DOI: 10.5061/dryad.9p8cz8wrr
title: Lion pride size versus feeding group size

description: The attached dataset provides a sampled distribution of 3230 feeding
 groups of adult female lions in relation to size of the pride that those
 females belonged to in Serengeti National park, Tanzania. Ecological
 theory suggests that large social groups of carnivores should have reduced
 foraging efficiency because they encounter prey no more frequently than
 solitary hunters, but the entire group must share any prey they encounter.
 We developed behaviorally-based foraging models to show that fragmentation
 of large social groups into smaller hunting subgroups or mutual
 cooperation during hunting are both plausible hypothetical mechanisms
 capable of sustaining larger lion prides. The attached dataset from the
 Serengeti ecosystem demonstrates that lion prides typically fragment into
 small hunting groups that are well approximated by an exponential
 distribution of group sizes typical of fission-fusion social systems. A
 model linking fission-fusion group dynamics with predator-prey interaction
 predicts both the surprising degree of population stability of the
 Serengeti lions as well as the long-term persistence of large prides.
 There is little evidence, however, that Serengeti lions cooperate during
 hunting except when they hunt Cape buffalo, so fission-fusion is
 apparently the dominant stabilizing process in Serengeti.
description: Lion social groups were sampled by vehicle every day by
 traversing the Serengeti National Park and from VHS radio-collar signals.
 If the group was feeding, the number of adult females in the group was
 noted, as well as the total number of adult females in the pride that the
 feeding group belonged to.
description: # Lion pride size versus feeding group size ## Description of the data and
 file structure Data for the paper are provided in the attached data file:
 Feeding_groups_vs_pride_size_Serengeti.txt. This is an exceptionally
 simple dataset, aggregating data from Serengeti National Park on the
 number of adult females found in lion feeding groups on an ad hoc basis
 over the course of a multi-decadal field study led by Prof. Craig Packer
 at the University of Minnesota. Basic procedures contributing to the
 dataset can be found in C. Packer (2023), The Lion, Princeton University
 Press.  There are 3560 observations in the dataset, with each observation
 on a separate line in the file. The variable 'Pride' refers to
 the number of adult females in the pride to which the feeding group
 belongs. The variable 'Females' refers to the number of females
 in the feeding group that was observed. In each case, the variables
 represent integer count data, with no SI units. ## Code/Software 6 files
 are archived on Zenodo (10.5281/zenodo.15620828) that replicate the 6
 figures shown in the publication. Figures 1 to 4 are written as R code
 (version 4.3.1). They all use the following data file stored on
 DRYAD: Feeding_groups_vs_pride_size_Serengeti.txt. No additional R
 packages are needed for any of the analyses or plots. Fig. 1 - Plot
 feeding group distribution vs Serengeti pride size.txt uses histograms to
 plot the observed frequency of feeding group sizes of Serengeti female
 lions in prides of different sizes. Fig. 2 - Fit feeding group
 distribution to exponential model.txt calculates the best fit loglinear
 relationship between frequency of feeding groups (from Fig. 1) and
 log(feeding group size) for each size of pride. Fig. 3 mean size of
 feeding groups vs pride size.txt plots the mean size of feeding groups
 observed in relation to pride size. Model evaluation is used to compare 3
 potential relationships between these variables: no relationship, a linear
 relationship, and an asymptotic exponential relationship between
 variables. The latter relationship provided the most parsimonious fit to
 the data and is displayed in the figure.  Fig. 4 - Plot lion intake vs
 prey density by pride size.txt plots the estimated rate of food intake by
 Serengeti lions that apply 4 different foraging strategies (A: feed as an
 entire pride uncooperatively, B: feed as an entire pride cooperatively, C:
 fragment into uncooperative groups according to the distribution of
 feeding groups shown in Fig. 1,  and D: fragment into cooperative groups
 according to the distribution of feeding groups shown in Fig. 1. Fig. 5
 and Fig. 6 are written as MATLAB code (version R2018b). Neither figure
 requires additional MATLAB packages to run.
 Fig_5_Stability_as_function_of_lion_group_size.m: MATLAB code to run
 simulation model that evaluates the the stability and persistence due to
 predator-prey interactions by a lion population with a baseline
 probability of capture success = 0.294 that (A) always forages as an
 uncooperative pride, (B) as a cooperative pride, (C) as uncooperative
 hunters whose feeding groups are distributed according to the observed
 frequency distribution for Serengeti, and (D) as cooperative hunters whose
 feeding groups are distributed according to the observed distribution for
 Serengeti shown in Fig. 1. Other parameters as shown in Table 1 of the
 main text. Each model scenario has its own section of annotated code.
 Fig_6_Stability_as_function_of_lion_group_size.m: MATLAB code to run
 simulation model that evaluates the the stability and persistence due to
 predator-prey interactions by a lion population with a baseline
 probability of capture success = 0.150 that (A) always forages as an
 uncooperative pride, (B) as a cooperative pride, (C) as uncooperative
 hunters whose feeding groups are distributed according to the observed
 frequency distribution for Serengeti, and (D) as cooperative hunters whose
 feeding groups are distributed according to the observed distribution for
 Serengeti shown in Fig. 1. Other parameters as shown in Table 1 in the
 main text. Each model scenario has its own section of annotated code.