Don't know if this helps or not Adam, but there are definitely urban Barn owls around, though not always as visible as one would like in summer. I saw one in winter near the Burlington Northern tracks west of Interbay. Another came out of the Queen Anne Green Belt and flew off under the superstructure of the Aurora St Bridge. Recently, in the process of gathering info about Barred owls, a person described a late Fall owl which came out of the power plant machinery at Gasworks and hunted around that park. It sounded not unlike a Barn Owl to me.
And finally, of course, they do nest adjacent to and hunt around, Discovery Park.
Best, Dave

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David Hutchinson, Owner
Flora & Fauna: Nature Books
Discovery Gardens: Native Plants