Fauna Series No. 5

Fauna of the National Parks — No. 5 The Wolves of Mount McKinley

CHAPTER THREE:
DALL SHEEP (continued)

Wolf and Sheep

Some of the information on the relationships between sheep and wolves that we should like to have would take several years to gather. Ideally, one should study the sheep in the absence of wolves for a few years, and in the presence of them for a similar length of time, and in several localities. What is not evident in one area is often readily revealed in another. But some data have been obtained which reveal their method of hunting mountain sheep, the sections of the sheep population suffering the heaviest mortality from them, and the lamb crop and its survival in the presence of wolves.

Significant observations on the actions of these animals in Mount McKinley National Park, and the wolf's hunting methods (with a number of hunting incidents) are enumerated below. This is followed by data regarding the portion of the white sheep population most subject to predation, based on examination of 829 sheep remains. Finally, consideration is given to the lamb crop and the question of its survival.

REACTION OF SHEEP TO WOLVES

A few incidents are here related which do not involve hunting but show how sheep and wolves sometimes behave when they meet.

On May 7, 1940, a scattered band of sheep moved slowly from one ridge to an adjoining one. The movement was so definite and consistent that I suspected the sheep were moving away from danger. A little later I peered into the draw below the ridge first occupied by the sheep and saw a black wolf investigating some cleanly picked sheep bones. The sheep had simply preferred to have a ridge between themselves and the wolf.

While eating breakfast at the Igloo cabin on May 3, 1940, a wolf was heard howling nearby. Stepping outside, we noticed three alert rams, each on a pinnacle, peering intently below them. They continued to watch for some time, evidently keeping an eye on the wolf we had heard. They apparently felt safe where they were even though the wolf was directly below them.

On August 3, 1940, Dr. Ira N. Gabrielson and I watched a black wolf trot leisurely down a short draw on the ridge opposite us and descend the narrow stream bed bordered by steep slopes. Two rams on the slope below us watched the wolf, and when it trotted out of their sight they moved to a point where they could again see it. Seven other rams grazing a short distance from the two paused but briefly to look. The wolf stopped a few times to look up at the rams, but continued on its way until finally hidden by a ridge. The rams and the wolf had shown a definite interest in one another, but that was all. The wolf probably examines all sheep in the hope of discovering an opportunity for a successful hunt, and the sheep keep alert to the movements of the wolf so as not to be taken by surprise or at a disadvantage.

On June 29, 1941, about 60 ewes and lambs on the south side of Sable Mountain all moved up the slope 100 yards or more and stood with their attention centered on the terrain between us. A search with the field glasses revealed a gray wolf loping westward between me and the sheep, about a half mile from them. Some of the sheep soon began to feed, others watched until the wolf had passed. The day was dark and rainy, so that the wolf, whose legs and lower sides had become wet from the brush, was unusually hard to see, yet the sheep had quickly discovered is.

Former Ranger Lee Swisher told me that he had seen six wolves suddenly come close to seven rams feeding out on some flats at Stony Creek. The rams bunched up and the wolves stopped 100 yards away. They made no move toward the rams, which, still bunched up, walked slowly and stiffly toward the cliffs. The slow gait was maintained until the cliffs were almost reached, then the rams broke into a gallop and quickly ascended the rocky slope. The incident seems to indicate that a wolf may to some extent recognize the ability of the rams to defend themselves. The wolves on this occasion may not have been hungry; possibly under other circumstances they at least would have made some attempt to single out one of the rams.

On one occasion Mr. Swisher said he let a sled dog chase some rams. They turned and faced the dog with lowered horns. After thus threatening the dog the rams started up the slope, and when the dog followed, they again turned on him. This incident is indicative of what the seven rams in the above incident would have done had they been attacked.

A dog belonging to Joe Quigley, a miner, is said to have escaped one night from his camp in the sheep hills. The dog returned 2 or 3 days later all battered. Sometime following this event when the team was driven up to some sheep carcasses this dog was not at all anxious to approach them. The inference drawn was that the bruises the dog had suffered during his absence had been administered by a sheep.

On June 19, 1939, 22 ewes and lambs were seen feeding among the cliffs a short distance above four resting wolves, one of which was lying only about 200 yards away. The sheep had already become accustomed to the presence of the wolves when I saw them for they grazed unconcernedly. Their confidence was probably due to the proximity of exceptionally rugged cliffs to which they could quickly retreat should the wolves attack.

On August 3, 1939, a band of 20 sheep ran up the slope of a ridge bordering East Fork River. A little later a wolf climbed the slope, making slow progress. Twelve sheep watched from a point up the ridge, three from some rocks not far from where the wolf went over the ridge top. Two eagles swooped at the wolf a number of times, continuing to do so after the wolf was out of my view so that its progress could be followed by watching the eagles. The sheep quickly resumed grazing. They had not moved far from the wolf but had watched to see what it was up to.

HUNTING INCIDENTS

Five Wolves on a Hunt.—On the morning of September 15, 1939, five wolves (the East Fork band) trotted along the road to Igloo Mountain then climbed half way up the slope which was covered with several inches of snow, and followed a contour level. I saw them a mile beyond Igloo cabin; three were traveling loosely together, a little ahead of the other two, Sometimes they were strung out, 50 yards or more apart. Generally they trotted, but occasionally broke into a spirited gallop as though overflowing with excess energy. Opposite me they descended to a low point, and the two gray wolves which had brought up the rear dropped to the creek bottom. A black one rounded a point and came upon three rams which it chased. The animals then went out of sight, but in a few minutes the wolf returned and I saw the rams descend another ridge and cross Igloo Creek. As they climbed a low ridge on Cathedral Mountain they kept looking back. When crossing the creek bottom they had not been far from the two gray ones which traveled a mile up the creek and then returned to join the others.

After chasing the three rams, the black wolf joined another black and the dark gray female and all moved up the slope. One of them stopped to howl, possibly a call to the two grays on the creek bottom. These two turned back about that time and later joined the others.

On a pinnacle of a high ridge stood a ewe peering down at the approaching wolves. She watched a long time but moved away while the hunters were still far off. The wolves went out of view on the other side of this same ridge. Later I saw some ewes farther along the ridge looking steadfastly to the west in the direction the wolves had last taken, and beyond these ewes there were three more gazing intently in the same direction. The sheep had fled to the highest points and were definitely cautious and concerned because of the presence of the wolves, which seemed to he coursing over the hills hoping to surprise a sheep at a disadvantage. The day before, I had seen a lamb in this vicinity with a front leg injured so severely it was not used. Such a cripple would not last long if found by these wolves. The habit of cruising far in his hunting gives the wolf opportunity to find weak sheep over a large range and to come upon undisturbed sheep, some of which he may find in a vulnerable location.

Sheldon observes Wolves Hunting.—Charles Sheldon (1930, p. 315) tells of following trails of two separate wolves in March and finding that on nine occasions they had chased sheep unsuccessfully. On eight of the chases they had descended on the sheep from above. He said that the sheep in the region had become badly frightened and that "most of them kept very high." So many unsuccessful hunts suggests that these two wolves were testing out each band, hoping eventually to find a weakened animal or gain some advantage. It appears that wolves chase many sheep unsuccessfully and that their persistence weeds out the weaker ones.

Sheep Escape a Wolf.—On October 7, 1939, I saw the track of a single wolf that had crossed Igloo Creek and then had moved up the slope of Igloo Mountain. After following the creek about a mile, I saw two ewes and two lambs on a spur of Igloo Mountain watching a black wolf which was curled up on a prominent knoll on the next ridge about 200 yards to the west. The two ears of the wolf were turned in my direction, so in order not to alarm him I walked along as though I had not seen him until I was out of his view. Then I doubled back close to the bank and ascended the draw toward him. But when I came near the knoll he was gone and the sheep were lying down.

After back-tracking the wolf, I deduced that its actions were as follows: After crossing Igloo Creek, it climbed part way up the mountain. It followed a trail along a contour at the edge of some spruces near the point where a wolf (perhaps the same one) had surprised a lamb among the spruces a few days before. The wolf crossed some draws and small spur ridges and arrived at a ridge on the other side of which the four sheep were feeding in a broad swale. The wolf climbed up the ridge, out of sight of the sheep, for 50 yards, so that he was slightly above them. He then advanced slowly until within 150 yards of the two ewes and two lambs and then galloped down the slope toward the sheep. The latter had escaped to the next ridge from which they were watching the wolf when I first saw them. The wolf chased up the slope after them but a short distance and then continued westward to the next ridge where he curled up in the snow. This time the sheep had the advantage and escaped. It is significant that they did not run far beyond the wolf; apparently they were confident that they were safe since above them was much rugged country. The behavior of the sheep is definitely conditioned by the terrain they are in and their position in relation to the enemy. Approach a sheep from above and he feels insecure and hurries away. A sheep on a flat is much more wary and timid than one in rugged country.

A Lamb Surprised in Woods.—On October 4, 1939, by back-tracking a wolf I found a freshly killed male lamb. The tracks in the snow plainly told this story: The wolf was following a trail along the side of Igloo Mountain within the edge of the uppermost timber. Suddenly he came upon five or six sheep feeding among the trees. Those above the trail ran up the slope to safety, but a lamb which had been feeding farthest down found itself cut off from a possible escape to the top of the mountain and was forced to run on a contour in the direction from which the wolf had just come. In chasing the lamb, the wolf was able to gallop back over the easy trail it had been traveling and thus keep above the lamb which was endeavoring to swing upward in front of it. The lamb traveled parallel to the trail over terrain broken up by the heads of numerous small draws. In one place he veered slightly upward until he came to the trail, but he must have been hard pressed for he again turned downward and now the wolf followed him directly. The chase led gradually down the slope, the lamb apparently keeping as much altitude as possible in the hope of gaining the rocks above. But he was too hard pressed to cut upward ahead of the wolf. Finally he descended a steep gravel bank to the creek bottom, crossed and recrossed the creek, started up the steep gravel bank at an angle, and returned to the creek where he was killed. He ran slightly more than a half mile before being overtaken. This time the wolf had the advantage not only of coming suddenly upon the lamb from above, but also in having a trail to follow while the victim was galloping over rough brushy country. If the sheep had been feeding in the open as they almost always do, the wolf probably would have been discovered before he was so close to them. This is an example of a situation where the predator gains an unexpected advantage.

Two Old Ewes Killed.—On October 5, 1939, there were fresh tracks of foxes, wolves, and a grizzly in the snow, all leading up a small cliff-bordered stream flowing into Igloo Creek. It was evident that there was some special attraction near at hand. My companion and I proceeded cautiously and soon saw a wolf run off. Farther on we saw a lone lamb in the rocks. An eagle flew away, and then we noticed a grizzly chewing on the skull of a ewe. I hoped the bear would leave the skull so I could get the age of the animal and examine the teeth, but when he finally moved off and climbed a low promontory the skull was in his jaws. He soon finished crunching the bones, then climbed to a rock a little higher where he lay down and after a few minutes went to sleep. The skull was a little close to the bear to retrieve, but that difficulty was solved by two magpies which, in fighting over it, knocked it off the cliff to a spot where we could safely get it. After considerable searching we found the skull of a second ewe on a grassy knoll a few feet above the gravel bed.

The two ewes had been killed 50 yards apart. Nothing now remained except a few large pieces of hide, some legs, entrails, stomach contents, and the two broken-up skulls. The assemblage of animals gathered at the kill may have consumed all the meat, or perhaps the wolves and foxes had cached what was not eaten.

The snow on the ground made it easy to back-track the chase. The story was simple. The two ewes and a lamb had been feeding on Equisetum on a broad moist swale not far above Igloo Creek. (The stomach contents of the two victims were made up mainly of Equisetum.) The wolves had been following along the mountain slope at a level slightly higher than that where the sheep fed. Coming over a rise they spied the sheep feeding in the swale 150 yards below them. The tracks showed that the wolves did not start running until they were within 75 yards of the sheep. The latter galloped out of the swale and ran downward at an angle toward Igloo Creek which they crossed after descending a steep dirt bank about 100 feet high. The wolves followed directly after the sheep, but, instead of running among the large rocks in the canyon stream bed as the sheep had done, they ran alongside the rocks on the smoother ground covered with a sod of Dryas. A distance of 250 yards up this creek the two ewes were captured just before reaching some cliffs. The lamb escaped, and, as stated, we saw it alone a short distance above the carcasses. The ewes had run a half mile before the capture.

These two ewes had lived almost their full span of life, for one was 10 years old and the other was 11. The teeth had been used up, and they were no longer pushing out to compensate for wear on the surfaces. In one ewe the tooth surface was worn below the gum. In the other a molar had worn a "crease" in the palate. They were weak animals, less able to escape the wolves than a lamb, which itself is apparently in a vulnerable age class.

Old sheep killed by wolves.—Late in the winter of 1940, in the rugged draws on the north side of the Outside Range between Savage and Sanctuary Rivers, Harold Herning and Frank Glaser found much sheep hair, bloody pieces of hide, and wolf tracks, all indicating that the wolves had been killing sheep. No skull remains were found. The bones were no doubt hidden in the deep snow which filled the bottom of the draws. After the snow disappeared I hunted in these draws for skull remains. The skulls of four recently killed sheep and the hair remains of a fifth sheep were found. Two of the skulls were those of 11-year-old rams, one of a 12-year-old ram, and the other of a 12-year-old ewe. Here the wolves had apparently eliminated some animals doomed soon to die of old age.

Old Ram Chased Down Bluff.—On January 7, 1941, the tracks of five or six wolves were seen along the road toward Savage Canyon. A short distance above the canyon the wolves abruptly left the road and climbed a gentle slope to the top of an isolated rocky promontory. They chased a lone ram down its steep side to the creek bottom where I found remnants of hide, as well as the stomach contents and the skull. Apparently the wolves had seen the ram on this isolated bluff and had turned aside to circle behind him and cut off his retreat to high ground. He was 12 years old, past his prime, a weak animal. The method employed in capturing him—that of coming down from above and driving him down the slope—seems to be a typical hunting technique.

Figure 36: The lamb made it!

Ewe Captured.—On March 12, 1941, Ranger Raymond McIntyre found the carcass of a recently killed 6-year-old ewe at Toklat River. Tracks showed that two wolves had chased her down a steep slope and captured her at its base. The usual manner of hunting, coming down on the sheep from above, had been practiced. There was no indication of necrosis on the skull. Of course the sheep may have had some other weakness not apparent in the skull.

Lamb Captured in Migration.—On September 28, 1939, Mrs. John Howard of Lignite, Alaska, saw three sheep, at least one of which was a lamb, crossing a valley a mile or more wide, between the "outside" mountain range and the mountains up Savage River. A little later she saw two of the sheep galloping up the long gentle slope leading to the "outside" range. The lamb ran down the slope and disappeared in a draw. The two sheep continued to the ridge, but she did not see the lamb again. Later in the morning she saw two black wolves near the spot where the lamb had disappeared. One of these crossed the flat to the south and returned, followed by two pups. Mr. John Howard investigated and found the lamb partly eaten and saw the wolves nearby. Sheep are especially vulnerable when crossing valleys, for wolves can outrun them on the flats.

Sheep easily avoid a Lone Wolf.—Some observations made in the sheep hills bordering East Fork River on the morning of May 26, 1939, show that, on a relatively steep smooth slope, sheep are easily able to avoid a single wolf. With a companion I had climbed to the top of a ridge from which I had a view of some snow-free ridges on the other side of a small creek below me. I noticed a band of sheep resting on a smooth slope, slanting at about a 40° angle or less. While I watched, the sheep bunched up and ran off to one side about 30 yards. Through the glasses I saw a gray wolf a short distance above. He loped toward them and the band split in two, some going upward around the wolf, the others circling below it. When the wolf stopped, so did the sheep, only 30 or 40 yards from him. He galloped after the lower band, which ran downward and then circled, easily eluding him. Compared to the sheep, the wolf appeared awkward. After a few more sallies the wolf lay down, with feet stretched out in front. One band lay down about 70 yards above him, the other about 50 yards below him. Only one sheep in the lower band faced him; the others as usual faced in various directions. One sheep fed a little before lying down. The lower group consisted of five ewes, one yearling, and three rams. In the upper group were four ewes, four yearlings, one 2-year-old, and two rams. All rested for 1 hour. Then the wolf again chased the lower band, which evaded him as before by running in a small circle around him. A flurry of snow then obscured my view. When it cleared a few minutes later, the wolf was disappearing in a draw and the sheep were grouped on the ridge above him.

In a short time he reappeared and slowly worked his way down the ridge to the creek bottom. Nine ewes, each with a lamb, appeared on the ridge near the draw which the wolf had just left. The lambs were at the time only a week or so old but still they apparently had been able to avoid the wolf. The utter lack of fear exhibited by these sheep is quite significant, indicating that a single wolf can easily be avoided on a slope.

Sheep avoids sled dog.—The behavior of a ram chased by Charles Sheldon's dog is somewhat similar to the behavior of the sheep attacked by the lone wolf. Sheldon (1930, pp. 368, 369) gives an excellent description of the event, as follows:

At that moment, a short distance ahead, I saw a three-year-old ram crossing the divide toward Intermediate Mountain. Here was a rare opportunity to observe the actions of a sheep when chased by a wolf. Quickly taking the pack off Silas, I led him ahead to within a hundred yards of the ram, which had not yet seen us. Silas dashed at him full speed. The ram rushed toward the slope a hundred yards ahead. For a hundred feet the dog did not gain, but during the next hundred he gained at least twenty-five feet, and during the next hundred he was gaining rapidly. Although the dog was clearly the speedier of the two, I thought that the ram deliberately slackened his speed as he neared the slope, which was sharply inclined. The dog was not forty feet behind when the ram reached it. Up he went bounding for forty feet; then turned and coolly stood a moment to watch the dog, which was running up at almost equal speed. Then the ram turned and rather leisurely ran upward a hundred feet, gaining somewhat on the dog, who by that time was going much more slowly. This time the ram stood and watched until the dog was within twenty feet, then easily ran up another hundred feet and again stood and looked at the dog. Silas, however, was now only trotting and his panting showed that he could not run upward any more. Yet he followed the ram, which kept repeating the same tactics, never losing sight of the progress of the dog, until within a hundred feet of the crest, where a sharp projecting rock rose almost perpendicularly from the slope. The ram quickly climbed to the top and looked down at the dog, which now was only walking. Nor did he move when Silas reached a point fifty feet below him. Then the two stood looking at each other. Finally the dog turned and trotted back to us.

Not once, after the first burst of speed on the level, did the ram show any fright. When he knew he could reach the slope he was deliberate in every movement, and after reaching it he coolly played with the eager dog. After each advance, however, he was careful to turn and watch his pursuer. He seemed to know that the dog would soon give up the chase, yet I believe he did not credit Silas with the persistence he had displayed. The actions of the ram led me to suspect that a wolf would not have followed more than a few feet up such a slope, its experience, which Silas lacked, having taught it that a sheep could easily escape when once headed upward on a steep slope."

Highway an Advantage to Wolf.—At several places, notably Igloo Creek, Polychrome Pass, Toklat, and a stretch opposite Mount Eielson, the automobile highway passes through winter sheep range. In some places it cuts into the heart of the more rugged cliffs utilized by sheep. The highway favors the wolves in three ways. First, it gives them an easy trail along the entire winter range so that they can move more readily from one part of it to another. Second, it gives the wolves easy access into the cliffs themselves; they need not make a laborious climb to get among the sheep but can follow a smooth easy grade. Finally, each blind corner in the road—and there are many of them—is a hazard, for the sudden appearance of a wolf may give the sheep no time to escape. This is especially true when the sheep are bedded down on the road.

A ewe, lamb, and yearling were killed on the road at Mile 67 on September 20, 1939. The victims had been bedded down near a sharp corner. Four or five wolves had come around the corner, made a dash at the sheep and captured them before they had run more than a few yards.

Several sheep killed by wolves were found on and beside the road at Polychrome Pass and at Igloo Creek.

While the road affects seriously only a small part of the winter range, it is a good illustration of disruption of natural wildlife relationships by an artificial intrusion.

Diseased Yearlings Captured.—In a high draw three yearlings were found which had been killed in early spring. Two of them showed necrotic lesions on the mandibles so probably were not in good health when captured by the wolves.

Lone Diseased Ewe Captured in Cliffs.—On the snow-covered mountain slope above our cabin at Igloo Creek on the morning of October 14, 1939, I saw a fox feeding, and on the same slope a raven and some magpies. Obviously there was a fresh kill. We climbed to the spot and found the remains of a 9-year-old ewe affected with severe necrosis of the jaws. The horns were short and stubby, perhaps indicative of a prolonged chronic ailment. The teeth were irregularly worn. Some were long and sharp, others were worn down to the gum. One tooth was shoved entirely out of line. A premolar was broken off. An upper premolar was bent outward. Cavities along the teeth were packed with vegetation. The animal had been alone on the cliff (sick animals are often solitary). Five wolves had killed the sheep on a steep slope below some cliffs. They had crushed the skull and eaten the brains. After feeding, the wolves had curled up in the snow on a rocky spur to one side of the remains, about a quarter of a mile from the cabin. There were seven beds, but only five of them were coated with ice. In the other two beds the wolves had not lain long. Although the ewe had been found in rough country under conditions favorable for escape, she was so weak that the wolves were able to make the capture.

Figure 37: The sheep feeding on this gentle terrain have access to nearby slide rock and cliffs for safety. [Igloo Creek, June 13, 1939.]

DISCUSSION OF WOLF HUNTING HABITS

A few generalizations can be made concerning the methods of the wolves in hunting Dall sheep. It is my impression that the wolves course over the hills in search of vulnerable animals. Many bands seem to be chased, given a trial, and if no advantage is gained or weak animals discovered, the wolves travel on to chase other bands until an advantage can be seized. The sheep may be vulnerable because of their poor physical condition, due to old age, disease, or winter hardships. Sheep in their first year also seem to be specially susceptible to the rigors of winter. The animals may be vulnerable because of the situation in which they are surprised. If discovered out on the fiats the sheep may be overtaken before gaining safety in the cliffs. If weak animals were in the band, their speed and endurance would be less than that of the strong and they would naturally be the first victims.

A wolf hunting alone apparently can be avoided easily by healthy sheep on a slope. The lone wolf must find his animals at a decided disadvantage to be successful. Two or more wolves can hunt with much more efficiency. The method is to get above a sheep and force it to run down, for a sheep running upward can quickly outdistance the wolves and escape. Sheep on somewhat isolated bluffs where space for maneuvering is limited are in danger of having their upward retreat cut off and of being forced to run down to the bottom. A number of carcasses were found in situations suggesting that the sheep had been chased down bluffs of limited extent. My general observations indicate that weak animals are the ones most likely to be found in such vulnerable situations. They often lack the energy to climb to more safe retreats to rest. Where the wolf population is relatively large its pressure on the sheep is probably proportionately great, eliminating a high percentage of weak animals and capturing more strong animals surprised at a disadvantage.

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