Our 8 year old Great Pyrenees barks at the hawks.
In fact, he barks at most things. The kitten's on the kitchen counter, the tea kettle is whistling, the oven timer is beeping, the phone is ringing, the chickens are trying to get into the compost heap.... You get the picture. He is always on guard. Be prepared. Barking is their hobby, it is how they tell you something is wrong.
By the way, I love our guy, Titan. He is without a doubt, the best dog we have ever had, and we've had many! We got him from a shelter when he was 1 1/2 years old, he's now almost 9.
He was never trained to be a LGD, just does it naturally. Our flock of chickens and our kitten like to hang out with him.
Seriously, introduce your dog to any other animals you own. This breed does best when it knows what it's limits are.... walk him around your property, fences are better. If he doesn't have boundries, he'll be trying to guard the neighboring farm 2 miles down the road too.
Great Pyrenees are very intelligent dogs. When we let Titan out in the morning, we tell him "Keep an eye on those chickens, don't play with them." He takes his job seriously.
I'm so very proud of this boy's natural talent, I've posted his picture all over this board... like here...
https://www.backyardchickens.com/forum/viewtopic.php?id=345&p=3