Drills are highly social primates with complex social hierarchies that require sophisticated group management strategies to achieve good welfare in zoo settings.
Drill welfare requires management of complex group dynamics. Hierarchical social stress, access to resources, and reproductive competition all affect individual wellbeing within a group. Zoos must provide sufficient space and visual barriers to allow subordinate animals to avoid dominant individuals. Behavioral observation is essential to detect signs of social suppression or chronic stress in lower-ranking animals. Drill social coloration provides a visible welfare indicator, as males in good social condition display brighter facial colors, offering zookeepers a non-invasive welfare monitoring tool.