Bird Migration and Vector-Borne Parasite Transmission

Abstract

Migration plays a significant role in the ecology and evolution of hosts and – consequently – their parasites. Migratory birds have evolved to cope with physiological and ecological demands of long-distance migration. While migrant hosts are expected to harbor a large diversity of parasites and thus facilitate cross-species transmission, migration allows hosts to escape parasites by moving away from high parasite pressure habitats during crucial stages of the migration cycle. In the context of vector-borne parasites, three factors play an important role in successful parasite transmission – the level of parasite host-specificity, the ecological and phylogenetic similarities with current and potential hosts, and parasite biology. Parasites with extremely high host-specificity are naturally limited in their ability to switch to new hosts compared to more generalist parasites. However, having closer phylogenetic relationships among hosts increases the likelihood that parasites are shared. Hence, if the migrant host belongs to a phylogenetic group represented in the wintering range, there may be more opportunity for both generalist and specialist parasites to expand their host range, whether from the wintering grounds to the breeding grounds or vice versa. Much of the literature is focused on bird movement and the exchange of parasites between regions, but we need a more in-depth study on the phenology (seasonal timing) of vector emergence and quantifying host and vector abundances, which in turn determines the interactions across taxa. Such data will help to develop a model to identify ecological factors associated with migration that influence host–parasite dynamics, which can further predict the spread of disease with climate change.