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We present census data for eight primate species spanning 32.9 years along the same transect at Ngogo, Kibale National Park, Uganda, demonstrating major changes in the composition of the primate community. Correlated with an estimated decline of ∼89% in the red colobus population was an increase in encounter rates with chimpanzee parties. Our data, along with the unusually high rates of predation by chimpanzees on red colobus at Ngogo and the fact that the chimpanzee community at Ngogo is the largest ever recorded, support the conclusion that the red colobus decline was caused primarily by chimpanzee predation. This seems to be the first documented case of predation by one nonhuman primate causing the population decline in another. We evaluated disease and interspecific competition as other possible causes of the red colobus decline, but judged them to be relatively insignificant compared with predation by chimpanzees. Notable changes in encounter rates with other primate species may have resulted from forest expansion. Those for mangabeys, redtails, and black and white colobus increased significantly. Encounter rates increased for l'Hoest's monkeys too, but the increased sightings may have been an artifact of increased habituation. Sightings of blue monkey and baboon groups declined. There was no significant change in encounter rates for all species combined. The Ngogo primate community seemed to be in a nonequilibrium state, changing from one dominated by two species, a folivore (red colobus) and a frugivorous omnivore (redtails), to one dominated by three species of frugivorous omnivores (redtails, mangabeys, and chimpanzees). This study demonstrates the importance of long-term monitoring in understanding population dynamics and the role of intrinsic variables in shaping the species composition of a community. Am. J. Primatol. 73:997-1011, 2011. © 2011 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

The article presents an abstract of the paper "Group size and daily travel distance in red colobus (Procolobus rufomitratus tephrosceles) in Kibale National Park: an inconsistency with the ecological constraints model," presented at the 21st Congress of the International Primatological Society held June 25-30, 2006 at Entebbe, Uganda.

The article presents the abstract of the paper "Can We See the Monkeys for the Trees? Visibility and Other Challenges for Analysis of Line Transect Data," by A.R. Marshall, T.T. Struhsaker and S.T. Buckland to be presented at the 21st Congress of the International Primatological Society, scheduled in Entebbe, Uganda from June 25-30, 2006.

The article presents the abstract of the paper "Plenary Session: Demographic Variability in Non-Human Primates: Implications for Theory and Conservation," by T.T. Struhsaker, that will be presented at the 21st Congress of the International Primatological Society in Entebbe, Uganda, from June 25-30, 2006.

The rapid disruption of tropical forests probably imperils global biodiversity more than any other contemporary phenomenon. With deforestation advancing quickly, protected areas are increasingly becoming final refuges for threatened species and natural ecosystem processes. However, many protected areas in the tropics are themselves vulnerable to human encroachment and other environmental stresses. As pressures mount, it is vital to know whether existing reserves can sustain their biodiversity. A critical constraint in addressing this question has been that data describing a broad array of biodiversity groups have been unavailable for a sufficiently large and representative sample of reserves. Here we present a uniquely comprehensive data set on changes over the past 20 to 30 years in 31 functional groups of species and 21 potential drivers of environmental change, for 60 protected areas stratified across the world’s major tropical regions. Our analysis reveals great variation in reserve ‘health’: about half of all reserves have been effective or performed passably, but the rest are experiencing an erosion of biodiversity that is often alarmingly widespread taxonomically and functionally. Habitat disruption, hunting and forest-product exploitation were the strongest predictors of declining reserve health. Crucially, environmental changes immediately outside reserves seemed nearly as important as those inside in determining their ecological fate, with changes inside reserves strongly mirroring those occurring around them. These findings suggest that tropical protected areas are often intimately linked ecologically to their surrounding habitats, and that a failure to stem broad-scale loss and degradation of such habitats could sharply increase the likelihood of serious biodiversity declines.

The redtail monkeys of the Kibale Forest, W. Uganda, live in social groups of about 35 members with only one adult male. In one of the study groups the harem male was replaced by a new male from outside the group. This male-replacement was followed by the new male killing and eating two newborn infants in the group. Infants and young juveniles older than one month were not attacked. Following the infanticide the new male copulated with several adult females in the group. 8 months after this male joined the group, 5 other adult and subadult males associated with it. This multimale influx was accompanied by frequent and intense aggression among the males. Comparisons are made with the studies of langurs in India and Ceylon and it is suggested that infanticide following male-replacement in the harem affords reproductive advantages to the new male.

A comparison of the communicative gestures of vervets with those of other cercopithecines reveals both similarities and differences. Examples have been given of gestures (i) exhibited by all cercopithecines, (ii) rare or absent in vervets and common in several other species, (iii) demonstrated by vervets and a few other cercopithecines, and (iv) common in vervets and rare or absent in other members of the subfamily. Vervets, baboons, and rhesus monkeys have approximately the same number of visual signals in their behavioral repertoires-46, 42, and 49, respectively. Patas monkeys seem to have a smaller repertoire. Fifty-nine percent of the vervet patterns have also been described for rhesus monkeys, 63 percent for baboons, and 54 percent for patas. In cercopithecines, visual communicative patterns seem to be evolutionarily one of the most stable forms of behavior, in structural terms. Some of the greatest differences in communicative gestures are differences in the temporal aspects. In species of this subfamily, vocal patterns seem to vary more than visual signals. Greater structural differences in communicative gestures may be found in the Cercopithecinae when systematic field studies are made of some of the forest-dwelling species, about which we know very little.