Raccoons and green roofs, not so perfect together

(What do you mean we're not supposed to be up here???)

Up on a green roof last week and I wasn't so happy to see evidence of raccoons. How does one know when they've been hanging around? When you can see this:

(they have bedded down for a night...or two...or thirty. Where there once were plants, now there is just medium.)

or this

(do I need to explain that one?)

Not sure what to do to dissuade them from visiting and something must be done as they can present problems.

The picture above is actually from my place, yes they are everywhere. Oh...and if the title of this post made you remember this classic jingle and smile, then my work is done for today.