“A sense of larger purpose” By David Quammen, Photographs by Joel Sartore, Nov. 2010

https://www.nationalgeographic.com/magazine/2010/11/great-migrations/

“Animal migration is a phenomenon far grander and more patterned than animal movement. It represents collective travel with long-deferred rewards. It suggests premeditation and epic willfulness, codified as inherited instinct. … All migrations… are prolonged movements that carry animals outside familiar habitats; they tend to be linear, not zigzaggy; they involve special behaviors of preparation (such as overfeeding) and arrival; they demand special allocations of energy.”