1. Evolutionary Biology
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Behavioural diversity of bonobo prey preference as a potential cultural trait

  1. Liran Samuni  Is a corresponding author
  2. Franziska Wegdell
  3. Martin Surbeck
  1. Harvard University, Department of Human Evolutionary Biology, United States
  2. Max Planck Institute of Evolutionary Anthropology, Germany
  3. Bonobo Conservation Initiative, United States
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Cite this article as: eLife 2020;9:e59191 doi: 10.7554/eLife.59191
1 figure, 1 video, 2 tables and 4 additional files

Figures

Figure 1 with 1 supplement
Predation patterns in Kokolopori bonobos.

Hunting locations (Figure 1—source data 1) of the three prey types: (a) anomalure (square), (b) duiker (circle), and (c) squirrel (triangle) in relation to the 95% Kernel usage area of Ekalakala (white polygon with solid border) and Kokoalongo (dark grey polygon with dashed border) and 50% Kernel usage area (Ekalakala in yellow, Kokoalongo in red). The overlapping 95% kernel area between Ekalakala and Kokoalongo is depicted in light grey. Also depicted are (d) the predicted hunt probabilities of the different prey types between Ekalakala and Kokoalongo as obtained from the BR model (Figure 1—source data 2).

Figure 1—source data 1

Hunt locations of the different prey types.

https://cdn.elifesciences.org/articles/59191/elife-59191-fig1-data1-v1.csv
Figure 1—source data 2

Predicted hunt probabilities of the different prey types.

https://cdn.elifesciences.org/articles/59191/elife-59191-fig1-data2-v1.csv
Figure 1—figure supplement 1
Prey species categories hunted by the Kokolopori bonobos.

Depicted from top to bottom. Congo rope squirrel (Funisciurus congicus; 108–113 g) – a diurnal social species that live in small groups. Congo rope squirrel nest in masses of twigs (‘drey’) located in the forks of branches or tree holes (Kingdon et al., 2013). Hunts of squirrels by bonobos appear solitary and opportunistic and are often unobserved, with a few observations suggesting that squirrels are hunted in proximity to their nests. Potentially due to the small size of squirrel prey, squirrel meat is rarely shared except within mother-offspring dyads. Lord Derby’s Anomalure (Anomalurus derbianus; 450–1,100 g) – a nocturnal arboreal species that dens in vertical hollow tree trunks. Adult individuals often nest alone but may occasionally share tree holes with few adults or other species (Kingdon et al., 2013). Bonobos will often climb and inspect tree holes, potentially in the search of anomalure prey. Upon detection, anomalure species usually attempt to escape by gliding from one tree to the other. Therefore, anomalure hunts typically involve several group members that shift between terrestrial and arboreal positions. Anomalure captures are typically accompanied by vocalizations and affiliative interactions (e.g., genital rubbing), and the meat is often shared between several adult individuals. Blue Duiker (Philantomba monticola; 3.9–6.5 kg) – a diurnal monogamous species that forage on the forest floor. After birth, females conceal their calf between tree buttresses for several weeks (Kingdon et al., 2013). Bonobos both actively chase adult duikers or, when detected, opportunistically seize duiker calves from their hiding locations. The only recorded duiker hunt in Ekalakala was the capture of a concealed duiker calf. As with anomalure hunts, the capture of duikers leads to heightened arousal amongst group members, expressed by vocalizations and affiliative gestures, and duiker meat is typically shared. We also once observed three Ekalakala females inspecting an injured adult female Bay duiker (Cephalophus castaneus), the other duiker species frequently hunted by the bonobos, hidden at the exit of a hollow log but they did not attempt to capture it.

Videos

Video 1
Duiker and anomalure hunting by Kokolopori bonobos.

Tables

Table 1
Successful hunts in Ekalakala and Kokoalongo between August 2016-Jan 2020.
GroupAnomalure*DuikerSquirrel
Ekalakala3111
Kokoalongo31112
  1. * Anomalurus derbianus, Anomalurus beecrofti.

    Philantomba monticola, Cephalophus castaneus.

  2. Funisciurus congicus.

Table 2
Bayesian Regression model results of the effect of group identity, number of available hunters and ecological variation on prey species captured (1anomalure and 2Ekalakala as reference categories). 

All numeric predictor variables were standardized to mean = 0 and sd = 1.

Coded levelTermEstimateSE95% CI
Duiker1Intercept−3.251.04−5.50,–1.51
Group (Kokoalongo2)4.561.571.93, 8.03
Available male hunters0.430.77−1.05, 1.99
Available female hunters0.420.75−1.07, 1.90
Association−0.770.74−2.30, 0.68
Usage difference0.390.55−0.63, 1.52
Sine of Date1.240.82−0.33, 2.89
Cosine of Date0.000.84−1.68, 1.63
Squirrel1Intercept−3.321.03−5.61,–1.52
Group (Kokoalongo2)4.991.512.34, 8.21
Available male hunters0.500.80−1.09, 2.11
Available female hunters−0.180.77−1.66, 1.30
Association−0.610.73−2.06, 0.79
Usage difference0.710.55−0.32, 1.89
Sine of Date1.030.79−0.47, 2.67
Cosine of Date0.360.81−1.21, 1.92

Data availability

The data reported in this paper are available as Source Data 1 and supplementary files. Source data files have been provided for Figure 1.

Additional files

Source data 1

Dataset used in the statistical analysis.

https://cdn.elifesciences.org/articles/59191/elife-59191-data1-v1.csv
Supplementary file 1

Successful hunt cases on anomalure, duiker, and squirrel species documented between August 2016 and January 2020 in Ekalakala (EKK) and Kokoalongo (KKL).

The identity and sex (M = male, F = Female) of the individual that caught the prey is noted whenever information was available (NA = unknown). The party composition columns depict the different group members that were present during the hunt scan. In bold presented are the individuals that participated in the hunt (i.e., chased prey) when known. Note, we have at times likely underestimated the number of hunters.

https://cdn.elifesciences.org/articles/59191/elife-59191-supp1-v1.docx
Supplementary file 2

Demography of the adult individuals of the Ekalakala and Kokoalongo groups, 2016–2020 (M = male, F = Female).

https://cdn.elifesciences.org/articles/59191/elife-59191-supp2-v1.docx
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https://cdn.elifesciences.org/articles/59191/elife-59191-transrepform-v1.docx

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