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Tuesday, May 8, 2018

Fifty Shades of Hornbill

Perhaps more so than any other group of animals, birds are renown for their courtship an.d breeding behavior.  They sing beautiful songs, participate in stunning breeding displays, and build elaborate nests.  Many species are monogamous, some of them for life.  There is a reason that we say "love birds" and not, say "love turtles."

Some people think of doves, or nightingales, or cranes or swans.  When I think of dramatic displays of avian romance, however, I don't think of those birds.  I think of hornbills.

The hornbills of Africa and Southeast Asia are a peculiar lot of weird-looking birds, some of them small, flying birds, others lumbering ground-dwellers the size of turkeys.  Some dwell on the savannas, others in the rainforest.  Some are colorful, others dull and drab.  What binds them together - apart from those crazy beaks - is a peculiar breeding behavior.

Knobbed hornbills at the St. Augustine Alligator Farm.  A barrel is taking the place of a nest cavity, where the female sits on her eggs, tended to by the male.
After breeding occurs, the female hornbill takes refuge in a hollow, usually a tree trunk.  There's nothing too odd about that - a lot of birds nest in tree hollows.  What is unusual is what happens nest.  The entrance of the nest is plastered up, bit by bit.  The wall is made of a mixture of mud and fecal matter.  When it is completed, all that is left is a small slit, just big enough for beaks to touch and to pass things.

The male, at liberty in the forest, collects food and faithfully brings it back to the female, hunched over on her eggs.  He passes it to her through the gap he has left in the wall.  Of course, she can only eat so much without having the opposite reaction.  Sitting on her eggs in a bed of her own feces isn't the healthiest of behaviors, of course, and certainly is no way to start her chicks off in life.  Instead, she passes the male her feces to dispose off (though some birds are able to defecate out of the small opening slit). 

The female also takes advantage of this time off her feet to undergo a molt of her feathers.  Even without the mud wall sealing her in, the female would be helpless without the male, unable to fly and feed herself.  Shortly after the chicks hatch, the female will leave the nest... and then seal the chicks back in for a little while.  Soon, they too will emerge from the tree trunk when they are ready to take to the wing.

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