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435 holly and yearlings blog

How does a bear family breakup?

By Mike Fitz

Through the Bearcam Question form Susan asks, “Have you seen bears ‘emancipate’ their cubs? How do they do it? Drive them away?”

I’ve witnessed a bear become emancipated from its mother just once, and at the time I didn’t realize what was happening. In late June 2014, bear 402 had a single yearling. By mid July though, 402 had separated from her cub and it was left to fend for itself. Much has been written about this saga before, so I’ll only focus on the separation process that I witnessed. It was likely a confusing event for the cub, who suddenly found himself alone at Brooks River among many other bears.

At the time, and until somewhat recently, I stated that 402 had “abandoned” her yearling (now known as 503). While this might be true in a sense, I no longer think that this is an accurate way of describing the event. After reading more about the emancipation process, I’ve come to believe 402 didn’t abandon her yearling in 2014. She emancipated him.

402 and yearling_1_07022014

402 is followed by her yearling in early July 2014.

Family break-up in brown and black bears (emancipation of offspring) is triggered primarily by two factors. 1. The mother bear begins to enter her estrous cycle, making her receptive to mating. 2. Adult male bear(s) sense an opportunity to mate with the female. Generally female bears enter estrous in May and June. Mother bears may not necessarily become intolerant of their cubs when they enter estrous, so the cubs stick with mom as long as she allows, although there are reports of mother bears chasing their offspring away during family breakup. She’s probably not nursing them either, but older cubs are not reliant on mother’s milk for their nutritional and energetic needs. What gets the cubs’ attention though is the presence of an adult male who seems particularly interested in their mother.

At this time, again usually in May or early June, the mother bear may no longer react with much concern for the male’s approach. She may not flee the approaching male like she would’ve in the past, or even later in the summer. She may eventually allow the male to approach very closely as she enters the peak of her estrous cycle.

The cubs, on the other hand, see the situation differently. The large male bear is a physical threat to them, and they’d be wise to keep their distance. In this way, the cubs are prompted to leave the close proximity of their mother and begin to wander across the landscape alone, because mom no longer appears to be willing to defend them from the larger bear. This scenario has been described as male-instigated break up of a bear family and I think that’s what ultimately prompted 402 to separate from her yearling for good in 2014.

In July 2014, I noted bear 856 paying a lot of attention to 402, not in an aggressive manner though. It was more like he perceived she was in estrous. He began to follow her in order to have the opportunity to mate. This confused me at first as 402 was still caring for a yearling and mother bears in Katmai typically keep their cubs through their second or third summers. If they keep their offspring around until mid June, then it’s very likely those cubs are sticking with their moms for the rest of the year, and I had never seen a mother voluntarily separate from a yearling or emancipate a cub in July.

So 402’s separation from her yearling in July 2014 was odd because the yearling was a year younger than most emancipated offspring and it happened in early July, weeks later than normal for this event. The other parts of the scenario are typical though. 402 did indeed enter estrous. 856 courted her for over ten days before they copulated. His interest in 402 and 402’s lack of interest in her yearling prompted the emancipation.

This is just one example of family break-up in bears. For the cubs, no matter their age, family breakup may be a stressful and confusing event for them. For their whole lives until that point their mother has been their protector and provider. Within days, perhaps hours, that changes. At best she ignores them while hormonal changes direct her interests elsewhere. As the former family members go their separate ways, each begins a new chapter in their lives.


If you have other questions for explore.org’s bearcam fellow, Mike Fitz, or Katmai National Park rangers you can ask them at anytime by using the Bearcam Question form. They may answer your questions during a live chat, in a blog-post, or during their twice-weekly text chats in the comments in the Brooks River live chat channel.

  • http://www.teatrremus.pl/ Kasia

    Wow… Different perspective… New and not new… Thanks!

  • sandiegojesse

    Interesting.

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  • Margaret

    Hard to comprehend for human mothers but necessary in the animal kingdom.

  • Amanda Thompson

    Thought provoking. Thanks Mike.

  • Susan Rennie

    Thank you so much, Mike Fritz, for answering my question. The possible more gradual separating ( indifference) of the mother bear makes sense, and is more bearable (no pun intended) anthropomorphically.

  • DarbyHollingsworthTheFourth

    Was 503’s survival made more likely by his being emancipated much later in the summer than normal? I guess another way to ask is, had 503 been emancipated earlier in the year, do you think 435 Holly would still have adopted him? I’m thinking about the increasing availability of resources in July and if that made her more likely to accept him. I know her behavior was unexpected anyway, but I wondered if the unusual timing of 503’s emancipation helped tip the odds ever so slightly in his favor.

    • https://fitznaturalist.com/ Mike Fitz

      If 503 was emancipated earlier in the summer (at a more “normal” time), then I think this would’ve reduced the likelihood that he would’ve been adopted by 435 Holly. Close proximity to other bears was probably a major reason why 503 found Holly. In mid spring, bears are dispersed widely across the landscape so the chances of a bear finding an adoptive mother would be even less.

  • Lindsay

    Well I wonder if she “abandons” the yearling to save him from harm by the male who seeks to copulate. True her behavior may also be driven by her hormonal changes, but if there were no big males around is it not likely she would keep the cubs longer? This location is somewhat unique in that all the food it has available aattracts so many large males. Another location may lead to more years of mother/ offspring cohabitation and partnership?

    • https://fitznaturalist.com/ Mike Fitz

      The presence of other bears certainly affects the timing and events of family break-up. Without another bear paying close attention to mom, then the yearling, I think it is reasonable to assume, would’ve tried to stay near her for longer. If 402 wasn’t nursing him or giving him much food, then it’s probable that he would’ve been forced to leave eventually by his own hunger.