Intermarriage with the local populations in these Portuguese colonies also took place. Britain quickly invaded and occupied most of Germany's overseas colonies in Africa. These houses were attached to sugar plantations in the Western colonies. Slavery existed in all of the original thirteen British North American colonies. Virtually all of the population of the Twelve Colonies is wiped out. Gulls nest in large, densely packed, noisy colonies. Minoan colonies or settlements of Minoan traders. Slavery was then legal in the other twelve English colonies. Slavery was legal and practiced in all of the Thirteen Colonies. England had no system of naturalizing immigrants to its island or its colonies. The Aleutians are home to many large colonies of seabirds. Malaria was deadly to many new arrivals in the Southern colonies. Colonial hydrozoans include siphonophore colonies, "Hydractinia", "Obelia", and many others. The Commonwealth is a voluntary association of mainly former British colonies. They led the way in establishing overseas colonies.