Sardinia is occupied by Spanish sparrows, while sparrows on Malta, Crete, and the adjacent islands are intermediates similar to the Italian sparrow. On Malta, sparrows resemble the Spanish sparrow, with urban birds behaving much like the house sparrow, and rural birds like the Spanish sparrow. The situation is complicated by house and Spanish sparrows which winter and migrate on Malta. A more complex situation occurs in parts of northern Africa, where a highly variable mixed, interbreeding population of house sparrows and Spanish sparrows occurs. This "hybrid swarm" shows a full range of characters from nearly pure house sparrows to nearly pure Spanish sparrows and everything between.