All-You-Can-Eat: Influence of Proximity to Maize Gardens on the Wild Diet and the Forest Activities of the Sebitoli Chimpanzee Community in Kibale National Park

Abstract

Frugivorous primates have developed several strategies to deal with wild fruit scarcity, such as modifying their activity budget or enlarging their diet. Agricultural expansion threatens primate habitats and populations (e.g., disease transmission, agrochemical exposure), but it also increases crop feeding opportunities. We aimed at understanding whether maize presence close to the natural habitat of chimpanzees, a threatened species, would lead to significant behavioral modifications. We monitored 20 chimpanzees over 37 months in Kibale National Park, Uganda, with maize gardens at the forest edge. Based on focal nest-to-nest data, we analyzed their diet, activity budget, and energy balance depending on wild fruit and maize availability. We found that the Sebitoli area is a highly nutritive habitat for chimpanzees, with large and caloric wild fruits available all year long. The chimpanzees opportunistically consume maize and exploit it by resting less during maize season. However, no significant variation was found in daily paths and energy expenditures according to maize availability. No behavioral or energy modification was observed regarding wild resources either. Despite the availability of nutritious domestic resources, chimpanzees still exploit wild fruits and do not limit their movements. Thus, their contribution to seed dispersal and forest regeneration in this area is not affected.

High urinary oxidative DNA damage in wild chimpanzees ranging in proximity of agricultural fields in Sebitoli area, Uganda

“…Both isoprostanes and lipid peroxides (markers of oxidative damage to lipids) did not differ among the three exposure levels, indicating that lipid peroxidation was not affected by the differences in the diet. The current results confirmed that feeding on maize does not make a significant difference in the caloric intake for Sebitoli chimpanzees sampled as previously shown (Couturier et al, 2022).…”

“…We used this as proxy for their pesticide exposure level as high, medium and low. To determine the category of exposure for a given individual, we used both the camera trap frequency of detection at the border between crops and the forest (Couturier et al 2022) and the long-term observations of the ranging pattern of individuals. We collected 33 urine samples from 4 female and 5 male chimpanzees in the high exposition group (5 from juveniles, 12 from subadults, 16 from adults).…”

“…However, the increased proximity of crops to tropical forests may also provide wildlife with alternative resources, like different nutrient composition when compared to wild plant species (McLennan & Ganzhorn, 2017). In addition, anthropogenic food is often found in great abundance throughout the year, usually clustered on the ground and thus easily accessible with low energy expenditure needed (Chiyo et al, 2005;Couturier et al, 2022;Naughton-Treves et al, 1998). In turn, this provides advantages also by reducing within-group feeding competition.…”

“…While adult male chimpanzees are travelling the whole territory and patrolling at the edge of the territory of the community, adult females and their dependents may be resident of only a part of it (Couturier et al, 2022;Mitani & Watts, 2005; M. E. Thompson & Wrangham, 2006;Watts & Mitani, 2001;Williams et al, 2002). In addition, individuals residing most of their time near crops also consume the crops more frequently (Couturier et al, 2022).…”

Survey of ticks and tick-borne pathogens in wild chimpanzee habitat in Western Uganda

“…In Kibale, ticks can be found in the nostrils of both young chimpanzees and researchers [ 31 , 32 ], highlighting the potential risk of cross-contamination between humans and chimpanzees. In the Sebitoli area, chimpanzees regularly visit surrounding gardens to feed on crops [ 96 ], a proximity that could favor the cross-transmission of pathogens as has been shown for malaria [ 97 ] and Oesophagostomum infection [ 98 ].…”