Disease Ecology and Ecological Immunology of Barnacle Goose Populations with Different Migrant Strategies

Seasonal migration is a commonly observed phenomenon in many avian species. Though the fundamental causes are still under debate, this phenomenon is an important component of a species’ life history trade-offs, including survival and reproduction. The advantages of seasonal migration can include better food resources, safer breeding environments, and lower disease threats etc., but seasonal migration also has costs to animals, including high energy expenditures and different predation pressures. Theory related to ecological immunology that suggests that changes of animal host immunity are the result of the trade-off of resources allocated between self-maintenance and important physiological/behavioural functions can also be applied to questions about seasonal migration. In this context, migrating to higher latitudes in summer provides birds with an environment of better food resources and lower parasite pressures, which can reduce competition for resources for self-maintenance (immune responses) and breeding output. In recent years, some migratory species have been observed to shorten their migratory routes, or even quit migration; the Barnacle goose (Branta leucopsis) is one of them. Populations of this species in the eastern flyway traditionally overwinter in temperate Europe and breed in the Russian Arctic. Since 1970s, a new resident population has become established in the Netherlands. The aim of my PhD project is to better understand how the trade-off in resource use is influenced by migration strategy and how immune responses and parasite pressures differ among sedentary and migratory populations.