Hmmm....rats? pocket gophers? I'd almost guess quail except they rarely deal with cacti. I've had some cute but damaging rodents raid my garden now and then over the years. Any signs of droppings? Little black tic tac looking things? Gross, now I'll never look at tic tacs the same, LOL. Keep us posted, good luck!

It is the oddest thing. I have not seen any droppings and there are no signs of rodents. Could be some of the small lizards I see around? I have no idea, but if I find out I will post here.

sounds like mice/rats... we live in the desert on acreage and have to deal with all kinds of varmints. its been a dry winter so all plants are in danger if not protected by wire or growing in pots on tables. not any weeds growing for them to eat. set a mouse trap, see if you can catch him, although mice usually leave "evidence" that they have been hanging around (tic tacs!! LOL Grant). I make little "houses" out of scrap cardboard and put the trap inside, so birds don't get caught. . oh, those lizards won't bother your plants - they are after bugs...tons of quail out here and they have never bothered my plants. could also be a rabbit, they will eat anything also, and will sit on their haunches to reach things. they will also eat cactus. if you are having problems in a back yard enclosed by a block wall and a gate low to the ground, so nothing can go underneath, i would say it is a mouse or rat. good luck, Mike, let us know if you catch the critter
Debbie