North-East European starlings migrate, but in southern and western Europe the birds are resident. Starlings are generally a highly social family. Most species associate in flocks of varying sizes throughout the year. These flocks may include other species of starlings and sometimes species from other families. This social activity is obvious in their roosting behaviour. In the non-breeding season some roosts can number thousands of birds. Flocks in Britain used to number millions of birds, though numbers are now fewer than they used to be.