Networking the underground: tracking social associations in burrowing mammals using proximity-light-sensor biologgers

Wild animals often socialize in microhabitats where direct observations are difficult or impossible, limiting the reconstruction of complete social networks and the understanding of variation in social structure. We designed and tested a novel proximity-logging radiocollar (MamTag) in semifossorial Columbian ground squirrels, Urocitellus columbianus , assessing collar effects, comparing collar- and observation-based social networks, and examining association data gathered in otherwise unobservable contexts. We did not detect a significant effect of collars on body mass or reproduction. Observation- and collar-based networks correlated moderately but consistently. Continuous collar data revealed diel shifts in social behaviour and coherent above- and belowground social organization, with individual centrality largely conserved and spatial proximity shaping network structure. Overall, MamTag collars provided reliable, biologically meaningful measures of social associations and a powerful tool for studying social organization in natural environments.