Bassin d’Arcachon

March 2008

Many migratory waders and waterfowl occupy widely separated, estuarine locations. Birds often move long distances, sometimes in response to unfavourable conditions (e.g. bad weather). Predicting the consequences of local environmental change on the wider population may be enhanced by adopting a multi-site modelling approach.

Issues

The dark-bellied brent goose is a migratory bird which has increased greatly in abundance due to a population recovery of its preferred food (eel grass) and protection from hunting. Is it possible to predict how the large-scale distribution and abundance of these birds would be affected by local and global environmental change (e.g. more human disturbance).

Modelling

A multi-site model has been developed in which a population of birds migrates between European wintering sites and its Arctic breeding grounds. The model tracks the location and body condition of every individual in the population. The model predicts mortality and body condition at the end of winter, which determines breeding success, and hence long-term changes in population size.

Results

The model will be used to simulate current circumstances and novel scenarios. Its outputs will be tested against the current distribution, movement patterns and winter mortality rates of brent geese. Simulations of novel scenarios will be used to explore the consequences of a range of local and global environmental changes on the population as a whole.

Funding and Collaboration

Alterra, Aarhus University National Environment Research Institute, Centre National de la Recherche Scientifique.

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