Well the details are coming back to me now. It is often hard to remember things once your pass 100. It was my understanding that you thought the Owl killed the bird, but another animal was attempting to eat it or carry it off?
In any case, I would be careful with the cat. It may have a taste for birds and/or you may end up with a double digit cat population there. They seem to multiply rapidly, but if you have Fishers in the vicinity they will work to keep the population in check.