MNN - Mother Nature Network

The world's great animal migrations are among nature's most inspiring events. Whether by wing, fin or hoof, the distance some creatures travel in search of new habitat is paralleled only by their endurance. Migrations also play a vital role in our natural ecosystems — they are the veins and arteries of Mother Earth — and they are a reminder that the world's biospheres are interconnected and can't be fenced off. Here's our list of some of the planet's greatest migrations.