And for hawks really fishing line crisscrossed in tight enough webbing will stop them from dive bombing a bird. That's a inexpensive top to deter hawks. Search around this site and you'll see how effective or not that is. Basically if the bird is hungry enough it can land on fence then drop between the fishing line to try and take on a bird one on one ground level. That's one very hunger hawk to jeopardize it's safety like that. That or you have small docile birds like Silkie that are just begging to be attacked.