1 The term migratory species does not refer to a specific class, order, or family of animals in the biological sense. Rather, it describes animals that display migratory behaviour. Of the world’s more than 1.5 million known animal species, an estimated 8,000–10,000 are migratory species, meaning that they regularly perform cyclic movements between two distinct geographical areas, one of which is usually the area in which they breed. The Arctic tern is an illustrative and record-breaking example: it migrates from its breeding grounds in the Arctic region to the...
Users without a subscription are not able to see the full
to access all content.