Summary: Climate change, migratory birds and their role in spreading infectious diseases – increasing risk in times of climate change?
Birds are affected by global warming. Migratory birds arrive earlier at breeding grounds in spring, and do have an either advanced or delayed autumn departure. Many species breed earlier today, and there are cases of climate driven mis-timing between onset of breeding and peak abundance of prey, with considerable impacts on the fitness of the birds.
Global warming is likely to lead to a reduction of migratoriness in short to medium distance migrants which will result in bird communities that will be increasingly dominated by non-migrating and short to medium distant migratory species. It is also expected an increase in species richness in temperate, boreal and arctic regions, while species richness is suggested to decline in more arid regions due to increased temperature and decreased precipitation.
Birds can carry pathogens and there are a few hints that migratory birds take a role in spreading a disease, although very much speculative. Pathogens likely for avian spread are West Nile Virus, USUTU virus, avian influenza, bacterial diseases, and blood parasites.
More likely than spreading human pathogens due to climate warming is the spread of avian diseases into regions where long-term co-evolutionary processes were missing so that a new emerging disease could be fatal for resident birds, as it is the case with West Nile Virus in North America, or avian malaria on Hawaii.