In Croatia, Jadro families are almost entirely Croats (from Kraljevica ), barely Serbs. In the past century, relatively most of Croatian residents bearing this family name were born in Rijeka and Zagreb.
Prevalence
About 50 people with faimily name Jadro live in Croatia today, in 16 households. There were 60 of them in the middle of the past century, and their number decreased by 10 percent. They are located in four Croatian counties, in 7 cities and 6 other places, mostly in Zagreb (20), Jadranovo (10), Rijeka (<10), Selce (<10), and in Veli Dol (<10).
Outside Croatia
Family name Jadro is present in 6 countries on two continents. The family name "Jadro " is used by some 90 people in the United States. "Yadro " is used by small number of people in the United States and small number in France.
In the sources analysed in the project Acta Croatica so far, the name is mentioned few times, the first time 1930 in source Emigration Commission Zagreb.