How much of the inter-individual variation in routes and the migratory schedule is genetically determined?

This project aims to describe and explain individual variation in migration behaviour among wild Alpine swifts. Individuals differ in the non-breeding sites they visit, the routes they take, the use of stop-over sites, and the timing of their journeys. We are particularly interested in linking this variation to factors such as sex, age, body size, life history, weather conditions, and relatedness between individuals. In particular, knowing heritability is key to understanding how quickly long-distance migrants can respond evolutionarily to a changing environment.

Models for calculating heritability are data-intensive. To this end, we have collected full annual tracks for many individuals using multisensor geolocators, with available information on their relatedness within the breeding population. We can infer offspring relatedness either by observing parental behaviour during reproduction or by using microsatellites. Data have been collected in several colonies across Switzerland (Baden, Biel, Lenzburg, Luzern, Seengen, Solothurn) and in two in Turkey. In these two countries, long-term monitoring programmes are also in place, providing key life-history information for most individual.

We seek answers to some of the longstanding fundamental questions in migration research: Are long-distance migrants able to adjust to a changing environment, and is the mechanism flexible enough to adapt quickly? The key question is how much of the variation in behaviour can be attributed to the individual and how much is owed to environmental stochasticity. The Alpine swift system is particularly powerful, as it allows us to link full annual-cycle migration behaviour with the complete life history of individuals and with repeated tracking of the same individual across consecutive years.

A decade of tracking Alpine swifts with multisensor geolocators has revealed a diversity of migration behaviour in this species. We have identified non-breeding sites in the Sahel zone where birds from different populations aggregate, and individuals appear to visit the same cluster consistently each year. The timing of the annual cycle is influenced primarily by the length of the period with favourable feeding conditions at the breeding ground. Air-pressure data further show that, outside the breeding season, birds regularly make brief ascents of approximately 1’000 m around twilight. The function of this behaviour remains to be discovered.

• Yrd.Doç.Dr. Hakan KARAARDIÇ (Hakan Karaadıç), Alanya Alaaddin Keykubat University Education Faculty, Math and Science Education Department
• Strahil Georgiev Peev, Institute of Biodiversity and Ecosystem Research
• Raül Aymí, Catalan Ornithological Institute
• Gwenael Jacob, Departement of Biology

• The Swiss Federal Office for the Environment (FOEN) contributed financial support for the development of the tags (grant UTF 400.34.11)
• Wolfermann-Nägeli foundation granted supported for fieldwork