Presently she relaxed and stood for a moment on all fours before moving on. One of the cubs concluded to suckle. Either this violated an ancient grizzly custom or else it was something that in the face of danger was too thoughtless to be excused; at all events the mother knocked the cub headlong with a side swing of her left fore paw. He landed heavily some yards away and tumbled heels over head. The instant he rolled on his feet he sniffed the earth eagerly, as though a remarkable discovery had been made; and immediately he started to dig rapidly with his fore paws, as if some good thing were buried just beneath. He may have been only pretending, however. Without uncovering a thing, he presently raced forward to overtake Mother Grizzly.
The hibernating habits of the grizzly are not completely understood. The custom probably originated, as did the hibernation of other animals, from the scarcity of food. In a long acquaintance with the grizzly my study of his hibernation has brought scanty returns, though all that I have actually seen has been of the greatest interest.
The grizzly hibernates each winter,—"dens up" from three to four months. The length of time is determined apparently by latitude and altitude, by the snow-fall, weather conditions,—whether severe or mild,—and the length of the winter; and perhaps, also, by the peculiarities or the condition of the individual animal. Commonly he hibernates in high altitudes, many going to sleep near or above the timber-line.
The place where he hibernates preferably is a natural cave or a large opening beneath rocks. If completely sheltered in a cave, he is commonly satisfied to lie on bare rocks, with nothing over him. In other places, where the snow might come in contact with him, he commonly crawls beneath a huge pile of trash, leaves, sticks, and roots. Snow had drifted deeply over each hibernating-place I have found.
That his winter-sleep is more or less restless is shown in the spring by his hairless hips and sides, the hair having been worn off during the winter. This probably is due to frequent turnings from side to side.
He is generally fat when he turns in for his winter's sleep; but usually he does not eat anything for a few days before going in. On the few occasions on which I was able to keep track of a bear for several days before he went to sleep he did not eat a single thing during the four or five days that immediately preceded retiring. I have examined a number of grizzlies that were killed while hibernating, and in every instance the stomach and intestines were entirely empty and clean. These facts lead me to think that bears do not eat just before hibernating.
Nor do they at once eat heartily on emerging. The instances in which I was able to watch them for the first few days after they emerged from winter quarters showed each time almost a fast. Those observed ate only a few ounces of food during the four or five days immediately after emerging. Each drank a little water. The first thing each ate was a few willow-twigs. Apparently they do not eat heartily until a number of days elapse.
On one occasion I carefully watched a grizzly for six days after he emerged from his hibernating-cave. His winter quarters were at timber-line on Battle Mountain, at an altitude of nearly twelve thousand feet. The winter had been of average temperature but scanty snow-fall. I saw him, by chance, just as he was emerging. It was the first day of March. I watched him with a field-glass. He walked about aimlessly for an hour or more, then returned to his sleeping-place without eating or drinking anything.
The following morning he came forth and wandered about until afternoon; then he broke his fast with a mouthful of willow-twigs. Soon after eating these he took a drink of water. After this he walked leisurely about until nearly sundown, then made himself a nest at the foot of a cliff in the woods. Here he remained until late the following afternoon, apparently sleeping. Just before sundown he walked out a short distance, smelled of a number of things, licked the snow a few times, and then returned to his nest.
The next morning he went early for a drink of water and ate more willow-twigs. In the afternoon of this day he came on a dead bird,—apparently a junco,—which he ate. Another drink, and he lay down at the foot of a tree for the night. The next morning he drank freely of water, surprised a rabbit, which he entirely devoured, and then lay down and probably slept until noon the following day. On this day he found a dead grouse, and toward evening he caught another rabbit.