Have you tried placing a plastic snake/s around the area yet? It is supposed to work, but I haven't ever had to do it. Could an imitation bird enemy work i.e. hawk or a mean looking crow. Even better, a bird pole with abodes attractive to your birds attached

For those out there who have trouble with birds eating fruit from trees, I have read hanging imitation fruit in the tree works. I saw a photo in a plant mag that showed a pecked imitation peach and pear. The accompanying article said the birds didn't come back the following year and the gardeners got the whole crop. Perhaps their beaks were blunt!