds further afield for germination, earning them the nickname "The Farmers of the Forests."

The birds have been designated near-threatened due to increased commercial and illegal logging and agricultural development in lowlands. Traditionally, the rhinoceros hornbill also has been hunted for food and hat feathers by local tribes in Borneo. Rhinocerous hornbills raised in captivity can live up to 35 years, but there is little information about their natural lifespan in the wild.

You can learn more about the rhinoceros hornbill at All About Birds, a comprehensive, online guide to birds from the Cornell Laboratory of Ornithology.

In the Bird Beaks lesson (3-5), students can explore the relationship between a bird's beak and its ability to find food and survive in a given environment. Scientists don't just study a bird's beak; they also look at its feathers. In Feathers: The Evolution of a Natural Miracle (9-12), students learn more about the predictive power of scientific theories and fossil evidence by studying the evolution of feathers.

In the Bird Populations lesson (9-12), students learn how scientists discern patterns and changes in bird populations. The Feather Analysis (6-12) episode of Science Update also discusses one technique for tracking birds. If you're interested in this topic, you might also enjoy this blog post about the tracking of the migratory path of the golden eagle

The Wild Trees (9-12) lesson does not cover trees in the areas of the world where you'd find hornbills, but it does talk about tall, coastal redwoods and the challenges faced by those who want to explore and study the forest canopy. Because rhinoceros hornbills prefer to nest high up in their native forests, there may be some crossover interest.

Finally, if unusual birds are your thing, check out two other wild and wonderful creatures: the potoo and the black-cheeked lovebird. You can also learn about the kakapo, the Victoria crowned pigeon, and the goshawk.


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