Upcoming thesis defense: Should I stay or should I go?

On Friday the 28th of April Cecilia Sandström will defend her thesis 'Should I stay or should I go? Do geese gain health benefits by migrating to the Arctic?'.

Bird migration is an impressive phenomenon, but why birds often travel long distances to and from their breeding grounds in the far North is still unclear. Benefits include more nutritious food, longer daylight hours, and/or fewer predators. In this thesis an alternative explanation was investigated: are there health benefits by migrating to the Arctic?

To this end, immune responses of barnacle geese breeding on Arctic Spitsbergen were compared with geese remaining in the temperate Netherlands throughout the year. Spitsbergen geese appeared to invest much less energy in their immune systems. Particularly the component responsible for general resistance to disease, possibly due to lower pathogen pressure on Spitsbergen as compared with The Netherlands. Additionally, the Dutch population showed less stress-related immune response to an acute stressor, likely due to a high overall immune activity. Furthermore, we showed that goslings raised in The Netherlands had a lower overall “health status”, as evidenced by much higher intestinal and renal parasitic burden and a slower growth rate.

We further investigated the role of migratory geese in the transmission of disease to the Arctic, specifically the parasite Toxoplasma gondii causing the disease toxoplasmosis. We concluded that newborn geese don’t get infested on Arctic Spitsbergen, but rather get infected when first arriving at wintering grounds in The Netherlands, then conveying the parasite with them to the Arctic the following summer.
The overall conclusion of this thesis is that geese gain health benefits by migrating to the Arctic, as geese in the Arctic are exposed to a lower disease load.