I incline to the belief that in the majority of cases the Black Bear, when in freedom, breeds every year. Most authorities on bears who base their opinions upon observations made on captive animals, claim that both the grizzly and the Black Bear breed annually. But a long series of observations and the closest possible attention given to this point has absolutely convinced me that it is the very rare exception when a free female grizzly breeds oftener than once in two years. I have seen many hundreds of grizzly mothers with cubs in the open, and fully as many of them were followed by yearling cubs as by spring cubs. But although (the Black Bear being much more numerous than the grizzly) I have seen many more Black Bears with cubs than grizzlies with cubs, I have never seen more than a dozen Black Bear mothers followed by yearling cubs.
I have therefore been forced to conclude that it is the habit of the Black Bear to wean its cubs and abandon them before denning up the first fall. In the case of the grizzly the mother and the cubs den up together the fall following the latter’s birth, and run together during the following summer, and it is not until late in the second season that the mother turns the cubs adrift to shift for themselves. This family of young grizzlies then usually den up together and continue to run together the third summer, at the close of which the litter disbands and the individuals belonging to it take up their separate lives. I have also seen a few litters of yearling Black Bears still running in company without their mother; but as this is by no means a common sight, I believe that ordinarily Black Bear cubs den up separately after they leave their mother at the close of their first summer.
Inasmuch, however, as I have seen a few Black Bear mothers followed by yearling cubs, I assume that in these cases the mother and cubs had denned up together in the same manner that the grizzlies habitually do. And I once actually found an old Black Bear and two cubs so settled for the winter. I have also tracked an old grizzly and her cubs to where they had gone into winter quarters together, and have seen where a grizzly mother and her year-old family had emerged from hibernation in company the second spring. I have also often seen where a litter of two-year-old grizzly cubs had wintered together in one cave after leaving their mother in their third fall, but I have never seen any actual evidence of young Black Bears wintering together in this manner.