Motherhood of the Grizzly  

After months of preparing, you finally get to go on that Backcountry Journeys’ Yellowstone photography tour you’ve had on the calendar for so long. You’ve spent weeks dreaming about geothermal features, towering waterfalls, and deep canyons. However, it’s the wildlife that truly calls you.

As a photographer, you chose to visit the Greater Yellowstone in the spring. A time when animals have awakened from hibernation and their babies are born. Baby animals were on your radar. A few days into the tour and you’ve already seen so much, but you still have yet to spot a bear. After some warm coffee to get the day jump-started, you joined the group for a hunt. Driving down the road, you come around a curve where your eyes are locked onto a grizzly bear grazing in the meadow.

Adrenaline fills your veins as you finally get to see a bear for the first time. After setting up your gear, you notice something bouncing in the sage. A cub! No! Two cubs! It’s a grizzly family! Love fills your heart as you photograph the adorable cubs wrestling next to their mom.  

Bears are fascinating creatures. There are about seven hundred grizzlies in the Greater Yellowstone Ecosystem. Seeing a mom and cubs is always a rewarding sight, but do you know what it takes to be a grizzly mother? If you love bears and want to learn more about the Yellowstone grizzly, then you have come to the right place.  

Let’s start at the beginning. No, I’m not talking about the Big Bang Theory. I’m referring to the reproductive age of female grizzlies. After growing up and leaving their mothers, a female bear has a couple of years of freedom before the boys start knocking on her door. A female will reach sexual maturity at age four. However, some North American bears have managed to be cub free until they reach ten years old. In Yellowstone, the maximum age reached without having cubs is seven. When a bear goes into estrus, the mating season can last up to 63 days, between May and July. During this time, a female can mate with multiple males. However, when a male grizzly finds a suitable female, he’ll follow her around for days, even weeks, guarding her against other potential suitors. This increases his chances for copulation. When copulation does occur, it can last anywhere from 25 minutes to an hour.  

After a job well done, the breeding season comes to an end and the embryo begins to develop, right? Wrong! Grizzly bears have an adaptation known as delayed implantation. What this means is that the fertilized egg, known as the blastocyst, will not be implanted into the uterine until late November to early December. As a result, the development of the embryo has been stalled. When autumn rolls around, the bear’s hunger goes into overdrive as they go through a phase known as hyperphagia. This is a period when the bears are driven to eat more carbohydrates so they can quickly gain body mass in preparation for hibernation. A pregnant female must obtain at least 20% body fat in order to have cubs. More than 30% is better. If she succeeds, she’ll waddle into hibernation as the embryo becomes implanted in the uterine. Then the development begins.  

For a grizzly bear, the gestation period is 60 days. After this time, the bear will give birth sometime between late January to early February while in hibernation. The combination period of delayed implantation and gestation is about 235 days. When the cubs are born, they’re about eight inches long and weigh about 1.1 pounds. They’re also blind and covered with very little fur and are highly dependent on their mother. By the time the bears emerge from their den in April, the cubs will be weighing about 8 pounds. Newborn cubs are known as COYS which is an acronym for ‘cubs of the year.’ The average number of cubs a grizzly bear will have in a single litter is two. But the bears have been known to have anywhere from one to three cubs per litter. Occasionally, they can have four which is a remarkable sight, especially if all four cubs make it to adulthood.  

Generally, in the Greater Yellowstone Ecosystem, grizzlies begin to emerge from their dens mid to late-March. But it’s the males who emerge first. When you’re a mother with cubs, life tends to move at a slower pace. If you have ever tried to go to the grocery store with kids, you’d know that it takes extra time to go anywhere.  

People often view grizzly bears as being really aggressive, but if you understand the reasoning behind their behavior, then maybe you’ll have a different perspective on the way they act. Grizzly bears have evolved to live a life in the open landscape. As a result, if the bear is ever faced with a threat, then their best option is to fight back because usually there isn’t anywhere for them to run and hide. This is why grizzlies are often known to charge when surprised. This is especially so with mother bears because it’s a dangerous world out there for her cubs, considering there is usually a 50% mortality rate for COYS. One of their biggest threats is other bears. Male grizzlies have been known to commit infanticide. The reason for this is when the female loses her cubs, she goes back into estrus so she can be bred again. In addition, large, dominant male bears can be very territorial, especially if the food is scarce. This puts any bear who enters its territory at risk. So, when you’re a mother bear, you are always on high alert trying to keep your babies safe.  

By mid-summer, the cubs could weigh 44-55 lbs. At the end of the summer, the cubs can weigh as much as 115 lbs before they return to the den with their mother for hibernation. At this point, you may have noticed that bears grow fast. After about five months in hibernation, the whole family emerges and the cubs are now yearlings. At two years of age, the cubs are weaned and by the time they reach 2.5 years old, their mother would have forced them to leave the nest and start their own journey as adolescent bears. The following year, the mother once again goes back into estrus, while the cubs find new homes until the day comes for them to start their own families.  

The lifestyle of a mother grizzly can be exhausting. Even though they are a large predator, it can be tough raising cubs. As a photographer, it is always rewarding seeing a thriving grizzly family, especially if you have observed the same mother year after year as she successfully raises cubs like a true warrior. The next time you photograph a grizzly family, you will have a greater understanding of the reproductive cycle of grizzly bears. If you have yet to visit Yellowstone National Park, then check out the spring and fall tour options with Backcountry Journeys to maximize your photographic adventure.   

Interested in seeing and photographing Yellowstone National Park this spring? The potential to see and capture images of grizzly bears described above blend perfectly with an immense wildlife display that includes bison, elk, bears, pronghorn, maybe even wolves… We have availability on one of two sets of spring 2022 dates but don’t expect it to last long. We’ve been traveling to Yellowstone & Grand Teton for years and years and have found this itinerary to be one of our best at blending exciting wildlife and landscape opportunities perfectly! We’d love to see you this spring in Yellowstone & Grand Teton National Parks.

Spring in Yellowstone & Grand Teton
May 2nd to 9th, 2022
with Trevor LaClair
3 Spots Left

Book Now! 

Trevor LaClair








Trevor LaClair is an explorer who is passionate about wildlife. He has spent many years working with and around animals of all kinds, both in captivity and in the wild. The animals he enjoys the most are megafauna and dangerous animals. After growing up in Missouri, Trevor ventured across the country guiding in different places, including the Greater Yellowstone Ecosystem where he spent his free time tracking grizzlies and watching wolves.

After receiving his Bachelors in Fisheries and Wildlife from the University of Missouri, Trevor obtained a Masters in Biology from Miami University.  During the past few years, Trevor has had epic adventures exploring places such as Komodo National Park, Serengeti, and the Great Barrier Reef. He loves playing outside and going on epic adventures. His mission is to inspire people around the world to appreciate nature and conserve this planet’s natural wonders. Through entertainment and education, Trevor uses the power of media to bring viewers on global adventures and up close to amazing animals. You can follow Trevor LaClair on his adventures by checking out his website

0 replies

Leave a Reply

Want to join the discussion?
Feel free to contribute!

Leave a Reply

Your email address will not be published.

Time limit is exhausted. Please reload the CAPTCHA.