Ecological constraints on group size: an analysis of spider monkey and chimpanzee subgroups

1995 ◽  
Vol 36 (1) ◽  
pp. 59-70 ◽  
Author(s):  
C.A. Chapman ◽  
L.J. Chapman ◽  
R.W. Wrangham
Keyword(s):  
Group Size ◽  
Spider Monkey ◽  
Ecological Constraints

Ecological constraints on group size: an analysis of spider monkey and chimpanzee subgroups

1995 ◽  
Vol 36 (1) ◽  
pp. 59-70 ◽  
Author(s):  
C. A. Chapman ◽  
Richard W. Wrangham ◽  
Lauren J. Chapman
Keyword(s):  
Group Size ◽  
Spider Monkey ◽  
Ecological Constraints

Manipulating foraging group size: spider monkey food calls at fruiting trees

1990 ◽  
Vol 39 (5) ◽  
pp. 891-896 ◽  
Author(s):  
Colin A. Chapman ◽  
Louis Lefebvre
Keyword(s):  
Group Size ◽  
Spider Monkey

scholarly journals Intra-Population Variability in Group Size of Indo-Pacific Humpback Dolphins (Sousa chinensis)

2021 ◽  
Vol 8 ◽  
Author(s):  
Mingming Liu ◽  
Mingli Lin ◽  
David Lusseau ◽  
Songhai Li
Keyword(s):  
Group Size ◽  
Group Living ◽  
Population Variability ◽  
Behavioral State ◽  
Ecological Constraints ◽  
Social Strategy ◽  
Temporal Variables ◽  
Sousa Chinensis ◽  
First Time ◽  
Large Groups

Group size is a key social trait influencing population dynamics of group-living animals. The Indo-Pacific humpback dolphins (IPHDs), Sousa chinensis, a shallow water delphinid species, display a fission-fusion social system. Yet little is known about how social organization of this species vary with temporal scales and behavioral state. In this study, we sampled group size estimates from the world’s second largest population of humpback dolphins (Sousa spp.), which inhabit the eastern waters of Zhanjiang, China. IPHD group sizes changed seasonally and inter-annually, but not with tidal phases. Group sizes also changed with behavioral state of IPHD groups and with number of mother-calf pairs present. IPHDs formed larger groups in the autumn than in other seasons, which might be related to seasonal changes in food availability and reproductive cycle. Of the groups observed, we recorded the presence of mother-calf pair in 85 groups (i.e., nursery groups: 47 ones with one pair, 25 ones with two pairs, and others with three pairs). Notably, nursery groups were about 2–4 times larger than non-nursery groups. In addition, group sizes greatly increased with the number of mother-calf pairs. Living in relatively large groups, more protection, food, and resources might be available for IPHD mothers and calves, and such social strategy provide higher reproduction efficiency and survival success for this species. During our observations, feeding (45.5%) and traveling (25.2%) represented the majority of IPHD’s behavioral budget, while socializing (8.4%) and resting/milling (6.8%) were not frequently observed. Resting/milling groups were approximately 50% smaller than feeding, traveling, or socializing groups, while the latter three types had a similar mean group size. Large groups when IPHDs foraged, traveled, or socialized, might provide more added group benefits. For the first time, our findings clearly revealed intra-population variability in IPHD group sizes across different behavioral and temporal variables, and provided a better understanding of IPHDs’ adaptations to various biological processes and ecological constraints.

scholarly journals Dissecting the two mechanisms of scramble competition among the Virunga mountain gorillas

2021 ◽  
Vol 75 (5) ◽  
Author(s):  
Andrew M. Robbins ◽  
Cyril C. Grueter ◽  
Didier Abavandimwe ◽  
Tara S. Stoinski ◽  
Martha M. Robbins
Keyword(s):  
Group Size ◽  
Scramble Competition ◽  
Ecological Constraints ◽  
Mountain Gorillas ◽  
Total Travel Time ◽  
Group Members ◽  
Per Capita ◽  
Travel Studies ◽  
The Individual ◽  
Group Travel

Abstract Two mechanisms have been proposed to explain why scramble competition can increase the travel requirements of individuals within larger groups. Firstly, individuals in larger groups may be more likely to encounter food sites where other group members have already eaten, leading to greater asynchronous “individual” travel to find fresh sites. Secondly, when food sites are aggregated into patches, larger groups may need to visit more patches to obtain the same amount of food per capita, leading to greater synchronous “group” travel between patches. If the first mechanism can be mitigated by increasing group spread, then we expect the second mechanism to be more sensitive to group size. Here, we examine the individual travel and group travel of the Virunga mountain gorillas, along with potential implications for the two mechanisms of scramble competition. Asynchronous individual travel accounted for 67% of the total travel time, and the remainder arose from group travel. Group spread increased significantly for larger groups, but not enough to prevent an increase in individual travel. Contrary to expectations, group travel decreased with size among most groups, and we found only limited evidence of patch depletion that would cause the second mechanism of scramble competition. Collectively, our results illustrate how the influence of group size can differ for individual travel versus group travel, just as it differs among species for overall travel. Studies that distinguish between the two mechanisms of scramble competition may enhance our understanding of ecological constraints upon group size, including potential differences between frugivores and folivores. Significance statement Feeding competition provides insight into how group size can influence the foraging patterns of social animals, but two key mechanisms are not typically compared. Firstly, larger groups may visit more patches to access the same amount of food per capita (group travel). Secondly, their individuals may also need to move past more spots where another member has already eaten (individual travel). Contrary to expectations, we found that group travel decreased with size for most groups of mountain gorillas, which may reflect extra travel by smaller groups to avoid larger groups. Individual travel increased with size in most groups, even though gorillas in larger groups compensated by spreading out over a broader area. The two mechanisms revealed patterns that were not apparent in our previous study of overall travel. Our approach may help to explain potential differences between folivores and frugivores.

An ecological basis for large group size in Colobus angolensis in the Nyungwe Forest, Rwanda

2001 ◽  
Vol 39 (1) ◽  
pp. 83-92 ◽  
Author(s):  
Cheryl Fimbel ◽  
Amy Vedder ◽  
Ellen Dierenfeld ◽  
Felix Mulindahabi
Keyword(s):  
Group Size ◽  
Large Group ◽  
Colobus Angolensis ◽  
Ecological Basis
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