Emperor Penguins

Emperor penguins produce a unique two-toned call that allows them to identify one another. This ability stems from the structure of their vocal organ, the syrinx, which divides into two branches where the trachea meets the lungs. Because of this split, many bird species, including emperor penguins, can generate two distinct sounds at the same time.

By using both sides of the syrinx, emperor penguins create calls with two different frequencies simultaneously, resulting in a “beating” pattern of sound. Researchers have found that these patterns contain enough individual variation for penguins to recognize each other. The dual-frequency call is also easier to pick out from the loud background noise of a crowded colony and travels more effectively through obstacles—such as groups of tightly packed penguins—than single-voiced calls.

 

Studies show that when emperor penguins are unable to vocalize, they struggle to identify one another by sight alone. A similar communication system has been documented in king penguins, which, like emperors, balance their eggs on their feet rather than building nests. In contrast, penguin species that construct nests don’t appear to use two-voiced calls, since they can locate their partners by returning to the nesting site.