For the Birds Radio Program: Penguins and Prostitution (UDY)
Scientists have learned that male Adelie Penguins pay females for sex, using stones as currency.
Although this is April, and although this program is going to sound rather like an April Fools joke, it’s really not. I’m going to summarize an article that appeared in The Auk, the journal of the American Ornithologists’ Union. It’s about penguins, which makes it humorous to begin with, and since the topic is penguin prostitution, it’s alliterative as well.
Yes, ornithologists have discovered a major red-light district in Antarctica. Scientists from Cambridge University observing Adelie Penguins on Ross Island, about 800 miles from the South Pole, found that males pay for sexual favors with rocks and stones.
Antarctica doesn’t provide much of a landscape for nesting. The few birds that actually breed there have no choice but to nest on the barren, icy ground, with no vegetation available for nest-building. To protect their eggs from the frozen ground, penguins construct a platform with the one item they can find, stones. The Antarctic ground is studded with loose rocks, cemented by ice and frozen mud. Pecking them out is hard work, but work that can mean the difference between babies surviving or freezing to death
Stones are so important that penguins sometimes steal them from each other, though if caught, the offended party will attack brutally. So some females have developed another strategy for getting this valuable commodity: they swap sexual favors from nearby males for the little rocks. I’ll quote one description:
[Females] slip away from their partner and wander over to the nest of an unpaired male. Standard courtship follows, with a dip of the head and a coy look from the corner of her eye. If he shows interest, she will lie prone which, in the language of penguin love, is an invitation to mate or carry out what scientists call “extra-pair copulation.” Once mating is over, the female picks up her payment, a stone, and carries it over to her nesting platform. Sometimes their customers are so satisfied that the females can return for second helpings of stones, without having to offer more sex. Other females found that a little courtship was enough to persuade a male to allow them to play with a rock, then cart it away. One especially teasing female managed to collect 62 stones this way, said Dr. Hunter [the principal researcher]. “The males were probably duped into thinking that she was a possible partner.”
The scientists don’t believe that the stones are the only advantage females get from this somehow not-quite-unique strategy. She may be doing it to increase the quality of genetic variability of her offspring. Or perhaps she is forming relationships that she can fall back on if her mate dies. All in all, penguin social systems are more complex, and somehow more human, than anyone had ever suspected. It’s nice to know that birds can once again make national news headlines, even competing with Bill Clinton and Monica Lewinsky.