Male Orangutans Attract More Females by Having Padded Cheeks

If you are an orangutan and aspire to be king of the jungle, you must meet the following criteria: you must have a large body, a pendulous throat sac and, of course, cheek pads. While such throat sacs are used for long, deep, clear calls, having cheek pads is essential for attracting females.

Researchers from the Max Planck Institute for Evolutionary Anthropology recently published a study in Behavioral Ecology and Sociobiology, explaining how some Orangutans develop cheek pads, while others do not--and how this affects their success in fathering offspring.

An orangutan named Kusasi was the former dominate male at Camp Leakey in Indonesia's Tanjung Puting National Park. In order to better understand male orangutans' reproductive success, Graham L. Banes and Linda Vigilant studied Kusasi for eight years.

According to a news release, they compared his reproductive success to that of lower ranking, non-cheek-padded males from the same area. They collected fecal samples and performed paternity tests, which allowed them to conclude that during Kusasi's dominance, he produced more offspring than any other male. 

"We performed paternity testing to see which of these males were fathering offspring at Camp Leakey, and to quantify Kusasi's reproductive success," Vigilant said in the news release. "Paternity could be assigned to 14 candidate offspring, conceived across multiple decades, ten of which were fathered by Kusasi."

The researchers noted that generally in any given area, only one male orangutan has cheek pads. This tends to be the dominate orangutan, which would explain why Kusasi was able to reproduce more often than fathering non-cheek-padded males -- the females were simply more attracted to his cheek pads.

"The timing, however, was interesting," Banes said. "These other males were typically reproductively successful at the beginning and end of Kusasi's dominant period, when the hierarchy was potentially unclear."

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