Help with Rostad family

Hello, I am wondering if anyone can help me figure out the next step tracing my Great Great Grandfather's paternal line. My gg grandfather was Jens Antonius Olsen Rostad (b 1876 in Rødø and died in 1953 in Winnipeg, Canada). I have located two birth records for him: https://www.digitalarkivet.no/en/view/255/pd00000028211114 https://www.digitalarkivet.no/en/view/255/pd00000031915865 I am having a hard time knowing where to go with he information about his father. In one record he is just listed as Ole Evensen, from Melhus parish, and in the other Ole Evensen Rostad, domiciled in Molhus. Provided I am searching/reading properly, it looks like my gg grandfather was illegitimate and my ggg grandparents never married. Where would it make sense for me to look for him next? Should I be trying to find him on a Rostad farm, looking in Melhus, or keep searching in Nordland? If anyone has any tips I would be most appreciative!