Climate warming, physical barriers such as dams and fences, and anthropogenic food subsidies have caused many historically migratory populations to travel shorter distances or form sedentary populations. This behavioral shift could alter interactions with parasites, in part by increasing the duration of exposure to infectious agents that accumulate in the hosts’ environment or by increasing local host densities. Here we present a modeling framework for understanding how migratory host-pathogen dynamics are influenced by two potential movement responses to global change: (i) shortened migrations and (ii) abandonment of migration by a fraction of the population (partial migration).
We find that shortened migrations that lead to increases in host population size and migratory survival of infected individuals can result in extremely high infection prevalence. We also find that the onset of sedentary behavior can allow invasion of more virulent pathogens and reduce the fitness benefits of migration to migratory individuals. For zoonotic pathogens harbored by migratory species, these results suggest that anthropogenic change can increase human exposures in areas where sedentary populations form, motivating urgent empirical research into pathogens harbored by species undergoing curtailed migrations.