PEPPER HAVING A "SNACK"

Not my choice of snack, but he's spent most of the morning since we let him out, abusing this poor prickly pear.  I don't know how they do it or why, but it seems to be important at certain times of the year.  Not sure what vitamins or minerals are in prickly pear.  They don't bother the barrels or the cholla at all.  In the spring and fall they will come in with greasewood i.e. creosote bush breath too.  According to the vets I've talked to, they won't eat greasewood........guess this bunch didn't get the message.......LOL