Yellow fever outbreak temporarily changes dispersal patterns in an endangered primate

Disease outbreaks can severely affect populations in the wild. However, their consequences on individual social behaviour and population demography are poorly understood. We used a multi-site capture-recapture model to investigate the impacts of a yellow fever outbreak on the endangered golden lion tamarin Leontopithecus rosalia, in the fragmented Atlantic forest, Brazil. Annual adult survival rate severely declined in 2017-2018, coinciding with the outbreak period. Simultaneously, dispersal patterns changed temporarily, with a reduction of settlement time for individuals dispersing within the same forest fragments, and a 10-fold increase of dispersal rates between forest fragments, from 0.004 ± 0.002 to 0.043 ± 0.015. On the contrary, dispersal rates within forest fragments slightly decreased, from 0.036 ± 0.006 to 0.028 + 0.011. The number of social groups remained stable until the end of the outbreak and increased afterwards while the number of individuals composing groups decreased during the outbreak and remained lower afterwards. Altogether, our results indicate a spatial rearrangement of individuals during the outbreak potentially due to non-random mortality leading to changes in social group structure. They advocate for a better integration of host movements, host social behaviour and habitat connectivity when evaluating species response to infectious diseases.