When you consider that fewer than 10 percent of male grizzly bear cubs make it to adulthood, it’s no surprise that those that do make it are pretty tough! Under normal circumstances, male bears tend to avoid each other and spend their time wandering around their territories looking for food. Fighting is a high-risk activity for a bear – it uses up a lot of energy and it risks serious injury or even death if things get very out of hand. There are, however, certain times of the year when male bears come to blows – and that is during the mating season.
Bear Reproduction and Bear Cubs
Finding a partner to mate with is a top priority for grizzly bears. It ensures that their genes are passed on to the next generation. Females enter their breeding season during spring and early summer.
Females will mate with one of more males at this time and that can lead to fights breaking out amongst the sexually mature males. However, mating does not necessarily result in a pregnancy. A pregnancy will only proceed if the conditions are right.
The development of the embryo is paused for several months – this is called delayed implantation. The female’s levels of fat stores control when and if the pregnancy proceeds. It will only go ahead if she is able to build up enough fat during the summer and fall to safely maintain the pregnancy. Then, the embryo will implant as she goes into hibernation. If she does not gain enough body fat, the embryo will simply reabsorb.
In successful pregnancies, the female gives birth to between one and four cubs in January or February. They are cared for initially within the den but then venture out into the world.

©iStock.com/Jillian Cooper
Fighting for the right to mate
In this video we see two males fighting over a female. There is a lot of posturing and pacing around before they have a physical confrontation. Some of the fighting techniques look remarkably human. It is remarkably like a wresting match but punches are also thrown. The bears use their power and weight to try to overcome the other one. It looks as if there could be some biting too.
At the end, the victor seems to chase the other bear away. He will have to look elsewhere for a mate this year!
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