It was the maker of the track, a large female lynx.

She was crouching as he had crouched once that day, in front of her the tight-rolled ball of quills.

If he had been a gliding shadow before, he now became the ghost of such a shadow, as he crept and circled around, and came up well to leeward of the silent, motionless pair.
He lay down in the snow, depositing the ptarmigan beside him, and with eyes peering through the needles of a low-growing spruce he watched the play of life before him--the waiting lynx and the waiting porcupine, each intent on life; and, such was the curiousness of the game, the way of life for one lay in the eating of the other, and the way of life for the other lay in being not eaten.

While old One Eye, the wolf crouching in the covert, played his part, too, in the game, waiting for some strange freak of Chance, that might help him on the meat-trail which was his way of life.
Half an hour passed, an hour; and nothing happened.

The balls of quills might have been a stone for all it moved; the lynx might have been frozen to marble; and old One Eye might have been dead.