, Germany s on
Terschelling,
Netherlands The Wadden Sea is famous for its rich
flora and
fauna, especially birds. Hundreds of thousands of
waders,
ducks, and
geese use the area as a
migration stopover or wintering site. It is also a rich habitat for
gulls and
terns, as well as a few species of
herons,
Eurasian spoonbills and
birds-of-prey, including a small and increasing breeding population of
white-tailed eagles. However, the biodiversity of Wadden Sea is smaller today than it once was; for birds,
greater flamingos and
Dalmatian pelicans used to be common as well, at least during the
Holocene climatic optimum when the climate was warmer. Due to human activity and a changing environment, species have gone extinct, while others are expected to migrate in. Larger fish including
rays,
Atlantic salmon and
brown trout are still present in several sections of the Wadden Sea, but others like
European sea sturgeon only survive in the region through a reintroduction project. The world's only remaining natural population of
houting survives in the Danish part of the Wadden Sea and it has been used as a basis for reintroductions further south, but considerable
taxonomic confusion remains over its status (whether it is the same as the houting that once lived further south in the Wadden Sea).
European oyster once formed large beds in the region and was still present until a few decades ago, when extirpated due to a combination of disease and the continued spread of the invasive
Pacific oyster, which now forms large beds in the Wadden Sea. Especially the southwestern part of the Wadden Sea has been greatly reduced. Historically, the
Rhine was by far the most important river flowing into this section, but it has been greatly reduced due to dams. As a result, about 90% of all the species that historically inhabited that part of the Wadden Sea are at risk. The Wadden Sea is an important habitat for both
harbour and
grey seals.
Harbour porpoises and
white-beaked dolphins are the sea's only resident
cetaceans. They were once extinct in the southern part of the sea but have also re-colonized that area again. Many other cetaceans only visit seasonally, or occasionally. In early history,
North Atlantic right whales and
gray whales (now extinct in the North Atlantic) were present in the region, perhaps using the shallow, calm waters for feeding and breeding. It has been theorized that they were hunted to extinction in this region by shore-based whalers in medieval times. They are generally considered long-extinct in the region, but in the Netherlands, a possible right whale was observed close to beaches on
Texel in the
West Frisian Islands and off Steenbanken,
Schouwen-Duiveland in July 2005. Recent increases in the number of North Atlantic
humpback whales and
minke whales might have resulted in more visits and possible re-colonization by the species to the areas especially around
Marsdiep. Future recovery of once-extinct local
bottlenose dolphins is also expected. == Conservation ==