The last pale light of the northern day was fading swiftly into night when they drew back, gorged until there were no longer hollows in their sides.  The faint wind died away.  The clouds that had hung in the sky during the day drifted eastward, and the moon shone brilliant and clear.  For an hour the night continued to grow lighter.  To the brilliance of the moon and the stars there was added now the pale fires of the aurora borealis, shivering and flashing over the Pole.

Its hissing crackling monotone, like the creaking of steel sledge-runners on frost-filled snow, came faintly to the ears of Kazan and Gray Wolf.

As yet they had not gone a hundred yards from the dead bull, and at the first sound of that strange mystery in the northern skies they stopped and listened to it, alert and suspicious.  Then they laid their ears aslant and trotted slowly back to the meat they had killed.  Instinct told them that it was theirs only by right of fang.  They had fought to kill it.  And it was in the law of the wild that they would have to fight to keep it.  In good hunting days they would have gone on and wandered under the moon and the stars.  But long days and nights of starvation had taught them something different now.

On that clear and stormless night following the days of plague and famine, a hundred thousand hungry creatures came out from their retreats to hunt for food.  For eighteen hundred miles east and west and a thousand miles north and south, slim gaunt-bellied creatures hunted under the moon and the stars.  Something told Kazan and Gray Wolf that this hunt was on, and never for an instant did they cease their vigilance.  At last they lay down at the edge of the spruce thicket, and waited.  Gray Wolf muzzled Kazan gently with her blind face.  The uneasy whine in her throat was a warning to him.  Then she sniffed the air, and listened—­sniffed and listened.

Suddenly every muscle in their bodies grew rigid.  Something living had passed near them, something that they could not see or hear, and scarcely scent.  It came again, as mysterious as a shadow, and then out of the air there floated down as silently as a huge snowflake a great white owl.  Kazan saw the hungry winged creature settle on the bull’s shoulder.  Like a flash he was out from his cover, Gray Wolf a yard behind him.  With an angry snarl he lunged at the white robber, and his jaws snapped on empty air.  His leap carried him clean over the bull.  He turned, but the owl was gone.

Nearly all of his old strength had returned to him now.  He trotted about the bull, the hair along his spine bristling like a brush, his eyes wide and menacing.  He snarled at the still air.  His jaws clicked, and he sat back on his haunches and faced the blood-stained trail that the moose had left before he died.  Again that instinct as infallible as reason told him that danger would come from there.