Saturday, November 24, 2012

Really Weird Birds: Part 8

Hornbills are very unusual looking birds.  

There are 54 species of hornbill in the world.  They have some of the most impressive beaks in size, shape, and color.  Even more fascinating are their courting displays and unusual nesting habits.  Their range extends from Africa across India and Asia to Papua New Guinea in the southeast Pacific Ocean.
The very colorful Knobbed Hornbill, native to tropical evergreen forests of Indonesia. 
Hornbills are characterized by long down-curved beaks which help them to reach food in tree branches.  Unique to most species of Hornbills is a large outgrowth on the upper beak called a casque.  This structure is hollow and made of keratin (the same substance that composes our own hair and fingernails), with the exception of the Helmeted Hornbill where the front end of the casque is solid ivory.  Their skull makes up 10% of the adult birds weight. 
 Helmeted Hornbill, native to evergreen forests of Southeast Asia. 
Hornbills are the only birds in which the first two neck vertebrae are fused together in order to provide a more stable platform for carrying their large bill.  The casque is larger in adult males and can assist in dominance displays and attracting mates.  In fact, a few species will undergo aerial “jousting.”  Helmeted Hornbills for example may joust to compete for food, territory or mates.  They fly towards each other and smash their casques together creating a loud clacking noise.  They may flip upside down or be pushed backwards from the force that is created.  The collisions may occur repeatedly and may last up to 2 hours.

Hornbills studied so far breed as monogamous pairs.  With the exception of ground hornbills, the female will lay her eggs in a tree cavity.  She will then seal up the hole using mud, leaving enough room for her to climb inside.  The remainder of the opening will then be sealed by the female using feces and regurgitated food, leaving only a small opening for the male to pass regurgitated food to his mate and their chicks.  While inside the females of some species will molt all of her flight feathers as she incubates the eggs.  Sealing the cavity of course protects the nest from predators, but in turn causes problems of sanitation in the nest, and a lot of work for the male.  Young of the previous year have been seen to help the males with feeding.  In some species of hornbill, when the chicks are half grown, the female will break out of the nest cavity.  The chicks will re-seal themselves in and the parents will continue to feed them until they are ready to fledge.

Many species of hornbills are threatened or endangered.  Habitat destruction and hunting are among the biggest threats.  Some are in danger of being captured for the exotic pet trade.  Many hornbills are killed for their casques, which are used for carvings and traditional medicines.  In Sarawak, Malaysia, local people hunt the hornbills for their feathers, which are used for headdresses and ceremonies.  Luckily however, ceremonial leaders have agreed to receive shipments of molted hornbill feathers from zoos.  

If you want to help endangered birds, you can help by simply visiting us and spreading what you’ve learned, becoming a member or friend, or adopting-a-bird, which feeds that bird for a year!

Submitted by Sara Oliver, World Bird Sanctuary Naturalist

No comments: