with the house sparrow. In southern Italy, there is a gradual clinal trend with the Spanish sparrow, with birds increasing in their similarity to the Spanish sparrow in appearance and ecology further south, from around Naples to western Sicily, where birds resemble pure Spanish sparrows. However, this trend may be superficial, and the Handbook of the Birds of the World recognises birds from Sicily and Crete as Italian sparrows. 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. The Italian sparrow is associated with human habitations, inhabiting towns, cities, and agricultural areas. In most cities in Italy, it shares the urban environment with the Eurasian tree sparrow, and in some parts of Naples, it is replaced entirely by this species. The Italian sparrow's breeding population is believed to comprise 5 to 10 million pairs, 750,000 to 900,000 of which are estimated to live in urban areas. It has a population density of 58 to 160 pairs per square kilometer. Up to the mid-1990s, its population increased steadily, probably due to increased urbanisation. Between 2000 and 2005, the Italian sparrow's population in Italy declined by 27.1 percent, mirroring the declines of the house sparrow throughout Europe. From 1998 to 2008, urban populations declined by about 50 percent. A study of the Italian sparrow's status listed a large number of potential causes for the Italian sparrow's decline, including shortages of insect food, agricultural intensification, and reductions of green areas. The Italian sparrow is among the most common birds in Italian cities, but other species, including the European goldfinch, are more common. Behaviour The Italian sparrow's behaviour is similar in many ways to that of the house sparrow. It is a social bird, which feeds mostly on seeds and insects. It is mostly sedentary, but it wanders to some extent outside its breeding season. These wanderings