One of the first lessons learned by young cubs is that of obedience. The mother insists on compliance with her every command, and enforces her authority with a heavy paw. It is fortunate the cubs are sturdily built, for some of the slaps they receive in the course of an average day’s instruction would kill a less durable animal. The first haven of refuge when danger threatens is in the trees. A special command note and a slap or two sends them hustling. Now the cubs are out of the way and the decks cleared for action, so to speak. The cubs will remain in the trees until the mother lets them know they may come down. This is not a time of boredom for the youngsters, however. Expert climbers, they carry on the same games and rough play indulged on the ground, with never a fall. Their confidence in the trees is amazing. It is not unusual to see a cub sound asleep on the end of a 20-foot branch that is bending down with its weight and swaying in the wind. As the months go on the cubs begin to lose their juvenile ways. By autumn, they have put on enough fat to last the winter. They usually hibernate with the mother, since they remain with her for well over a year. During the following summer they are well able to take care of themselves, and the mother deserts them. [Illustration: Habitat map] It is normal, rather than unusual, among black bears to breed only every other year. The youngsters usually do not breed until about three years old. No account of this bear would be complete without mention of the so-called “bear trees.” These are trees situated at the crossroads, that is, near the intersections of bear trails or otherwise prominently located. When a bear encounters one, it stands up and scratches at the bark with its front claws as high as it can reach. Sometimes it will also bite at the bark. Bears have been observed rubbing the sides of their jaws against the bark. Whether this is a way of leaving their scent is not known. It is thought this may be a way of communication with others of the species, but this has not been definitely proven. Many of the trees chosen for this purpose in mountains of the Southwest have been aspens. The heavy black furrows left in the white bark will persist until the death of the tree. Often they are the only evidence that bears have ever been in the locality. Another custom which will be observed very early in one’s experience with bears is the scratching that goes on. It may be due in part to the presence of ectoparasites, but the bear takes such an obvious satisfaction in scratching that, one feels, this must be only incidental. Trees, posts, rocks, and claws are all employed for this purpose. Some of the smaller trees often suffer severe damage from the treatment accorded them.