Please answer the following questions about the reproduction and development of birds by combining the picture analysis: (1) The poem whose Chun Yan pecks at spring mud describes the reproductive beha

Please answer the following questions about the reproduction and development of birds by combining the picture analysis: (1) The poem whose Chun Yan pecks at spring mud describes the reproductive behavior of swallows. (1) The reproductive behavior of birds includes several stages: courtship, mating, nesting, spawning, hatching and brooding. The poem whose Chun Yan pecks at spring mud describes the nesting behavior of swallows in their reproductive behavior.

(2) In the future, it will be ④ blastoderm, which contains nucleus and is the place for embryo development. ⑤ Egg white and ⑤ yolk provide nutrition for embryo development, and air chamber provides oxygen for embryo development. The air chamber stores air, which is beneficial to embryo breathing. From the internal conditions, the condition for eggs to hatch into chicks is that eggs must be fertilized in disorder. From the external conditions, if eggs are excreted, they must have a suitable temperature to continue to develop.

(3) Eggs must be fertilized to develop into chicks, and the hatching time of bird eggs is directly proportional to the size of the eggs. Generally speaking, the smaller the egg, the shorter the incubation period, and the larger the bird egg, the longer the incubation period.

So the answer is:

(1) nesting?

(2)④ blastoderm; 5 egg white; 3 egg yolk; ⑥ air chamber; Eggs must be fertilized eggs; comfort temperature

(3) Generally speaking, the smaller the egg, the shorter the incubation period, and the larger the bird egg, the longer the incubation period.