The brown bear is the most widely distributed species of bear in the world, found in the northern regions of North America, Europe, and Asia. It is also the most broadly defined of bear species, with subspecies ranging from the smaller 350 pound “grizzlies” found in mountainous inland regions to the massive 1700 pound “Kodiaks” native to coastal lowlands regions like southern Alaska.
Mating season for brown bears lasts from early May through late July, although a process of “delayed implantation” allows a pregnant female to actively hunt, fish, and forage for several months before embryo gestation begins. For brown bears on the coastal plains of Alaska, the annual culmination of this feeding season is the “salmon run,” during which salmon swim upstream to spawn and die in the rivers where they were hatched. For this, the entire brown bear population descends in concentrations of up to several dozen to fish in the teeming streams.
Brown bears are omnivores, meaning they will eat whatever is available, from plants to animals to insects. While their smaller grizzly cousins in Wyoming’s Yellowstone Park consume half their annual calorie intake by eating up to 40,000 moths a day, Alaskan brown bears rely heavily on the fatty calories of salmon and salmon roe (eggs), consuming up to 40 pounds a day to see them though the long and lean months of winter hibernation, during which time they will lose up to half their body weight.
During hibernation—or “dormancy”—pregnant female brown bears give birth to litters of between one to four cubs, which generally weigh less than 1 pound each at birth. The cubs feed on their mother’s milk through the spring and into the summer, until they reach a weight of between 15 to 20 pounds and are able to learn fishing, hunting, and foraging skills from their mother. These skills are acquired by following and observing their mother over the course of two to four years, during which time the mother avoids male bears, which are known to kill and eat cubs. Male brown bears take no part in raising their own cubs.
Being at the top of the food chain with no need for safety in numbers, brown bears are generally solitary animals. Their concentration along rivers during the salmon run provides wildlife researchers with rare opportunities to observe their social interactions, which include physical competition among females for males, females teaching their cubs survival by demonstration, and female protection of their cubs against larger and aggressive males.
NARRATOR: The feast has begun, the salmon are coming home it feels as if the river itself has been anticipating this moment and for a short time, salmon will be the life-blood of this place but now the clock has started on this narrow window for the bears.
This is a pretty mature female, and she really knows what she’s doing, and she’s got this really healthy, fat, cuddly looking cub. He’s never more than ten feet behind his mom. She shares nearly every fish she catches with her young cub. He’ll grow fast, and her determination will pay off in how quickly he learns how to live here. With all his needs met, he is relaxed to hone his skills. Oh look he’s snorkeling. He’s got his head right under the water so he can see the fish. It’s incredible; time after time she’s catching female fish. And it’s important that she catches the female fish because they are full of fat, in the form of their eggs, that the cub can really benefit from. And that’s why he’s so chunky looking. This young male has been closely watching her, and now that she’s resting he’s decided to test out her fishing spot.
Probably in his first year of life without mom and he is suitably overwhelmed by the environment and the number of bears here. The river is so densely packed right now that bears need to employ a number of strategies to catch salmon, and keep a safe distance from each other.
The bears that are forced into the deeper water have to snorkel to track their prey. The salmon hide in these deep pockets out of reach even as some of the bears are struggling to catch anything, others are being much more selective, and giving some lucky salmon a second chance.
The salmon pack the dense channels. Trying to reach the spawning ground, the completion of their journey. But first, they have to get through this gauntlet of bears. Still many will make it far, far up river where they will spawn, and end their journey. Life is not so easy for the wolves. The salmon taunt them, but the chase is more an act of desperation then anything. The salmon are still too deep for the wolves to catch. This mom has just arrived with three cubs. The first triplets we’ve seen this year. It’s unusual for her to still have all three cubs this far into the season. It’s probably her first trip down to the river, and they will take whatever they can get.
It’s certainly a different situation than fatso is used to. The river definitely shows off the social diversity here. But even poaching scraps around this many bears is more than she’s comfortable with, so they’ll eat this meal on the road. She’s found a quieter stretch of the river.
It seems that for a couple of them at least, these are their first litters. So first time they’ve experienced having to look after their young cubs. And there is this incredible, almost panic, more then urgency, it’s almost just a panic to feed right now. The anticipation of denning for the whole winter without enough fat, is just this innate fear that they have. The density of bears here makes things tense for these larger families. Wow, she is just frantic! She senses that if she doesn’t catch something fresh, they won’t last very long. The cubs aren’t comfortable yet with mom thrashing off into the deep without them.
She tries to reassure them, and guides them to safe beach to wait for her, but they aren’t so easily convinced. You definitely can tell that she sense the pressure to catch fish right now. She’s just arrived, later then the other bears, and it’s just a matter of time before these fish dry up here, and so she’s got a lot of work on her hands.
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