Secula/Seculo and Belle

I am researching a family with the last name Seculo. On their 1920 census they listed their native country as Austria and that the native language as Slavish. In the 1930 census they have their native country as Bohemia and Bohemian a their native language.

John Seculo – b.abt 1882, immigrated abt 1904, was in Trinidad, Colorado by 1905. wife Francisca Belle – b. abt 1883, immigrated abt 1904, was in Trinidad, Colorado by 1905.

Does the name even sound Bohemian to anyone? Any ideas?

I’m stuck.