I don't think there is a convention prohibiting the posting of owl reports, but there is a very basic question that we should all consider before making a post about any bird: "Will this report put the health and safety of the bird at risk?" The answer in the vast majority of cases is, "No", but it should always be considered.
Owls are a group of special concern because they are often very approachable and don't demonstrate their stress in a way that most of us can recognize. While a songbird will simply fly away if you get too close, some owls don't. Also, the owls found in winter in Toronto are often in poor health, usually due to lack of food. Expending extra energy to evade curious humans is the last thing they need.
So, should you report owls? I think it's a judgment call. A lot depends on the bird's location: vulnerability, accessibility, the availability of food and cover, and also how specific you are about the location.
BB