Oh they are
We are dealing with a LOT of predators -- but the birds are definitely an issue! Hawks, owls, ravens, eagles... all will jump on the opportunity if handed to them! We went for a thicker metal mesh but a lot of people here just do string every foot or so. They say it works to deter the birds of prey, but I'd still be wary.
I understand from another BYCer that Tasmania has an issue with raptors also. I'm with you about being wary of slim measures against predators. Sometimes you don't even know you have chicken predators until one night driving home you see a raccoon as big as a goat crawling out of the city gutter. We see 'coon & 'possum roadkill often on our suburban city street.