For Family Survival, Penguins Play a Game Of 'Name That Tune'

[question everything]

The Wall Street Journal

September 9, 2005

SCIENCE JOURNAL
By SHARON BEGLEY

For Family Survival, Penguins Play a Game Of 'Name That Tune'
September 9, 2005; Page B1

Seventy miles is a heck of a distance to waddle to a gathering. Especially in a tuxedo. Especially on solid ice, when it's 80 degrees Fahrenheit below zero and winds blow at 100 miles per hour. But as scientists see it, the most astonishing feat of the emperor penguins is not the multiple treks they make between the edge of the pack ice surrounding Antarctica and their inland breeding grounds. Nor is it that mom goes without food during the 63-day gestation period, nor that dad (taking over after she lays the egg so she can return to the sea to feed) fasts for four months while waiting for junior to hatch.

No, what impresses scientists is that, when mom returns to the breeding colony with food for the new chick, and when dad returns after making his own food run to the distant sea, both travelers manage to find their family in a colony that can number thousands of identical-looking birds, none of whom can be counted on to be where they were when the returning mate last saw them... All the returnee has to go on is its mate's call -- which it has to extract from the surrounding din of beak clicks, wing flaps and other calls, and which it hasn't heard for weeks.

(snip)

Of the 17 species of penguin, only emperors and kings breed without a nest. Because whichever parent is chick- or egg-sitting has no fixed address, the parent returning from the sea has no landmark to aim for. Penguins may look pretty much alike even to other penguins, but they don't sound alike. To generate their unique calls, scientists have discovered, the birds use two voice boxes. That lets them emit different calls simultaneously, modulating frequency, amplitude and beat, write Thierry Aubin of the Université Paris-Sud, Orsay, and Pierre Jouventin of the Center for Functional Ecology and Evolution, Montpellier, France... Adults emit highly individual calls of four to eight syllables. A chick, which memorizes dad's call during the five weeks it spends sitting atop his feet, plays a life-or-death game of "name that tune," identifying him as he waddles through the colony like a bowling pin with feet and calls at regular intervals.

Playing recorded calls for king penguin chicks, Prof. Aubin and Prof. Jouventin find that even a syllable or two is enough for most hatchlings to recognize mom or dad (though they usually wait for at least four before leaving the crèche, apparently wanting to be sure)... "Chicks have an exceptional capacity to discriminate the correct call from extraneous calls," conclude the scientists.

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