There are at least 20-30 Heronry in there......
There are some more at the back from where you stand (the school) and inside, if you go north on 404, you can see them. Those Heronry are there for a long time, every year, they come back and bring more Heron to come. If I am not mistaken, the school used to be not a school, it was something like community centre/ something like that and I used to go there to watch them. When there's snow in Oct/Nov, those Heron used to hide under the bushes, like little children, one by one, form a line and I used to park my car alongside and watch them. Until the snow's stop, they fly back again.
Ever since the place become a school and after last year renovation, I think they are really in caution if any stranger goes near the school. But I think it is good in a way that, those Heron won't get disturb. I enjoy watching them from a distance.
You can always find the Heron in the Richmond Green Park, as they catch little minnow in the pond with some sea gull, sandpipper, Goose, Killdee....etc
Excuse me for my poor English grammer since English is not my first language.
Besides, most of the areas near the school are private as there's a farm around that area.