Dynamics of capercaillie in the Swiss Alps: metapopulation modelling at the landscape level

Large contiguous coniferous forests with an intermediate canopy cover and well developed ground vegetation are optimal habitats for capercaillie in the Alps (Foto: Kurt Bollmann)

The capercaillie (male top, female bottom) is an umbrella species for high-species richness in coniferous forests (Fotos: Sébastien Sachot).

The regression of the distribution area in combination with a population decline is a common phenomenon of threatened wild animal species. Habitat deterioration and fragmentation of the natural or semi-natural landscape by human activities are often mentioned causes. As a consequence the remaining wildlife populations are organized in spatially discrete patches of suitable habitat within a matrix of unsuitable habitat.
During the last 40 years island biogeography and metapopulation theory has provided much input for the theoretical understanding of spatially structured populations. But it has only sporadically been tested with empirical data (especially of long-lived organisms). The understanding of the dynamics of small, spatially structured populations is of high significance for conservation biology – both in scientific and applied aspects.

The capercaillie Tetrao urogallus is a threatened grouse species of Switzerland. With its large home ranges and its sensibility towards human disturbance the capercaillie is emblematic for many other threatened organisms of coniferous forest landscapes. After a pronounced population decline during the last decades the capercaillie population actually amounts only about 1000 adults and is separated in five independent regions.
The main goal of our research is to identify the major factors limiting the abundance and distribution of the species. Especially, we want to address the significance of the amount and distribution of suitable habitat for the persistence of the populations and to develop a quantitative assessment of the relative importance of a particular habitat patch.

We are studying the metapopulation biology of Alpine capercaillie using a) traditional field methods, and b) landscape ecological, and c) population genetic approaches. To guide the conservation of the species we will develop a population-habitat-model by combining spatial explicit results from the ecological, demographic and genetic analyses. Further we will propose guidelines and schemes for conceptual and practical decisions of stakeholders and practitioners. 

Contact

• Kurt Bollmann