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Navigational Cues in Animal Migration

Animal migration is one of the most remarkable phenomena in the natural world, involving journeys that can span thousands of kilometers. To successfully complete these arduous trips, animals rely on a sophisticated suite of navigational abilities. Researchers have discovered that migrating species use a variety of external cues from their environment to orient themselves and maintain their course. One of the most fundamental of these is the sun compass. By observing the position of the sun in the sky and using an internal biological clock to account for its movement, many birds and insects can determine their direction of travel.

For journeys that occur at night or on overcast days, other cues become essential. Many nocturnal migratory birds have been shown to navigate using the stars. They can recognize patterns in the night sky and orient themselves relative to a fixed point, such as the North Star. Another powerful navigational tool is the Earth's magnetic field. Species ranging from sea turtles and salmon to birds and bats possess a magnetoreception sense, which allows them to perceive the planet's magnetic field lines and use them as a sort of global map to guide their long-distance movements.

In addition to these global cues, many animals use landmarks and sensory information for fine-tuning their routes, especially as they near their destination. Familiar coastlines, mountain ranges, and river systems can serve as visual signposts. Olfaction, or the sense of smell, is also critically important for some species. Salmon, for example, are famous for their ability to return to the exact stream where they were born by recognizing its unique chemical scent. This multi-cue approach provides redundancy and ensures that the animals can navigate successfully under a wide range of conditions.