Animal migration has fascinated humans for millennia ... Fat stores about 8–10 times more energy than the equivalent mass of either carbohydrate or protein, making fat the fuel of choice ...

These are the animals with the longest migrations. In the Yukon, Porcupine caribou travel 3,000 miles. This is the longest migration by land of any mammal on Earth. Monarch butterflies fly about ...

(Arterra Picture Library / Alamy Stock Photo) Migration can happen around the world at any time. But it's most common for animals to migrate when the seasons and weather conditions change.

Some animals that migrate across the globe—such as birds, salmon, lobsters and sea turtles—are known to navigate using the magnetic field lines that stretch from Earth's north to south pole.