The Wadden Sea influences nature far beyond its own boundaries. The region is extremely suitable as a nursery for fish species from the North Sea due to several factors: it contains lots of food, the water temperature warms up quickly in the spring and there are no large predator fish where water changes with the tides. The Wadden Sea is also an important transition area for fish that live in salt water during certain stages of their life and fresh water at other times. For these kinds of fish, such as eel, there is more than enough food to be found. Some eel even stay in the area until becoming adults.
This same wealth makes the Wadden Sea an important tanking station for migrating birds and winter guests. Worms, crustaceans and shellfish live in and on the tidal flats from which waders such as oystercatchers, redshanks, curlews and bar-tailed godwits can profit. Their long bills are totally adapted to searching for food in the shallow and exposed areas of the Wadden Sea. There are places where more than 1 kilogram of 'meat' per square meter can be found. The daily rhythm for most tidal flat birds is not determined by day and night but by ebb and flood. As high tide approaches, they fly in large swarms to unflooded areas, the so-called high-tide refuges. Diving duck species have no problems foraging for food during high tide. You can see eiders disappearing under the surface as they dive for shellfish on the bottom of the channels. Geese such as the brent goose and the barnacle goose graze on the green salt marshes. The Wadden Sea is one of the most important winter areas for the barnacle goose.
It is not just the wealth of food that makes the Wadden Sea so important for animals. Exposed sandbanks and uninhabited islands provide areas for resting and moulting. Seals use the sandbanks and other undisturbed exposed areas to rest and nurse their young. This is also the reason why the Wadden Sea is especially important for seals.