Meeting Abstract

31.3  Monday, Jan. 5  Energetics, immunology and corticosterone response of four subspecies of stonechats in winter VERSTEEGH, MA*; HELM, B; GOYMANN, W; TIELEMAN, BI; University of Groningen; Max Planck Institute for Ornithology; Max Planck Institute for Ornithology; University of Groningen m.a.versteegh@rug.nl

The balance between current and future reproduction is one of the foundations of life history theory. If adult survival is high, investment in current reproduction is expected to be low, while if adult survival is low current reproduction is expected to be high. Tropical stonechats from Kenya produce fewer offspring per year than their temperate conspecifics. Also, they are resident birds in contrast with stonechats from Central Europe or Kazakhstan, which are migrants, and Irish birds, which are partial migrants. Because tropical stonechats invest less in current reproduction then temperate stonechats, we expect them to invest more in self-maintenance, thereby increasing their survival chances. To obtain insights in the physiological differences among the four subspecies of stonechats, we measured basal metabolic rate, several measures of the innate constitutive immune system, and baseline and stress induced corticosterone levels during winter. Individuals from all four subspecies were kept in captivity in a common garden set up. We hypothesized that mass-specific basal metabolic rate and immune function were inversely related with life expectancy, although we realized that pathogen pressure may strongly influence immune function as well. The results suggest that metabolic and corticosterone measures depend on migratory strategy, while immune measures depended more on the environment that free-living stonechats animals would have experienced during winter. Pathogen pressure is thought to be high in the tropics and low in temperate regions, and birds might well have adapted their innate constitutive immune system to these varying threath levels.