Crumbs, that's infuriating. Could it be pigeons?

The partially eaten leaves look like caterpillar damage--a big caterpillar! You might want to go out at night with a torch and try to catch the culprit.

It could very well be one of the Hawk moths. A few years ago I found an enormous catterpilar on my Fuschia and it was a Hawk moth. Please don't kill it, it'll stop eating it soon and pupate.