I'm going to call the grizzly in question a him though he may have been a her. Our first sighting of him was a moment I will never forget - and one I hope my daughter will remember when she's older. He was the talk of the staff and visitors at the lodge. They thought he was about two years old and had only recently left mom. Learning to fend for himself he was loving the wildflowers around their site, but hadn't yet learned the message about not mixing company with people.
But enough about my encounter - what have I since learned about grizzlies?
Top Predator...or Is It?
With the exception of polar bears perhaps, the grizzly has to be the most feared and revered mammal in North America. A sub-species of the brown bear (Ursus arctos) which is found across the northern hemisphere, the North American grizzly itself has several sub-species - the most common being the Mainland Grizzly (Ursus arctos horribilis). The word grizzled means streaked or white tipped hair. Its Latin name Horribilis first penned in 1815 is indeed Latin for horrible, but personally I think that's a sad description for this beautiful animal.
They are at the top of the food chain. But here's the thing...they're not the best of hunters and eat mostly plants which can make up a whopping 90% of their diet. Grass, moss, berries, roots, wild flowers - you name it, they seem to eat it. Given the chance they will prey on animals of any size including squirrels, deer, elk and even black bears. But despite their power and speed, they are not very agile so prefer to hunt the small, old, sick or young. They also eat insects and will scavenge for carrion. And as most of us know, fish, especially salmon, is an important food source. In other words, these mighty mammals are not fussy eaters.
Their foraging behaviour is known to be important for our ecology. They can consume around eighty pounds of food per day when preparing for hibernation (the most common number I've seen). If most of that is plants then just think of what that can do for seed dispersal. Studies have also shown that the ground stirred up by a foraging bear leads to greater nitrogen distribution and plant diversity. Those that catch salmon do not eat the whole fish, leaving the rest for carrion-loving birds and other animals. Through their waste they also distribute nutrients from the salmon on land.
As you might expect, not all grizzlies are equal. Those that survive mostly on plants are smaller than the luckier ones with a fish or meat rich diet. The Alaskan bears, with their ready access to salmon can be twice the size of those found in the American Rockies.
For an animal that can weigh upwards of one thousand pounds (average sizes vary greatly between male/female and locality so this is a very round number), it's staggering to know that when cubs are born they weigh only one pound. Just one....that's tiny!
Although breeding takes place in spring, the fertilized egg is not implanted until nearer hibernation time. This incredible feat of evolution waits to find out if the bear is nutritionally healthy enough to continue with a winter pregnancy, giving a safe and warm birth in the hibernation den. So although it may be around nine months between conception and birth, gestation is only around six to eight weeks. It never ceases to amaze me how smart nature is. On reading more, I see there are around one hundred different mammals that use this clever tactic.
Six to eight weeks doesn't seem a long gestation for such an animal. But the cubs are essentially born premature. The safety of the den allows mama bear to rear them with her milk, while not having to go through an energy-depleting full term pregnancy.
Unlike bald eagles that mate for life, grizzlies are a promiscuous bunch. It's even possible for cubs from the same litter to have different dads. Despite this grizzlies have a very low reproductive rate. The average litter is two cubs, and they will stay with mom - and her super-protective-nurturing instinct - for two to three years during which time she won't mate again. In her lifetime of twenty to thirty years, she may only have ten cubs, not all of which will survive.
The hibernation den is a safe, warm haven in which to shelter in a state of torpor - or dormancy - while the climate is harsh but more importantly, when food supplies are scarce. This will last four to seven months of the year, though in milder climates where food is less of an issue, some grizzlies may not hibernate much at all.
Yes they sleep over winter, but they are not in a deep sleep and can be easily woken. Their body temperature and heart rate drops to preserve precious energy, but nowhere near as much as those animals in 'true hibernation'. They will not eat or drink, nor will anything come out the other end. Their body fat is converted to a water source and they are even able to recycle the urea in their waste products into nutritious nitrogen.
Any pregnant mamas will give birth around January. The blind, helpless and furless cubs have about three months to put on enough weight and garner enough strength from mom's milk to be able to leave the den with her. Grizzlies leave their dens in a sensible order. First come the males in March, next the lone females followed by the mamas with one or two year old cubs. Last but not least come the mamas with their newborns around late April. Understandably, newborn mortality is quite high, with roughly one third not reaching their first birthday.
Grizzlies are very adaptable to different habitats - alpine, tundra and forest among others. From their high winter snow-bound dens, to the lower springtime plant-rich elevations, high summer alpine meadows, and fall salmon-run rivers, they follow the food source. To be honest I gave up trying to discover the average size of their home range. I've seen everything from 25 to 4000 square kilometres. What is clear though is that it depends largely on habitat, food availability and status, and that males have the biggest ranges.
In British Columbia, home to an estimated sixteen thousand grizzlies, most areas have a 'viable' population. I was surprised to learn that in the Southern Chilcotins they are instead 'threatened'....and there was me thinking that their grizzly population was above average. The area offers prime grizzly habitat - rich alpine meadows, old growth forests and mammals of all sizes to prey on - from moose to marmot. Not least a wilderness with little human intervention. A 2012 study put the population there at thirteen grizzlies per thousand square kilometres. By comparison, Garibaldi-Pitt (closest to home for me) is under one and the highest is fifty three at Flathead (on the BC/Alberta/US border).
Yet even on my home turf grizzlies occasionally get close to our daily lives, causing concern and excitement among residents, probably in equal amounts. The timing of my writing this post is bizarrely perfect as only yesterday a grizzly was spotted north of Squamish, hanging around the landfill which is so sad to hear.
And so back to my own grizzly encounter. By our third sighting it had become bittersweet. It was amazing to see him but it was also becoming apparent that he just wasn't learning to stay away from people, despite the best efforts of the lodge staff. Encouragingly, he was still wary but even so, it didn't bode well for his future. I've thought about him many times since. I don't know the outcome but I hope that he was indeed smarter than the average bear...which gives him a good head start....and figured out that his best chance in life was to head for the hills.
Grizzly catching fish: © Brian W. Schaller, licensed under Creative Commons
Grizzly reclining in water eating plant material: Tony Hisgett, licensed under Creative Commons
Grizzly cubs: Public domain
All others: © Diane Mitchell