Hi
Here in RSA we have plenty owls as well as other raptors esp the smaller ones that really like to hone in on averies and cause major injuries to our birds esp finches

, I am talking broken wings,legs bleeding heads broken beaks all this just as they try to get away from the raptors species, many methods have been tried and work , but one that has really worked for Owls is to take strips of tin foil and hang them from post or trees around the averies , I have been told that the tin foils reflection from the lux given by the moon or starts or any light for that matter really messes the owl sight and hunting abality, similar effect have been very sucsessful with the eradication of bats as the tin foil reflects their sonar that they use for hunting and they leave the location they have inhabitied.
Obviously this is not a pretty sight around ones avery however if it does the trick for a few nights then I am sure the Owl will relocate or simply find an additional hunting ground.
My 5c worth out of Africa....
Good luck
G..
Breeding Finches isn't a hobby its a way of LIFE....