How Do We Know Anything About Migrating Birds?

Each August, billions of birds rally themselves for the long, dangerous migration south. With the abundant foods offered by the summer breeding season now dwindling in supply, these animals must face an exhausting long-haul flight to warmer—and safer—lands. Some species, like the striking cedar waxwing, might only move a few hundred miles; others, like the arctic tern, could cover over 55,000 miles in just a month and a half.

Regardless of the distances they may travel, all migratory birds must utilize a very strange and enigmatic ecosystem—the air itself. This ecosystem, called the aerosphere, can be thought of much like any other habitat. It has its own set of unique climate conditions, physical structures, evolutionary pressures, and threats.