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Bears as Predators ~
Bears as Predators ~
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Bears as Predators ~
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Nice Tshokwane. A young grizzly; probably his first year away from "Momma Bear."
Interesting article on the caribou and moose predation by bears:
Bears are bigger killers than thought, gruesome video footage reveals "The scenes start out innocently enough, often with a springtime stroll through Alaska’s Nelchina River Basin. But without warning, things turn grim: tableaus of blood and gore, usually with an unlucky caribou calf at the center. Such is the video footage collected by scientists over 3 years from cameras strapped around bears’ necks, offering the first “bear’s eye view” of life in this bucolic but harsh reserve. One of the team’s main findings: These bears kill a lot more than we think they do. A whole lot more. “It was really exciting because it’s the kind of thing you know occurs,” says Christopher Brockman, a wildlife biologist with the Alaska Department of Fish and Game (ADFG) in Palmer and lead author of the study. Figuring out the “kill rate” of large carnivores is notoriously difficult, says study author Bruce Dale, a wildlife science coordinator at ADFG in Palmer. It’s hard tracking them for long periods over large distances, and it’s also easy to miss a kill. A brown bear might spend a couple days eating an adult moose, compared with just 40 minutes for a caribou calf. So preferred tracking methods—like twice-daily aerial observations—can’t capture the full scope of bears’ hunting and feeding habits. They also can’t capture individual variation in kill rates, resulting in wildly different estimates for entire populations. To come up with a more accurate estimate, Brockman and his colleagues decided to try something new: outfitting the bears with camera collars and GPS trackers. Similar to security cameras, the collars filmed 10-second clips every 5 to 15 minutes for more than a month, from mid-May to late June. “We were focusing on the period of time when the [moose and caribou] calves are most vulnerable to predation,” Brockman says. He and his team collared 17 bears in total from 2011–13. Just seven collars provided the researchers with decent data—the others either fell off, didn’t work properly, or were chewed off their mothers by meddlesome bear cubs. But the ones that did work gave the team more than 100 hours of footage—36,376 clips in total. From those, the scientists reconstructed the bears’ days. Most of their time was spent resting or traveling (60.5% and 21.3%, respectively), and just 6.3% was spent feeding. There were even a few instances of bear mating caught on camera, Brockman says. Although researchers found that bears ate a lot more caribou and moose calves than was previously believed, a bear's life is generally not particularly strenuous. Researchers tracking brown bears in Alaska’s Nelchina River Basin by GPS and collar cameras found that the animals only spent 6.2% of their time feeding, on average—most of their time is spent resting. By carefully analyzing the most gruesome footage, the researchers were also able to identify the bears’ prey. More than half of their meals came from moose or caribou calves, whereas vegetation made up nearly 20%, and adult moose made up just over 12%, they report this month in the Wildlife Society Bulletin. But there were also some unusual items on the menu: snowshoe hares, swans, and even other brown bears. In one case, a 10-year-old male killed—and ate—a 6-year-old female bear. Overall, the bears killed an average of 34.4 moose and caribou calves over 45 days. That’s far higher than average kill rates from previous studies using other methods, including aerial observation. Compared with one 1988 study in which scientists counted an average of 5.4 moose calf kills from the air in a different part of Alaska, the new study found an average of 13.3 moose calf kills. The new study also found wide variation in the number of calves killed by any one bear, with one killing 44 calves in 25 days and another killing just seven in 27 days. That matters because kill rates are often used to manage wildlife living in protected areas. For example, if too many calves are being killed by bears, then removing a few of the predators could have a big impact on allowing the moose and caribou population to increase. Alternatively, Brockman says if the management goal is to increase bear numbers in an area, it may be important to pay attention to whether there are enough calves around in the spring to support more of the predators. Still, the study has its weaknesses. The low numbers make it hard to draw any firm conclusions about predation rates, says Martin Leclerc, a Ph.D. student at the Université de Sherbrooke in Canada who has studied how female brown bears use human settlements to shield their cubs. He also points out that the bears chosen in the first year of the study were known calf killers and could thus represent a bias in the overall numbers. But the use of camera collars could greatly improve knowledge about population dynamics in the future, Leclerc says. “The technological development will really help biologists and ecologists to have a more precise understanding of predator-prey relationships.”"
Not surprising, just like any other predator, the grizzly prefers the younger calves of bigger prey species. But why so?
Maybe they hunt young ones to get ready to hunt bigger ones in the future? Grizzlies (along with other predators) are extremely intelligent and are often known to "plan ahead". If they wanted smaller prey, there are groundhogs, prairie dogs, some birds, smaller carnivores, other protein-rich food, and they can subside on that. But they prefer the real deal--the smaller ones of the larger species. 
It depends, maybe the Grizzlies in the future could convergently evolve toward the Pleistocene Short Faced bear with the more cursorial body structure, while the Brown bears from Eurasia would remain more Cave bear-like.
(07-22-2017, 10:49 PM)GrizzlyClaws Wrote: It depends, maybe the Grizzlies in the future could convergently evolve toward the Pleistocene Short Faced bear with the more cursorial body structure, while the Brown bears from Eurasia would remain more Cave bear-like. I don't know if there will be any grizzlies in the future with the way we destroy our habitats (just kidding, there will be some), but they will most likely evolve into the more Arctodus-like body type since their food sources will be very few in between extremely far distances. Europe is a much more closed environment, and there are a lot of humans condensed in one small continental mass. Protein food sources are smaller and less abundant there than even modern America, so the grizzlies will most likely adapt to vegetation much like the Western European cave bears. 
*Copied
This amazing photo comes from lake louise, apparently a photographer was taking photos of a black bear grazing in a meadow, when a sow grizzly came charging out of the woods straight at the black bear. The black bear briefly stood up to try and intimidate the grizzly, but she wasn't bluffing and the black bear ran away before any more photos could be taken.  *This image is copyright of its original author
Thank you Wolverine. I have watched that old video so many times! My take: One killing strategy of a grizzly is to wear down his prey or opponent until it is completely exhausted. Then, he can take his time in the actual killing which is often, as is in this case, a bite to the spine. Too bad this event was not filmed by naturalists instead of a truckload of Russian red-necks.
http://articles.extension.org/pages/6365...feral-hogs
Black Bear – The black bear is known to prey on feral hogs of all ages; however, the impact of predation by this bear on feral hog populations is not known. Some researchers have speculated that black bears probably kill few if any feral hogs, especially given that an adult hog would represent a formidable adversary for a black bear. In fact, in the 1920s a feral boar in the Okefenokee Swamp was reported to have killed a black bear in a fight between the two animals. Similar accounts of feral boars killing bears during fights in the Ozark Mountains of Arkansas were reported in the 1880s. Being opportunistic, black bears have been reported to raid nylon net live traps used for feral hog control at high elevations in the GSMNP to obtain any trapped hogs contained within these devices.
What are their greatest perils? Orphaned cubs, poachers, access to human food and garbage, vehicular homicides, wildfires, non-native species including wild hogs, and general ignorance on the part of the public about the character and behavior of black bears. - http://www.drellenrudolph.com/blackbear/...avior.html
(01-14-2018, 02:43 PM)brotherbear Wrote: Thank you Wolverine. I have watched that old video so many times! My take: One killing strategy of a grizzly is to wear down his prey or opponent until it is completely exhausted. Then, he can take his time in the actual killing which is often, as is in this case, a bite to the spine. Too bad this event was not filmed by naturalists instead of a truckload of Russian red-necks.Despite the brown bear and the male wild boar with similar body mass are probably almost equal in physical power its obvious that bear is much more enduring, sturdy and capable to exhaust the boar. The bear is like an energiser, for boar is easier to get tired. Endurance is probably one of the main advantages of brown bear to majority of other animals including cats. Thick lyers of fat also protect brown bear from sharp canine teeth of the boar, sometimes in Eastern Europe hunters kill a bears with broken boar's canine teeth in their bodies without being inflicted any life-threatening consiquenses. And of course the bear is smarter. The boar is braver, exactly when wounded doesn't know any fear.
www.sciencedirect.com/science/article/pii/S207815201630027X
Behavior of Brown Bears During Feeding in the Sikhote-Alin Open Access funded by Far Eastern Federal University Predation on Ungulates Predation on the ungulates is a trait of ecology of brown bears typical for different areas of the species range (Bromlei, 1965, Semyonov-Tyan-Shansky, 1979, Zavatsky, 1979, Lavov, 1987, Pazhetnov, 1990 and Bobyr, 1991). The extent and nature of predation vary with the seasons. In most cases, this method of feeding behavior is of the greatest importance for bears in the spring (Pazhetnov, 1990). This statement is typical for brown bears in Sikhote-Alin (Bromlei, 1965, Yudakov and Nikolaev, 1987, Yudin, 1993 and Kostoglod, 2006). In summer there is a decline of predation related to the abundance of feed (Bromlei, 1965). In autumn with the abundance of fattening feed of vegetable origin predation is not expressed, but during hungry years it is on the contrary typically occurring among bears (Bromlei, 1965, Rakov, 1966 and Abramov, 1972). Wild boar and red deer (Cervus elaphus) are the most common ungulate prey of brown bears in Sikhote-Alin.
During childhood I red one curious hunting story from Bulgaria, probably there is some fantasy there, but maybe in same time the story was based on a real case. Its happen that that on narrow game trail in the forest a brown bear and a huge male wild boar ran into each other. Both animals were surprised and nobody wanted to withdrow from the trail first, the tention started to increase. Suddenly the bear noticed a branch above its head and climbed on it, leaving the boar opportunity to pass the trail beneath. Than that scenario start to repeat almost every day for many weeks, both the bear and wild boar strangely liked to do same weird ritual. Sometimes even the bear waited the boar above the same tree for a hour and than climbed to the branch kinda playng with the huge boar. But one day a tragedy happened. Branch suddenly crashed and the bear fell exactly on the head of the boar... Both animals were shocked, suddenly became very aggressive to each other and a mortal fight began. The bear killed the boar but the boar succeeded to penetrate with his sharp canine teeth the bear's abdominal aria and it also died not long after that later found by hunters... Don't know how this old story from the hunting novel is true, but in generally bears are enough smart animals and probably sometimes could be in "playing mood" with other animals.
In general brown bears of course have a weight advantage to the boar. As long as I know the largest both brown bears and wild boars in Europe live in Carphatian mountains in Romanian Transilvania (also known as a "Draculla-land") with average weight of adult male Carphatian brown bear at 260 kg and average weight of adult male Carpathian wild boar of about 110-130 kg if I am not wrong. So that is 2,3 times advantage of the body mass... and such a struggle would not be very fear. But in case a boar is huge (the record for Romania is 275 kg) and equal to the bear's mass he could be formidable adversary. I don't think that a wild boar could kill a brown bear, but for sure sometimes boars inflict a wounds on the bears trying to hunt them, and the prove of this is that sometimes the hunters discover a broken boar's canine teeth in bear's flash. |
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