A、To let in the sunshine. B、To serve as its door. C、To keep the nest cool. D、For the bird to lay eggs. B

Do you know that there’s a kind of bird that can sew? This bird, called the tailorbird, uses its mouth as a needle. It sews leaves together in a shape of a cup. Then it adds a layer of straw to the inside of the cup and lays its eggs there. Each bird species builds its own special kind of nest. The most common materials used for nests are grasses, branches and feathers. A bird must weave these materials into a nest. Just imagine building a house without cement or nails to hold it together. Another bird is called the weaverbird. The weaverbird builds a nest that looks like a basket. The nest is shaped like a pear with a hole in the middle. The hole is the door of the nest. The third bird is called the ovenbird. The ovenbird makes a nest that is very solid. The nest is made of mud. The ovenbird forms the mud into the shape of an oven and then lets it dry in the sun. The sun bakes the mud, making it very hard. Not all birds make their homes in branches. Some birds build their nests on the ground, while others bury their eggs under the ground. And some birds do not build nests at all. So when you look for nests and eggs in the branches of trees and bushes, remember, that some nests may be right under your feet.