Problem description:

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Analysis:

(a) Hornbill-a kind of self-imprisoned bird

Hornbills have a big beak, so they should look clumsy, but they are not. Some hornbills have a huge helmet at the top of their beaks, which is made of light and porous bones.

Most hornbills live in tropical rainforests in Africa and Asia, and nest in tree holes pecked out by woodpeckers. After giving birth, the female bird seals the entrance of the nest with a mixture of soil and saliva and shuts herself in. Sometimes the male will come and help him seal the nest.

The male and female birds filled the entrance until there was only a crack left. In this way, when the female is hatching eggs, the male can feed her through this seam. The female will stay in the cave for 1 ~ 4 months. In this closed hole, the female bird and her eggs or young birds can avoid the enemy's invasion and will be safe.

Note: After the chicks hatch, some kinds of female hornbills will break out of their holes. Young birds will repair this hole by themselves, and then adult birds will feed them through this gap.

(2)

The biggest feature of hornbill is its big mouth, which is more than a foot long. Its helmet-like protrusion is like the horn on the nose of rhinoceros, so it is called hornbill. Although its mouth looks clumsy, it is actually very clever. Peeling nuts is easy; Picking berries is light and comfortable; It is so convenient to catch mice and insects. The helmet process of most hornbills is horny and hollow, and a few are solid. Hornbill's huge body is one meter long and its eyes have thick eyelashes, which is rare among other birds. There is a spotted hornbill in Xishuangbanna, China, which has been listed as a second-class protected animal. Spotted hornbills are very careful about giving birth. They found a big tree hole and laid a foundation in it, and the female bird entered the "delivery room". Then the female spits out the gelatinous secretions in her stomach, mixes the plant seeds with the rotten wood and seals herself up. The male helps the female to seal the hole tightly with wet soil and fruit residue outside the hole, leaving only a vertical gap for the female to stick out her mouth and accept the male's feeding. Throughout the incubation period, males run around looking for food. The female bird just hatches eggs in the cave, and when the birds hatch, she lifts the "confinement" and flies out of the cave, and then seals the birds inside until the chicks are about to fly out, and the wood releases them. This strange way of hatching eggs helps to protect future generations from snakes and other animals.