Influence of experience and migratory distance on the variation of the realised and endogenous migration behaviour

• Applicant: Professor Dr. Heiko Schmaljohann
• Subject Area: Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions
• Term: from 2013 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 237654588

Juvenile nocturnally migrating songbirds travel thousands of kilometres to their wintering areas independently of conspecifics. To arrive at the spot and in time, their innate migration program defines birds spatiotemporal organisation of migration and their reaction norm to environmental factors. Tracking the first migration at a high spatiotemporal resolution indicates how the endogenously controlled migration program guides birds through space and time, whereas adults migration is influenced by their experience. With an increasing migration distance the strength of stabilizing (directional) selection is supposed to increase towards an accurate timing for reproduction especially in the Arctic. The main aims are to investigate the realised migration behaviour of free-flying naïve and experienced birds indicating the genetic basis of migration and whether the variation of the innate migration behaviour decreases with increasing migration distance and consequently increased stabilizing (directional) selection pressure.The Northern Wheatear (Oenanthe oenanthe) has one of the largest ranges of any songbird in the world, breeding from eastern Canada across Greenland, Eurasia and into Alaska. As all populations winter in sub-Saharan Africa, migration distance varies between populations. Their movements can be tracked in a high spatiotemporal resolution by light-level geolocators. Methods drawback, i.e., no information about latitude around equinoxes, is minimized in the Alaskan population due to its large longitudinal migratory component allowing precise temporal information about stopover and flight stages. This enables studying possible age differences in the orientation performance, spatiotemporal migration strategy and reaction norms to varying environments. In addition to Alaskan birds (migration distance: 14000 km), German wheatears (4000 km) will be studied also by light-level geolocation. As the usage of light-level geolocators requires re-trapping; only returning birds can be considered. To study coherently the importance of the innate migration program on the realization of migration, we need considering migration behaviour of free-flying individuals in combination with the variation of the endogenous components (fuel deposition, migratory restlessness) in naïve birds of different populations by common-garden experiments. Here we will consider additionally birds from Morocco (1500 km), Norway (5000 km) and Island (6000 km). As migration distance might be equivalent with strength of the natural selection pressure experienced during travelling, this study will show how natural selection affected the variation of the innate migratory traits. The problem of considering only returning birds will be overcome with the ICARUS-Project in the near future allowing remote sensing of small organisms. A future perspective is studying the individual repeatability and consistency of the migration behaviour of initially naïve individuals over years.

• DFG Programme: Research Grants