Migration ecology and bird health

Migratory birds can host a large variety of parasites. Understanding the mechanisms of host-parasite-interactions is complex and the transient nature of migrants makes it difficult to follow them throughout the annual cycle, monitoring their infection status, physiological state or behaviour.


We aim at closing gaps in our current knowledge about the manifold consequences of parasites on their migrating avian hosts by specifically addressing the following questions:

  • Which of the consequences of parasites on their avian hosts do indeed occur?
  • How do they depend on the severity of infection?
  • How long do effects last?
  • How are individual consequences mechanistically linked?


The specific time-scales, at which these consequences appear, can be categorized as follows:

  1. physiological performance, at the scale of minutes to days,
  2. daily activity budgets at the scale of days to weeks,
  3. migration behaviour at the scale of weeks to months, and finally,
  4. survival and reproductive success at the scale of years to life-time.

We employ a suite of empirical, experimental, lab-based and theoretical methods, of which the most important ones are measurements of metabolic rates, experimental medication, geolocation as well as activity tags, state-dependent optimal migration models and network models.


Our research will elucidate mechanisms that mediate the spread of diseases, which has implications for both human health and nature conservation. Infectious diseases pose an ongoing threat to global health security and identifying their consequences and mechanisms form the basis for the development of successful prevention strategies.


Migratory animals can importantly influence communities and ecosystems by a variety of transport and trophic effects, most of which are yet to be fully understood. One of these transport effects is the suggested role of migratory animals in the long-distance dispersal of parasites, which can both be facilitated and hampered by the migration process.

We currently investigate the prevalence of avian malaria parasites in different migratory birds and combine this with migration behaviour and daily activity. Furthermore, we measure the physiological capacity of infected and non-infected birds to quantify the short-term consequences of parasitemia.

Project management

Silke Bauer, Steffen Hahn, Tamara Emmenegger


Staffan Bensch (Department of Ecology, Animal Ecology, Lund University),
Bill Buttemer (Centre for Integrative Ecology, Deakin University, Australia)

Financial support

Financial support: Swiss National Science Foundation, Projekt 31003A_160265


Buttemer, W., S. Bauer, T. Emmenegger, D. Dimitrov, S. Peev & S. Hahn (2019):
Moult-related reduction of aerobic scope in passerine birds
Emmenegger, T., S. Bauer, D. Dimitrov, J. Olano Marin, P. Zehtindjiev & S. Hahn (2018):
Host migration strategy and blood parasite infections of three sparrow species sympatrically breeding in Southeast Europe
Emmenegger, T., S. Bauer, S. Hahn, S. Müller, F. Spina & L. Jenni (2018):
Blood parasites prevalence of migrating passerines increases over the spring passage period
Hahn, S., S. Bauer, D. Dimitrov, T. Emmenegger, K. Ivanova, P. Zehtindjiev & W. Buttemer (2018):
Low intensity blood parasite infections do not reduce the aerobic performance of migratory birds
Lisovski, S., J. G. B. van Dijk, D. Klinkenberg, B. A. Nolet, R. A. M. Foluchier & M. Klaassen (2018):
The roles of migratory and resident birds in local avian influenza infection dynamics.
Bauer, S., S. Lisovski & S. Hahn (2016):
Timing is crucial for consequences of migratory connectivity