Breathing synchrony shapes respiratory disease risk in bottlenose dolphins.

Infectious diseases cause mass mortalities in wildlife populations globally, but the impact of host sociality on the spread of pathogens is often unknown. While host behaviors drive pathogen transmission, these behaviors vary individually which impacts both individual- and population-level disease outcomes. For example, delphinid species are regularly affected by serious respiratory diseases, but a lack of social behavior data means the structure of vulnerability in these ecosystem sentinels is poorly understood. To assess the role of variable social behavior on disease risk empirically, we collected behavioral data from two wild bottlenose dolphin populations (Tursiops spp.), developed network models that synthesize transmission contacts, and used an epidemiological model to predict disease consequences. We find that contacts are highly structured by age and sex, and that individuals preferentially contact others in their own demographic group. These patterns, in turn, drive heterogeneity in infection risk, which we support using empirical data from a past disease outbreak. Our work characterizes the impact of social dynamics on infectious disease risk, which can inform the structure of vulnerability for future epizootics across diverse delphinid species.