Social network shrinking is explained by active and passive effects but not increasing selectivity with age in wild macaques
Cite this dataset
Sadoughi, Baptiste; Mundry, Roger; Schülke, Oliver; Ostner, Julia (2024). Social network shrinking is explained by active and passive effects but not increasing selectivity with age in wild macaques [Dataset]. Dryad. https://doi.org/10.5061/dryad.r4xgxd2mq
Abstract
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.
README: Social network shrinking is explained by active and passive effects but not increasing selectivity with age in wild macaques
https://doi.org/10.5061/dryad.r4xgxd2mq
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).
Methods
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.
Funding
Deutsche Forschungsgemeinschaft