DOI: 10.5061/dryad.r4xgxd2mq
title: Social network shrinking is explained by active and passive effects but not increasing selectivity with age in wild macaques

description: Evidence of social disengagement, network narrowing, and social
 selectivity with advancing age in several non-human animals challenges our
 understanding of the causes of social ageing. Natural animal populations
 are needed to test whether social ageing and selectivity occur under
 natural predation and extrinsic mortality pressures, and longitudinal
 studies are particularly valuable to disentangle the contribution of
 within-individual ageing from the demographic processes that shape social
 ageing at the population level. Data on wild Assamese macaques (Macaca
 assamensis) were collected between 2013 and 2020 at the Phu Khieo Wildlife
 Sanctuary, Thailand. We investigated the social behaviour of 61 adult
 females observed for 13,270 hours to test several mechanistic hypotheses
 of social ageing and evaluated the consistency between patterns from
 mixed-longitudinal and within-individual analyses. With advancing age,
 females reduced the size of their social network, which could not be
 explained by an overall increase in the time spent alone, but by an
 age-related decline in mostly active, but also passive, behaviour, best
 demonstrated by within-individual analyses. A selective tendency to
 approach preferred partners was maintained into old age but did not
 increase. Our results contribute to our understanding of the driver of
 social ageing in natural animal populations and suggest that social
 disengagement and selectivity follow independent trajectories during
 ageing.
description: The data presented were collected as part of an ongoing long-term
 field research project at the Phu Khieo Wildlife Sanctuary. Macaques'
 behaviour is collected through standard animal focal follow protocols.
 Data are subsequently archived, and the behaviour relevant to the current
 study extracted, and aggregated or directly indexed to the respective time
 window following the definition detailed in the manuscript associated with
 this dataset.
description: # Social network shrinking is explained by active and passive effects but
 not increasing selectivity with age in wild macaques
 ## Description of the data
 and file structure Data is provided as separate .csv files, and as
 single-object .RData workspaces because the latter ensure robust
 formatting across operating systems and operating systems' regional
 settings. RData are loaded at the start of the respective R scripts which
 include the code to analyze the behavior specified. ### Dataset
 **approach_behaviour_data.RData/csv:** Female metadata and count of
 approach given and received. Variables: * focal_animal: identification of
 the focal female for whom the count of approaches is calculated. *
 season_year: time window considered for analysing the behaviour.
 Combination of the season (mating / non-mating) and year. * group: social
 group identity as a categorical variable (STU, MST, SST, OTH, MOT). *
 season: mating (Oct–Mar) and non-mating (i.e., period of birth, Apr–Sep).
 * ap_other: number of approaches given by the focal. * ap_by: number of
 approaches received by the focal. * obs_time: time in seconds the focal
 was observed in that season-year. * age: age of the focal in years. *
 repro_focal: reproductive state of the focal. Dummy coded variable (0=
 non-reproductively active, 1 = reproductively active). * elo_focal:
 Elo-score for the focal at the end of the season-year or on the last day
 observed in the season-year. * nfemale: number of adult females in the
 group in the season-year. **time_alone_data.RData/csv:** Female metadata
 and proportion of instantaneous scan the female was observed without other
 adult females in proximity. Variables: * focal: identification of the
 focal female for whom the instantaneous scan was collected. * season_year:
 see above. * group: see above. * season: see above. * prop.is.alone:
 proportion of instantaneous scans in which the focal was observed without
 any other female in proximity. * weight: statistical correcting variable
 for beta regression models proportional to the total number of scans
 performed over the season-year for the individual. * age: see above. *
 repro_stage: reproductive state of the focal. Dummy coded variable (0=
 non-reproductively active, 1 = reproductively active). * elo_focal: see
 above. * nfemale: see above. **grooming_degree_data.RData/csv:** actor and
 receiver metadata, duration of directed grooming (sec/sec) and frequencies
 of directed grooming (count/h) interactions. Used for analyses of grooming
 degree and directed strength. Variables: * season: see above. *
 season_year: see above. * group: see above. * dyad: identification of the
 actor and receiver (alphabetically ordered). * dyads_obs_time: time in
 seconds the the two individuals in a dyad were observed over the
 season-year. * actor: identification of the female grooming the partner. *
 receiver: identification of the female being groomed by the partner. *
 age_actor: age of the actor in years. * age_receiver: age of the receiver
 in years. * repro_actor: reproductive state of the actor. Dummy coded
 variable (0= non-reproductively active, 1 = reproductively active). *
 repro_receiver: reproductive state of the receiver. Dummy coded variable
 (0= non-reproductively active, 1 = reproductively active). * elo_actor:
 Elo-score for the actor at the end of the season-year. * elo_receiver:
 Elo-score for the receiver at the end of the season-year. * groom_count:
 number of times the actor groomed the receiver. * groom_freq: frequency of
 grooming given by the actor to the receiver (groom_count/dyads_obs_time).
 * absolute_groom_duration: time in seconds the actor groomed the receiver.
 * groom_duration: proportional time the actor groomed the receiver
 (absolute_groom/dyads_obs_time). * degree: the actor was observed grooming
 the receiver (yes=1, no=0). * nfemale: see above.
 **selective_approach_data.RData/csv:** actor and dyad metadata, count of
 approach directed towards the partner, and cumulated DSI (Dyadic Sociality
 Index) based on approach and grooming interactions between partners.
 Variables: * actor: identification of the female performing the approach
 towards a partner. * receiver: identification of the female being approach
 by the actor. * season_year: see above. * season: see above. * group: see
 above. * ap_directed: number of approaches towards the receiver performed
 by the actor. * dyad: see above. * dyads_obs_time: see above. * cumuDSI:
 cumulated DSI (Dyadic Sociality Index) value for the dyad until the
 current season-year. * age_actor: see above. * repro_actor: see above. *
 elo_actor: see above. * nfemale: see above. * season_year_rank:
 numerically coded and ordered season-years. * cumuDSI_prev: cumulated DSI
 (Dyadic Sociality Index) value for the dyad considering behaviour until
 the previous season-year. ## Code/Software ### R script
 **Approach_behaviour_analyses.R:** Exploration and statistical analyses of
 number of approach given and received across all partners. Loads
 approach_behaviour_data.RData. **Time_alone_analyses.R:** Exploration and
 statistical analyses of time spent alone with no other female in
 proximity. Loads time_alone_data.RData. **Grooming_degree_analyses.R:**
 Exploration and statistical analyses of directed grooming degree. Loads
 grooming_degree_data.RData. **Grooming_strength_analyses.R:** Exploration
 and statistical analyses of directed grooming strength based on grooming
 duration. Loads grooming_degree_data.RData.
 **Selective_approach_analyses.R:** Exploration and statistical analyses of
 approach given to partner according to cumulated DSI (Dyadic Sociality
 Index) shared with partner. selective_approach_data.RData.
 **diagnostic_fcns.R:** support functions for data wrangling sourced in all
 scripts. **glmm_stability.R:** support functions to calculate model
 stability by excluding levels of random effects one at a time (provided as
 a case demo to use on strength models).