Post by grrraaahhh on Mar 22, 2010 15:25:03 GMT -9
That sighting in August 2008 spurred Rockwell and Gormezano to look through records to get a better picture of the bear population in the park. There was no evidence of grizzly bears before 1996, not even in the trapping data from centuries of Hudson Bay Company operation. But between 1996 and 2008 the team found nine confirmed sightings of grizzly bears, and in the summer of 2009 there were three additional observations.
"The opportunistic sightings seem to be increasing," says Gormezano. "This is worrying for the polar bears because grizzly bears would likely hibernate in polar bear maternity denning habitat. They would come out of hibernation at the same time and can kill polar cubs."
This is a grizzly Bear (Ursus arctos), photographed in Wapusk National Park, Manitoba, Canada, on August 9, 2008. (Credit: Linda Gormezano)
Before this study, researchers thought that the barren landscape north of the Hudson Bay was an impassable gap in resources for potentially migrating grizzly bears. But some U. arctos horribilis have managed to move from their historic ranges in the Rockies, the Yukon, and Nunavut, probably because of their flexible, mixed diet of berries and meat. The potential gap was navigable, and now some grizzly bears have reached the abundant caribou, moose, fish, and berries found to the south in Canada's Wapusk National Park.
Post by grrraaahhh on Mar 22, 2010 15:54:41 GMT -9
The territorial range for the Barren Ground Grizzly is the largest (reaching several thousand square miles) for any bear and as others have noted their sparse tundra environment makes them extremely aggressive.
It's not surprising, then, that in the absence of caribou in early springtime--when the animals emerge from their dens to find only snow and cold--barren ground grizzlies will occasionally venture onto the sea ice. The scent of a seal, dead or alive, or the tracks of a caribou herd that has crossed to an Arctic island may be all that's required for them to take that first step away from land.
Although genetically identical to the eight-foot, 900-pound coastal brown bears of southern Alaska, the barren ground grizzly rarely tops six feet and 500 pounds. A scarcity of food in northern Alaska makes these grizzlies smaller, and they behave very differently from coastal brown bears. Well-fed brown bears sleep a lot and shamble around a ten-square-mile territory. In contrast, hungry barren ground grizzlies can prowl 5,000-square-mile territories, constantly sniffing the air for scent. In the Arctic—where there are no streams filled with fat salmon, no forests to provide shade or cover, and food gathering is cut short by the long winters—the omnivorous barren ground's mission is simple: relentlessly hunt down and consume every available scrap of food.
Post by grrraaahhh on Apr 26, 2010 13:50:32 GMT -9
Honestly, there is just not enough information. We do know the form of tundra brown bear penetrating into Polar Bear territory to be smaller but very aggressive and predatory - a byproduct of their sparse vegetation environment. My guess is there are too few recorded encounters to really make an educated guess. Without looking at the data (I will plan to do so) I can't imagine too many times the female Polar Bear is out sized by a male tundra grizzly even the larger ones. I think it has to do with something more primal (a natural aversion) as seen in the following video clip.
From the video clip, it is clear we are seeing something more primal (a natural aversion to brown bears) in these polar/tundra grizzly bear encounters. There is little reason to think a 300 lb grizzly could seriously injure a polar bear weighing 1200 lb let alone drive off two of them. We see that the scent of the tundra grizzly alone was a big enough factor to rattle the male polar bears.
Two address your second point, the weight difference between male tundra grizzlies and female polar bears are closer. According to biologist Steven Amstrup (1988), adult female polar bears range between 440-750 lbs. The reason I mentioned this relates to the 2006, Banks Island Hybrid bear that was killed. The speculation is that a male tundra grizzly migrated over the frozen ice pack to mate with a female polar bear. It is believed the bear killed the polar bear's cubs to force her into heat to mate with. In either case, whether the polar bear had cubs or not - the fact that she likely out-sized her grizzly counterpart but still mated is interesting. Perhaps the polar bear was a young (not mature) smaller sow of similar weight but here again I am just speculating.
As for the lion/bear match up, keep in mind these tundra grizzlies are very aggressive - charging helicopters, assaulting humans, and attacking anything that moves. Even against their larger grizzly cousins, I think these bears would be a dangerous adversary. There are other smaller size brown bear populations, Gobi bear, Himalayan bear, or some populations from southern Europe; but I think to address the larger point (the at parity argument) is that we see these kind of collisions in the RFE between tigers & bears. In the RFE, almost every kind of bear/big cat scenario is present but with the caveat that in this region this form of brown bear (U.a.lasiotus) are bigger and mature later. In other words, at parity, by in large, we are talking about a young adult male brown bear or possibly a sick old bear . Many people fail to understand or accept the bigger point and that is what the literature tells us: we already have our answer about the at parity encounters.
What's fascinating, is the fact the female Grizzly (300 lbs?) has driven off (2?) male Polars, claimed to be 1,200 lbs! Would she dare to drive off a 400 lb male Grizzly with cubs in tow?
I believe the grizzly sow would do the same to a male grizzly, there are videos and accounts of those as well. A female polar bear just like the female grizzly is willing to fight till death to protect her cubs, therefore, there is a good chance she might do the same to a male grizzly as she does to a male polar bear. Honestly, it seems the bears are close in size, could it be the polar bears higher bone density makes it heavier in weight (ursus posted that data) or the larger ones have moved off earlier? Anyway, big bons claimed that a brown bear named goliath is acctually taller than the exceptionally large polar bear weighing 2200 pounds (11.4 ft vs 11.2 ft), the polar is heavier not just because of greater fat but also heavier bone density.
It's difficult to imagine the Grizzly managing to inflict any serious damage on the Polar Bears.
Agreed. I too have a hard time imagining a 400 pound bear able to injure a 1200 pound bear without the bear getting slightly anoyed and throwing its smaller adversary around like a 'rag doll'. Another source acctually said the large male polar bears were pushing 1000 pounds.