Print PageMany animals migrate long distances to track seasonal changes in resources and habitats. Species from groups as diverse as mammals, birds, fish, insects and other invertebrates undertake regular long-distance movements. The most dramatic migrations can span entire continents or hemispheres, take several months to complete, and are accompanied by high energetic demands and extreme physiological changes. As a result, these migratory journeys can have profound ecological and evolutionary consequences. Owing to their long-distance movements and exposure to diverse habitats, migratory animals can have far-reaching implications for the emergence and spread of infectious diseases. On the one hand, migrations could enhance pathogen transmission through increased contact in dense populations or between multiple species at migratory staging areas or stopover sites, and migratory animals might harbor a greater diversity of parasite species or strains following exposure at different points in their migratory cycle. On the other hand, studies indicate that long-distance movements can reduce parasite prevalence by allowing animals to leave behind contaminated habitats or by lowering the survival of infected animals during long migratory journeys. The energetic demands of migration could lead to immunosuppression, leaving animals at risk for additional opportunistic infections.
Results/Conclusions
Despite the pervasiveness of animal migrations and their often-spectacular nature, their effects on host-pathogen dynamics remain largely unknown for many systems. Knowledge of these interactions is necessary to assess the consequences for both public health and biodiversity. Many populations of migratory animals are declining and consequently particularly vulnerable to changing landscapes. Responses of migratory species to climate change might further influence infectious disease dynamics. Some migratory species have already responded to these changes. By shifting geographic distributions and migration routes in response to temperature and temperature-dependent availability of key resources, the composition of ecological communities may change, with new groups of species coming into contact with one another, potentially facilitating cross-species transmission of infectious diseases and causing devastating pathogen-induced population declines in previously unexposed host populations. Additionally, conservation management of many migratory species requires international collaborative efforts to monitor large-scale movements and assess global patterns of disease emergence. Thus, understanding how human activities that alter migratory patterns influence wildlife-pathogen dynamics is urgently needed to help guide conservation and management of migratory species and mitigate future risks from infectious disease.
