Bears presumably mate every 2 years, although possibly the interval is sometimes longer. A female with three yearlings, observed regularly during the mating season, was not seen with a mate, so in her case it would seem the interval would be at least 3 years. The young follow the mothers during two summers. Grizzlies have from one to three cubs, and perhaps occasionally four. Three young are common and several such families were seen.
Breeding takes place in the spring and early summer. In 1939 two large grizzlies probably a pair, were seen together on June 23. On June 10, 1940, an exceptionally large dark grizzly was seen following a small straw-colored grizzly. Two bears of this description, reported together about a week before, may have been the same as the two I saw. The large dark one was probably the male. Ranger Harold Herning and Frank Glaser reported seeing a pair of bears mating on June 18, 1940.
On May 15, 1941, two grizzlies were seen together digging roots. When I approached them one ran away and the other came toward me. A short bluffing run of about 10 feet was followed by a swipe in the air with the paw. The grizzly then went into the woods and later was seen with the other one a half mile away. On May 28 two bears that appeared to be these same ones were seen where the caribou were calving about 10 miles from the place where they had been on May 15. When I first saw them at 10:30 a. m. they were sleeping a few feet apart. Soon they started to wrestle and play. They stood up on their hind legs, hugged, pushed, rolled over each other, and then did it all over again, first one on top, then the other. When they saw me they stood erect, then moved on down the slope and played for half an hour. They then traveled to some calf caribou remains near me. Both of them fed together on the same piece at times. Sometimes the remains were shaken and waved in the air to tear them apart. Later both bears moved off together, stopping to wrestle at intervals. One of them, probably the female, took the initiative in the play. An hour later these bears were seen some distance up a slope, still at play. On the following day they were again seen wrestling about 2 miles from the spot where they had been seen the previous day. These two were apparently paired.
About May 10, 1941, a female grizzly was seen at Toklat River near a small road camp. She spent most of the day digging roots, and fed on garbage thrown away near the camp. About a week later she was joined by a lighter-colored male, noticeably smaller. They were seen breeding on May 20. They were together must of the time and were often seen playing together and hugging much like the two bears referred to above. On May 22 it became a triangle affair, for a huge dark male appeared on the scene. He endeavored to drive the small male away, chasing it far up the mountainside, back to the bar, and up the mountain a second time. When the large male followed the female she also ran away from him. On May 23, at 9 a. m., the female was seen digging roots. A little later, a half mile away, the large male was following the small male across the broad river bar. The large male grunted at intervals. The bears climbed up a slope where they fed on roots, the smaller one keeping an eye on the rival. Later he descended to the bar and started across to the female. But the observant bigger male hurried down the slope and on the bar came up within 200 yards of him. Both bears then galloped away, disappearing behind a patch of woods, and then reappeared four or five hundred feet up the slope on the other side of the bar. The small male returned to the bar, started to cross it, but changed his mind and came back to the female. The big bear, seeming to be winded by the exertion rested high on the slope for a long time, then came down and was lost to view in the trees. The female and small male wrestled, then fed close together on roots. Later they wrestled again and the male grabbed the female back of the ear and tried to mount her but she rolled over. They continued to wrestle and play for some time, then resumed feeding on roots. When I left at 2:30 p. m., the pair was crossing the bar. The big male was not seen after he came off the mountain and disappeared in the woods. It appeared that the female was being true to her first love and that the strongest bear was unable to win her affections.
On May 24 the small male was in the woods. Later he was joined by the female which apparently had been chased, for not long after she arrived the large male came through the woods on her trail, grunting and bawling loudly at intervals. At his approach the other two bears ran away together. On June 2 the small male was again seen mating with the female.
The large male continued following the pair of bears at Toklat. On June 8, when the three were seen moving toward Mile 66, the large male was chasing the female. On June 9 I saw the three bears 2 miles from Mile 66, 14 miles from Toklat. All three were sleeping only a few feet apart, on a point of rock. They lay sprawled on their backs, stomachs, and sides, occasionally changing positions or stretching a leg. Most of the time they lay on their sides. When I returned 3 hours later they had moved to the gravel bar where they were sleeping on their sides on the wet mud. The persistence of the large male had been rewarded to the extent of sharing the female. It was reported that the large male mated with the female on June 10. Soon after this date the mating activities of the bears apparently terminated.
These grizzlies had mated over a period of several weeks. The small male and the female were together for at least 23 days. All observations indicated that breeding generally takes place during May and June.
According to the data gathered the grizzlies have a rather definite home range. Possibly these ranges shift, but for periods the bears' activity is restricted to certain areas. The mother and three yearlings observed in 1940 ranged over an area about 10 miles across. Their movements, however, were restricted by the road camp garbage pit which they visited nearly every evening during the summer.
Another female with a cub did not frequent any garbage pit, but ranged throughout the summer of 1940 between the cabin on Igloo Creek and East Fork River over an area about 9 miles across. Only once did I see them beyond this area, and then they had wandered 4 miles westward. They were easily identified because of the runty appearance of the cub. On May 25, 1941, I saw what I took to be these same two bears in their range used the previous year. On June 14 I saw the yearling alone, and after that did not see either of them. Other bears were sometimes seen in the range of this female. A small dark bear, about a 2-year-old, was seen several times at one end of this range. Once the female discovered the small bear and ran a few yards toward it. The small bear climbed far up the mountain, watched for a time, then circled widely and went deeper into the range occupied by the female.
A "spoiled" bear which frequented garbage pits was known to range from Mile 66 to Mile 42 on the highway. This distance of 24 miles was at least on one occasion, traveled in one day.
Grizzlies in Mount McKinley National Park go into hibernation in October and emerge in early April. Tracks were seen in late October. In 1939 I saw bear tracks on April 17the first day I was in the field and in 1941 the first bear track was seen on April 8.
On October 11, 1939, when there was a foot of snow on the ground a grizzly was seen digging a den on a steep slope far up a mountain. In digging, the bear disappeared in the hole, then came out tail first. Pawing the dirt out of the entrance. At intervals the pile of dirt at the entrance was pawed back and it rolled far down the slope on the snow. The entrance was just large enough to permit the bear to enter. The following spring I saw fresh tracks leading away from the den so it was undoubtedly used by the bear for his winter sleep. When I climbed to the den later in the summer the chamber had caved in, so it could not be used a second year. The chamber was 4 feet from the entrance and was about 5 feet in diameter The burrow led upward to it at an angle of about 10 degrees. Where the den was dug the mountain sloped upward at a 45 degree angle. Another den, also caved in, was seen in a similar situation.
Grizzly Wolf Relationships
As a rule grizzlies and wolves occupy the same range without taking much notice of each other, but not infrequently the grizzlies discover wolf kills and unhesitatingly dispossess the wolf and assume ownership. This loss is usually not a serious matter to the wolves, for if food is scarce the kills will generally be consumed before the bears find them. In the relationship existing between the two species, the wolves are the losers and the meat-hungry bears are the gainers.
When the bears take possession of a kill in the presence of wolves they are much harassed, but they are so powerful that the wolves must be careful to avoid their strong arms. The wolves must confine their attack to quick nips from the rear. But the bears are alert, so usually the wolves must jump away before they come near enough for even a nip. At the East Fork wolf den two encounters were observed. The first one, which took place on June 5, I did not see, but it was reported to me by Harold Herning and Frank Glaser. A female with three lusty yearlings approached the den from down wind. They lifted their muzzles as they sniffed the enticing smell of meat, and advanced expectantly. They were not noticed until they were almost at the den, but then the four adult wolves that were at home dashed out at them, attacking from all sides. The darkest yearling seemed to enjoy the fight, for he would dash at the wolves with great vigor, and was sometimes off by himself, waging a lone battle. (On later occasions I noticed that this bear was particularly aggressive when attacked by wolves.) The four bears remained at the den for about an hour, feeding on meat scraps and uncovering meat the wolves had buried. During all this time the bears were under attack. When the pillaging was complete the bears moved up the slope.
The following morning I was at the wolf den a little before 8 o'clock. The female grizzly and the three yearlings were on a snowbank about half a mile above the den. The yearlings were inclined to wander down to the den when the bears started for the river bar, but the female held a course down a ravine to one side. On the bar the bears fed on roots, gradually moving out of view behind a hump of the ridge I was on.
At 10 o'clock the black male wolf returned to the den, carrying food in his jaws. He was met by four adults and there was much friendly tail wagging. While the wolves were still bunched, a dark object loomed up in the east. It was a grizzly and it appeared to be following a trail, probably the trail of the female grizzly with the yearlings, for they had come along that way the day before. The bear was in a hurry, occasionally breaking into a short gallop. It is possible that this was a male interested in the female with the yearlings. As it came down wind from the den it threw up its muzzle and sniffed the air, no doubt smelling both meat and wolves. It continued to gallop forward. The five wolves did not see the grizzly until it was a little more than 100 yards away. Then they galloped toward it, the black male far in the lead. When the bear saw the approaching wolves, it turned and ran back over its trail, with the black wolf close at its heels. The bear retreated a few jumps at a time but had to turn to protect its rear from the wolves which tried to dash in and nip it. When all the wolves caught up with the bear they surrounded it. As it dashed at one wolf another would drive in from behind, and then the bear would turn quickly to catch this aggressor. But the wolves were the quicker and quite easily avoided its rushes. Sometimes the lunge at a wolf was a feint and in the sudden turn following the feint the bear would almost catch a wolf rushing in at his rear. In lunging at a wolf both paws reached forward in what appeared to be an attempt to grasp it. There was no quick slapping at a wolf with its powerful arms. The target was perhaps too distant for such tactics. After about 10 minutes the two female wolves withdrew toward the den and shortly there after the wolf identified as Grandpa moved off.
The black male and the black-mantled male worried the bear for a few minutes and then the latter lay down about 75 yards away. A few minutes later the black father also departed. Left alone, the bear resumed his travels in a direction which would take him a little to one side of the den, but not for long. The black-mantled male quickly attacked and the other four wolves approached at a gallop. After an other 5 minutes of worrying the bear, the wolves moved back toward the den, the black male again being the last to leave. The bear turned and slowly retraced his steps, disappearing in a swale a half mile or more away. It did not seem that the wolves actually bit the bear. The bear did not touch any of the wolves, although once the black-mantled male escaped from the bear's outstretched arms only by strenuous efforts. On this occasion, at least, the wolves had surely discouraged the bear with their spirited attack.
Harold Herning reported seeing a grizzly appropriate a calf caribou soon after it was killed by a wolf. Two of the five wolves present attacked the bear, but after being chased a few times they retired. Having killed three other calves and eaten their fill, they probably did not have a strong desire to attack the bear.
At a road camp garbage dump the female with the three yearlings, and the wolves often met in their common search for choice bits. Here the wolves walked about within a few yards of the bears. One evening the bear family approached the pit four abreast as the black-mantled male and the black male wolf fed. The black one moved off a few yards to one side and the other wolf looked back at the bears a few times as they came, but fed with tail toward them until they were 8 or 9 yards away. Then he easily avoided a charge made by one of the yearlings. The two wolves maneuvered among the bears, who brought their food out of the pit to eat. Frequently the yearlings chased the wolves but the latter easily avoided the rushes. Once a wolf walked between two bears which were only 7 or 8 yards apart, but in doing so he watched them closely. After a half hour of this activity the wolves lay down to wait for the bears to depart.
On September 22, 1940, the bear family and the wolves met not far from the garbage pit. On this occasion the black male chased one of the yearling bears for a short distance, then the yearling turned and chased the wolf. Variations of this were repeated several times. These particular bears and wolves had more frequent contact than usual because of the road camp garbage pit which attracted them. These bears were seen robbing the wolf den only once.
Effect of the Grizzly on the Fauna and Flora
The influence of the grizzly on the fauna and flora appears to be moderate. Its effect on the mountain sheep and caribou populations is negligible. As grizzlies are relatively scarce they have little effect on the vegetation, their principal food. Their root digging is sometimes concentrated so as to cause the ground to be torn up over a small area, but usually this is not at all harmful. At times the bear may have some influence on plant distribution, for the seeds of the grasses and berries eaten are scattered widely by means of its droppings. It thus tends to increase its own food supply. But the plant associations are probably adjusted so that the bear as a rule has little influence on them.