We had a trip to our local Wildfowl & Wetlands Centre just down the road at Washington ( not the USA version, but the original one, the birthplace of George & his family ).
A pleasant walk round & whilst we didnt see any owls, we did see evidence of them in one of the main hides:-
The Diego hide at Washington
bench whitewashed & a large fresh pellet
Info notice - i dont go to many bird hides but i have seen some a lot messier than this one !