A Little Bird Either Learns Its Name Or Dies (NPR)

Biologist Daine Colombelli-Negrel, from Flinders University in South Australia, discovered that Superb Fairy-wren moms have a way to detect an imposter. When they lay their eggs, they wait nine days, and then park themselves by the eggs and start singing. They will sing and sing the same tune every four minutes, over and over for a week, and the chicks inside those eggs not only hear the tune, they commit it to memory.

Scientists call this an “incubation call” and Colombelli-Negrel found that these songs contain a special note that is, in effect, a familial password. When the embryonic chicks hatch and then begin to cry out for food, they will include that note in their begging calls, so the mother knows, “Ok, that one is mine.”