I tend to blame everything devoured in my garden on the woodchuck, especially since I don't have deer (knock wood). Squirrels tend to do mostly cosmetic damage, not devouring anything, nor do my rabbits for some strange reason (again, knock wood)...

I'm voting for the deer...why do you think partially fenced is keeping them out?

Gone overnight does sound suspiciously like a larger animal, and I've seen the deer effortlessly clear the neighbors 5' gate (as recently as Sunday night) to the 6' high fenced yard, no running start but from standing still right in front of it. Up and over, doesn't deter them at all.

Thank you both for your responses. Tracey, I don't think we have woodchucks here in SoCal, but given some of the other wildlife I've seen around here, nothing would surprise me!

Morz8, the plot is in a place that's not easily accessible to a large animal - it's in a side yard only about 8 feet wide, next to the garage. If an animal as large as a deer was getting in, I think I'd see some evidence - tracks, things knocked over, etc. Nothing. I also have ornamental plants in the unfenced front yard which have never been touched, and I understand deer are voracious.

I should mention that the critter has also eaten a hot pepper plant (with peppers!) and hasn't (yet) touched the sage. I know there are rats in the yard, but I've never heard of rats eating plants. Is that a possibility?

It's the rats!
My husband went deep in the garden shed today and found whole stems of cherry tomatoes hidden away, along with copious amounts of rat poo. I've never heard of rats doing this before!