Feeding Competition and Patch Size in the Chimpanzee Species Pan Paniscus and Pan Troglodytes

Behaviour ◽  
1988 ◽  
Vol 105 (1-2) ◽  
pp. 148-164 ◽  
Author(s):  
Richard W. Wrangham ◽  
Frances J. White
Keyword(s):  
Social Organization ◽  
Pan Troglodytes ◽  
Patch Size ◽  
Pan Paniscus ◽  
Feeding Competition ◽  
Feeding Time ◽  
Pan Troglodytes Schweinfurthii ◽  
Relative Importance ◽  
Party Size ◽  
Ecological Basis

AbstractThe relative importance of feeding competition in Pan paniscus and Pan troglodytes schweinfurthii is examined in an attempt to understand the major differences in social organization of the two species. P. paniscus at Lomako is characterized by a stronger tendency for association among females than among female P. troglodytes at Gombe. Party size in P. paniscus is dependent on patch size. Feeding competition was more important in small patches than in large patches. The total amount of feeding time by a party in a patch (chimp-minutes) was a measure of patch size that was available for both chimpanzee species. P. paniscus was found to have larger party sizes and to use larger food patches than P. troglodytes. The importance of dispersed ground foods for each species of chimpanzee was compared and, although the results are not conclusive, they indicate that this type of food was equally important in the diets of both populations. Two hypotheses of the ecological basis for differences in social structure are compared in light of this evidence.

Food Competition Among Individuals in a Free-Ranging Chimpanzee Community in Kibale Forest, Uganda

Behaviour ◽  
1988 ◽  
Vol 105 (1-2) ◽  
pp. 135-147 ◽  
Author(s):  
Gilbert Isabirye-Basuta
Keyword(s):  
Patch Size ◽  
Fruit Trees ◽  
Food Competition ◽  
Foraging Efficiency ◽  
Limiting Factor ◽  
Feeding Time ◽  
Food Patch ◽  
Party Size ◽  
Per Capita ◽  
The Difference

AbstractCompetition for fruit within chimpanzee foraging parties was investigated by testing the hypotheses that food patch size was a limiting factor to foraging party size and to foraging efficiency while chimpanzees were foraging in Pseudospondias microcarpa trees for fruit. Large food patches (as measured by phenological score or the product of diameter at breast height and phenological score) supported significantly larger parties than did smaller food patches. In addition, foraging efficiency was apparently higher for small parties than for large ones, although the difference was marginally statistically significant. Per-capita feeding time for individuals in small parties was significantly higher than for those in large parties when chimpanzees had access to both Pseudospondias and Uvariopsis congensis fruit trees. Per-capita feeding time was not significantly correlated with food patch size. When Uvariopsis fruit trees became exhausted in mid-August, some chimpanzees apparently avoided severe competition for fruit by leaving the C.C. area, where they had been feeding on both Uvariopsis and Pseudospondias fruit. Social factors did not significantly affect foraging party size nor per-capita feeding time.

scholarly journals Flexibility in the social structure of male chimpanzees (Pan troglodytes schweinfurthii) in the Budongo Forest, Uganda

2021 ◽  
Author(s):  
Gal Badihi ◽  
Kelsey Bodden ◽  
Klaus Zuberbühler ◽  
Liran Samuni ◽  
Catherine Hobaiter
Keyword(s):  
Social Organization ◽  
Pan Troglodytes ◽  
Group Living ◽  
Social Organisation ◽  
Pan Troglodytes Schweinfurthii ◽  
Trade Off ◽  
Large Community ◽  
Data Support ◽  
Association Data ◽  
Large Groups

ABSTRACTIndividuals of social species face a trade-off between the competitive costs and social benefits of group living. Species show a range of social strategies to deal with this trade-off, for example atomistic fission-fusion dynamics in which temporary social groups of varying size and membership form and re-form; or molecular fission-fusion dynamics which contain stable sets of multilevel nested subgroups. Chimpanzees are considered an archetypical atomistic fission-fusion species, using dynamic changes in day-to-day association to moderate the costs of within-group competition. It has been argued that humans’ highly flexible social organisation allows us to live in extremely large groups. Using four years of association data from two neighbouring communities of East African chimpanzees (Pan troglodytes schweinfurthii), we describe new levels of flexibility in chimpanzee social organisation and confirm the presence of subgrouping in a second, large community of chimpanzees. We show that males from the larger Waibira community (N males 24-31) exhibited additional levels of semi-stable subgrouping, while males from the smaller Sonso community (N males 10-13) did not. Subgroup membership showed stability across some years, but flexibility across others. Our data support the hypothesis that chimpanzees can incorporate strategies other than fission-fusion to overcome costs of social living, and that their social organisation may be closer to that of modern humans than previously described.SIGNIFICANCE STATEMENTSocial living offers benefits and costs; groups can more easily locate and defend resources, but experience increased individual competition. Many species, or individuals, flexibly adjust their social organization when faced with different competitive pressures. It is argued that humans are unique among primates in combining multigroup social organisation with fission-fusion dynamics flexibly within and across groups, and that doing so allows us to live in extremely large groups. Using four-years of association data we show new levels of flexibility in chimpanzee social organization. Males from a typically-sized community employed atomistic fission-fusion dynamics, but males in an unusually large community incorporated additional semi-stable levels of subgrouping. Our data support the hypothesis that chimpanzee males combine social organization strategies, and that doing so may allow them, like humans, to mitigate individual costs at larger community sizes.

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