Male Bears & Cubs: Update from Ranger Mike
Read this update on today’s BearCam drama from Ranger Mike in Katmai National Park:
In case you missed it, just a little while ago a lone spring cub (mother’s whereabouts are unknown) walked to the mouth of the Brooks River. An adult male bear (later ID’d as 879, seen in the picture above) was sleeping in the woods near the cubs location. The male bear got up and walked to the river at the same time the cub was there. They were likely both aware of each other’s presence. Were you worried about the cub when both bears were near each other? After all, don’t male bears kill cubs?
Male bears have a reputation for killing cubs, and this does happen. However, it doesn’t happen often and I’ve seen far more adult males ignore cubs than pursue and kill them. There also are many documented cases of female bears killing cubs, so this behavior is not sex specific. Why male bears kill cubs is subject to debate. Several hypotheses have been proposed to explain why bears kill cubs.
Food: Bears will kill cubs for food, so certainly in some situations hunger plays a role. Yet, cubs are sometimes killed and not eaten.
Increase the male bear’s reproductive potential: Motivation to mate with a female bear may drive a male to kill her cubs. Female bears will not go into estrus as long as they are nursing. If a female loses her cubs in the spring or very early summer, then she may enter estrus and be receptive to mating. However, bears are promiscuous. A female may mate with several males especially in places with densities of bears, like the Brooks River, so there is no guarantee that a male bear that kills a cub would sire another litter with the mother, nor is their any guarantee that the male bear would even have access to the female. Another more dominant male could appropriate the female for himself.
Reduced competition: Perhaps some bears view cubs are potential competitors in the future. Through infanticide, a bear can eliminate a competitor at its weakest point. This is one less bear that the adult may have to compete with in the future.
There is no “one size fits all” explanation for infanticide in bears. Female bears have been observed killing cubs as well, so the behavior is not restricted to males. Infanticide may be difficult to reconcile from a human’s point of view, but bears exist and behave outside of our moral and ethics boundaries.
Wow! I remember as a child at Algonquin park. Dad took us to the dump in hopes we might see some bears. They would ear there, this was long before the garbage was compacted. There was Mom and her three cubs. Within about five minutes of watching, we heard a growling coming from the far side of the dump. Momma bear chaced her cubs up the tree and up came a male bear. They grumbled at each other for a bit and after he took off, the cubs came back and joined Mom. Thanks for your explanation Ranger Mike. I didn’t figure it was about food since there was much there for them. Maybe he did want something else.