THE DEPENDENCE OF WADERS AND WATERFOWL MIGRATING ALONG THE EAST ATLANTIC FLYWAY ON THEIR COASTAL FOOD SUPPLIES - WHAT IS THE MOST PROFITABLE RESEARCH-PROGRAM

Predicting the effects of human activities, like shell-fisheries, expl oitation of gas, recreation, chemical pollution, land reclamation and man-induced sea-level rise, on the population dynamics and migratory b ehaviour of the waders and waterfowl using the Wadden Sea and other in tertidal areas along the East Atlantic Flyway is a tall order. Mathema tical models with a strong empirical basis are our only hope for achie ving this aim. Though applied models almost always sacrifice generalit y to achieve precision and realism, it is important to develop unifyin g concepts that can guide empirical research. We should aim to underst and the underlying processes at the level of the individual consumers and consumed. These processes include social competition among the wad ers and waterfowl(the consumers) for nesting territories and wintering sites, as well as seasonal changes in availability of the prey (the c onsumed). With regard to the former it can be remarked that ultimately social competition revolves around access to resources vital for repr oduction and survival. With regard to the latter we suspect that chang es in prey availability are often due to changes in risk-taking behavi our on the part of the prey. In all these cases behavioural ecology an d life history theory provide the concepts that link the 'decisions' o f individuals to the population processes we aim to predict. The resea rch programme that we describe has proven very useful in investigation s 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 popula tion dynamics of the affected birds.