Meeting Abstract
Seasonal migration exposes animals to a variety of habitats and parasites, thus energetic constraints may prevent simultaneously investing in immunity and migration. If infected migratory birds migrate successfully, there is great potential for birds to transport infectious diseases long distances. To determine whether parasitic infection alters or interferes with songbird migration, we inoculated captive white-throated sparrows (Zonotrichia albicollis) with malaria parasites (Plasmodium spp.) in late winter, corresponding to the initiation of spring migration. We assessed infection success and parasite loads, nocturnal migratory restlessness (zugunruhe), and body composition (fat mass, lean mass, and hematocrit). Experimentally-infected birds did not differ from controls in their in fat and lean mass, however, infected birds had lower hematocrit than controls following peak infection. All birds exhibited migratory restlessness, however, at the onset of infection infected individuals displayed less zugunruhe. This may reflect a delayed migratory departure in wild birds. Thus, although infected birds appear to exhibit normal zugunruhe, there may be subtle effects on migration onset and capacity for sustained flight. Models of disease spread depend on knowing whether or not infection affects migratory behaviour, making this research crucial to understanding future host/pathogen dynamics in our changing climate.
