if you are standing right there with her, no she can't chew through the leash that fast. As soon as she takes it into her mouth, give a leash pop and tell her NO. A leash is only meant to give you a handle for the dog. They shouldn't be tied up with one.
The dogs should NOT be anywhere outside if you aren't right beside them. If they must be outside alone, then it's in a secure kennel - concrete floor and roof included if she is an escape artist and most northern breeds are.
If you aren't outside, the dogs are contained or the chickens are contained. If you can't trust her not to try to get into the chicken pen, she is either leashed right at your side or in a kennel that she can't escape from.
Every time you let her fulfill her desire to chase the birds, you are making it 1000% harder to train out of her. Being a northern breed noted for extreme prey drive, it's likely you will never train it out of her anyway. It's just their nature - it moves, they chase. It's like trying to get a beagle not to sniff or a wolf not to howl. You can take steps to manage it though.