I have been fascinated by interdisciplinary research at the cutting edge of biology, mathematics and engineering for a long time. Specializing in ecological modelling and bird migration, my current interest focuses on understanding how bird migration is influenced by the environment and the individual’s state, and on how migratory movements affect the population dynamics of birds, their life histories and local biodiversity in turn. In this context, I am studying potential impacts of global change on migratory birds, existing carry-over effects and the evolutionary trade-offs in their decision-making by combining ecological modelling with animal movement analysis. In a second step of my PhD, I will then concentrate on how anthropogenic changes in migratory bird links may affect feedback loops to regional biodiversity.
Anthropogenic changes of climate and land use have a direct impact on regional biodiversity (Vitousek 1994 Ecology; Newbold et al. 2015 Nature). However, they also affect the population dynamics of migratory birds. Indeed, 19 % of extant bird species are estimated to be migratory (Kirby et al. 2008 Bird Conserv Int), providing a mobile link between different ecosystems and transporting energy, nutrients and parasites between vastly separated regions (Bauer and Hoye 2014 Science). Since local biodiversity as well as ecosystem functioning are seriously altered during their regular temporary presence or absence (Bauer and Hoye 2014 Science), human-caused landscape changes also have an important indirect impact on regional biodiversity. Anthropogenic changes in habitat quality may further lead to carry-over effects on survival and breeding success and influence the abundance and schedule of migratory birds. Carry-over effects occur when processes in one season influence the performance of an individual in subsequent seasons. Though they are suspected to be widespread and to be responsible for a large amount of variation in the fitness of individuals, their role in an animal’s life history is far from understood. One major reason for this knowledge gap is that the experimental study of carry-over effects between periods of the annual cycle has proven to be difficult, and new research approaches and tools for their investigation are needed (Harrison et al. 2011 J Animal Ecology; O’Connor et al. 2014 Ecosphere).
This PhD project focuses on the following key questions:
How do short-term changes in anthropogenic landscapes, a major cause of biodiversity decline, affect the population dynamics of migratory
What carry-over effects can landscape changes induce in migratory birds?
How do the abundance of migrants and the timing of their migration affect local biodiversity at the breeding habitat?
To tackle these research questions, a set of different models will be employed over various spatial and temporal scales. These models will be adapted to the white stork (Ciconia ciconia) which will serve as a model species for a long-distance migrant breeding in Brandenburg, Germany, and wintering in Sub-Saharan Africa. In particular, state-based dynamic optimization will be used to calculate optimal life history strategies based on the potential state an individual bird could be in, integrating stochastic environmental conditions. The optimal strategy will then be applied to simulate population dynamics under different scenarios of altered land-use and to analyze resulting carry-over effects. Subsequently, the predicted variable phenologies will be used in supplementing small-scale, spatially explicit individual-based models (SEIBMs) to investigate the influence of a migrant population on local biodiversity at the breeding grounds and the consequences of changes in their abundance and in their timing of behavior. Here, the focus will lie on foraging pressure of seasonally abundant migrants on local food resources.