Something is eating the bark of my citrus trees. At first I thought it was rats because I do have rats and caught them with peanut butter and rat traps. This time, the traps are being left untouched so I'm suspecting something else. A type of bird perhaps? They just strip the bark off and eat it or leave some shreds behind, in some cases the whole trunk or some branches. Any idea what this could be? I haven't taken pictures yet to upload.

Btw, these are all potted trees up on a garage-top deck. Its already attacked 3 citrus trees, blood orange, lemon and orange, with no end in sight. They don't seem to like my other trees but appeared to have sampled some, such as my Suebelle Sapote, mango and papaya. I've wrapped the trunks of the remaining untouched citrus trees in bubble wrap and sprayed the damaged ones with prune sealer.

Any idea what they could be or other suggestions to catch these critters would be appreciated before its too late. Thanks.