Caught In The Act

I've got this theory about trees, and statues too if it comes to that.
I'm sure that in the wee small hours they can, and do, move about.
However, the moment they are discovered, they have to freeze wherever they are, and whatever they're doing.
This one has been well and truely caught with his barks around his ankles so to speak.
Copulatus Arbuscula!