It is the wind.

There couldn't be a man out there, and it wasn't a rifle we heard.

It is the wind--with the devil himself behind it!" With a few sweeps of his hands and arms he scooped out the loose snow from the hole.

The opening was on the sheltered side of the drift, and only the whirling eddies of the storm swept about him as he thrust out his head and shoulders.

But over him it was rushing like an avalanche.
He could hear nothing but the moaning advance of it.