Unit 5 Into the wildAnimal migrationAnimal migration is the relatively longdistance movement of individual animals, usually on a seasonal basis
It is the most common form of migration in ecology
It is found in all major animal groups, including birds，mammals, fish, reptiles, amphibians, insects, and crustaceans
Different kinds of animal migrate in different ways
·In birdsApproximately 1,800 of the world's 10,000 bird species migrate long distances each year in response to the seasons
Many of these migrations are north—south, with species feeding and breeding in high northern latitudes in the summer, and moving some hundreds of kilometres south for the winter
Some species extend this strategy to migrate annually between the Northern and Southern Hemispheres
The Arctic tern is famous fo
