Once again, I will suggest the use of white woven netting over the black monofilament. To stop crows you don't even need to tie the netting around the tree in my experience. Just throwing it over the top and tying a couple corners around branches will do. Other bird species need to be excluded top and bottom. If the tree is a bit too large for the netting I tie the net to itself with multiple knots to make navigation impossible for smaller birds. Monofilament is a cheap waste of time even if you don't mind untangeling dead or dying animals.