 The land was ice-covered until 10,000 years ago, and species diversity is still lower than other European biogeographic regions, but wildlife is abundant, including large flocks of migratory birds and many marine organisms fed by nutrients carried by the Gulf Stream from the Caribbean.The land has been drastically modified by humans with forests cleared to make way for farming and large urbanized areas.Pollution is a problem on both land and sea, and over-fishing is also a threat.