How do you know that the first owl was a female and the second owl a male? There is very little visual difference in the sexes of barn owls. The female may be a little darker on the breast and belly. Owls, like all birds, lay eggs, but first select a nesting site, which for barn owls is usually a barn or a silo of a barn. Then the female will lay an average of 5 to 7 eggs, usually 2 to 3 days apart. She may begin incubation with the first eggs, which would separate the ages of the young by as much as two weeks. It requires more than three weeks for one egg to hatch. There is no way to know if the bird you saw was ready to lay eggs, was laying eggs, or was raising young.