In Croatia, Duca families are predominantly Croats (from Zadar ), rarely Italians (also from Zadar ). In the past century, relatively most of Croatian residents bearing this family name were born in Zadar.
Prevalence
About 10 people with faimily name Duca live in Croatia today, in four households only. There were 10 of them in the middle of the past century, and their number remains constant. They are located in one Croatian city only, in Zadar (<10).