In the emperor penguin courtship call, male vocalizations are composed of long, slow bursts with lower frequency tones than the female version. But calls of SeaWorld San Diego male penguin E-79 defied ...

Cheryl E. Leonard listening to granite. Courtesy Cheryl E. Leonard. The natural world is celebrated for its visual beauty, but also often heralded for its peace and quiet — almost an absence of sound.

Emperor E-79 shown at the end of a display sequence after calling. When the birds call, their bills are facing generally downward and only slightly opened. The sound is radiated downward from the bill ...