The Abenaki people of the Northeastern US and Eastern Canada, have some of the coolest monsters in their myths.
Pomola is a powerful bird spirit who causes cold weather. In some legends, he is described as having the head of a moose, the body of a man and the wings of an eagle. I went for a far simpler design of the classic Thunderbird of the tundra who is said to pick up full grown moose or horses as its prey.
In the darkness of winter nights, Pomola is said to swoop down and take men prison in his mountain top roost. That would make a fantastic western style fantasy epic!