Finding what is normal - Consistency in individual behaviour and movement patterns in laboratory-housed Macaques and how this relates to individual personality traits

Abstract

This thesis investigates individual differences in behaviour of laboratory-housed Rhesus macaques (Macaca mulatta) through the utilization of automated methods designed for in-cage observation. Animals consistently exhibit differences in movement and behaviour over time, this is often described as personality or temperament. Previous research found associations between temperament and physiological indicators, such as well-being and welfare of non- human primates. Rhesus macaques serve as a pivotal model species in biomedical research, and considerable efforts are made in optimizing their welfare for both ethical and scientific purposes. This emphasizes the significance of comprehending these individual differences and to specifically identifying behavioural needs. However, evaluating welfare and temperament typically entails labour-intensive processes reliant on human observers. Recent advancements in computational techniques to automate video analysis have transformed animal behaviour studies, reducing costs and labour intensity. Furthermore, such methods are non-invasive and less susceptible to observer bias. This thesis presents a self-built in-cage camera system (based on a Raspberry Pi), as well as a pipeline (based on YOLOv8, a state-of-the-art image-segmentation model) to automate video analysis and predict the location of pair-housed Rhesus macaques in their home cage. Utilising the camera module and pipeline, over 1500 hours of video material was collected and analysed. The findings reveal distinct individuality in movement trajectories as well as variations in space utilization across different contexts related to welfare and personality traits. In conclusion, the findings suggest the potential of automated methods to assess behavioural needs, temperament, and welfare on an individual level, thereby contributing to more precise and comprehensive care strategies for laboratory-housed macaques. Furthermore, I present an effective solution of monitoring home cage space use on a long-term basis during light periods (5:30AM-7PM).