Data from: The importance of partner inclusion criteria for understanding drivers of social variation among individuals: Data from blue monkeys
Data files
Mar 06, 2024 version files 262.59 KB
-
annual_social_contact_all_partners.csv
86.17 KB
-
annual_social_contact_non_peers_only.csv
85.72 KB
-
annual_social_contact_peers_only.csv
85.61 KB
-
README.md
5.09 KB
Abstract
Individuals in social species vary in their sociality, allowing inferences about how social ties influence fitness, but also raising questions about the drivers of observed variation in sociality. We examined how sociodemographic, social, and individual factors were associated with inter-individual variation in the sociality of wild blue monkeys (Cercopithecus mitis stuhlmanni), and how these associations are affected by the set of partners included in the analysis. Using data from focal follows of adult females in 12 groups over 13 years, we measured individual variation in five measures of sociality (number of ties, number of strong ties, number of weak ties, total tie strength, and evenness of tie strength), binned in annual periods. We used linear mixed models to assess the effects of sociodemographic, social, and individual factors on these five measures. We repeated this analysis while limiting observations to peer partners (other adult females) or to non-peer partners (juveniles and adult males) to evaluate how including different sets of partners in the analysis affected the results. Three data files were used in these analyses, each the result of applying different criteria for who was included as a potential partner for the adult female subjects.
README: Data from: The importance of partner inclusion criteria for understanding drivers of social variation among individuals: Data from blue monkeys
https://doi.org/10.5061/dryad.b2rbnzsns
Description of the data and file structure
There are three data files in this dataset. Each file summarizes the social ties and sociodemographic, demographic, and individual characteristics of adult female blue monkeys (Cercopithecus mitis stuhlmanni) living in multiple groups in the Kakamega Forest, western Kenya, collected over 13 years through focal follow behavioral observations (see Methods in accompanying manuscript). Two individuals are considered to have a social tie (and thus be social partners) if they lived in the same group for at least three-quarters of a year, and were observed to interact with friendly social contact (i.e., grooming each other in either direction or sitting in contact). The strength of ties is defined as the proportion of dyadic observation time (i.e., the proportion of beeps when either of the two individuals was under focal observation) that the two individuals were observed in friendly social contact. In each file, a row corresponds to data for one female in one study year. Each of the three files has the same columns.
The three files were prepared by considering social interactions with different sets of social partners. For each of the three files, a different set of partner selection criteria was applied, and the potential partners who met those criteria are the “eligible partners”.
The data files contain raw values; in our analysis, we standardized (Z-score) values in the columns observation_time, relatives, age, and infant_days. The field available_partners was increased by 1e-6 (to avoid negative infinities) and then log-transformed before being standardized. See the associated paper for more details on the collection and preparation of these data.
The three files are named as follows:
- annual_social_contact_all_partners – In this file, ties to all partners are included.
- annual_social_contact_peers_only – In this file, only ties to peers (other adult females) are included.
- annual_social_contact_non_peers_only – In this file, only ties to non-peers (non-adults or males) are included.
In each file, the columns are as follows:
subj – A unique code for each individual adult female
year – The “study year”, or year of observations summarized in this row. Study years started on September 1 of the preceding calendar year, and ran through August 31 of the corresponding calendar year. For example, study year 2018 started on September 1, 2017, and continued through August 31, 2018.
group – A unique code identifying the group that the subject belonged to in the specified study year.
observation_time – The total number of minutes of focal follow observation for each subject/study year combination.
available_partners – The number of eligible social partners available to the subject in the specified group and study year
relatives – The number of close relatives present in the group and available as social partners for the subject. Close relatives are defined as those whose matrilineal coefficient of relationship to the subject is at least 1/16 (0.0625).
age – The subject’s age in years at the end of the study year.
dominance_scaled – The subject’s dominance position in the given study year, scaled to group size. Ranks were computed with DomiCalc, and are expressed as a value between 0 and 1 (lowest to highest rank). Represents the proportion of peers who are lower-ranked than the subject.
infant_days – The proportion of days in the study year that the subject had her own infant (<1 year old) present with her in the group.
number_of_ties – The total number of partners with whom the subject was observed to interact (grooming and sitting in contact) in the specified group and study year.
strong_ties – The number of partners with whom the subject had a “strong tie” in the specified study year. A strong tie is defined to be a tie with a strength that is more than 1 standard deviation above the mean for a given group in a given study year.
weak_ties – The number of partners with whom the subject had a “weak tie” in the specified study year. A weak tie is defined to be a tie that is not a strong tie, i.e., the strength of the tie is not at least 1 standard deviation above the group-study year mean.
total_tie_strength – The sum of the strengths of all ties the subject had in the specified study year.
evenness – A measure of how evenly the subject’s social activity was distributed among all eligible partners in a given group and study year. Calculated as the Shannon diversity index taken across all tie strengths (including 0-strength ties), divided by the maximum possible diversity index, which is the natural log of the number of eligible partners.
Methods
These data were collected as part of a long-term observation program, which began in 1979, focusing on individually identified arboreal blue monkeys (Cercopithecus mitis stuhlmanni) inhabiting the Kakamega Forest, a rain forest in western Kenya (0°19 N, 34°52 E, 1,580 m., ca. 2000 mm rainfall annually. The data represent a 13-year period (September 2006-August 2019 inclusive), during which the number of study groups increased from 4 to 8 via natural group fissions. We considered parent and daughter groups as distinct units in our analyses, which included 4-8 groups at any one time (N=12 total), ranging in size from 6-76 individuals. Members of all study groups were identifiable by sight using natural physical variation, and their life histories (date of birth, age at each offspring’s birth for females) were known from long-term near-daily monitoring.
Data on social behavior were collected during focal animal samples of adult (parous) females in all study groups. We first trained the observer team to correctly identify all group members (they had to do this without error five times in a row) and to achieve >95% agreement in focal sample scoring. Observers chose focal subjects to prioritize an equal accumulation of observation time across groups, individuals, and time of day (morning, midday, and afternoon hours). Focal follows were scheduled to last 30 min, but subjects occasionally went out of sight. Observers searched for them for up to 15 minutes and continued the follow if they found the focal subject, counting only in-sight time. We aborted and discarded follows that lasted less than 20 minutes.
During each follow, the observer made instantaneous records at 1-minute intervals of the focal subject’s activity, identifying any social partners. We examined affiliative social contact in this report, which included both giving or receiving grooming and sitting in body contact. We defined social partners as those individuals who were grooming, being groomed by, or sitting in contact with the focal subject. A focal subject could have multiple social partners at once.
Observers also monitored agonistic behavior, both during focal follows and whenever it was witnessed at other times. Agonistic interactions included aggressive and submissive behavioral elements, as well as approach-avoid interactions. These interactions served as input for calculating dominance ranks, using the I&SI method as implemented in Domicalc (Schmidt and DeVries 2013).