A Voice in Forty Thousand

An Emperor penguin colony on the Antarctic ice shelf can number over forty thousand birds. They look virtually identical — same height, same tuxedo markings, same waddle through the wind. Yet when a parent returns from a two-month fishing journey across sixty miles of frozen sea, it walks straight into that roaring crowd and begins to call. Researchers at France's Dumont d'Urville station in Adélie Land discovered that each penguin produces a unique vocal signature — a frequency pattern as distinct as a fingerprint.…