Demographic modeling of a predator-prey system and its implication for the Gombe population of Procolobus rufomitratus tephrosceles

We evaluated the viability of colobus populations under conservative estimates of predation by chimpanzees. If fertility and mortality schedules remain constant, intensely hunted red colobus populations will experience negative growth rates if one allows the assumption of stable age structure to persist into the future. Demographic models have many advantages in studies of primate behavior and ecology. Researchers use them to investigate the quality of observed data and to project population growth rates to changes in mortality, fertility, and migration schedules. We used published age-specific death rates for red colobus (Procolobus rufomitratus tephrosceles) in Gombe National Park, Tanzania, to construct model life tables under various mortality scenarios. Selection in life-history traits toward shorter interbirth intervals, reduction in gestation length, and increased dispersal of individuals from source to sink populations and antipredator behavior, show a limited ability to counter the effects of intense predation. At Gombe, where factors such as small reserve size and isolation prevail, current levels of predation by chimpanzees may depress intrinsic growth rates low enough to cause the extirpation of red colobus in the near future.