Robyn, try going out at night before you go to bed, with a flashlight. Be stealthy, and don't turn on the light until you get close, to try and see if there's something eating on those berries at night.
If you don't have a cat, you could try spreading around some scent deterrent. It's available at any garden center and doesn't smell too bad to people, but makes the varmints think there is a predator in the area.
