A soft wind blowing from the south and east brought the scent of the invaders to Gray Wolf’s nose when they were still half a mile away.  She gave the warning to Kazan and he, too, found the strange scent in the air.  It grew stronger as they advanced.  When two hundred yards from the windfall they heard the sudden crash of a falling tree, and stopped.  For a full minute they stood tense and listening.  Then the silence was broken by a squeaking cry, followed by a splash.  Gray Wolf’s alert ears fell back and she turned her blind face understandingly toward Kazan.  They trotted ahead slowly, approaching the windfall from behind.  Not until they had reached the top of the knoll on which it was situated did Kazan begin to see the wonderful change that had taken place during their absence.  Astounded, they stood while he stared.  There was no longer a little creek below them.  Where it had been was a pond that reached almost to the foot of the knoll.  It was fully a hundred feet in width and the backwater had flooded the trees and bush for five or six times that distance toward the burn.  They had come up quietly and Broken Tooth’s dull-scented workers were unaware of their presence.  Not fifty feet away Broken Tooth himself was gnawing at the butt of a tree.  An equal distance to the right of him four or five of the baby beavers were at play building a miniature dam of mud and tiny twigs.  On the opposite side of the pond was a steep bank six or seven feet high, and here a few of the older children ­two years old, but still not workmen ­were having great fun climbing the bank and using it as a toboggan-slide.  It was their splashing that Kazan and Gray Wolf had heard.  In a dozen different places the older beavers were at work.

A few weeks before Kazan had looked upon a similar scene when he had returned into the north from Broken Tooth’s old home.  It had not interested him then.  But a quick and thrilling change swept through him now.  The beavers had ceased to be mere water animals, uneatable and with an odor that displeased him.  They were invaders ­and enemies.  His fangs bared silently.  His crest stiffened like the hair of a brush, and the muscles of his forelegs and shoulders stood out like whipcords.  Not a sound came from him as he rushed down upon Broken Tooth.  The old beaver was oblivious of danger until Kazan was within twenty feet of him.  Naturally slow of movement on land, he stood for an instant stupefied.  Then he swung down from the tree as Kazan leaped upon him.  Over and over they rolled to the edge of the bank, carried on by the dog’s momentum.  In another moment the thick heavy body of the beaver had slipped like oil from under Kazan and Broken Tooth was safe in his element, two holes bitten clean through his fleshy tail.  Baffled in his effort to get a death-hold on Broken Tooth, Kazan swung like a flash to the right.  The young beavers had not moved.  Astonished and frightened at what they had seen, they stood as if stupefied.  Not until they saw Kazan tearing toward them did they awaken to action.  Three of them reached the water.  The fourth and fifth ­baby beavers not more than three months old ­were too late.  With a single snap of his jaw Kazan broke the hack of one.  The other he pinned down by the throat and shook as a terrier shakes a rat.  When Gray Wolf trotted down to him both of the little beavers were dead.  She sniffed at their soft little bodies and whined.  Perhaps the baby creatures reminded her of runaway Ba-ree, her own baby, for there was a note of longing in her whine as she nosed them.  It was the mother whine.

But if Gray Wolf had visions of her own Kazan understood nothing of them.  He had killed two of the creatures that had dared to invade their home.  To the little beavers he had been as merciless as the gray lynx that had murdered Gray Wolf’s first children on the top of the Sun Rock.  Now that he had sunk his teeth into the flesh of his enemies his blood was filled with a frenzied desire to kill.  He raved along the edge of the pond, snarling at the uneasy water under which Broken Tooth had disappeared.  All of the beavers had taken refuge in the pond, and its surface was heaving with the passing of many bodies beneath.  Kazan came to the end of the dam.  This was new.  Instinctively he knew that it was the work of Broken Tooth and his tribe and for a few moments he tore fiercely at the matted sticks and limbs.  Suddenly there was an upheaval of water close to the dam, fifty feet out from the bank, and Broken Tooth’s big gray head appeared.  For a tense half minute Broken Tooth and Kazan measured each other at that distance.  Then Broken Tooth drew his wet shining body out of the water to the top of the dam, and squatted flat, facing Kazan.  The old patriarch was alone.  Not another beaver had shown himself.

The surface of the pond had now become quiet.  Vainly Kazan tried to discover a footing that would allow him to reach the watchful invader.  But between the solid wall of the dam and the bank there was a tangled framework through which the water rushed with some violence.  Three times Kazan fought to work his way through that tangle, and three times his efforts ended in sudden plunges into the water.  All this time Broken Tooth did not move.  When at last Kazan gave up the attack the old engineer slipped over the edge of the dam and disappeared under the water.  He had learned that Kazan, like the lynx, could not fight water and he spread the news among the members of his colony.

Gray Wolf and Kazan returned to the windfall and lay down in the warm sun.  Half an hour later Broken Tooth drew himself out on the opposite shore of the pond.  He was followed by other beavers.  Across the water they resumed their work as if nothing had happened.  The tree-cutters returned to their trees.  Half a dozen worked in the water, carrying loads of cement and twigs.  The middle of the pond was their dead-line.  Across this not one of them passed.  A dozen times during the hour that followed one of the beavers swam up to the dead-line, and rested there, looking at the shining little bodies of the babies that Kazan had killed.  Perhaps it was the mother, and perhaps some finer instinct unknown to Kazan told this to Gray Wolf.  For Gray Wolf went down twice to sniff at the dead bodies, and each time ­without seeing ­she went when the mother beaver had come to the dead-line.

The first fierce animus had worn itself from Kazan’s blood, and he now watched the beavers closely.  He had learned that they were not fighters.  They were many to one and yet they ran from him like a lot of rabbits.  Broken Tooth had not even struck at him, and slowly it grew upon him that these invading creatures that used both the water and land would have to be hunted as he stalked the rabbit and the partridge.  Early in the afternoon he slipped off into the bush, followed by Gray Wolf.  He had often begun the stalking of a rabbit by moving away from it and he employed this wolf trick now with the beavers.  Beyond the windfall he turned and began trotting up the creek, with the wind.  For a quarter of a mile the creek was deeper than it had ever been.  One of their old fording places was completely submerged, and at last Kazan plunged in and swam across, leaving Gray Wolf to wait for him on the windfall side of the stream.

Alone he made his way quickly in the direction of the dam, traveling two hundred yards back from the creek.  Twenty yards below the dam a dense thicket of alder and willow grew close to the creek and Kazan took advantage of this.  He approached within a leap or two of the dam without being seen and crouched close to the ground, ready to spring forth when the opportunity came.  Most of the beavers were now working in the water.  The four or five still on shore were close to the water and some distance up-stream.  After a wait of several minutes Kazan was almost on the point of staking everything on a wild rush upon his enemies when a movement on the dam attracted his attention.  Half-way out two or three beavers were at work strengthening the central structure with cement.  Swift as a flash Kazan darted from his cover to the shelter behind the dam.  Here the water was very shallow, the main portion of the stream finding a passage close to the opposite shore.  Nowhere did it reach to his belly as he waded out.  He was completely hidden from the beavers, and the wind was in his favor.  The noise of running water drowned what little sound he made.  Soon he heard the beaver workmen over him.  The branches of the fallen birch gave him a footing, and he clambered up.

A moment later his head and shoulders appeared above the top of the dam.  Scarce an arm’s length away Broken Tooth was forcing into place a three-foot length of poplar as big around as a man’s arm.  He was so busy that he did not hear or see Kazan.  Another beaver gave the warning as he plunged into the pond.  Broken Tooth looked up, and his eyes met Kazan’s bared fangs.  There was no time to turn.  He threw himself back, but it was a moment too late.  Kazan was upon him.  His long fangs sank deep into Broken Tooth’s neck.  But the old beaver had thrown himself enough back to make Kazan lose his footing.  At the same moment his chisel-like teeth got a firm hold of the loose skin at Kazan’s throat.  Thus clinched, with Kazan’s long teeth buried almost to the beaver’s jugular, they plunged down into the deep water of the pond.

Broken Tooth weighed sixty pounds.  The instant he struck the water he was in his element, and holding tenaciously to the grip he had obtained on Kazan’s neck he sank like a chunk of iron.  Kazan was pulled completely under.  The water rushed into his mouth, his ears, eyes and nose.  He was blinded, and his senses were a roaring tumult.  But instead of struggling to free himself he held his breath and buried his teeth deeper.  They touched the soft bottom and for a moment floundered in the mud.  Then Kazan loosened his hold.  He was fighting for his own life now ­and not for Broken Tooth’s.  With all of the strength of his powerful limbs he struggled to break loose ­to rise to the surface, to fresh air, to life.  He clamped his jaws shut, knowing that to breathe was to die.  On land he could have freed himself from Broken Tooth’s hold without an effort.  But under water the old beaver’s grip was more deadly than would have been the fangs of a lynx ashore.  There was a sudden swirl of water as a second beaver circled close about the struggling pair.  Had he closed in with Broken Tooth, Kazan’s struggles would quickly have ceased.

But nature had not foreseen the day when Broken Tooth would be fighting with fang.  The old patriarch had no particular reason now for holding Kazan down.  He was not vengeful.  He did not thirst for blood or death.  Finding that he was free, and that this strange enemy that had twice leaped upon him could do him no harm, he loosed his hold.  It was not a moment too soon for Kazan.  He was struggling weakly when he rose to the surface of the water.  Three-quarters drowned, he succeeded in raising his forepaws over a slender branch that projected from the dam.  This gave him time to fill his lungs with air, and to cough forth the water that had almost ended his existence.  For ten minutes he clung to the branch before he dared attempt the short swim ashore.  When he reached the bank he dragged himself up weakly.  All the strength was gone from his body.  His limbs shook.  His jaws hung loose.  He was beaten ­completely beaten.  And a creature without a fang had worsted him.  He felt the abasement of it.  Drenched and slinking, he went to the windfall, lay down in the sun, and waited for Gray Wolf.

Days followed in which Kazan’s desire to destroy his beaver enemies became the consuming passion of his life.  Each day the dam became more formidable.  Cement work in the water was carried on by the beavers swiftly and safely.  The water in the pond rose higher each twenty-four hours, and the pond grew steadily wider.  The water had now been turned into the depression that encircled the windfall, and in another week or two, if the beavers continued their work, Kazan’s and Gray Wolf’s home would be nothing more than a small island in the center of a wide area of submerged swamp.

Kazan hunted only for food now, and not for pleasure.  Ceaselessly he watched his opportunity to leap upon incautious members of Broken Tooth’s tribe.  The third day after the struggle under the water he killed a big beaver that approached too close to the willow thicket.  The fifth day two of the young beavers wandered into the flooded depression back of the windfall and Kazan caught them in shallow water and tore them into pieces.  After these successful assaults the beavers began to work mostly at night.  This was to Kazan’s advantage, for he was a night-hunter.  On each of two consecutive nights he killed a beaver.  Counting the young, he had killed seven when the otter came.

Never had Broken Tooth been placed between two deadlier or more ferocious enemies than the two that now assailed him.  On shore Kazan was his master because of his swiftness, keener scent, and fighting trickery.  In the water the otter was a still greater menace.  He was swifter than the fish that he caught for food.  His teeth were like steel needles.  He was so sleek and slippery that it would have been impossible for them to hold him with their chisel-like teeth could they have caught him.  The otter, like the beaver, possessed no hunger for blood.  Yet in all the Northland he was the greatest destroyer of their kind ­an even greater destroyer than man.  He came and passed like a plague, and it was in the coldest days of winter that greatest destruction came with him.  In those days he did not assault the beavers in their snug houses.  He did what man could do only with dynamite ­made an embrasure through their dam.  Swiftly the water would fall, the surface ice would crash down, and the beaver houses would be left out of water.  Then followed death for the beavers ­starvation and cold.  With the protecting water gone from about their houses, the drained pond a chaotic mass of broken ice, and the temperature forty or fifty degrees below zero, they would die within a few hours.  For the beaver, with his thick coat of fur, can stand less cold than man.  Through all the long winter the water about his home is as necessary to him as fire to a child.

But it was summer now and Broken Tooth and his colony had no very great fear of the otter.  It would cost them some labor to repair the damage he did, but there was plenty of food and it was warm.  For two days the otter frisked about the dam and the deep water of the pond.  Kazan took him for a beaver, and tried vainly to stalk him.  The otter regarded Kazan suspiciously and kept well out of his way.  Neither knew that the other was an ally.  Meanwhile the beavers continued their work with greater caution.  The water in the pond had now risen to a point where the engineers had begun the construction of three lodges.  On the third day the destructive instinct of the otter began its work.  He began to examine the dam, close down to the foundation.  It was not long before he found a weak spot to begin work on, and with his sharp teeth and small bullet-like head he commenced his drilling operations.  Inch by inch he worked his way through the dam, burrowing and gnawing over and under the timbers, and always through the cement.  The round hole he made was fully seven inches in diameter.  In six hours he had cut it through the five-foot base of the dam.

A torrent of water began to rush from the pond as if forced out by a hydraulic pump.  Kazan and Gray Wolf were hiding in the willows on the south side of the pond when this happened.  They heard the roar of the stream tearing through the embrasure and Kazan saw the otter crawl up to the top of the dam and shake himself like a huge water-rat.  Within thirty minutes the water in the pond had fallen perceptibly, and the force of the water pouring through the hole was constantly increasing the outlet.  In another half hour the foundations of the three lodges, which had been laid in about ten inches of water, stood on mud.  Not until Broken Tooth discovered that the water was receding from the houses did he take alarm.  He was thrown into a panic, and very soon every beaver in the colony tearing excitedly about the pond.  They swam swiftly from shore to shore, paying no attention to the dead-line now.  Broken Tooth and the older workmen made for the dam, and with a snarling cry the otter plunged down among them and out like a flash for the creek above the pond.  Swiftly the water continued to fall and as it fell the excitement of the beavers increased.  They forgot Kazan and Gray Wolf.

Several of the younger members of the colony drew themselves ashore on the windfall side of the pond, and whining softly Kazan was about to slip back through the willows when one of the older beavers waddled up through the deepening mud close on his ambush.  In two leaps Kazan was upon him, with Gray Wolf a leap behind him.  The short fierce struggle in the mud was seen by the other beavers and they crossed swiftly to the opposite side of the pond.  The water had receded to a half of its greatest width before Broken Tooth and his workmen discovered the breach in the wall of the dam.  The work of repair was begun at once.  For this work sticks and brush of considerable size were necessary, and to reach this material the beavers were compelled to drag their heavy bodies through the ten or fifteen yards of soft mud left by the falling water.  Peril of fang no longer kept them back.  Instinct told them that they were fighting for their existence ­that if the embrasure were not filled up and the water kept in the pond they would very soon be completely exposed to their enemies.  It was a day of slaughter for Gray Wolf and Kazan.  They killed two more beavers in the mud close to the willows.  Then they crossed the creek below the dam and cut off three beavers in the depression behind the windfall.  There was no escape for these three.  They were torn into pieces.  Farther up the creek Kazan caught a young beaver and killed it.

Late in the afternoon the slaughter ended.  Broken Tooth and his courageous engineers had at last repaired the breach, and the water in the pond began to rise.

Half a mile up the creek the big otter was squatted on a log basking in the last glow of the setting sun.  To-morrow he would go and do over again his work of destruction.  That was his method.  For him it was play.

But that strange and unseen arbiter of the forests called O-ee-ki, “the Spirit,” by those who speak the wild tongue, looked down at last with mercy upon Broken Tooth and his death-stricken tribe.  For in that last glow of sunset Kazan and Gray Wolf slipped stealthily up the creek ­to find the otter basking half asleep on the log.

The day’s work, a full stomach, and the pool of warm sunlight in which he lay had all combined to make the otter sleepy.  He was as motionless as the log on which he had stretched himself.  He was big and gray and old.  For ten years he had lived to prove his cunning superior to that of man.  Vainly traps had been set for him.  Wily trappers had built narrow sluice-ways of rock and tree in small streams for him, but the old otter had foiled their cunning and escaped the steel jaws waiting at the lower end of each sluice.  The trail he left in soft mud told of his size.  A few trappers had seen him.  His soft pelt would long ago have found its way to London, Paris or Berlin had it not been for his cunning.  He was fit for a princess, a duke or an emperor.  For ten years he had lived and escaped the demands of the rich.

But this was summer.  No trapper would have killed him now, for his pelt was worthless.  Nature and instinct both told him this.  At this season he did not dread man, for there was no man to dread.  So he lay asleep on the log, oblivious to everything but the comfort of sleep and the warmth of the sun.

Soft-footed, searching still for signs of the furry enemies who had invaded their domain, Kazan slipped along the creek.  Gray Wolf ran close at his shoulder.  They made no sound, and the wind was in their favor ­bringing scents toward them.  It brought the otter smell.  To Kazan and Gray Wolf it was the scent of a water animal, rank and fishy, and they took it for the beaver.  They advanced still more cautiously.  Then Kazan saw the big otter asleep on the log and he gave the warning to Gray Wolf.  She stopped, standing with her head thrown up, while Kazan made his stealthy advance.  The otter stirred uneasily.  It was growing dusk.  The golden pool of sunlight had faded away.  Back in the darkening timber an owl greeted night with its first-low call.  The otter breathed deeply.  His whiskered muzzle twitched.  He was awakening ­stirring ­when Kazan leaped upon him.  Face to face, in fair fight, the old otter could have given a good account of himself.  But there was no chance now.  The wild itself had for the first time in his life become his deadliest enemy.  It was not man now ­but O-ee-ki, “the Spirit,” that had laid its hand upon him.  And from the Spirit there was no escape.  Kazan’s fangs sank into his soft jugular.  Perhaps he died without knowing what it was that had leaped upon him.  For he died ­quickly, and Kazan and Gray Wolf went on their way, hunting still for enemies to slaughter, and not knowing that in the otter they had killed the one ally who would have driven the beavers from their swamp home.

The days that followed grew more and more hopeless for Kazan and Gray Wolf.  With the otter gone Broken Tooth and his tribe held the winning hand.  Each day the water backed a little farther into the depression surrounding the windfall.  By the middle of July only a narrow strip of land connected the windfall hummock with the dry land of the swamp.  In deep water the beavers now worked unmolested.  Inch by inch the water rose, until there came the day when it began to overflow the connecting strip.  For the last time Kazan and Gray Wolf passed from their windfall home and traveled up the stream between the two ridges.  The creek held a new meaning for them now and as they traveled they sniffed its odors and listened to its sounds with an interest they had never known before.  It was an interest mingled a little with fear, for something in the manner in which the beavers had beaten them reminded Kazan and Gray Wolf of man.  And that night, when in the radiance of the big white moon they came within scent of the beaver colony that Broken Tooth had left, they turned quickly northward into the plains.  Thus had brave old Broken Tooth taught them to respect the flesh and blood and handiwork of his tribe.