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Fruit production in tropical forests varies considerably in space and time, with important implications for frugivorous consumers. Characterizing temporal variation in forest productivity is thus critical for understanding adaptations of tropical forest frugivores, yet long‐term phenology data from the tropics, in particular from African forests, are still scarce. Similarly, as the abiotic factors driving phenology in the tropics are predicted to change with a warming climate, studies documenting the relationship between climatic variables and fruit production are increasingly important. Here, we present data from 19 years of monitoring the phenology of 20 tree species at Ngogo in Kibale National Park, Uganda. Our aims were to characterize short‐ and long‐term trends in productivity and to understand the abiotic factors driving temporal variability in fruit production. Short‐term (month‐to‐month) variability in fruiting was relatively low at Ngogo, and overall fruit production increased significantly through the first half of the study. Among the abiotic variables, we expected to influence phenology patterns (including rainfall, solar irradiance, and average temperature), only average temperature was a significant predictor of monthly fruit production. We discuss these findings as they relate to the resource base of the frugivorous vertebrate community inhabiting Ngogo. [ABSTRACT FROM AUTHOR]

Although numerous ecological and social factors influence range use in vertebrates, the general assumption is that ranging patterns typically accord with principles of optimal foraging theory. However, given temporal variability in resource abundance, animals can more easily meet nutritional needs at some times than at others. For species in which sociality is particularly important for fitness, such as chimpanzees ( Pan troglodytes) and other group-living primates, the influences of social factors can be particularly strong, and likely interact closely with ecological factors. We investigated home range use by a community of chimpanzees at Ngogo, Kibale National Park, Uganda, to determine whether range use corresponded to energy-based optimality principles. Chimpanzees were particularly attracted to areas of the home range where individuals of Ficus mucuso (a large but low-density resource) were found, but only if those areas also offered other preferred or important resource classes. The aggregation of large foraging parties at F. mucuso crowns (frequently seen year-round) facilitates a number of socially beneficial activities for both males and females. Because chimpanzees apparently seek out F. mucuso in areas where other high-quality feeding opportunities exist, these social benefits likely do not come at the expense of fitness benefits accrued from feeding on high-quality resources. Am. J. Primatol. 78:432-440, 2016. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Highly frugivorous primates like chimpanzees ( Pan trogolodytes) must contend with temporal variation in food abundance and quality by tracking fruit crops and relying more on alternative foods, some of them fallbacks, when fruit is scarce. We used behavioral data from 122 months between 1995 and 2009 plus 12 years of phenology records to investigate temporal dietary variation and use of fallback foods by chimpanzees at Ngogo, Kibale National Park, Uganda. Fruit, including figs, comprised most of the diet. Fruit and fig availability varied seasonally, but the exact timing of fruit production and the amount of fruit produced varied extensively from year to year, both overall and within and among species. Feeding time devoted to all major fruit and fig species was positively associated with availability, reinforcing the argument that chimpanzees are ripe fruit specialists. Feeding time devoted to figs-particularly Ficus mucuso (the top food)-varied inversely with the abundance of nonfig fruits and with foraging effort devoted to such fruit. However, figs contributed much of the diet for most of the year and are best seen as staples available most of the time and eaten in proportion to availability. Leaves also contributed much of the diet and served as fallbacks when nonfig fruits were scarce. In contrast to the nearby Kanywara study site in Kibale, pith and stems contributed little of the diet and were not fallbacks. Fruit seasons (periods of at least 2 months when nonfig fruits account for at least 40% of feeding time; Gilby & Wrangham., Behavioral Ecology and Sociobiology 61:1771-1779, 2007) were more common at Ngogo than Kanyawara, consistent with an earlier report that fruit availability varies less at Ngogo [Chapman et al., African Journal of Ecology 35:287-302, 1997]. F. mucuso is absent at Kanyawara; its high density at Ngogo, combined with lower variation in fruit availability, probably helps to explain why chimpanzee population density is much higher at Ngogo. [ABSTRACT FROM AUTHOR]

Chimpanzees ( Pan troglodytes) are ecologically flexible omnivores with broad diets comprising many plant and animal foods, although they mostly eat fruit (including figs). Like other ecologically flexible nonhuman primates (e.g., baboons, Papio spp.) with broad diets, their diets vary across habitats. Much data on diets come from short studies that may not capture the range of variation, however, and data are scant on variation within habitats and populations. We present data on diet composition and diversity for chimpanzees at Ngogo, in Kibale National Park, Uganda, collected over a 15-year period, with a focus on the plant components of the diet. We compare Ngogo data to those on chimpanzees at the nearby Kibale site of Kanyawara, on other chimpanzee populations, and on some other frugivorous-omnivorous primates. Results support the argument that chimpanzees are ripe fruit specialists: Ngogo chimpanzees ate a broad, mostly fruit-based diet, feeding time devoted to fruit varied positively with fruit availability, and diet diversity varied inversely with fruit availability. Comparison of Ngogo and Kanyawara shows much similarity, but also pronounced within-population dietary variation. Chimpanzees fed much more on leaves, and much less on pith and stems, at Ngogo. Figs accounted for somewhat less feeding time at Ngogo, but those of Ficus mucuso were quantitatively the most important food. This species is essentially absent at Kanayawara; its abundance and high productivity at Ngogo, along with much higher abundance of several other important food species, help explain why chimpanzee community size and population density are over three times higher at Ngogo. High inter-annual variation at Ngogo highlights the value of long-term data for documenting the extent of ecological variation among chimpanzee populations and understanding how such variation might affect population biology and social dynamics. Am. J. Primatol. 73:1-16, 2011. © 2011 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Chimpanzees (Pan troglodytes) have hostile intergroup relations throughout most or all of their geographic range. Hostilities include aggressive encounters between members of neighboring communities during foraging and during patrols in which members of one community search for neighbors near territory boundaries. Attacks on neighbors involve coalitions of adult males, and are sometimes fatal. Targets include members of all age/sex classes, but the risk of lethal intergroup coalitionary aggression is highest for adult males and infants, and lowest for sexually swollen females. The best-supported adaptive explanation for such behavior is that fission-fusion sociality allows opportunities for low-cost attacks that, when successful, enhance the food supply for members of the attackers' community, improve survivorship, and increase female fertility. We add to the database on intergroup coalitionary aggression in chimpanzees by describing three fatal attacks on adult males, plus a fourth attack on an adult male and an attack on a juvenile that were almost certainly fatal. Observers saw four of these attacks and inferred the fifth from forensic and behavioral evidence. The attackers were males in two habituated, unprovisioned communities (Ngogo and Kanyawara) in Kibale National Park, Uganda. We also summarize data on other intercommunity attacks at Ngogo. Our observations are consistent with the “imbalance of power” hypothesis [Manson & Wrangham, Current Anthropology 32:369–390, 1991] and support the argument that lethal coalitionary intergroup aggression by male chimpanzees is part of an evolved behavioral strategy. Am. J. Primatol. 68:161-180, 2006. © 2006 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

In an attempt to describe hormone–behavior interactions in a sample of wild male chimpanzees, we quantified testosterone in 67 fecal samples obtained from 22 adult male chimpanzees at Ngogo, Kibale National Park, Uganda. A mixed-model methodology that controlled for age-class identified a significant positive association between testosterone levels and dominance rank. The results are consistent with those reported from a separate, smaller chimpanzee community in the same population in a study that analyzed testosterone levels in urine [Muller & Wrangham, 2004]. As in that earlier study, our results held during a period of social stability, which is not consistent with predictions of the “challenge hypothesis.” We concur with Muller and Wrangham [2004] that the challenge hypothesis requires modification to explain the chimpanzee data, because fission-fusion sociality in chimpanzees makes challenges unpredictable. We also discuss the utility of fecal samples and a mixed-model statistical method for behavioral endocrinology studies. Am. J. Primatol. 64:71–82, 2004. © 2004 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Presents information on a study which investigated the demographic effects on the hunting behavior of a community of wild chimpanzees at Ngogo in the Kibale National Park, Uganda. Methods; Results; Discussion and comparisons with other studies.

Chimpanzees (Pan troglodytes) hunt various primates, but concentrate on red colobus monkeys (Piliocolobus spp.) wherever the two species are sympatric. The extraordinarily large Ngogo chimpanzee community in Kibale National Park, Uganda, preys heavily on the local population of red colobus (P. tephrosceles). Census data showed a steep decline in this population in the center of the chimpanzees' home range between 1975 and 2007 [Lwanga et al., 2011; Teelen, 2007b]. Given no obvious change in food availability, predation by chimpanzees was the most likely cause [ibid.; Teelen, 2008]. However, census data from other parts of the home range raised the possibility that the decline was restricted to this central area [Teelen, 2007a] We present data from 1998 to 2012 on the rate of encounters between chimpanzees and red colobus that provide a chimpanzee-centered estimate of red colobus density, thus of predation opportunities, throughout the home range. These corroborate census data by showing a long-term decline in encounters near the center. They also show that encounters become relatively more common at increasing distances from the center, but encounter rates have decreased even in peripheral areas and, by implication, the red colobus population has declined throughout the study area. These data corroborate Teelen's [2008] conclusion that chimpanzee predation on red colobus during the 1990s and early 2000s was unsustainable. Hunting rates and prey offtake rates have also declined markedly; whether this will allow the red colobus population to recover is unknown. In contrast, rates at which chimpanzees encountered redtail monkeys (Cercopithecus ascanius) and grey-cheeked mangabeys (Lophocebus albigena) did not decrease. Neither did they increase, however, contrary to long-term census data from the center of the study area [Lwanga et al., 2011]., (© 2013 Wiley Periodicals, Inc.)