The dependence of waders and waterfowl migrating along the East Atlantic Flyway on their coastal food supplies:What is the most profitable research programme

Predicting the effects of human activities, like shell-fisheries, exploitation of gas, recreation, chemical pollution, land reclamation and man-induced sea-level rise, on the population dynamics and migratory behaviour of the waders and waterfowl using the Wadden Sea and other intertidal areas along the East Atlantic Flyway is a tall order. Mathematical models with a strong empirical basis are our only hope for achieving this aim. Though applied models almost always sacrifice generality to achieve precision and realism, it is important to develop unifying concepts that can guide empirical research. We should aim to understand the underlying processes at the level of the individual consumers and consumed. These processes include social competition among the waders and waterfowl(the consumers) for nesting territories and wintering sites, as well as seasonal changes in availability of the prey (the consumed). With regard to the former it can be remarked that ultimately social competition revolves around access to resources vital for reproduction and survival. With regard to the latter we suspect that changes in prey availability are often due to changes in risk-taking behaviour on the part of the prey. In all these cases behavioural ecology and life history theory provide the concepts that link the 'decisions' of individuals to the population processes we aim to predict. The research programme that we describe has proven very useful in investigations of prey choice, migratory behaviour and local distribution patterns. It is only very recently that attempts are made to put the programme to full use in predicting the effects of habitat changes on the population dynamics of the affected birds.