The emerging field of macrobehaviour explores behavioural variation across large geographic, taxonomic, and temporal scales, and its ecological and evolutionary consequences. This unifying framework merges macroecology with ethology, both enhancing our understanding of how behaviour mediates ecological dynamics at scales above the population level, and offering an approach that can broaden the impact of ethological research. Here, I urge ethologists to engage with the field, outlining what “macro” means, why we must act now, why we need your expertise, how you can get involved, and how this line of research offers reciprocal benefits to both disciplines. Together, we can amplify the impact of ethological research while accelerating insight that could inform solutions to the global biodiversity crisis.