Avoiding Predators: Expectations and Evidence in Primate Antipredator Behavior

Predation and antipredator behavior are important but poorly studied influences on the evolution of primate societies. I review recent evidence of predation and antipredator strategies among primates. I describe patterns of antipredator behavior and attempt to explain the variation among primate taxa and among antipredator strategies. I use predation by chimpanzees on red colobus and antipredator strategies by the colobus as a case study of how a primate prey species may respond to the threat of predation.     

Influence of Chimpanzee Predation on Associations Between Red Colobus and Red-tailed Monkeys at Ngogo,Kibale National Park,Uganda

Colobines often associate with cercopithecines at various African sites. Such polyspecific associations presumably have an antipredation function. At Ngogo, Kibale National Park, Uganda, red colobus (Procolobus rufomitratus) spend considerable time in association with red-tailed monkeys (Cercopithecus ascanius), and they are also heavily hunted by chimpanzees (Pan troglodytes). I conducted behavioral observations and playback experiments to test the hypothesis that red colobus and red-tailed monkeys obtain mutual protection and predator-related benefits by associating. Despite high chimpanzee hunting pressure on red colobus and much lower hunting pressure on red-tailed monkeys, red-tailed monkeys initiate, maintain, and terminate the associations. The results suggest that rather than providing red colobus with protection against chimpanzees, the associations occur mostly because they protect red-tailed monkeys against predation by eagles.     

Positional behavior in five sympatric old world monkeys

Observations of positional behavior and habitat use were recorded on focal individuals of five species of Old World monkeys at Kibale Forest, Uganda, through the dry season of 1990 and 1991. Cercopithecus ascanius, Cercopithecus mitis, Cercocebus albigena, Colobus badius, and Colobus guereza commonly utilize five similar types of positional behavior (i.e., quadrupedalism, leaping, climbing, sitting, and standing), but in varying frequencies and situations. As a group, colobines use oblique supports and leap more often, and cover greater linear distances during leaps than do cercopithecines. Colobines also prefer to sit (about 90% of all postures), while cercopithecines stand more frequently. Body size differences between the sexes of a species are not reflected in positional behavior. The two small-bodied species climb more and leap less often than the three larger species, which is the reverse of what we would expect. Leaping is the most common method of crossing open spaces within the canopy; but most spatial gaps and leaps are over short distances, usually one meter or less. All five species, regardless of body size or the availability of forest supports, prefer mediumsized supports. Incorporating our work from Uganda with previous investigations of positional behavior reveals few consistent trends with respect to body size or habitat use across primates. © 1995 Wiley-Liss, Inc.     

Habitat,annual, and seasonal effects on positional behavior in red colobus monkeys

Positional behavior in adult red colobus monkeys (Colobus badius) was examined in a variety of ecological contexts. Using a focal-animal methodology, we assessed how data collected by different observers, in different years, in different seasons, and in different forests affected estimates of positional behavior. In all, 23,000 bouts were recorded. Variation in frequency is greatest in the common behaviors, especially arboreal quadrupedalism. Significant behavioral differences occur more often in the context of different forests than in annual or seasonal comparisons. The activity of feeding exhibits the largest frequency changes across positional behavior and ecological context. In all, red colobus monkeys exhibit substantial amounts of flexibility in positional behavior across different ecological contexts. © 1995 Wiley-Liss, Inc.     

Variation in the Nutritional Value of Primate Foods: Among Trees, Time Periods, and Areas

The study of nutritional ecology has proven to be useful for understanding many aspects of primate behavior and ecology and is a valuable tool in primate conservation. However, to date this approach has had limited application since chemical analyses of food items is very time-consuming and collections of perishable food material are often made in remote field locations. Such logistic difficulties have led to plant material being collected in a variety of fashions, and it is not known how variation in collection method might influence our understanding of the chemical basis of dietary selection. A standardization of collection methods is greatly needed to allow for direct comparison among studies. To develop an appropriate standardized method and to evaluate past research, it is necessary to understand along what dimensions plant chemistry varies. We evaluated variation in nutritional value—protein, fiber, digestibility, alkaloids, saponins, cyanogenic glycocides, and minerals—of leaf material from species eaten by red colobus (Piliocolobus tephrosceles) and black-and-white colobus (Colobus guereza) of Kibale National Park, Uganda. We consider variation at 3-levels: among trees, time periods, and areas. While there was considerable variation among species with respect to protein, digestibility, and saponins, there was also variation among individuals of the same species; in fact, individuals may vary by as much as 20%. The average coefficients of variation (CV) among individuals of the same species are 13.4 for protein, 12 for digestibility, and 43 for saponins, while the average CV among species are 35, 31.3, and 82.4, respectively. No species showed a variable response with respect to testing for the presence or absence of cyanogenic glycocides, while 2 of 11 species tested for alkaloids showed a variable response. Over 2 years there was evidence of variation among time periods in the chemical composition of the same food items. The protein-to-fiber ratio of mature leaves of the same species collected from 4 sites separated by 12 km within Kibale was also variable and in some cases the variation among sites was greater than the differences among species. For example, while Funtumia latifolia had little variation in protein-to-fiber ratio at 3 sites (0.44 at all sites), the remaining site was 28% greater. Because temporal variation is less than variation among individuals, it is likely more important to sample from multiple trees at a single point in time than to sample across time. However, the most accurate assessment of nutrient intake is obtained by collecting plant material from the specific trees selected for consumption.     

Population Declines of Colobus in Western Uganda and Conservation Value of Forest Fragments

The processes of habitat loss and fragmentation are probably the most important threats to biodiversity. It is critical that we understand the conservation value of fragments, because they may represent opportunities to make important conservation gains, particularly for species whose ranges are not in a protected area. However, our ability to understand the value of fragments for primates is limited by the fact that researchers have conducted many studies in protected areas, which do not represent most fragments, and studies are typically short term. Here we determine the long-term survival probability of red (Procolobus pennantii) and black-and-white colobus (Colobus guereza) inhabiting forest fragments outside of Kibale National Park, Uganda. Local communities use the fragments primarily for subsistence agriculture and fuelwood. We surveyed primate populations 3 times over 8 yr, made a total inventory of all trees 2 times, contrasted behavior of groups inhabiting 1 fragment with groups in the continuous forest, and judged the conservation value of the fragments by quantifying patterns of forest use by local people. Of the 20 fragments surveyed, 16 supported resident populations of colobus in 1995, 2 were cleared in 2000, and an additional 2 fragments were cleared by 2003. In 1995 we counted 165 black-and-white colobus, whereas in 2000 and 2003, we counted 119 and 75 individuals, respectively. Seven fragments supported red colobus in 1995, 11 in 2000, and 9 in 2003. In 2000 we counted 159 red colobus, while in 2003, we saw 145 individuals. For both species, activity patterns in continuous forest were similar to those in a fragment, with the exception that individuals in the fragment rested more. Colobus in the fragment ate more mature leaves than colobus in the continuous forest did. Fragments supported all the fuelwood needs of an average of 32 people who lived immediately adjacent to them, and partially supported families up to 3 farms away (ca. 400 m), representing 576 people. Intensive harvesting for fuelwood occurred when neighboring households engaged in beer brewing (an average of 9.6% of the households), gin distilling (8.8%), or charcoal production (14.5%). Overall, between 2000 and 2003, the average density of trees declined by 14 trees/ha (range = 0–60 trees/ha). If current rates of clearing continue, the probability that the fragments will continue to support colobus populations is low.     

Breeding birds in the tropical rain forests of Kibale National Park, Uganda

A combination of trapping and foot surveys was used to assess the breeding status of birds in unlogged and logged sites in the tropical rain forest of Kibale National Park, Uganda. Breeding of forest edge and gap species was greatly enhanced by logging, whereas crevice and hole nesting specialist breeders were adversely affected. Egg‐laying periods corresponded to higher rainfall regimes at the nearby field station. The relevance of these findings to bird conservation is discussed.