I have cats around at night, from some unknown neighbor. But I think the box, as recommended,is so deep that the cat could not reach in and get to the young. I also,suspect, but don't know, that that cat's paw would be attacked,if it reached into the box while the parent was on the nest. Interesting to me is that both the screech owl and cat are food for the great horned owl, which is common here, judging by the calls from numerous places at night. My house will be going into it's second Spring with no takers, but I am patient.