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Rhinoceros Hornbill and the Horned Guan: Birds and Their Features

Linda Crampton is a writer and teacher with an honors degree in biology. She loves to study nature and write about living things.

A female rhinoceros hornbill reaching for a  peanut

A female rhinoceros hornbill reaching for a peanut

Two Birds With Head Ornamentation

Like mammals, some birds have horn-like structures on their head. Two birds with interesting head ornamentation are the rhinoceros hornbill and the horned guan. The first bird has a large and impressive casque. The casque is orange and extends over part of the bird’s head and bill. It’s sometimes curled upwards at the tip like the horn of a rhinoceros. The animal's population is classified as vulnerable. The second bird has a thick and upright horn that’s bright red and contrasts beautifully with the glossy back feathers on the upper part of the body. Unfortunately, this species is endangered.

The word "rhinoceros" is of Greek origin -- "rhino" meaning "nose", and "ceros" meaning "horn." This means that the Rhinoceros Hornbill's name could be translated to "Nose Horn Hornbill!"

— The National Aviary Website

Hornbill Family, Range, and Habitat

The rhinoceros hornbill has the scientific name Buceros rhinoceros. It belongs to the class Aves (like all birds), the order Bucerotiformes, and the family Bucerotidae (hornbills). The members of the hornbill family are large birds with big bills. Their casque varies in appearance. Some species have a large casque while others have just a bump on their upper bill or no visible cache at all.

The rhinoceros hornbill is found in Indonesia, Malaysia, and Thailand. It lives in the rainforest and emits a call that is often described as a "honk". The bird is sometimes heard before it's seen. The call can be heard in the video below.

A male rhinoceros hornbill has a red iris.

A male rhinoceros hornbill has a red iris.

Physical Features of the Rhinoceros Hornbill

Probably the first thing that most people would notice about the bird is its impressive casque. The casque sometimes looks like a third bill, especially when it's straight. If it's strongly curved upwards, it looks more like a horn. In a mature bird, it's a mixture of yellow, orange, and red in color.

The males and the females have a casque of almost the same size (though the female's is slightly smaller), so the structure can't be used to tell them apart. If someone is close enough to see the bird's eyes, a male can be distinguished from a female. The male's eyes have a red iris (the part of the eye that surrounds the central pupil), as shown in the photo above. The females have a white iris and a red ring around the outside of the eye, as shown below.

The bird is mostly black in color, with the casque providing a colorful highlight. The belly is white. The feathers at the top of the legs are white and have a fuzzy appearance. The long tail is also white but has horizontal black bands on both its upper and lower surface.

A close-up view of a captive female

A close-up view of a captive female

Facts About the Casque

Color

According to the National Aviary, the casque takes up to six years to reach its final size. The beak and the casque are white at first. During its life, the bird frequently runs its bill (and the attached casque) over an oil gland under its tail during the preening process. This action gradually changes the casque's color.

Structure

The casque is made of spongy keratin. Keratin is a protein in the human body as well as in birds. It's found in our skin cells, hair, and nails. It's also found in animal claws. The protein exists as fibers. The firmness of structures containing keratin in influenced by how compact the fibers are and by structural variations in the keratin molecules. The casque of the rhinoceros hornbill has a relatively low weight because of its spongy composition.

Function

The casque of Buceros rhinoceros is believed to amplify the bird's calls. It's thought to act as a resonating chamber and to be significant in communication, especially during the mating process.

Diet and Feeding

The rhinoceros hornbill spends most of its life in the tree canopy. The bird is a good flier. It has an omnivorous diet. It eats a lot of fruit—especially figs—but occasionally eats small animals. Its beak is long but its tongue is short. It often grabs hold of its food with the tip of its beak and then jerks its head back to move the food into its throat.

The bird is an important distributor of seeds. Many seeds are unharmed during their journey through the animal's digestive tract, and some are even helped by the conditions in the gut. When the bird drops feces containing the seeds, they are able to germinate. Since the bird is often in a new place when this happens, it enables the plant to spread.

Rhinoceros hornbills feeding at the Singapore Zoo

Rhinoceros hornbills feeding at the Singapore Zoo

Rhinoceros Hornbill Reproduction

Rhinoceros hornbills usually mate for life. They have an unusual and interesting method of reproduction. After mating and shortly before the eggs are laid, the female finds a hollow space in a tree and enters it. The male and the female then build a wall of mud, regurgitated food, and feces to seal the female in the tree. A small opening is left, through which the male feeds the female.

Once her eggs are laid and hatched, the mother and her family stay in the tree until the youngsters are about three months old. The mother periodically drops the feces produced by the group through the chamber opening, which keeps the area reasonably clean.

About three months after the birth of the chicks, the female breaks out of the hole. The family—reportedly including the chicks—then rebuild the wall. The chicks stay in the hole for another three months and are cared for by their parents. The youngsters then break the wall and fly away.

The video below shows part of a mating display in the species as well as preening behavior. It has no sound, but the behavior is interesting to see.

Population Status of the Rhinoceros Hornbill

The International Union for Conservation of Nature (IUCN) maintains a Red List. The list describes species and categorizes their population status. Buceros rhinoceros has been placed in the "Vulnerable" category, based on a 2018 assessment. The population is said to be decreasing.

The rhinoceros hornbill lives in primary evergreen forest. The IUCN says that the bird is currently widespread within its range, but its total population is thought to be low. Unfortunately, its habitat is undergoing rapid deforestation. In addition, the bird is attractive to hunters. It's caught for food and for the use of its casque and feathers in ceremonial dress and events.

The bird lives in some protected areas. This is helpful, but it's not enough. The IUCN has proposed certain conservation actions, including the following ones.

  • Determine the rate of contraction of the bird's range.
  • Investigate the cause of range contraction.
  • Attempt to protect the animal's habitat in the areas where it's most vulnerable.
  • Restrict hunting of the animal.

Galliformes Order and the Cracidae Family

The scientific name of the horned guan is Oreophasis derbianus. It belongs to the order Galliformes and the family Cracidae. The order includes some birds that are familiar for many people, including turkeys, chickens, grouse, pheasants, partridges, ptarmigans, and quail.

The Cracidae family contains guans, curassows, and chachalacas. The animals live in Central and South America. The range of the plain chachalaca (Ortalis vetula) extends into southern Texas, however. Some members of the family have a casque or a knob above their bill.

Physical Features of the Horned Guan

The horned guan is an attractive animal. It can be seen in the video screen above and in the videos below. Unfortunately, the only suitably-licensed photos of the bird that I've found are of low quality. Some physical features of the bird are listed below.

  • The bird has a white to pale-yellow beak, a white iris, and a red horn protruding from the top of its head.
  • The upper bill is longer than the lower one. Its tip curves downwards over the lower bill.
  • The bird's head is dark brown. The head is covered with feathers of a finer texture than the ones on most of the body.
  • The head is small in relation to the bulky body. The bird's neck is extensible.
  • The upper part of the body is black and has an attractive blue or green sheen.
  • The chest and upper belly are white with black flecks.
  • The lower belly is light brown.
  • The tail is long and black and has a horizontal white band.
  • The legs and feet are dark pink to light red.
  • On some birds, a small, red dewlap can be seen under the chin.

Males and female horned guans look the same. They can be distinguished by the sounds that they make, as described in the quote below. A vocalizing bird is shown in the video below the quote.

Females produce more guttural types of calls than the deep booming vocalizations of the males. Other sounds include bill-clacking, snorts and clicking. Sounds help identify the sex of this species.

— The Dallas World Aquarium

Formation and Structure of the Horn

The horn extends from an unfeathered location on the top of the skull. Its surface is covered with skin. The Saint Louis Zoo has raised two horned guan chicks. According to a photo on their website, a chick's head is at first covered with feathers. The zoo says that the horn starts to form when a chick is about three months old. Two small bumps appear on the head of a chick. The bumps gradually twist together as they grow and eventually form the typical, unfeathered horn of the animal. The mature horn is about two inches long.

According to the last reference below, the bird's horn is an integumentary outgrowth. The integument is the protective outer layer of an animal and consists of skin plus hair, feathers, scales, and nails or claws. The guan's horn may contain a small core of bone that is an extension of the skull, but most of its structure is composed of keratin. The function of the horn may be to attract a mate.

Daily Life of the Bird

The horned guan lives in the high-elevation cloud forests of southeastern Mexico and Guatemala. It appears to spend most of its life in the trees, where it feeds, preens, and sleeps, but it comes to the ground at times. It's usually seen on its own. It does fly, but it's not a very strong flier. A horned guan is shown taking to the air in the video below, though unfortunately the video ends after the bird has taken off.

The guan eats mostly fruit, leaves, and flowers. It also eats some animals, including insects and small vertebrates. When the environment is dry, the bird leaves the trees once a day in order to bathe in the dust on the ground. Many other bird species dust bathe. It's thought that the activity helps to remove parasites from the skin and keeps the feathers in good shape. In some species, the dust baths have been found to control the amount of oil on the feathers and keep the substance at the optimum level.

Reproduction

The male mates with several females in a season. Dust-bathing is part of the courtship ritual. The nest is usually created in the trees. Some researchers have discovered nests on the ground, however. There may well be aspects of the bird's life that haven't yet been discovered. It's still a slightly mysterious animal.

The female produces two eggs per clutch. She incubates them for around thirty-six days. Unlike the case for the rhinoceros hornbill, only the female cares for the hatched youngsters.

Population Status of the Horned Guan

According to the IUCN, the horned guan is endangered. The status is based on a 2016 assessment. The organization says that the bird's population is decreasing and that only 600 to 1700 adults exist. The problem is mostly due to human actions. The upland forests where the bird lives are being destroyed as coffee plantations move up the mountains. The forests are also being destroyed for logging purposes and to create land for various forms of agriculture. New roads are being built, which makes it easier for humans to enter and modify the forest. In addition, the birds are hunted for their flesh.

The Future for the Birds and Other Wildlife

Nature has created some impressive animals. In many cases, humans are causing or contributing to the decrease in the populations of animal species, as in the two birds discussed in this article. Creating conservation plans is an excellent action, but the plans must be put into action in order the protect animals that are in trouble. Satisfying the needs of humans in a particular area and the needs of the wildlife that lives there is sometimes tricky. It's a problem that we need to resolve.

References

© 2020 Linda Crampton

Comments

Linda Crampton (author) from British Columbia, Canada on July 05, 2020:

Hi, Eman. I think they are beautiful birds, too. Thank you for the comment.

Eman Abdallah Kamel from Egypt on July 05, 2020:

So beautiful birds. A useful and informative article. Thanks, Linda.

Linda Crampton (author) from British Columbia, Canada on June 17, 2020:

Hi, Adrienne. Thank you for commenting. The hornbill is impressive, especially with respect to its method of rearing the chicks.

Adrienne Farricelli on June 17, 2020:

What amazing bird you have presented in this detailed article! I never heard about the rhinoceros hornbill before. It's even amazing the way these birds raise their chicks.

Linda Crampton (author) from British Columbia, Canada on June 11, 2020:

Thank you very much, Ann. I appreciate your kind comment.

Ann Carr from SW England on June 11, 2020:

Such striking birds, these two. Interesting facts, especially the use of the 'casque'. You always provide such detail in your captivating hubs, Linda.

Ann

Linda Crampton (author) from British Columbia, Canada on June 10, 2020:

Thank you very much for the comment, Peggy. I think they are beautiful birds, too.

Peggy Woods from Houston, Texas on June 10, 2020:

Both of these are beautiful birds. The fact of the female rhinoceros hornbill being enclosed in a tree with her chicks for so long a time after hatching them is amazing. You always provide such fascinating information in your posts.

Linda Crampton (author) from British Columbia, Canada on June 09, 2020:

Hi, Nithya. I hope the conservation plans are successful. too. It would be sad if the birds disappeared.

Nithya Venkat from Dubai on June 09, 2020:

Interesting article about the Hornbill and the Horned Guan. I got to know these unique birds through your informative article. I hope the conservation plans help future generations to get to see these birds.

Linda Crampton (author) from British Columbia, Canada on June 08, 2020:

Hi, Mary. Yes, the world contains some beautiful and interesting birds.

Mary Norton from Ontario, Canada on June 08, 2020:

It is so interesting to know more about birds from other countries. These ones are so colorful and so unique.

Linda Crampton (author) from British Columbia, Canada on June 08, 2020:

Thank you very much, Devika. I appreciate your kindness.

Devika Primić from Dubrovnik, Croatia on June 08, 2020:

Hi Linda this is a fascinating hub on what beauty of nature has to offer. All facts and an incredible research thank you

Linda Crampton (author) from British Columbia, Canada on June 07, 2020:

The bird's behaviour is certainly amazing. I think it's a very interesting animal.

Blessings to you as well, Denise.

Denise McGill from Fresno CA on June 07, 2020:

It is so sad about their habitat being lost due to coffee plantations. It makes me glad I don't drink coffee. I'm amazed that the Rhinoceros Hornbill is closed in a tree with her eggs for three months and fed through a small hole. Incredible.

Blessings,

Denise

Linda Crampton (author) from British Columbia, Canada on June 07, 2020:

Thank you, Heidi. Some very interesting animals live on Earth!

Heidi Thorne from Chicago Area on June 07, 2020:

Another animal that looks like something out of a fantasy land! Impressive, for sure. I always learn about something I never knew about in your posts. Thanks for sharing the wonders of our animal world!

Linda Crampton (author) from British Columbia, Canada on June 07, 2020:

Hi, Genna. Thank you for the comment. Nature has some wonderful surprises for us!

Linda Crampton (author) from British Columbia, Canada on June 07, 2020:

I love your comment, Mel. Humanity does need to share. Thanks for the visit.

Mel Carriere from San Diego California on June 07, 2020:

Definitely it is a problem we need to resolve. If we lose our forests, we lose these beautiful creatures. There has to be enough room for all animals on our threatened planet. Humanity needs to learn to share. Great work.

Genna East from Massachusetts, USA on June 07, 2020:

What a strange yet beautiful bird, Linda. It's well named. And how interesting that it uses the horn outgrowth to attract mates. Life always finds a way. :-)

Linda Crampton (author) from British Columbia, Canada on June 07, 2020:

Thank you for such a kind comment, Bill. I hope you have a good Sunday, too.

Linda Crampton (author) from British Columbia, Canada on June 07, 2020:

I would love to visit Malaysia. Thank you very much for the comment, Manatita.

Linda Crampton (author) from British Columbia, Canada on June 07, 2020:

Thank you for commenting, Lisha. I think the animal kingdom is very interesting.

Linda Crampton (author) from British Columbia, Canada on June 07, 2020:

That must have been an interesting experience, Sam. Thanks for the visit and the comment.

Linda Crampton (author) from British Columbia, Canada on June 07, 2020:

It's certainly an interesting nest! I hope the population status of both birds improves.

Bill Holland from Olympia, WA on June 07, 2020:

As a kid, I never missed an episode of "Mutual of Omaha's Wild Kingdom" on television. Loved learning about animals. The show is gone, but you have taken its place, and for that I thank you!

Happy Sunday, Linda!

manatita44 from london on June 07, 2020:

Very soothing rhinoceros hornbill in a musical setting for interior work. You have done a very thorough job here. Lovely to hear them in this tree canopy of a silent pathway. Maybe I'll see some on my next visits to Malaysia or Mexico.

A very well-researched and thorough piece, as is your trademark. Wonderful and amazing creatures!

Lisha C on June 06, 2020:

I enjoyed reading this article. It reminded me of my school days when I loved reading about different animal and bird species; I had forgotten that they make such interesting reads. It is sad to hear that these beautiful birds are vulnerable and endangered. Thanks for sharing.

Sam Shepards from Europe on June 06, 2020:

Saw these in Indonesia, now a decade ago I guess, in a "jungle" on Java. Beautiful creature. Excellent article on this Hornbill.

FlourishAnyway from USA on June 06, 2020:

It requires a lot of trust to allow your mate to lock you in a tree like that. I know they can technically get out but I cannot imagine this is the best nest! Very interesting. I hope this beautiful bird survives.

Linda Crampton (author) from British Columbia, Canada on June 06, 2020:

Hi, Bill. Like you, I hope that both birds survive for a long time to come. They are very interesting animals.

Linda Crampton (author) from British Columbia, Canada on June 06, 2020:

Hi, Linda. There are some incredible animals on Earth. Hornbills certainly belong in the category!

Bill De Giulio from Massachusetts on June 06, 2020:

There are some amazing creatures on this planet. I have seen pictures of the Rhinoceros Hornbill before but knew nothing about them. What a fascinating bird. And the Horned Guan I don’t recall ever seeing or hearing about. Thank you for educating us on these incredible creatures. I only hope that enough is being done to ensure a lasting future for them.

Linda Chechar from Arizona on June 06, 2020:

Wish I had seen these hornbills in zoo areas. They are incredibly amazing rhino birds wildlife.

Linda Crampton (author) from British Columbia, Canada on June 06, 2020:

Thank you, Chitrangada. It's a beautiful bird. The casque is certainly amazing!

Chitrangada Sharan from New Delhi, India on June 06, 2020:

Excellent and detailed information, about the amazing bird, Rhinoceros Hornbill. Such amazing creatures, with beautiful colours. I learnt a lot from your well written article. You covered it so well.

Thanks for sharing.

Linda Crampton (author) from British Columbia, Canada on June 06, 2020:

Thank you, Liza. I hope you're having a good weekend.

Liza from USA on June 06, 2020:

You're welcome, Linda. I'm glad to clarify that. By the way, thanks for sharing this awesome article :)

Linda Crampton (author) from British Columbia, Canada on June 06, 2020:

Thank you so much for commenting and for sharing the information, Liza. I did find information linking Malaysia and the bird symbolically, but some sources said that the bird was a symbol of the whole country and others said that it was the symbol of one state. I didn't want to get the information wrong, so I decided to leave it out of the article. I'm very glad that you clarified the situation.

How wonderful to see the birds in your mom's garden! I would love to see them on my tree.

Linda Crampton (author) from British Columbia, Canada on June 06, 2020:

I appreciate your comment very much, Pamela. I like birds, too. They are interesting animals to observe and study.

Liza from USA on June 06, 2020:

Linda, I'm so thrilled about this article. Did you know that a Rhinoceros Hornbill or Burung Kenyalang is a significant symbol of Sarawak? Sarawak is the largest state among the 13 states in Malaysia. It is an iconic symbol of the people of Sarawak and uses as an emblem of the official state government. By the way, I used to see them flying and eating some fruits from the tree in my mom's garden. They were so beautiful.

Pamela Oglesby from Sunny Florida on June 06, 2020:

It think it is so interesting that so many birds mate for life and the Rhinoceros hornbills is no exception. These birds are so interesting, as is your article, which is excellent, Linda. I really like birds and I found this article to be so interesting. These are very unique looking birds, Linda. I thoroughly enjoyed this article.

Linda Crampton (author) from British Columbia, Canada on June 06, 2020:

Thank you for the comment, Liz. The birds are kept in animals parks and zoos, so you may well have seen them.

Liz Westwood from UK on June 06, 2020:

This is a very detailed and well-structured article. I have learnt a lot from it. Some of these birds look vaguely familiar and I wonder whether I might have come across them in animal parks when I have been abroad.

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