Data from: Variable intergroup encounters: What drives neutral and intolerant encounters in blue monkeys?
Data files
Feb 17, 2024 version files 211.74 KB
-
Cords-Thurau_Datafile_1__Rate_data.csv
-
Cords-Thurau_Datafile_2_Encounter_data.csv
-
Cords-Thurau_Datafile_3_Group_behavior_data.csv
-
README.md
Abstract
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).
README: Data from: Variable intergroup encounters: What drives neutral and intolerant encounters in blue monkeys?
https://doi.org/10.5061/dryad.31zcrjdt8
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.
Methods
Data were collected from January 2019 through December 2020 via field observations of wild, individually recognized blue monkeys (Cercopithecus mitis stuhlmanni) 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 >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.