Each spring I lead a bunch of wildlife photo tours. Dozens of photographers from around the world spend anywhere from a few hours up to a week with me pursuing a number of natural subjects. One of the favorite subjects are American black bears (Ursus americanus).
The black bear is unique to North America and is not closely related to the other two bear species found in North America, the brown bear and polar bear. There are eight species of bear in the world, the American black bear, brown bear, polar bear, Asian black bear, giant panda, sloth bear, sun bear, and spectacled bear.
The American black bear is the smallest of our three bears in North America, but they are the most widely distributed. They are found in good numbers from Florida up to New England. They are also found across the northern states and slipping down into parts of the Rocky Mountains. Small populations even extend down into Mexico. They are also found throughout most of Canada and Alaska.
Black bears in the southern states are much smaller than the bears in northern locations. This is the biological rule called Bergmann’s Rule. It is an ecogeographical rule that states that within a broadly distributed species, such as the American Black Bear, the largest ones are found in the northern latitudes and the smallest are located in the warmest latitudes. So, the bears in Florida range from 250 to 350 pounds while black bears in Minnesota are 250 to 650 pounds.
The reason for this size difference is all based on keeping warm or staying cool. It is easier for larger animals to conserve warmth and stay warm in winter and for smaller animals to shed heat and stay cooler during summer.
During my bear photo tour this year, we were lucky to see several mating encounters. This is not something you regularly see. The mating season spans several months, most of June and well into July. Male bears, called a bore, wander the woods following their nose looking for receptive females.
The females need to be at least 3 to 5 years of age before breeding. Females only mate every other year because their babies take 1.5 years to become large enough to be on their own. Black bear females have two to four young on average, but occasionally they can have as many as six cubs at once.
After mating, the female, called a sow, doesn’t become pregnant right away. Bears have a unique reproductive system. Instead the fertilized eggs stay in a suspended state until autumn, usually in October or November. At this point the number of fertilized eggs that will implant into the mother’s uterine wall depend upon her overall health. If she has enough fat reserves and is in good overall heath, more eggs will implant and start to grow. If she doesn’t get enough to eat and is low on fat and is in poor health, she won’t have any young at all.
Baby black bears are born in February while the mother is still in the winter den. At birth the baby bears eyes are closed, and they weigh only about 1 pound. They are only about 8 inches long and are covered in a fine black hair. They are completely dependent upon their mother. They don’t open their eyes until they are nearly 40 days old and will feed on their mother’s milk for up to 30 weeks.
We were able to capture some PG-rated images of the mating black bears. Witnessing these natural, intimate moments are so special. Not a lot of people are lucky enough to see a wild black bear and even fewer are lucky enough to witness mating black bears.
Mating is a brief encounter. The female is only receptive for mating for a few short hours, so the male often follows the female for many days before the time is right. He gets closer and closer to her, and when she accepts his advances, he has just a few moments to mate.
The coupling lasts less than a minute and she often turns and becomes aggressive towards the male. More times than not, he just turns and walks off in search of another receptive female.
Until next time …