HOPE Report No.14, 11th, May 2005.
Program No.14 (Joint research)
Mixed-species associations of two Cercopithecus species for
ant-chimpanzee hunting in the Kalinzu Forest, UGANDA.
Doctor Course Student, Primate research Institute , Kyoto University.
Place of visit: Kalinzu Forest, UGANDA
Period of visit: 31 July,2004－9 December,2004
Mixed-species association is a phenomenon that members of two or more
species move and forage together like one species. Various primate species
living in Africa and South America, including red-tailed monkeys (Cercopithecus
ascanius) and blue monkeys (C. mitis), are reported to make
mixed-species associations. A variety of functions (e.g. anti-predator
behavior, effective foraging, etc.) have been proposed for such
associations. Cords（1987）reported that red-tailed and blue
monkeys made associations for the anti-raptor predators in the Kakamega
Forest, Kenya. In the Kalinzu forest of Uganda, however, predators on
these two species are not only raptors but also chimpanzees.
To examine whether red-tailed and blue monkeys make associations to
avoid predations by chimpanzees, I studied how members of the associations
respond to approaches by chimpanzees in the Kalinzu forest. Red-tailed and
blue monkeys were both strictly arboreal in this study site. A target
troop of red-tailed monkeys (R1 group) had 23 individuals and its home
range size was about 26 ha , while a target troop of blue monkeys (B1 group)
had 24 individuals and its range was about 25 ha. The overlap of the two
troops was very large. We collected data on the movement pattern, distance
and vocalization of the two Cercopithecus species by following troops of
each species simultaneously.
Alarm calls against chimpanzees were emitted by females, but not by
males. When a male chimpanzee approached a mixed association, members of
both species emitted always alarm calls. In contrast, monkeys did not give
alarm calls to groups of female chimpanzees and/or juveniles. Distances
between chimpanzees and monkeys had no correaltion with the occurrence of
alarm calls. These findings suggest that red-tailed and blue monkeys may
evaluate the risk of predation according to the sex/age class of
Red-tailed monkey (Cercopithecus asucanius)
Blue monkey (C. mitis)
L'hoest's monkey (C. lhoesti)