HPAIV outbreak triggers long-distance movements in breeding Northern gannets -- implications for disease spread

Animal movement is a fundamental driver of disease spread. We show that an outbreak of high pathogenicity avian influenza (HPAI) is coincident with unprecedented behavioural changes in GPS tracked Northern gannets. Previously characterised by strong fidelity to their nest sites and foraging areas (2015 – 2019; n = 120), breeding gannets tracked before, during and after the 2022 outbreak showed half of ten birds stopped transmitting and most likely died, while the survivors instigated unusual long-distance movements. Two adults visited one - three other gannetries – the first such incidence of prospecting in this age class. Our findings suggest the HPAIV outbreak triggered changes in space use patterns of possibly infected individuals that amplified the epidemiological connectivity among colonies and may generate super-spreader events that accelerate disease transmission across the metapopulation. Such self-propagating transmission from and towards high density animal aggregations may explain the rapid pan-European spread of HPAIV in the gannet.