Around December on one of the beaches of Vlieland (an island at the north of The Netherlands) seals bring up their offspring. The newborn pups are white. After about five weeks they start to get their adult colours and from that moment on, they are able to swim.
The grey seal is found on both shores of the North Atlantic Ocean. It is a large seal of the family Phocidae or "true seals". It is the only species classified in the genus ''Halichoerus''. Its name is spelled gray seal in the US; it is also known as Atlantic grey seal and the horsehead seal.