Migration is a survival mechanism for many species. Animals travel to find food, reproduce, reduce competition, escape predators or escape winter. Whether mammal, bird, fish or insect, a migrating ...

Migrating animals have for a long time been tracked by recapturing tagged individuals. More recently, radio-telemetry, which requires an observer to physically follow the tagged animal, has been used.

For most of the past half century, one of the planet’s greatest wildlife spectacles has unfolded almost entirely unseen. South Sudan spans nearly 250,000 square miles across East Africa, and it’s ...