There are three different views about the origin of bird migration. Birds originated in the south. As the continental plate drifted from south to north, many birds were brought to the north, so they tried to return to their hometown in the south, forming the habit of bird migration. Birds originated in high latitudes, and the invasion of Quaternary glaciers from north to south forced birds to migrate south, until the retreat of glaciers in summer made birds regularly migrate back and forth between breeding grounds and wintering grounds, forming migration behavior. Birds originated from tropical forests in the south, and the large-scale population reproduction increased the demand for food. Therefore, ecological pressure makes some birds spread to the retreat of the northern glaciers in summer, and when the glaciers arrive, they return to the south for the winter, forming a regular migration behavior. Relatively speaking, the first view is somewhat doubtful. Because modern geological research shows that the obvious continental plate movement was completed long before the appearance of birds. The second and the third have some evidence, but the third view is more in line with modern ecological thought and more reasonable.
The significance of migration mainly lies in that birds have been living in the most suitable climate, and the food sources are rich and diverse, which is conducive to maintaining their vigorous metabolism; Migration can also create the most suitable conditions for raising offspring, because breeding offspring requires a lot of food; In the north, they can hatch the most eggs, with a long season and many insects, while in the north of China, parents can have the opportunity to collect them fully, and there are few enemies. The appearance of one-year-old vulnerable chicks will not promote reproduction and form enemy groups; Migration can greatly expand the activity space, which is conducive to the behavior of breeding and competing for occupied areas; It is conducive to automatic balance and can avoid climate differences; Migration also provides opportunities for bird populations to spread to new distribution areas. Therefore, as the contact and mating between different individuals, it is also of great significance in evolution.
At present, there are three different views about bird migration's reasons. One is the continental plate theory, the other is the glacier invasion theory, and the third is the southern origin theory. Now, the third one is more acceptable. People think that the third method is more in line with modern ecological thought and more reasonable. Of course, migration is not just a feature of birds. Many animals on the road and fish in the water will also migrate. The great migration of wild animals in East Africa, which started in June every year, is world-famous. Nearly 2 million grassland dwellers, including 1 10,000 wildebeests and1.5,000 zebras, have worked hard for the 4,800-kilometer grassland migration and written shocking life legends.