Interesting article about the use of Barn Owls to help control rat populations in parts of Johannesburg. I was surprised by the total number of Barn owls released since 1998 - over 83,000.
Scope of the rat problem: http://www.iol.co.za/news/south-africa/gauteng/ratlehong-plagued-by-rats-1.1675209
We recently moved to a new 17 acre property that has a couple of pastures with mature trees around the edges. I haven't had much free time to scout for birds, but I did manage to take a walk early one evening and was able to call a pair of Screech owl using a recording. Late Friday night I was pleasantly surprised when a Screech owl called from some trees right next to our bedroom window. Based on these developments, I decided it was time to put up my owl box. I decided to put it up in my backyard, where I'll be able to keep an eye on it. The new location is very close to where the owl was calling. Sunday I spent a hot afternoon digging through bed rock to get the post down to a decent depth. The owl box is on a 12 foot post, so you have to get it down at least 2 feet to ensure that wind and wildlife won't pull it down. After a few hours of digging I was at a good depth and the owl box went up. Last night my wife called me and told me that the Screech owl was 'going crazy'. I managed to hear the tail end of some pretty serious vocalization. All of this is pretty good news, but I am trying to stay calm. Maybe I will finally get lucky this year in my new location!