Diet of chimpanzees (Pan troglodytes schweinfurthii) at Ngogo, Kibale National Park, Uganda, 2. temporal variation and fallback foods

Abstract

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.

Food mechanical properties and isotopic signatures in forest versus savannah dwelling eastern chimpanzees

“…These measurements included 17 plant species from Ngogo (Table 2) that comprised all species observed above 1% of the feeding time of chimpanzees during 36 h of dry season focal feeding observations. These species feeding times agreed well with long-term observations of the dry season at this site 8 . At Issa, 19 species were tested, including samples from Ficus , Saba , and Garcinia (Table 3) that are considered year-round staple foods 10 .…”

“…Indeed, there is up to 73% overlap in feeding species between the two sites 3,7 . Ngogo and Kanyawara provide an example of tropical rainforest, and the chimpanzees at both sites have diets comprised largely of fleshy ripe fruits even in times of reduced production 3,8 . This pattern of high fruit consumption characterises chimpanzees inhabiting tropical and subtropical moist broadleaf forests 21 .…”

“…This information was checked against the substantial literature on chimpanzee diet in the Ngogo study area 7,8,59 to confirm that the items seen eaten were typical for the time of year and habitat. With such guidance, we determined the most important foods to test by conducting day-long follows of chimpanzees, employing the focal techniques used by Vogel et al 18 .…”

Chimpanzee (Pan troglodytes verus) Diet Composition and Food Availability in a Human-Modified Landscape at Lagoas de Cufada Natural Park, Guinea-Bissau

“…It is commonly assumed that frugivore biomass correlates with fruit abundance and fruit tree density, which highlights the importance of fruit availability in maintaining frugivorous primate populations (Stevenson 2001). Fruit availability varies among plant species, seasons, and study sites: at some sites ripe fruits are highly abundant during the wet season (Basabose 2005;Hernandez-Aguilar 2009;Suzuki 1969;Tutin et al 1997), whereas at other sites fruit abundance peaks during the dry season (Hockings et al 2009), or there is a bimodal pattern with peaks in both seasons (Watts et al 2012a).…”

The ecology of primate retroviruses – An assessment of 12 years of retroviral studies in the Taï national park area, Côte d׳Ivoire

“…For example, red colobus are also the most frequently hunted prey of the eastern chimpanzees ( P. t. schweinfurthii ) at Ngogo, in Kibale National Park, Uganda (Mitani and Watts, 1999; Watts et al, 2012), but unsustainable levels of chimpanzee hunting pressure have recently caused this red colobus population to undergo a major decline (Teelen, 2008). This dynamism in the backdrop in which retroviruses circulate creates new evolutionary pressures and epidemiological processes which might result in new patterns of cross-species and zoonotic transmission.…”