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From New Scientist:
http://www.newscientist.com/news/news.jsp?id=ns99991048


Gorillas make an impressive splash

19:00   18  July  01
Andy Coghlan

In the lowland forests of western Africa, male gorillas reach the top by 
out-splashing their rivals. The finding is one of the first examples of 
land-based animals communicating using water, says Richard Parnell of the 
Wildlife Conservation Society of New York.

"It's a highly visual display, created by a gorilla either running or 
leaping into standing water," Parnell says. For three years, he catalogued 
the water-splashing antics of gorillas in the Congolese Nouabale-Ndoki 
National Park.

The lowland gorillas (not to be confused with the better-known mountain 
gorillas) regularly visit large swampy forest clearings called bais. The 
bais are full of aquatic herbs, which the gorillas eat. But the visits are 
social as well. Often, as many as five groups come to the bai 
simultaneously. While they eat, they eye each other up from 20 metres or 
more and the males signal by splashing.

Because the splashing displays can be seen from a distance, they are clearly 
designed to intimidate males and impress females in adjacent groups, Parnell 
says. "Large plumes of spray result from all styles of the display," he 
says. "The big 'silverback' males did almost 70 per cent of the displays."


"Serious bruiser"


But Parnell found that solitary males splashed the most. These males 
"displayed almost as often to other solitary males as to groups," says 
Parnell. "Therefore, it's more to do with intimidating other males."

Of the 130 named individuals he observed at one large clearing called the 
Mbeli Bai, the most macho by far was a male he christened "Mad Max".

"He was spectacularly successful at picking up females," says Parnell. "But 
he was a serious bruiser". Within two years, Max had built up the most 
numerous group of the 14 which regularly visited the bai.

Parnell says that chimpanzees have been seen intimidating other males with 
splashes made by throwing rocks in water. But this is the only other example 
he could find of land-based mammals communicating via water.

Journal reference: Nature (vol 412, p 294)


19:00   18  July  01



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