City,Country,area ,human popn density,human popn size,Duration of checklist,Methodology,Source /citation,Taxonomic authority,other Sofia,Bulgaria,5723 km2,271/km2,"1,549,659 (in 2017)",pre-2005,,"Iankov P. 2005 Sofia. In Birds in European Cities (eds Kelcey JG, Rheinwald G), pp 279-305. St. Katharinen: Ginster Verlag.",,