DOI: 10.5061/dryad.ttdz08m5t
title: Vocal consensus building for collective departures in wild western gorillas

description: The ability to coordinate actions is of vital importance for group-living
 animals, particularly in relation to travel. Groups can only remain
 cohesive if members possess a cooperative mechanism to overcome
 differences in individual priorities and social power when coordinating
 departures. To better understand how hominids achieve spatio-temporally
 coordinated group movements, we investigated vocally-initiated group
 departures in three habituated groups of western gorillas (Gorilla
 gorilla) in the Central African Republic. The large sexual dimorphism of
 gorillas has led to the untested assumption that the silverback males are
 the sole decision-makers in gorilla groups although there are also
 observations that suggest otherwise. To address this, we analysed the
 direction and timing of group departures and found that high-ranking
 individuals (silverbacks and high-ranking females) were more successful in
 indicating the direction of future travel than others, but that the timing
 of departure was the apparent result of a cumulative vocal voting process
 amongst all adult group members. Our findings illustrate that even in
 species with a large sexual size dimorphism, travel decisions can be taken
 collectively via a consensus-building process.
description: Data have been collected on three groups of western gorillas in
 the Central African Republic during a 12 month field study. 
description: # Vocal consensus building in wild western gorillas dataset
 [https://doi.org/10.5061/dryad.ttdz08m5t](https://doi.org/10.5061/dryad.ttdz08m5t) The data were collected on three gorilla groups (N=14 adult individuals) during a 1-year field study in Central African Republic. The goal of this study was to investigate decision-making and leadership in western gorillas. We focussed on group departures after resting. To this study belong the following data and codes: ### Figure 1 data: data_figure1_GLMM1.csv #contains all-occurrence data with for each subject present at the resting site whether they initiated or not code: Figure1_GLMM1.R columns explanations: * group = study group * subject = code for individual * subject_date = subject linked with the date (dd.mm.yyyy) * nr.id.present = number of individuals (&gt;2y) present at resting site * id.was.sb = whether subject was a silverback * norm.elo = normalized elo score of subject * id.was.focal = whether subject was focal subject during that day or not * id.initiated = whether subject initiated during the resting event (y/n) * age.sex = age.sex class subject (adult female, silverback blackback) * date = date of the observation (dd.mm.yyyy) * norm.elo = normalized elo score of subject ### Figure 2 data: data_figure2_GLMM2 #contains data on initiations and whether they were successful code: Figure2_GLMM1.R columns explanations: * group = study group * subject = code for subject -&gt; refers to id initiator * subject_date = initiator linked with the date  (dd.mm.yyyy) * nr.id.present = number of individuals (&gt;2y) present at resting site * id.was.sb = whether initiator was a silverback * succesful = whether the initiation was succesful (y/n) * age.sex = age.sex class initiator (adult female, silverback blackback) * date = date of the observation  (dd.mm.yyyy) * norm.elo = normalized elo score of initiator ### Figure 3 data: Figure3_data.csv #showing timing of vocalizations code" Figure3.R columns explanations: * timing.from.travel = timing of vocalizations in minutes before or after focal subject departed (max 15 minutes before and 5 minutes after) * caller.is.focal = whether caller was focal ### Figure 4 data: data_figure4_GLMM3 #calling rate of focal individuals at resting event code: Figure4_GLMM3.R columns explanations: * group = study group * subject = code for focal subject * date = focal subject linked with the date * nr.id.present = number of individuals (&gt;2y) present at resting site * subject.is.silverback = whether focal subject was a silverback * norm.elo = normalized elo score of subject * age.sex = age.sex class focal subject (adult female, silverback blackback) * duration_rest_s = lenght of the resting events (in seconds) * nr.calls = number of grunt-like calls focal subject produced during the resting event ### Figure 5 data: data_figure5_S4_S7_Survival1_2 #Effect of vocalizations on departure probability. Resting events were devided into 1 minute intervals. Only the intervals after 15 minutes were used for analysis. reduced data set: data_Survival1_2_reduced_dataset #same as data before but with resting events excluded that had unknown callers code: Figure5_S4_S7_survival1_2.R columns explanations: Columns: * subject = code for focal subject * interval_count = count of the 1 minute interval. * subject.called = focal subject vocalized in respective 1-minute interval * others.called = focal subject did not vocalize in respective 1-minute interval * adults.called.last.five.min = number of adult individuals that vocalized in the current or any of the previous 4 1-minute intervals - i.e. in the past 5 minutes * group = study group * subject.is.silverback = whether focal subject was a silverback * others.stopped.r = whether other individuals than focal stopped resting in the current interval (does not necessarily mean they departed, but they stood up and moved) * nr.id.present = number of individuals (&gt;2y) present at resting site * nr.adult.present = number of adult individuals present at resting site * event.info = whether resting event was seen untill the end or not (censored) * date = date of the observation (dd.mm.yyyy) * norm.elo = normalized elo score of subject * nr.adult.present.5.min.ago = number of adults that was present during the last 5 minutes * resting_id = identifyier for resting event ### Figure 6 data: Figure6_data.csv #Number of vocalizers over cumulative proportion of departures code: Figure6.R columns explanations: * nr.adult.present = number of adult individuals present at the resting site * nr.adult.callers = number of adults that vocalized in the 5 minutes before departure * cumulative_proportion = cumulative proportion of departues, per number of adults present * n.events = number of resting events * n.events.total = total number of resting events ## Supplementary: ### Figure S2 data: FigureS2_data.csv #Data frame with agonistic interactions recorded for Elo-calculations main code: FigureS2.Rmd #script will automatically source the functions in elo_functions.R additional functions: elo_functions.R columns explanations: * group = study group * date = date of the agonistic interaction (dd.mm.yyyy) * time = time of the agonistic interaction  * winner = individual that initiated the aggression * loser = individual that was the target of aggression * reaction.intensity = outcome of the interaction: 1 or 2) "loser" displaced or does not return ago 3) "loser" returns aggression (tie) 4) "loser" displaces "winner" (script then switches winner loser) * courtship = whether ago was likely courtship. Did not make difference for elo to exclude these, so let these cases in to remain oblivious to reason agression ### Figure S3 data: FigureS3_data.csv  #Visualisation of the length of resting events. contains lenght of all complete (seen from start to end) resting events that data was collected on code: FigureS3.R columns explanations: * resting.minutes = duriation resting event in minutes ### Figure S5 data: FigureS5_data.csv #cumulative probability of departure over the cumulative proportion of callers code: FigureS5.R columns explanations: * group = study group * cumulative_callers = relative number of vocalizers (number of vocalizers/number of individuals present) * cumulative_proportion = cumulative proportion of departues * n.events = number of resting events * n.events.total = total number of resting events all scripts are annotated. \#Figure2_GLMM1.R; Figure3_GLMM1.R; Figure4_GLMM1.R make use of functions provided by Roger Mundry for diagnostic testing. These are publicly available in the supplementary information of [https://doi.org/10.1038/s41598-021-01356-6](https://doi.org/10.1038/s41598-021-01356-6)