The simplest deterrent for bark nibblers OR trunk climbers is a chunk of metal stove pipe snapped around the trunk, but if you don't have some lying around it can be pricey.
Split and taped or strapped PVC or AB'S pipe will work as well,
wood stove install companies may be able to offer used pipe.
Particularly useful for bearing
trees, just for the last few weeks before harvest, pull them out, snap on, move to the next tree a few weeks later. Good Luck!