Patchwork : patch use, habitat exploitation and carrying capacity for water birds in Dutch freshwater wetlands

Both from a theoretical (foraging theory) and a practical (wetland development and management) point of view, insight is required how animal populations depend on their habitat. Wetlands are considered to be threatened habitats all over the world . Water birds such as ducks, geese and swans constitute an eye-catching element, relatively easy to study and representing a high natural value from the point of view of nature conservation. The biological integrity of a wetland can therefore be judged by the presence of these water birds. Vice versa, many species of migratory water birds completely depend on the presence of well functioning wetlands along their flyway. Little is known about the casual background of the relationship between habitat quality and the number of animals the area can sustain, a concept often referred to as Carrying Capacity. The aim is twofold: first, to provide basic data describing food-consumer relationships for water birds in Dutch freshwater wetlands outside the breeding season and second, to compile this information, together with data from literature, into a concept which concerns food exploitation theory in relation to the issue of carrying capacity at the level of a stopover site.