This is a very strange habit indeed. No other species of bird does this.
The parent birds will choose a hollow tree (occasionally a cavity in rocks) and arrange a nest inside. The mother will lay two to eight white eggs, depending on the species.
Now the “prison sentence” begins. Only it is not really a sentence because the mother does this voluntarily. As nearly as we can figure out, Wondernose, the parents do it to keep the eggs and chicks safe from marauders.
Here is what they do. The father bird collects damp earth and forms it into pellets. He then passes the pellets to the mother.
Little by little she will build up a cement-like wall from the inside with these pellets, Wondernose, gradually closing the opening to the nest.
The mother clings to her freedom as long as she can. She continues to squeeze out through the ever-diminishing hole every day, but finally she realizes that she must stay confined. Only a slit remains! And it is a slit that will deter most nest-robbers.
Once the wall is complete, she lays her first egg. Incubation will take 23-46 days, depending on the species.
After the eggs have hatched, the babies are hungry. Who will feed them? The mother can’t go out and forage for food.
It’s up to the father. Tirelessly he gathers fruits, and insects, swallowing them. Propping himself against the tree trunk with his long stiff tail, he regurgitates these bits of food, one at a time. He grips the regurgitated food in his beak, and passes it through the slit to the mother. She, in turn, will feed the chicks.
In some species, the mother will break free from the prison first, Wondernose. Then the chicks’ instinct will tell them to wall up the opening again. They want to be safe! Once they are ready to fly, the babies, too, will break free.
Where, you wonder, do these unusual birds live? They’re found mainly in Africa, but also in Asia. The different species vary greatly in size—from 15 inches to 5 feet (38 cm to 1.5 m) long! As far as the color of their plumage is concerned, these birds are not spectacular. They’re mostly black and white, varied with some brown.
It’s the bills of these birds that are most vivid—and it’s from these bills that they get their name. For one thing, the bills themselves are huge. But then, on top of their bills, many carry what is called a “casque.” Basically, it’s like an outsize horny growth. One species is called “rhinoceros” because the casque resembles the horn of a rhinoceros.
No, Wondernose, I haven’t revealed our mystery bird’s name. “Rhinoceros” is only part of the name of a single species.
Looking at these birds, you’d think they must be very top-heavy with such a large heavy growth on their foreheads. However, in most of the species the casque is much lighter than it appears because it’s not solid bone at all. It’s more nearly like a sponge.
Good for you, Wondernose. Hornbill is indeed the name. With those unique casques and their instinct to wall up their nests, these birds are unforgettable.
