During migration, movement periods alternate with periods on stop-over sites, where birds accumulate body reserves for the next migratory leg. For a successful migration and timely arrival in the breeding grounds, the choice of high-quality stop-over sites is of utmost importance.
How can migrant birds effectively time migration and use resources on sites with varying phenology?
We aim to identify the factors and cues that determine stop-over site choice and migration schedules in migrant passerine birds. In particular, we investigate the role that food availability (quality, quantity and timing) and other site-specific parameters play in the decision to commence or resume migration.
(Simulation) models can aid in answering these questions. Among others, we use state-dependent optimisation models, where organisms are characterised by state-variables, e.g. body reserves, age, experience, etc., and they are assumed to behave such that they maximize their fitness.
In a first step, we will focus on the spring migration from African wintering grounds to European breeding grounds as this is often the most sensitive part of the annual cycle, directly affecting reproductive success. Thereafter, we will develop models for the autumn migration to the wintering grounds and finally, we will consider the whole annual cycle of migrants. Consequently, we can compare the results of the different modelling approaches and scrutinize their predictions with empirical data.
Models can help understanding complex systems since we can test hypotheses, which are difficult or impossible to test in the field. Furthermore, we can follow the fate of birds in environments that are changed beyond those presently found in reality. Thus, we can estimate the consequences of potential future environmental (climatic, human-made habitat) changes on mortality and reproduction of the migrants, which eventually results in predicting their population dynamics under such changes.
Prof. Zoltan Barta, Behavioural Ecology Research Group, University of Debrecen, Hungary
Prof. J. McNamara, University of Bristol, UK
Dr. Judy Shamoun-Baranes IBED – Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, The Netherlands
Swiss National Science Foundation SNSF project 31003A_160265