Phenology of migration – environmental factors and individual attributes

More than 2 billion passerines migrate from their European breeding grounds to their residence areas in sub-Saharan Africa. The bird’s behaviour and migratory pattern is shaped by the seasonal food availability en route and in the African residence areas, as well as by the short term weather conditions. The critical factors for a successful return to the breeding grounds are barely known for most species and populations of trans-Sahara migrants.


  • What are the temporal and spatial patterns of migration and residency for trans-Sahara migrants during the non-breeding period?
  • What is the influence of seasonality of environmental factors on these patterns and their variability?
  • How much are environmental factors in the African residence areas responsible for reproductive success?
  • Are populations with high connectivity between breeding and non-breeding ranges more affected by local environmental conditions in the African residence area than those with low connectivity?


For selected populations, their African residence areas and to some extent their migratory routes and stopover sites are identified by using miniaturized geolocator . This allows investigating the impact of environmental conditions on the timing and spatial patterns during the non-breeding period. In addition, it enables the investigation of habitat use.

Comparing the relationship between environmental factors en route and the African residence areas with the breeding success will allow extracting the most relevant factors governing species- and population-specific migratory strategies. In addition, looking at kinship will shed light on the pheno- and genotypic variability in migratory patterns.

These questions are being investigated in hoopoes, Alpine swifts and wheatears. Several other species are similarly studied in cooperation with international partners.


The degree of flexibility in migratory patterns in relation to environmental conditions allows for estimating the potential and the limits of phenotypic plasticity, and thus the potential capacity to adapt to fast environmental changes, which can affect reproduction.

To learn more about these dynamic processes is fundamental for our understanding of bird migration, but can also be crucial for species-specific conservation measures.


  • Quantification of the number of individuals migrating from Europe to sub-Saharan Africa.
  • Denomination of African non-breeding residence areas for populations of hoopoes, Alpine swifts, barn swallows and nightingales.
  • Confirmation of non-stop flights of Alpine swifts during their stay in sub-Saharan Africa.
  • Bee-eater migration
  • Barn swallow migration

Project management

Christoph Meier, Felix Liechti, Martins Briedis, Silke Bauer, Steffen Hahn


  • Peter Adamík, Palacký University in Olomouc, Czech Republic (collared flycatcher, tawny pipit)
  • José A. Alves, University of Aveiro, Portugal (European bee-eater)
  • Franz Bairlein, Institut für Vogelforschung "Vogelwarte Helgoland", Wilhelmshaven (wheatear)
  • Oskars Keišs, Institute of Biology, University of Latvia (common starling)
  • Petr Procházka, Institute of Vertebrate Biology, Czech Republic (great and common reed warblers)
  • Martin Schulze, NABU Sachsen-Anhalt Regionalverband Merseburg-Querfurt (European bee-eater)

Financial support

Schweizerischer Nationalfonds (SNF, Hoopoe)
Wolfermann-Nägeli Stiftung (Alpine Swift)
Rosmarie und Armin Däster-Schild Stiftung (Alpine Swift)
Stiftung Accentus (Hoopoe)


Briedis, M., S. Bauer, P. Adamík, J. Alves, J. Costa, T. Emmenegger, L. Gustafsson, J. Koleček, M. Krist, F. Liechti, S. Lisovski, C. Meier, P. Procházka & S. Hahn (2020):
Broad‐scale patterns of the Afro‐Palaearctic landbird migration
Hahn, S., J. Alves, K. Bedev, J. Costa, T. Emmenegger, M. Schulze, P. Tamm, P. Zehtindjiev & K. Dhanjal-Adams (2020):
Range‐wide migration corridors and non‐breeding areas of a northward expanding Afro‐Palaearctic migrant, the European Bee‐eater Merops apiaster
Briedis, M., S. Bauer, P. Adamik, J. Alves, J. Costa, T. Emmenegger, L. Gustafsson, J. Koleček, F. Liechti, C. Meier, P. Procházka & S. Hahn (2019):
A full annual perspective on sex-biased migration timing in long-distance migratory birds
Hahn, S., D. Dimitrov; T. Emmenegger, M. Ilieva, S. Peev; P. Zehtindjiev & M. Briedis (2019):
Migration, wing morphometry and wing moult in Spanish and House Sparrows from the eastern Balkan Peninsula.
Briedis, M., P. Kurlavicius, R. Mackeviciene, R. Vaisviliene & S. Hahn (2018):
Loop migration, induced by seasonally different flyway use, in Northern European Barn Swallows.
Dhanjal-Adams, K., S. Bauer, T. Emmenegger, S. Hahn, S. Lisovski & F. Liechti (2018):
Spatiotemporal Group Dynamics in a Long-Distance Migratory Bird
Meier, C. M., H. Karaadiç, R. Aymí, S. G. Peev, E. Bächler, R. Weber, W. Witvliet & F. Liechti (2018):
What makes Alpine swift ascend at twilight? Novel geolocators reveal year-round flight behaviour.
Bauer, S., S. Lisovski & S. Hahn (2016):
Timing is crucial for consequences of migratory connectivity
Briedis, M., S. Hahn, L. Gustafsson, I. Henshaw, J. Träff, M. Král & P. Adamík (2016):
Breeding latitude leads to different temporal but not spatial organization of the annual cycle in a long-distance migrant.
Emmenegger, T., S. Hahn, R. Arlettaz, V. Amrhein, Z. Pavel & S. Bauer (2016):
Shifts in vegetation phenology along flyways entail varying risks of mistiming in a migratory songbird
Liechti, F., C. Scandolara, D. Rubolini, R. Ambrosini, F. Korner-Nievergelt, S. Hahn, R. Lardelli, M. Romano, M. Caprioli, A. Romano, B. Sicurella & N. Saino (2015):
Timing of migration and residence areas during the non-breeding period of barn swallows Hirundo rustica in relation to sex and population.
Hahn, S., T. Emmenegger, S. Lisovski, V. Amrhein, P. Zehtindjiev & F. Liechti (2014):
Variable detours in long-distance migration across ecological barriers and their relation to habitat availability at ground.
Liechti, F., W. Witvliet, R. Weber & E. Bächler (2013):
First evidence of a 200-day non-stop flight in a bird.
Van Wijk, R. E., M. Schaub, D. Tolkmitt, D. Becker & S. Hahn (2013):
Short-distance migration of Wrynecks Jynx torquilla from Central European populations.
Bächler, E., S. Hahn, M. Schaub, R. Arlettaz, L. Jenni, J. W. Fox, V. Afanasyev & F. Liechti (2010):
Year-Round tracking of small Trans-Saharan migrants using light-level geolocators.