In search of food each spring and fall, bird species of all kinds take to the skies to travel away from their summer breeding grounds and winter warmth. According to National Geographic, many species who partake in this mass migration travel at night when the wind doesn't blow as strong and the moon lights their flight path.
Birds usually follow flyways, a typically north to south route that offers the same kind of rest stops humans look for on a long drive - places to refuel and relax when necessary. But, there isn't one path per species. Luckily, several kinds of birds share paths of travel.
Along their way, the flying creatures may experience "Rough weather, dehydration, starvation, and the threat of predation," according to National Geographic. However, more birds in the same flyway mean more eyes looking out for those that could potentially fall into harm's way amidst travel.
To put into perspective the kind of travel some bird species endure; the Arctic Tern, a grey-bodied bird with a jet black head takes on the travel of over 60,000 miles. This is believed to be the world's longest migration of any animal by many researchers including Carsten Egevang of the Greenland Institute of Natural Resources.
Even birds that do not fly, such as the Adelie penguin, make the long trek when migration times come around. This flightless bird makes a nearly 8,000-mile journey through the freezing Antarctica ice to get to safer weather. And when tired, seeking shelter from predators or diseases might give them the extra push to keep going.
Martin Wikelski, National Geographic Explorer and director of the Max Planck Institute for Ornithology, has come up with a new GPS tagging system. He designed it as part of his ICARUS project, along with Fitbit-like devices that track bird movements to globally monitor the animals.
According to National Geographic, about half of the world's known bird species migrate. That's about 5,000 kinds of wings in the sky! "There's just so much to learn," Wikelski said. "I've been tracking birds for over two decades, and the ease with which birds seamlessly migrate between worlds is absolutely astounding."