Imagine you’re an albatross, a large seabird that spends months aloft over the open ocean. Now it’s the breeding season: time to head back to your favorite island, do some amusing courtship dances, and lay an egg. But you’re in the middle of the vast, featureless open ocean. How do you find your way back?
Homing pigeons, taken from their roosts and driven up to 800 km away, can fly home. (Several pigeons have received the animal version of the medal of honor for doing this while carrying messages in wartime.) Arctic shorebirds like the Red Knot will fly from the Arctic to southern South America, over 13,000 km, twice a year. Birds are very good at navigation. How do they do it?