The effects of social context and food abundance on chimpanzee feeding competition

Abstract

Feeding competition is thought to play a role in primate social organization as well as cognitive evolution. For chimpanzees (Pan troglodytes), social and ecological factors can affect competition, yet how these factors interact to affect feeding behavior is not fully understood; they can be difficult to disentangle in wild settings. This experiment investigated the differential effects of food quantity, the presence of a co-feeding partner, and the contestability of a food patch on feeding rate. We presented tolerant pairs of chimpanzees from a semi-captive social group with an apparatus comprising a matrix of transparent tubes between two adjacent rooms, of which, either all (abundant condition) or only a small proportion (scarce condition) were baited with peanuts. Dyads were either grouped into the competitive treatment, in which peanuts were accessible from both sides of the apparatus simultaneously, or the non-competitive treatment, in which the peanuts were pre-divided; half of the tubes were accessible to one chimpanzee from one side, and the other half were accessible only from the opposite side of the apparatus. We compared dyadic tolerance levels with individual feeding rates across quantity conditions and between competitive treatments. While tolerance and food quantity had no effect on feeding rate, partner presence significantly increased feeding rate relative to individual feeding. This increase was much larger when the dyads directly competed over the peanuts than when they were co-feeding on a pre-divided set of peanuts. Thus, in a co-feeding situation, the presence of another individual and, to an even larger extent, the contestability of the food source play a larger role in chimpanzee feeding behavior than dyadic tolerance or food quantity. These findings highlight the relative impact of social facilitation and direct competition on co-feeding behavior between pairs of chimpanzees.

Chimpanzees’ understanding of social leverage

“…the payoffs of the game, their partner’s potential actions), resulting in an increased likelihood to opt out for less rewarding but secure outcome to reduce uncertainty and competition. Supporting this interpretation, a recent study shows that the mere presence of another chimpanzee while co-feeding, accelerated chimpanzees feeding rate relative to individual feeding [35].…”

Gut microbiota of homologous Chinese soft-shell turtles (Pelodiscus sinensis) in different habitats

“…Considering the similarity of natural conditions, such as geographical location, climate, rainfall and temperature, among the mentioned three habitats, the food intake and relative living space might be the main factors determining the growth and physiology of turtles in this study, referring to the researches of aqutaic animals as perch ( Perca fluviatilis ), crucian carp ( Carassius auratus ) and African cichlid fishes [ 34 – 36 ]. Wild turtles are predominantly carnivorous and prey on small fish, mollusks, crustaceans, insects or their larvae, and occasionally some plant seeds, but food abundance is affected by the aquatic environment, competitors and natural enemies in different habitats [ 37 , 38 ]. In the present study, turtles in paddy fields and ponds were regularly fed artificial feeds, but no such feeds were provided for turtles in the lake during the experiment.…”

A review of research in primate sanctuaries

“…For instance, the study of cooperative behaviours among great apes has been widespread in sanctuary settings, with studies involving chimpanzees at Ngamba [97][98][99][100][101][102][103][104], Tchimpounga [105][106][107] and Sweetwaters [108], as well as bonobos at Lola [105,109]. In addition to cooperation, chimpanzee resource competition [110,111], helping behaviour [112][113][114] and altruism [115] have also been studied. Such studies, as well as extensive research on prosociality with both chimpanzees [116][117][118][119] and bonobos [97,[120][121][122][123][124], use behavioural measures to assess apes' cognitive abilities.…”