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The Mechanisms of Animal Migration

Animal migration is the large-scale, seasonal movement of a species from one environment to another. This behavior is found in a wide variety of animals, including birds, mammals, fish, and insects. Migrations are typically triggered by a combination of factors such as changes in day length, food availability, or temperature. The journeys can cover astounding distances; for example, the Arctic tern travels from the Arctic to the Antarctic and back each year, a round trip of about 70,000 kilometers.

A key question in the study of migration is how animals navigate with such precision over long distances. Research has revealed that animals use a variety of cues. Many birds use a sun compass, orienting themselves based on the sun's position, and a star compass for nighttime travel. Some species, including sea turtles and salmon, are able to detect the Earth's magnetic field, a sense known as magnetoreception. Olfaction, or the sense of smell, is also used by animals like salmon to find their native stream for spawning. This complex navigational toolkit is essential for their survival.

Despite these remarkable abilities, migration is a perilous undertaking. Migrating animals face numerous threats, including predation, starvation, and exhaustion. Extreme weather events can be devastating to a migrating population. Furthermore, human activities pose significant new dangers. Obstacles like tall buildings, wind turbines, and power lines can cause fatal collisions, while habitat destruction at stopover points or breeding grounds can disrupt ancient migratory routes and threaten the survival of entire species.