Book reviews

No abstract.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/55855/1/20483_ftp.pd

Meat-Eating and Human Evolution

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66124/1/aa.2002.104.3.999.pd

Book Review: The Chimpanzees of the Taï Forest. Behavioural Ecology and Evolution. By Christophe Boesch and Hedwige Boesch-Achermann , Oxford University Press, Oxford, UK. 2000, x + 316 pp., $39.50 (paperback)

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44565/1/10764_2004_Article_371029.pd

Book reviews

No abstract.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34276/1/10143_ftp.pd

Diet of chimpanzees ( Pan troglodytes schweinfurthii ) at Ngogo, Kibale National Park, Uganda, 1. diet composition and diversity

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90275/1/ajp21016.pd

BOUNDARY PATROLS AND INTERGROUP ENCOUNTERS IN WILD CHIMPANZEES

Chimpanzees are among the few mammals that engage in lethal coalitionary aggression between groups. Most attacks on neighbors occur when parties made up mostly of adult males patrol boundaries of their community's range. Patrols have time, energy, and opportunity costs, and entail some risks despite the tendency of males to attack only when they greatly outnumber their targets. These factors may lead to a collective action problem. Potential benefits include protection of community members, particularly infants; range expansion and increases in the amount and quality of food available; and incorporation of more females into the community. Males may not share these equally; for example, those able to obtain large shares of matings may stand to gain most by participating in patrols and to lose most by refraining. Despite the attention that boundary patrolling has attracted, few relevant quantitative data are available. Here, we present detailed data on boundary patrolling and intergroup aggression in a chimpanzee community at Ngogo, Kibale National Park, Uganda, that is unusually large and has more males than any other known community. Males there patrolled much more often, and patrol parties were much larger on average, than at two other sites for which comparative data exist. Our findings support the argument that male participation varies along with variation in potential gains, in willingness to take risks, and in skill at handling these risks. Both the overall frequency with which individual males patrolled and their willingness to join patrols as others set off on them were positively associated with variation in mating success, in participation in hunts of red colobus monkeys, and in hunting success. Males patrolled relatively often with others with whom they associated often in general, with whom they often groomed, and with whom they formed coalitions in withincommunity agonism. This indicates that they were most willing to take risks associated with patrolling when with others they trusted to take the same risks.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43613/1/10520_2004_Article_brill_00057959_v138n3_s2.pd

Demographic influences on the hunting behavior of chimpanzees

We investigated hunting in an unusually large community of wild chimpanzees at Ngogo in the Kibale National Park, Uganda. Aspects of predation were recorded with respect to the prey, the predators, and hunting episodes. During 23 months of observation, the Ngogo chimpanzees caught 128 prey items from four primate and three ungulate species. Chimpanzees preyed selectively on immature red colobus primarily during group hunts, with adult males making the majority of kills. Party size and composition were significant predictors of the probability that chimpanzees would hunt and of their success during attempts. Chimpanzees were more likely to hunt red colobus if party size and the number of male hunters were large; party size and the number of male hunters were also significantly larger in successful compared with unsuccessful hunts. The Ngogo chimpanzees did not appear to hunt cooperatively, but reciprocal meat-sharing typically took place after kills. Hunts occurred throughout the year, though there was some seasonality as displayed by periodic hunting binges. The extremely high success rate and large number of kills made per successful hunt are the two most striking aspects of predation by the Ngogo chimpanzees. We compare currently available observations of chimpanzee hunting behavior across study sites and conclude that the large size of the Ngogo community contributes to their extraordinary hunting success. Demographic differences between groups are likely to contribute to other patterns of interpopulation variation in chimpanzee predation. Am J Phys Anthropol 109:439–454, 1999. © 1999 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34267/1/2_ftp.pd

Hunting Behavior of Chimpanzees at Ngogo, Kibale National Park, Uganda

Chimpanzees ( Pan troglodytes ) prey on a variety of vertebrates, mostly on red colobus ( Procolobus spp. ) where the two species are sympatric. Variation across population occurs in hunting frequency and success, in whether hunting is cooperative, i.e., payoffs to individual hunters increase with group size, and in the extent to which hunters coordinate their actions in space and time, and in the impact of hunting on red colobus populations. Also, hunting frequency varies over time within populations, for reasons that are unclear. We present new data on hunting by chimpanzees at Ngogo, Kibale National Park, Uganda, and combine them with earlier data (Mitani and Watts, 1999, Am. J. Phys. Anthropol. 109: 439–454) to examine hunting frequency and success, seasonality, and cooperation. The Ngogo community is the largest and has the most males of any known community. Chimpanzees there mostly hunt red colobus and are much more successful and make many more kills per hunt than at other sites; they kill 6–12% of the red colobus population annually. The number of kills and the offtake of meat per hunt increase with the number of hunters, but per capita meat intake is independent of hunting party size; this suggests that cheating occurs in large parties. Some behavioral cooperation occurs. Hunting success and estimated meat intake vary greatly among males, partly due to dominance rank effects. The high overall success rate leads to relatively high average per capita meat intake despite the large number of consumers. The frequency of hunts and of hunting patrols varies positively with the availability of ripe fruit; this is the first quantitative demonstration of a relationship between hunting frequency and the availability of other food, and implies that the chimpanzees hunt most when they can easily meet energy needs from other sources. We provide the first quantitative support for the argument that variation in canopy structure influences decisions to hunt red colobus because hunts are easier where the canopy is broken.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44564/1/10764_2004_Article_360868.pd

Introduction to the International Symposium on African Great Apes

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41613/1/10329_2005_Article_137.pd

General Gregariousness and Specific Social Preferences among Wild Chimpanzees

Wild chimpanzees form temporary parties that vary in size and composition. Previous studies have revealed considerable intraspecific variation in party compositions. We examined patterns of association among age, sex, and reproductive classes of chimpanzees at Ngogo in the Kibale National Park, Uganda. We employed a class-based association index and a randomization procedure to control for confounding factors and to test for differences between classes. Results indicate that males associated with other males significantly more than expected if all classes behaved equivalently, while females generally associated with individuals of the same sex less than expected. To interpret these patterns we used two additional indices that separate associations into two components: general gregariousness and preference for particular classes of associates. Males and estrous females were more gregarious than other classes, while anestrous females were less so. After controlling for general gregariousness, adult males as a class showed no specific preference for associating with each other. Anestrous females preferred each other as party members, and estrous females avoided each other. These results are consistent with previous findings that adult males are more gregarious than females. They diverge from the standard picture of chimpanzee society, however, by suggesting a mutual affinity among anestrous females, but not among adult males as a class.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44563/1/10764_2004_Article_409685.pd