She’s my only isbar hen
I do have chicks from someone else but they are only a month old. Hopefully the rooster isn’t a lost cause. If this stupid Marans hen would end her laying strike I can find out!
Is the rooster covering any of your other hens? Edited to add, I went back and read your first post. No other hens with this rooster. Keep the tidbit of advice for another time.
If so, put an egg in a sunny window for two days. Then crack open the egg and look for the "blast" or embryo spot on the surface of the yolk. If it is a dot inside a ring, it is fertile.
You can use the egg as it is still fresher than anything from the grocery. Or cook the egg for the chickens or give it to your dog.