The Jerusalem Biblical Zoo boasts one of the world´s largest troops of captive mandrills. The mandrill (Mandrillus sphinx) is perhaps the most colourful of the primates. The adult male is most conspicuous, thanks to the bold colors on his face and hindquarters, and by virtue of his sheer size, which may be double that of the female. Mandrills are quite common in zoos throughout the world, and the behavior of this species in captivity has been well documented. But recent studies have shown that mandrill populations in the wild have a most intriguing social structure, and that their social behavior bears little resemblance to that of a troop in captivity. Captive adult males dominate and dictate the course of their troop´s daily life; apparently, however, in the wild, mature males are almost entirely solitary, unlike the females, which are exceptionally gregarious. Wild females and juveniles have been found to live in troops that actually number many hundreds of individuals, while the adult males evidently have nothing to do with the troops, except during the relatively short mating season.

http://www.jerusalemzoo.org.il/english/upload/tour/mandrill.html