This nesting box started off at my mother's house. Wood ducks used it. Then the screech owls took over. I've had it for 7 years now and screech owls use it every year. I have found that screech owls are very tolerant of humans, cats, and dogs. They perch on a Camphor tree limb not more than 10 feet away, and stare at us as much as we stare at them. The few fortunate times I've been able to see them fly to the limb or box are worth the wait...silent and swift.
It must be great to have owls nesting in your garden. I hope this years family fledge without any problems and go on to breed themselves.
Every once in a while we'll get a screech owl showing itself. But like you said... mostly can just hear them.