Making Cubs

I have written many a blogs and told countless stories about black bears that I have known. Spending a portion of my career taking care of orphaned and injured cubs was not only a once-in-a-lifetime blessing but it was also an incredible learning experience, much more so than any book or lesson plan can give. That's is because higher education prepares you for generalities. It is only when you get to specialize and get your hands in the mix that you truly learn how incredibly complex and beautiful some things are.

If you have been a follower of my blog for any period of time I'm sure you have realized by now that I am truly fascinated by bears. They encompass all attributes, ranging from powerful and fearsome to gentle and playful. Yet their biological uniqueness is what I find most interesting. The combination of their unequalled sense of smell, their sheer size and strength, coupled with their remarkable intelligence makes them a truly special animal to begin with but also throw in their hibernation and reproductive adaptations and you have an animal that is not only fit to survive but one that lands squarely on top of the food chain. With understanding comes appreciation, it is my hope the lessons I write will instill a greater appreciation for the animals that walk among us.

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Most people have seen a newborn fawn, while many may have even witnessed it as it took its first wobbly and uncertain steps. I also imagine everyone, as a child, has peered into a nest containing the fragile wide-mouthed, featherless forms of recently hatched birds. And undoubtedly most folks have tried catching tadpoles in a waning and muddy spring puddle. As certain as death, almost as certain is birth. It happens all the time and all around us.

So how come no one ever sees new born bears?

I am not talking about those rascally buggers that frolic around and follow their mom at a clumsy gallop. At that point, those cubs are already close to six months old. I'm talking about the wet-behind-the-ears, eyes-still-closed look of a bear that has just been born. Believe it or not there is a reason why few have seen this and hence the lesson begins.

Making Cubs: In the beginning...

I am not going to go into too much detail about how a male and female bear get together but it occurs in early summer and although I can't prove it, I'm sure the courtship includes a healthy dose of Barry White (or should I say Bear-y White), a bed of roses and a heap of chocolate covered berries strewn about the forest floor. All kidding aside, when the deed gets done the end result is a fertilized egg. And this is where bears begin to separate themselves. Bears have an amazing evolutionary adaptation called "delayed implantation". Before I explain what that is, let me first explain what happens typically in mammals once an egg becomes fertilized.

In most mammals, once the sperm enters the egg and fertilization occurs, the fertilized egg begins its developmental process. To put it simply, it attaches to the uterine wall and almost immediately begins to grow. In other words, pregnancy begins shortly after conception.

Now let's talk about bears again.

Remember my last blog about hibernation and how amazingly cool bears are when it comes to sleeping through the winter? They pretty much burned all their fat reserves and use very little of their muscle to help them survive the winter. Well, what would happen if a bear didn't have enough fat? It's body would have to resort to using energy stored in more valuable tissues and organs, thus seriously impacting the health of the animal.

Can you imagine if a female bear entered its den three or four months pregnant?

The stress of hibernation alone may seriously jeopardize not only the life of the cubs but also the life of the mother. Thus, female bears have an amazing adaptation. It is called delayed implantation. Let me explain...

Back in the summer, after Barry White played and the bears had their "moment", the female's body did an incredible thing...it called a "time-out". It more or less told the egg or eggs (since they usually give birth to multiple cubs) to "hold off and wait a while" before implanting in the uterus, which ultimately would start the eggs growing into embryos and eventually into little bears. The eggs were literally held in the state of suspended animation all the way up until the fall. That is what we call delayed implantation.

Bears are extremely small at birth compared to their adult size.

The female's body was literally waiting to see how much fat she accumulated prior to entering the den for hibernation. If she was underweight and at risk of dying through the hibernation if she gave birth, her body would abort the eggs in late fall. This would give her a better chance of surviving hibernation. If on the other hand, she was fat and healthy, her eggs would implant and start growing around the time she entered the den. And thus this answers another question about why cubs are born so small. They are typically born in late January and early February meaning they literally have only been growing for a few months!

Now onto the actual birthing...

I am sure many who read this would love to have given birth to their kids when they were tucked snugly in their warm cozy bed. Believe it or not that is exactly what female bears do. Though they may be somewhat awake, they are still in the midst of their hibernation when their cubs are born. Remember, their bodily functions slow tremendously during hibernation so mom is not up and around doing too much. Given the fact that they give birth in the middle of their long winter's nap, I would say female bears have it quite easy when it comes to childbirth. Can you imagine waking up and finding multiple "kids" you didn't have when you went to sleep?

The Den Life: Moms sleep...Cubs eat.

From a cub standpoint, they have one job. After they are born, they climb up to mom's teat and suckle. That's pretty much all they do for a few months until the spring time comes.

Ain't that somethin'!

Alas, so much more to say and so much more to learn but I think I will save it for another blog. For some reason I simply cannot get Barry out of my mind.

Note:

Please leave all wildlife alone.

People are captivated by newborn animals, so much so they sometimes rescue them when they don't need rescuing. It may be their cuteness or perhaps their fragility that is the lure for the would-be rescuer. Regardless of the reason, it is almost certainly not necessary for there is no better caregiver than the one that provided the life. If there is any concern whatsoever for a newborn wild animal, please contact the proper authorities first (state wildlife agency or rehabilitation facility). It's for their sake, not yours.