While it is not the norm, it does happen. Male black bears will kill cubs if they get the chance, in order to initiate the sow to go into estrus so they can breed with the sow. A sow with cubs does not breed. Sometimes cubs will not be run off by the sow for two years or more and will not come into estrus until she runs off the cubs. You are correct Muley Hunter, for a guide the guy should know more about bears than his posts indicate.