Why Do Bears Kill and Eat their Cubs? Bear Infanticide and Cannibalism

Why Do Bears Kill and Eat their Cubs? Bear Infanticide and Cannibalism

There are many mammals in the animal kingdom that disturbingly eat their own offspring, such as lions, chimpanzees, rats, and others. The bears of North America, including black bears, grizzly bears, coastal brown bears, Kodiak bears, and polar bears also all practice cub infanticide and cannibalism to varying degrees. Common questions that people often ask about this phenomenon are, “Why do bears kill their own cubs? Do bears eat their cubs? Do bears kill baby bears? Are bears cannibals?” In this blog and video, you will learn the answers to these questions and more.

The Adventures of King Kodiak, The Biggest Brown Bear in the World, Joseph Classen
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According to wildlife biologists, there are a number of reasons that bears eat their cubs, which include the following…

Food

Bear Infanticide and Cannibalism

Bears are cannibalistic and will eat other bears of their own species, as well as bears of other species, such as grizzly bears who will hunt down, kill and eat black bears. One of the reasons that bears kill other bears, including their cubs, is for food. In situations where food sources are scarce, such as during times of poor or late salmon runs in coastal areas of Alaska, both male and female bears will kill and eat cubs as well as young subadult bears if they get desperate enough for something to eat.

Increased Reproduction Potential

One of the most common reasons that male bears will kill cubs is for reproduction purposes. If a lactating mother bear loses her cubs in the early spring or summer months, there is a good chance that she will once again go into heat and become receptive to breeding, which is why male bears will sometimes purposely kill a female’s cubs. This is the reason that most mother bears are so incredibly protective of their young and will aggressively fight off threatening male bears. As a side note, this is also why older male bears who are susceptible to cub killing behavior are especially targeted for bear hunting purposes in places like Alaska. Bear hunting is very strictly regulated, and in many states bear hunting is used as a conservation tool to help maintain a healthy bear population, as cub killer male bears can drastically reduce what would otherwise be a healthy bear population in certain regions.

Reduced Competition

Why do bears kill and eat their cubs?

The idea of bears killing cubs as a means of reducing their competition remains a hypothesis among some wildlife biologists, as there is conflicting evidence on this matter. Nonetheless, the facts remain that bears do sometimes kill cubs and other young bears for seemingly no other apparent reason. Indeed, there is a great deal of competition in the world of bears for things such as food, territory, breeding rights, etc., and some scientists believe that bears, both male and female, will kill younger, less dominant bears, as a means of reducing their current and perhaps future competition while they are still at a vulnerable, weaker stage of development.

This is something I personally witnessed several years ago while working as a bear viewing guide in coastal regions of Alaska. There was a rather aggressive male brown bear who over the course of the summer killed several other bears in the area for what seemed like no good reason. The bears he killed were not cubs, so it wasn’t a breeding issue, there was plenty of fish in the rivers and he didn’t eat his victims, so it wasn’t a food issue. He simply killed these other bears and dragged them off in the woods to rot. He was either just a crazy, psychopath killer bear or perhaps he was indeed trying to reduce his future competition. No one knows for sure. No matter the case though, all this is a reminder that, as I often say, wild nature and the animal kingdom is certainly not like a Disney movie. It’s a beautiful domain, but also one of great violence and savagery that demands the utmost respect and caution at all times.

Watch the video below to see more!

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