‘Tis the season, and a few days ago I was able to observe part of the complex mating ritual that bears engage in during the months of May and June.

Estrus females eagerly laying down a scent trail traverse their territory at 3 times their normal rate.

black bear Males on the prowl quickly hone in on the scent. More than one male may catch the female’s scent and this can lead to some potentially violent showdowns between competing bears.

black bear, maleLarge males chase younger males away, of course, but mature, evenly-matched, males fight for dominance and mating rights. You can spot the battle-hardened by their scars.

The mating pair spends several days getting to know each other. Females continue to forage during this time and generally can maintain their weight. Males, however, forage very little during mating season and lose approximately 20% of their fall weight over a period of 7-8 weeks.

[This loss is on top of the 20% of fall weight lost over the winter. This means a mature male weighing 500 lbs in the fall would leave the den in early spring weighing 400 lbs and would weigh 300 lbs at the end of mating season – and thus needs to regain those 200 lbs in 3 months to weigh 500 lbs again by fall.]

Couples often play and rest together during courtship. Males may follow individual females and guard them against rivals for up to 9 days before the cautious female becomes receptive and mating occurs.

Males have even been observed “herding” females into smaller and smaller areas in order to limit their scent-marking!

black bears courtingWith the ‘wine & dine’ phase out of the way, mating begins, usually lasting only a few minutes at first. The pair mate repeatedly over several days, and some of the later copulations may last as long as an hour.  (The event I observed lasted circa 45 minutes, thus probably was not their first encounter.)  Sows may mate with one or several boars over the course of about a week.

black bears matingWith the end of mating, the sow will have nothing more to do with the male.

black bears After mating, the female may be pregnant, but that does not mean she will give birth to cubs. There is an old joke that you can’t be half pregnant, but bears have proven this statement to be false. Bears, weasels and some seals have developed a process called ‘delayed implantation’.

The fertilized egg develops into a small embryo called a blastocyst. After this brief period of development, the fertilized egg suddenly stops growing and simply floats freely in the uterus for several months.

If a sow is in peak condition when she heads into her winter den, the embryo implants in the uterus and begins to develop. She’ll wake up during January or February to give birth.

If the sow is not in peak condition at the onset of hibernation, her body will reabsorb the embryo and not give birth that year. This gives bears more control over their reproductive rate than just about any other animal.

Once an elk or deer is pregnant, for example, they are pregnant, and winter pregnancy can be fatal. Animals diverting energy to reproduction during the difficult winter months run the risk of falling victim to predation.

black bears matingWhile I was shooting this episode a yellow bus pulled up and a slew of talkative cell-phone addicted students disembarked. They climbed up on a hill for a better look.

kids on hill

I would love to know how their teacher was handling this “teaching moment.”

🙂 🙂 🙂

14 thoughts on “Two Bears Engaged In A ‘Teaching Moment’

  1. What a teaching moment from the photographer. I had no idea about any of it and feel an admiration for bears I never had before. The whole business of controlling birth time is just astounding, and the endearing foreplay for days, zen-like. What is the fabulously lush Yellowstone underbrush they are frolicking in. At first I thought it was rushing water, then it looked like lavender fields. Sage? In any event a splendid rendezvous locale. This was very touching, filled with kind regard. I hope the line of yellowbus students felt so too.

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  2. Sounds all’s so finely tuned for best reproductive results. Fascinating adaptations to resolve the inhospitable winters. Clever creatures…. Wonder if next installments may cover carbo- loading? Wonderful photography John and factual discretion on commentary :). As for the teacher and the students … !

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  3. I loved learning this. She looks so contented once she is fully “engaged” with Mr. Bear! And then she shoos him off, maybe putting more truth into what men say about women, that we just want them for protection (sustenance) and sex, difference being that if they provide enough of both, we don’t tend to send them away! Part about the blastocyst only implanting if the female is healthy enough is a wonderful genetic twist that would do a lot of good in the underdeveloped human societies, or even in developed societies where the mom is anorexic and undernourished, all too often the case these days with young women who “can’t get pregnant.” Makes me wonder if the fall in sperm counts, which is drastic in lighter skinned males worldwide, has to do with greater physical stamina and health in darker-skinned males or is it from refined diets of “whiter” people?

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    • Just as often as that look of contentment when they are “engaged,” I have noticed, is a grimace on the part of the female, and an answering growl and nip on the part of the male. “Love is a hurting thing,” sang Lou Rawls! 🙂

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