DOI: 10.5061/dryad.31zcrjdt8
title: Data from: Variable intergroup encounters: What drives neutral and intolerant encounters in blue monkeys?

description: In group-living animals, between-group relations are often revealed during
 intergroup encounters, which may be intolerant (competitive), affiliative
 (cooperative), or neutral. Our study investigated factors that predict
 different encounter types in blue monkeys, where intolerant encounters
 predominate but neutral encounters also occur. Using data from 9 groups
 monitored over 24 months in equatorial forest, we first examined whether
 the availability of fruit, a preferred and important food, predicted
 monthly encounter rates for individual groups. We then examined
 how fruit availability and time of day influenced the odds that individual
 encounters were intolerant vs. neutral. For a subset of encounters between
 study groups with well-known histories, we examined the effects of
 additional social and location factors, which included group size, the
 proportion of females with infants, the time elapsed since the opposing
 groups had split from each other in the past years, and the encounter’s
 location on edge-centre axes for both groups. Finally, we examined how
 ecological and social factors predicted individual group
 behaviour (aggressive, fleeing, neutral) during encounters. The variables
 we examined included encounter location, group size, group size
 differential, time since the two groups split from each other, fruit
 availability, and time of day. These investigations required 3 data sets
 (one for each italicized item in this abstract, namely rates, encounters,
 and records of group behavior).
description: Data were collected from January 2019 through December 2020 via
 field observations of wild, individually recognized blue monkeys
 (<em>Cercopithecus mitis stuhlmanni</em>) living in nine
 groups in the Kakamega Forest, Kenya. The study groups were part of a
 long-term project that began in 1979. During the study period, each group
 was monitored on a nearly daily basis from ca. 0800-1700 hrs by members of
 an experienced field team that recorded all occurrences of intergroup
 encounters, both intolerant and neutral (see publication for definitions
 of these two categories). These records included the time of the
 encounter, whether it was intolerant or neutral, and (for intolerant
 encounters) a brief description of the opponent groups' behavior. All
 encounters included at least one study group, as we detected them by
 following these groups; however, opponent groups could be another study
 group or a non-study group. In addition, the field team
 took a daily census of the group/s they monitored, as all group members
 could be individually identified based on natural features. If an
 individual adult female or juvenile was not spotted on a given day, we
 assumed it was present if it had been seen in the group both before and
 after that day. We did not make the same assumption for males, as they are
 more ephemeral members of social groups. To measure group size on each
 day, we totaled the records of individuals present (or assumed present) in
 the group. A single field assistant, E. Shikanga, also
 collected monthly data on fruiting phenology, scoring the same ~10
 individual trees from each of the 29 main feeding trees, on a
 semi-quantitative (0-4) scale for the presence of fruit. From these
 records, we computed mean monthly scores for each of the 29 species, and
 combined this information with data on the abundance and size of
 individual trees to compute a fruit availability index (FAI). The
 abundance and size of individual trees were assessed through vegetation
 surveys, which preceded the data collection period of this study. The
 survey enumerated and measured the diameter at breast height (DBH) of all
 trees with DBH &gt;10 cm in 29 randomly placed
 transects (4-16 per group home range, proportional to varying home range
 sizes; each transect plot measured 10m x 100m). From these vegetation
 survey data, we calculated the mean basal area per transect for each of
 the 29 phenology species. To compute the monthly FAI for each study group,
 we multiplied the mean monthly fruit score of a given phenology species by
 its mean basal area per transect in that group's home range, and
 summed these products for the 29 monitored species. The monthly FAI values
 were then standardized as a Z-score, using the mean and standard deviation
 for each study group across the months in this study in which it was
 monitored. Further details are available in the associated
 publication. We used the intergroup encounter records
 to specify the behavior of study groups involved in each encounter. Group
 behavior fell into one of three categories: (1) aggressive (any group
 member threatened, chased, or grappled with the opponent group); (2)
 fleeing (group fled from opponents without any members showing aggressive
 behaviour); or (3) neutral (neither aggressive nor fleeing). 
 From the data collection and processing described above, we
 created three data files for analysis in the publication, all of which are
 included in this Dryad submission.  (1) In
 "Cords-Thurau_Datafile_1_Rate_data", each line of data
 represents a particular group in a particular study month. We included a
 rate variable, based on the monthly sum of intergroup encounters recorded
 relative to total group observation time in that same month. Other
 variables in this data set are described in the ReadMe text.
 (2) In "Cords-Thurau_Datafile_2_Encounter_data", each
 line of data represents a single intergroup encounter, classified as
 intolerant or neutral. Other variables in this data set are described in
 the ReadMe text. (3) In
 "Cords-Thurau_Datafile_3_Group_behaviour_data", each line of
 data represents a record of the behavior of one study group in one
 encounter, with behavior categorized as aggressive, fleeing or neutral.
 Other variables in this data set are described in the ReadMe
 text.
description: # Data from: Variable intergroup encounters: What drives neutral and
 intolerant encounters in blue monkeys?
 Three data files were used
 to analyze variable intergroup encounter types in wild blue monkeys,
 including data on encounter rates, encounter types, and group behavior
 during encounters. ## Description of the data and file structure This
 submission includes 3 data files: (1) In
 "Datafile_1_Rate_data.csv", each line of data represents a
 particular group in a particular study month. We include a rate variable,
 based on the monthly sum of intergroup encounters recorded relative to
 total group observation time in that same month. This and other variables
 in this data set are described below. (2) In
 "Datafile_2_Encounter_data.csv", each line of data represents a
 single intergroup encounter, classified as intolerant or neutral. This and
 other variables in this data set are described below. (3) In
 "Datafile_3_Group_behaviour_data.csv", each line of data
 represents one study group in one encounter, with its behavior categorized
 as aggressive, fleeing, or neutral. This and other variables in this data
 set are described below. The three data files are all based on the same
 field records. Nearly all encounters included in Datafiles 1 and 2
 contributed information to Datafile 3, but there were some exceptions:
 specifically, in a few cases, field records were not sufficiently complete
 to allow us to categorize opposing groups' behavior, and these
 encounters were therefore not included in Datafile 3.  Below are
 descriptions of the data fields (columns) in each of the data files. In
 all data files, missing values are denoted with the entry
 "null". **Cords-Thurau_Datafile_1 \_Rate_data.csv**  * Each line
 of data represents one group in one month. * Columns 1 and 2 indicate
 month and group respectively. * Column 3 “hours” shows number of
 observation hours for that group-month combination. * Columns 4-6 show
 respectively the counts of neutral intergroup encounters (IGEs),
 intolerant IGEs and total IGEs for the group-month combination. * Columns
 7-9 show respectively the rates of neutral, intolerant and total IGEs
 (count per 100 hours of group observation time) * Column 10 (“zFAI”) shows
 standardized Fruit Availability Index for each group-month. This index
 derives from combining (1) monthly mean fruit abundance scores (0-4) of 29
 food tree species with (2) vegetation survey data specific to each home
 range, measuring tree basal area (m2 per transect, where transects
 measured 10 x 100 m2), as described in Methods and in the manuscript. zFAI
 values were standardized separately for each group using mean and standard
 deviation of FAI values for that group across the months in which it was
 observed. **Cords-Thurau_Datafile_2_Encounter_data.csv** * Each line of
 data represents one IGE (intergroup encounter). * Column 1 “date” shows
 date of IGE. * Columns 2-3 show focal group and opposing group
 participating in the IGE. * Column 4 (“grp-dyad”) represents the group
 dyad identity. If either group here is identified as “UID” (unidentified,
 meaning a non-study group), this row of data was excluded from the subset
 of data that represented only study groups in which we knew the years in
 which two study groups fissioned.  * Columns 5-shows whether an intergroup
 encounter was intolerant (coded as 0 for “no” and 1 for “yes”). * Columns
 6-7 (“zFAI”) show standardized Fruit Availability Index for each
 group-month. “zFAI_Focal” shows the standardized FAI for the focal group
 while “zFAI_Opp” shows the standardized FAI for the opposing group. This
 index derives from combining (1) monthly mean fruit abundance scores (0-4)
 of 29 food tree species with (2) vegetation survey data specific to each
 home range, measuring tree basal area (m2 per transect, where transects
 measured 10 x 100 m2), as described in the manuscript. zFAI values were
 standardized separately for each group using mean and standard deviation
 of FAI values for that group across the months in which it was observed. *
 Column 8 (“zFAI_avg”) shows the average of columns 6 and 7, i.e., the
 average zFAI of the focal and opposing groups. * Column 9 (“time”) shows
 the time of day in which the IGE occurred, binned into 3 levels: midday
 (1100-1300 hrs), near midday (0900-1100 hrs and 1300-1500 hrs) and
 beginning/end of day (0700-0900 hrs and 1500-1700 hrs). * Columns 10 and
 11 show the proportion of adult females that had infants, averaged over
 the month, in the focal and opposing groups respectively. * Column 12
 (“avg_af_w_inf”) shows the average of columns 10 and 11, i.e.  the average
 proportion of adult females that had infants across the focal and opposing
 groups. * Column 13 (“yrs_since_split”) shows the number of years that had
 passed since the two opposing groups had been in one group together, i.e.,
 the year of the intergroup encounter minus the year in which a common
 progenitor group had fissioned, producing the two opposing groups. *
 Column 14 (“grpsize_diff”) shows the absolute value of the difference in
 the number of adult females in focal vs. opposing groups. * Columns 15-16
 show the edge score assigned to the specific IGE location (50m x 50 m
 quadrat) for the focal and opposing groups respectively. Edge scores are 0
 at the edge of the home range, positive in the interior, and negative
 outside the home range. Edge scores can take a non-integer value if the
 encounter location was specified to two quadrats. See manuscript for
 further detail. * Column 17 (“edge_disparity”) shows the absolute value of
 the difference between the edge scores of focal and opposing groups.
 **Cords-Thurau_Datafile_3_Group_behavior_data.csv** * Each line of data
 represents a single group’s behavior during an intergroup encounter (IGE)
 * Column 1 “date” shows date of IGE. * Columns 2-3 show focal group and
 opposing group participating in the encounter. * Column 4 represents focal
 group’s behavior in the encounter, classified as “agg” if any group
 members threatened, chased, or grappled with the opponent group, “flee” if
 the group fled from opponents without any members showing aggressive
 behavior, and “neutral” otherwise (neither aggressive behavior nor
 flight).. * Column 5 (“zFAI_Focal”) shows the standardized Fruit
 Availability Index for the focal group in the month of the encounter. This
 index derives from combining (1) monthly mean fruit abundance scores (0-4)
 of 29 food tree species with (2) vegetation survey data specific to each
 home range, measuring tree basal area (m2 per transect, where transects
 measured 10 x 100 m2), as described in the manuscript. zFAI values were
 standardized separately for each group using its mean and standard
 deviation across the months in which it was observed. * Column 6
 (“focal_af”) shows the number of adult females in the focal group. *
 Column 7 (“prop_af_w_inf_focal”) shows the proportion of adult females in
 the focal group that had infants. * Column 8 (“af_diff_foc_opp”) shows the
 difference in the number of adult females in focal vs. opposing groups,
 calculated as N-focal minus N-opponent. Can take negative values if the
 focal group is outnumbered. * Column 9 (“time”) shows the time of day in
 which the IGE occurred, binned into 3 levels: * A1: beginning/end of day
 (0700-0900 hrs and 1500-1700 hrs) * A2: near midday (0900-1100 hrs) * A3:
 midday (1100-1300 hrs) * Column 10 (“focal_edge”) shows the ‘edge score’
 assigned to the specific IGE location (50m x 50 m quadrat) for the focal
 group. Edge scores are 0 at the edge of the home range, positive in the
 interior, and negative outside the home range. Edge scores can take a
 non-integer value if the encounter location was specified to two quadrats.
 See manuscript for further detail. * Column 11 (“yrs_since_split”) shows
 the number of years that had elapsed since the two opposing groups had
 been together as members of single group, i.e., the year of the intergroup
 encounter minus the year in which a common progenitor group had fissioned,
 producing the two opposing groups.