Looked at geologically, the Wadden Islands are young: as actual islands, no more than several thousand years. In addition, they are situated relatively close to the mainland, so that many species of land animals have been able to reach the islands. Consequently, no endemic species have evolved here. However, there are unique variations, which deviate from their mainland families. On Texel, the water shrews are smaller than those on the mainland, and totally black instead of black and white. The fur color of the wood mice on Helgoland is brick-red, while elsewhere it is yellow to light brown on its back and greyish white on the belly.
All of the Wadden Islands have a unique land animal fauna, due to the obvious lack of some common species. Moles, squirrels and foxes are not found on any of the Dutch Wadden Islands. They could easily live there however they have never reached the islands and therefore have never colonised them. This phenomenon has had definite consequences for other animals. The lack of larger land predators is one of the reasons why there is such a large variety of ground-breeding bird species: gulls, ducks, curlews and short-eared owls. The root vole is a species rare for Western Europe and only found in swampy regions. However, it is common on Texel, even in dry terrains because there is no competition from the common vole.
