Presenter(s): Caitlin Shreeve—Anthropology
Faculty Mentor(s): Kylen Gartland, Frances White
Session: Prerecorded Poster Presentation
Typically, dominance in primates is determined through aggressive interactions with initiation of aggression indicating higher dominance rank . David’s Score analyses using aggression are frequently used to calculate dominance hierarchies in primates . However, if fights are rare then it can be hard to identify male rank . Non-aggressive behaviors like grooming can also indicate rank based on directionality . For example, higher-ranking males are often groomed more whereas lower-ranking males will do more grooming . For this study, we were interested in: 1) whether a dominance hierarchy could be constructed from non-aggressive behaviors, and 2) whether there were significant changes in grooming directionality and intensity over time . We examined a group of Japanese macaques (Macaca fuscata) at the Oregon National Primate Research Center . We collected a total of 475 hours of behavioral data between two summer study periods in 2018 and 2019 . We collected data on 11 adult males using 15-minute focal follows with 1-minute instantaneous scans . We calculated David’s Scores for each male for 2018 and 2019 from grooming interactions and found hierarchical differences . Comparison between these scores demonstrated that the high-ranking males did not show a change in their David’s Score, indicating that their grooming effort remained constant . Lower- ranking males increased their grooming efforts directed at higher-ranking males while middle-ranking males showed only minor changes in their David’s Score . These data suggest that David’s Scores based on non-aggressive behaviors may be used to measure behavioral strategies and that the greatest increase in grooming effort is made by the low-ranking males .