Info Source: nation-wide Birding Lists Digest.
Yesterday, Mario Giazzon of the PA Game Commission banded three Barn Owl owlets in Hartleton, Union County. Barn owls have been present at the site for many years and have been banded there for several years. It was not the usual banding session, however. The adult female owl had been observed to already have a band on. She was captured yesterday and the band number was obtained. This owl had been banded at this same site last August. She was just under 9 months old and had replaced her mother as the breeding female at this site. The owlets were between 5 and 6 weeks old and based on the egg incubation time, the female owl would have been breeding at 6- 6 1/2 months of age.
This I find fascinating because of all the literature that is out , states that a barn owl breeds between 10months to a year of age.