鸟类在其生长发育过程中,要经过雏鸟阶段。根据发育程度的不同,可将鸟类分为早成鸟和晚成鸟两类。早成鸟的雏鸟在孵出时,发育已较为完善。眼睛睁开,全身履盖着稠密的绒羽,腿足健壮有力。一旦羽毛干松,就能随亲鸟到各处觅食或离开亲鸟独立生活。驼鸟、鸡、鸭、大雁等属于这一类。晚成鸟的雏鸟刚出卵壳时,发育还很不完善。眼睛没有睁开,身体裸露或只有几簇稀疏的小绒毛.腿足软弱无力。只能伏在巢中等待亲鸟的饲喂。经过十几天、几十天、甚至长达8个 Birds go through the chickling stage during their growth and development. According to the different degree of development, birds can be divided into early and late adult birds. Early hatchling chicks have developed well when hatched. Eyes open, his body covered with dense fleece, legs strong and strong. Once the feathers are dry and loose, you can go for food or leave the birds to live independently. Ostriches, chickens, ducks, geese and so on fall into this category. When the young birds of the late birds just emerged from the eggshell, their development was still incomplete. The eyes are not open, the body is bare or there are only a few clusters of sparse small fluff. The legs and feet are weak. Only stay in the nest and wait for the feeding of the bird. After 10 days, dozens of days, even up to 8