In Croatia, Kollert families are Czechs (from Pakrac ). In the past century, relatively most of Croatian residents bearing this family name were born in Daruvar area and in Pakrac.
Prevalence
Only a few people with faimily name Kollert live in Croatia today, in two households only. They are located in one Croatian city only, in Daruvar (<5).
Outside Croatia
Family name Kollert is present in 19 countries worldwide. "Collert " is used by some 80 people in the United States and small number in Sweden.