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Bears as Predators ~

LazarLazar Offline
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Here is bunch of brown bear predation accounts
https://www.tapatalk.com/groups/animalparadise/brown-bear-predation-t3.html

Some from polar bears
https://www.tapatalk.com/groups/animalparadise/polar-bear-predation-t7.html
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LazarLazar Offline
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GRIZZLY BEAR PREDATION ON MUSKOX

*This image is copyright of its original author

Ovibos moschatus is a formidable beast that is sometimes preyed upon by grizzly bears.Photo CreditUselessS Fish and Wildlife Service.


The muskox (Ovibos moschatus) is a large ungulate (the average male weight is from 273 to 364 kg [600 to 800 pounds]) equipped with curved horns and a shaggy pelage which can be up to 10 cm (4 inches) thick. It is a close relative of the sheep or goats (subfamily Caprinae) and is able to withstand incredibly frigid, arctic conditions (down to at least – 70 ºF). Muskox tend to live in herds and are famous for their defensive posturing – they often form a defensive circle with their heads (i.e., armament) facing outward toward the potential threat. Youngsters often hide amongst the adults for protection.



The barren-ground grizzly bears and muskox overlap in their distribution in northern Canada and Alaska. This shaggy beast would appear to be fairly impervious to grizzly attack. But, this is not the case. Grizzlies were originally reported feeding on muskox by early explorers and with recent reintroduction of these ungulates in parts of the Arctic, there have been a number of papers written on the predator-prey relationship of U. arctos and O. moschatus. Below I have reviewed what is known about the barren-ground grizzly predation on muskox.



Multiple Hunting Strategy



In the Thelon Game Sanctuary, grizzlies and muskox coexist, but the relationship is not always copasetic. Near the Thelon River, bears may use thick willow stands along the waterway to ambush muskox feeding on sedge in nearby clearings. Willows also attract muskox, as it is a preferred food of this beast. Gunn and Miller (1982) report finding a bear on a freshly killed, bull O. moschatus. They were able to scare the adult bear off and examine its kill and concluded that the bear had dispatched the big ungulate by first grasping its nose (crushing the nasal turbine bones and tearing off the nose in the process) and then inflicting a crippling bite to its skull. By grasping the nose, the bear may have prevented the muskox from bringing its horns to bear and also may have been more effective at throwing the animal to the ground.



In another study carried out in the northeastern Arctic slopes of Alaska, 92 grizzly-muskox interactions were observed (Reynolds et al. 2002). Fifty percent of these were known kills, 40 % were possible kills or scavenging events, and 10 % were incidents where a grizzly was seen chasing muskox. It was estimated that 16-39 % of muskox mortality was the result of bear predation. During the study period (1982-2001) the number of muskox killed by grizzly bears was zero to two deaths per year before 1993, one to four musk ox per year from 1994-1997 and five to ten deaths per year from 1998-2001. This increase in kill numbers was a function of an increase in the size of musk ox herds. An increase in kills may also be indicative of the bears learning how to better attack and take down these big, formidable animals. While solitary adult bears were most often seen attacking muskox (69 occasions), pairs or trios of adult bears were seen chasing, killing or eating these animals (three episodes). Sows with cubs or yearlings were seen interacting with muskox on three occasions.



Surplus Killing



Grizzly bears sometimes engage in surplus killing of muskox. In the study carried out by Reynolds et al. (2002) there were ten episodes where one to three bears killed from two to four adult muskox. On several occasions even more muskox were dispatched during a single hunting bout. For example, in one case five individuals (two adult females, a yearling and unsexed adult musk ox) were incapacitated by a single bear. In another case, a grizzly killed four calves and in another incident the victims were one adult female, one two-year old male and one yearling. In most cases, solitary bears were involved in these killing sprees, but in one case three grizzlies instigated the melee.



Clarkson et al. (1993) reported a fascinating case of surplus killing of muskox calves by a heterosexual pair of adult grizzlies. Within a distance of about two km, the two bears took down five young musk ox. By doing a little forensic work, the researchers were able to put together a likely picture of what had happened. Rather than form a defensive circle to try and parry the bear attacks, this herd of musk ox tried to out run the grizzlies. The researchers postulated that the calves trailed behind the adults and, therefore, were more vulnerable. The two bears chased the herd, which consisted of 40 to 50 muskox (with a minimum of eight calves). They killed the first calf and ate 90 % of the carcass. They then chased the herd down again and about 1.5-2.0 km from the first kill dispatched a second young musk ox. They ate 60 % of this second calve and began the hunt again. They killed the third calf about 300 m from the second. The third calf was about 30 % consumed by the bears and a wolverine (Gulo gulo) that was feeding on the carcass when the researchers arrived on the scene. The fourth calve was killed 400 m from the third. A golden eagle had just begun to feed on calf four when the researchers arrived. The final calf was killed about 200 m from the fourth – this last young muskox was not eaten either.



References:



Clarkson, P. L. and I. Sarma Liepins. 1993. Grizzly bear, Ursus arctos, predation on muskox, Ovibos moschatus, calves near the Horton River, Northwest Territories. Canadian Field Nat. 107:100-102.



Gunn, A. and F. L. Miller. 1982. Muskox bull killed by a barren-ground grizzly bear, Thelon Game Sanctuary, N.W.T. Arctic 35:545-546.


Reynolds, P. E., H. V. Reynolds and R. T. Shideler. 2002. Predation and multiple kills of muskoxen by grizzly bears. Ursus 13:79-84.
https://gobiestogrizzlies.blogspot.com/2008/07/muskox-on-menu-grizzly-predation-on.html
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United Kingdom Sully Offline
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(01-31-2020, 01:50 AM)LazarLazar Wrote: GRIZZLY BEAR PREDATION ON MUSKOX

*This image is copyright of its original author

Ovibos moschatus is a formidable beast that is sometimes preyed upon by grizzly bears.Photo CreditUselessS Fish and Wildlife Service.


The muskox (Ovibos moschatus) is a large ungulate (the average male weight is from 273 to 364 kg [600 to 800 pounds]) equipped with curved horns and a shaggy pelage which can be up to 10 cm (4 inches) thick. It is a close relative of the sheep or goats (subfamily Caprinae) and is able to withstand incredibly frigid, arctic conditions (down to at least – 70 ºF). Muskox tend to live in herds and are famous for their defensive posturing – they often form a defensive circle with their heads (i.e., armament) facing outward toward the potential threat. Youngsters often hide amongst the adults for protection.



The barren-ground grizzly bears and muskox overlap in their distribution in northern Canada and Alaska. This shaggy beast would appear to be fairly impervious to grizzly attack. But, this is not the case. Grizzlies were originally reported feeding on muskox by early explorers and with recent reintroduction of these ungulates in parts of the Arctic, there have been a number of papers written on the predator-prey relationship of U. arctos and O. moschatus. Below I have reviewed what is known about the barren-ground grizzly predation on muskox.



Multiple Hunting Strategy



In the Thelon Game Sanctuary, grizzlies and muskox coexist, but the relationship is not always copasetic. Near the Thelon River, bears may use thick willow stands along the waterway to ambush muskox feeding on sedge in nearby clearings. Willows also attract muskox, as it is a preferred food of this beast. Gunn and Miller (1982) report finding a bear on a freshly killed, bull O. moschatus. They were able to scare the adult bear off and examine its kill and concluded that the bear had dispatched the big ungulate by first grasping its nose (crushing the nasal turbine bones and tearing off the nose in the process) and then inflicting a crippling bite to its skull. By grasping the nose, the bear may have prevented the muskox from bringing its horns to bear and also may have been more effective at throwing the animal to the ground.



In another study carried out in the northeastern Arctic slopes of Alaska, 92 grizzly-muskox interactions were observed (Reynolds et al. 2002). Fifty percent of these were known kills, 40 % were possible kills or scavenging events, and 10 % were incidents where a grizzly was seen chasing muskox. It was estimated that 16-39 % of muskox mortality was the result of bear predation. During the study period (1982-2001) the number of muskox killed by grizzly bears was zero to two deaths per year before 1993, one to four musk ox per year from 1994-1997 and five to ten deaths per year from 1998-2001. This increase in kill numbers was a function of an increase in the size of musk ox herds. An increase in kills may also be indicative of the bears learning how to better attack and take down these big, formidable animals. While solitary adult bears were most often seen attacking muskox (69 occasions), pairs or trios of adult bears were seen chasing, killing or eating these animals (three episodes). Sows with cubs or yearlings were seen interacting with muskox on three occasions.



Surplus Killing



Grizzly bears sometimes engage in surplus killing of muskox. In the study carried out by Reynolds et al. (2002) there were ten episodes where one to three bears killed from two to four adult muskox. On several occasions even more muskox were dispatched during a single hunting bout. For example, in one case five individuals (two adult females, a yearling and unsexed adult musk ox) were incapacitated by a single bear. In another case, a grizzly killed four calves and in another incident the victims were one adult female, one two-year old male and one yearling. In most cases, solitary bears were involved in these killing sprees, but in one case three grizzlies instigated the melee.



Clarkson et al. (1993) reported a fascinating case of surplus killing of muskox calves by a heterosexual pair of adult grizzlies. Within a distance of about two km, the two bears took down five young musk ox. By doing a little forensic work, the researchers were able to put together a likely picture of what had happened. Rather than form a defensive circle to try and parry the bear attacks, this herd of musk ox tried to out run the grizzlies. The researchers postulated that the calves trailed behind the adults and, therefore, were more vulnerable. The two bears chased the herd, which consisted of 40 to 50 muskox (with a minimum of eight calves). They killed the first calf and ate 90 % of the carcass. They then chased the herd down again and about 1.5-2.0 km from the first kill dispatched a second young musk ox. They ate 60 % of this second calve and began the hunt again. They killed the third calf about 300 m from the second. The third calf was about 30 % consumed by the bears and a wolverine (Gulo gulo) that was feeding on the carcass when the researchers arrived on the scene. The fourth calve was killed 400 m from the third. A golden eagle had just begun to feed on calf four when the researchers arrived. The final calf was killed about 200 m from the fourth – this last young muskox was not eaten either.



References:



Clarkson, P. L. and I. Sarma Liepins. 1993. Grizzly bear, Ursus arctos, predation on muskox, Ovibos moschatus, calves near the Horton River, Northwest Territories. Canadian Field Nat. 107:100-102.



Gunn, A. and F. L. Miller. 1982. Muskox bull killed by a barren-ground grizzly bear, Thelon Game Sanctuary, N.W.T. Arctic 35:545-546.


Reynolds, P. E., H. V. Reynolds and R. T. Shideler. 2002. Predation and multiple kills of muskoxen by grizzly bears. Ursus 13:79-84.
https://gobiestogrizzlies.blogspot.com/2008/07/muskox-on-menu-grizzly-predation-on.html

I posted this already on page 16
"When the tiger stalks the jungle like the lowering clouds of a thunderstorm, the leopard moves as silently as mist drifting on a dawn wind." -Indian proverb
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TigerJaguar Offline
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A grizzly was seen killing 4 bison bulls

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https://www.google.com/search?q=bull+bisons+killed+by+tiger&sxsrf=ACYBGNSuSLW-VH8ZtS0wPLFm4pg16xC-lQ:1581284930811&source=lnms&tbm=bks&sa=X&ved=2ahUKEwjiu9u0ucXnAhXS854KHcqiBnUQ_AUoAXoECA0QCQ&biw=1920&bih=973
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Switzerland Spalea Offline
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" Polar Bear rips into a live harp seal "


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Sri Lanka Apollo Offline
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(02-14-2020, 12:14 AM)Spalea Wrote: " Polar Bear rips into a live harp seal "



Very hard to watch.
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Switzerland Spalea Offline
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@Apollo :

About #246: Yes, I'm agree it's hard to watch. Sometimes I don't relay these pictures because it's really hard - especially with hyenas and wild canids -, in this case we can quess what the polar bear was doing, but we don't see any close-up of the seal's face. Thus I choose to put this short video nevertheless. But I confess to have hesitated !
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Romania ApexKing17 Offline
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A bit long post but here is the best info I found about brown bear predation

Some notes from Ursus Arctos 1758 linnaeus


Mammals Beyond the regular predation of salmon, most brown bears are not particularly active predators. Nonetheless, brown bears are capable of obtaining practically all forms of the mammals that they encounter: from mouse-like rodents to those as fearsome as a tiger or as large as a bison. Over 100 species of mammal have been recorded either in the scats of brown bears or have been observed as being killed or consumed by the species, although much of this consumption probably represents merely scavenging on carrion.Forsyth, A. (1999). Mammals of North America: temperate and arctic regions. Firefly Books. An Arctic ground squirrel burrow that has been excavated by a hunting barren-ground grizzly bear

The leading ungulate prey for brown bears is normally deer. Up to a dozen species have been eaten by brown bears, but the main prey species are the larger species they encounter: elk (Cervus canadensis), moose (Alces alces) and caribou (Rangifer tarandus). Larger deer are preferred because they tend to be less agile and swift than small or medium-sized deer (although a caribou can handily outpace a grizzly bear in the open), they are found in large quantities in several areas inhabited by brown bears and provide a larger meal per carcass. Moose may be preferred where found in large numbers because of their solitary habits and tendency to dwell in wooded areas, both of which makes them easier to ambush. Despite its diminished reputation as a predator, the brown bear is the most dangerous solitary predator of moose, with only packs of wolves a more regular predator; even Siberian tigers take other prey, primarily (elk and boar), in areas where they co-exist with the giant deer. Brown bears normally avoid the potential risks of hunting large deer, which can potentially fight back but usually escape bears by running, by picking out young calves or sickly adults from deer herds. In northeastern Norway, it was found that moose were the most important single food item (present in up to 45% of scats and locally comprising more than 70% of the bear's dietary energy) for local brown bears and several local bears appear to be specialized moose hunters, most often picking off sickly yearling moose and pregnant but healthy cows. In Yellowstone National Park, grizzly bears who derived much of their food energy from ungulates were studied, and 30% of the ungulates consumed were through predation, the remaining amount from scavenging of carcasses. Elk, bison and moose (the three largest native ungulates in the region) each constituted nearly a quarter of the overall ungulate diet. 13% of the total of ungulates actively hunted and killed per that study in Yellowstone were elk calves, while 8% of the actively and successfully hunted prey there were adult cow elk. Despite their lack of preference for smaller deer, other species including red deer (Cervus elaphus), sika deer (Cervus nippon ), axis deer (Axis axis), European roe deer (Capreolus capreolus), Siberian roe deer (Capreolus pygargus), fallow deer (Dama dama), mule deer (Odocoileus hemionus) and white-tailed deer (Odocoileus virginianus) have turned up in their diet. As many as 20 species of bovids are also potential prey, including various sheep, goats, antelope, bison (Bison ssp.) and muskoxen (Ovibos moschatus). Bovids are mostly taken in random encounters when bears come across a vulnerable, usually young or sickly individual, as smaller species are extremely agile (and often live in rocky environments) and larger varieties are potentially dangerous, especially if aware of the bear's presence. In some parts of eastern Europe and Russia, wild boar (Sus scrofa) may be taken in surprisingly large quantities, considering the mostly herbivorous reputation of bears in these regions. One study from the Amur territory of Russia found that brown bears were actually more prolific killers of wild boars than both tigers and gray wolves, but these results are probably biased due to the scarcity of tigers in the region because of overhunting of the big cat. In rare cases, brown bears are capable of killing bulls of the largest ungulates in regions they inhabit, reportedly including moose, muskox, wild yak (Bos mutus) and both American and European bison (Bison bison and B. bonasus). Remarkably, such attacks are sometimes carried out by bears that were not particularly large, including interior sow grizzlies or small-bodied bears from the Central Arctic, and some exceptional ungulates taken may be up to two to three times the weight of the attacking bear.Persson, I. L. (1998). Brown bear Ursus arctos predation upon adult moose Alces alces in Scandinavia: a study at two levels of scale. Cand. scient. thesis. However, most of the bears who took adult moose in east-central Alaska and Scandinavia were large, mature males.

Enemies and competitors



Taxidermy exhibit portraying a brown bear fighting a Siberian tiger, Vladivostok Museum



While feeding on carrion, brown bears use their size to intimidate other predators, such as gray wolves (Canis lupus), cougars (Puma concolor), tigers (Panthera tigris) and American black bears (Ursus americanus) from their kills. Owing to their formidable size and aggressive disposition, predation by wild animals outside of their own species is rare for brown bears of any age; even cubs are often safe due to their watchful mother. There are two records of golden eagles (Aquila chrysaetos) preying on brown bear cubs. Adult bears are generally immune to predatory attacks except from tigers and other bears. Siberian tigers (Panthera tigris altaica) prefer preying on young bears but smaller, fully grown adult female brown bears outside their dens may also be taken. Successful predatory attacks by tigers on adult brown bears are usually on females, with or without cubs, in their dens. In the past, exceptionally large male Siberian tigers, such as one weighing approximately 300 kg, were reportedly capable of killing even adult male brown bears, but such bears are otherwise more or less safe from attack. Of 45 recorded encounters between tigers and brown bears in the Russian Far East, tigers initiated 13 of the fights, bears started 8, and the attacker was unknown for the remaining fights; in 51.1% of these cases, the bear was killed, in 26.7% the tiger was killed, and 22.2% of the cases ended with both animals surviving and parting ways despite injuries sustained in the conflict. Some bears emerging from hibernation seek out tigers in order to steal their kills. Despite the possibility of tiger predation, some large brown bears may actually benefit from the tiger's presence by appropriating tiger kills that the bears may not be able to successfully hunt themselves and follow tiger tracks. Geptner et al. (1972) stated that bears are generally afraid of tigers and change their path after coming across tiger trails.Geptner, V. G., Sludskii, A. A. (1972). Mlekopitaiuščie Sovetskogo Soiuza. Vysšaia Škola, Moskva. (in Russian; English translation: Heptner, V. G.; Sludskii, A. A.; Bannikov, A. G.; (1992). Mammals of the Soviet Union. Volume II, Part 2: Carnivora (Hyaenas and Cats). Smithsonian Institution and the National Science Foundation, Washington DC). pp. 95–202. In the winters of 1970–1973, Yudakov and Nikolaev recorded one case of a brown bear showing no fear of the tigers and another case of a brown bear changing its path upon crossing tiger tracks. Other researchers have observed bears following tiger tracks to scavenge tigers' kills or to prey on tigers. Bears frequently track down tigers to usurp their kills, with occasional fatal outcomes for the tiger. A report from 1973 describes 12 known cases of brown bears killing tigers, including adult male tigers; in all cases the tigers were subsequently eaten by the bears. There are reports of brown bears specifically targeting Amur leopards and tigers to appropriate their killsIn the Sikhote-Alin Reserve, 35% of tiger kills were stolen by bears, with the tigers either departing entirely or leaving part of the kill for the bear. A mother grizzly bear and her cubs threatened by a pack of gray wolves, which reportedly did not or could not harm the cubs in this instance.

Brown bears regularly intimidate gray wolves (Canis lupus) away from their kills, with wolves occurring in most of the brown bear's worldwide distribution. In Yellowstone National Park, brown bears pirate wolf kills so often, Yellowstone's Wolf Project director Doug Smith wrote, "It's not a matter of if the bears will come calling after a kill, but when." Similarly, in Denali National Park, grizzly bears routinely rob wolf packs of their kills. On the contrary, in Katmai National Park and Preserve, wolves, even lone wolves, may manage to displace brown bears at carrion sites.Smith, T. S., Partridge, S. T., & Schoen, J. W. (2004). Interactions of brown bears, Ursus arctos, and gray wolves, Canis lupus, at Katmai National Park and Preserve, Alaska. The Canadian. Despite the high animosity between the two species, most confrontations at kill sites or large carcasses end without bloodshed on either side. Although conflict over carcasses is common, on rare occasions the two predators tolerate each other on the same kill. To date, there are only a few cases of fully-grown wolves being killed by brown bears and none of wolves killing healthy adult brown bears.Ballard, W. B. 1980. Brown bear kills gray wolf. Canadian Field-Naturalist 94:91.PDF. Given the opportunity, however, both species will prey on the other's cubs. Conclusively, the individual power of the bear against the collective strength of the wolf pack usually results in a long battle for kills or domination. In some areas, the grizzly bear also regularly displaces cougars (Puma concolor) from their kills, with some estimates showing cougars locally lose up to a third of their dietary energy to grizzly bears. Cougars kill small bear cubs on rare occasions, but there was one report of a bear killing a cougar of unknown age and condition between 1993 and 1996.ADW: Ursus arctos: Information . Arlis.org. Retrieved 9 August 2012.Hornocker, M., and S. Negri (eds.) (2009). Cougar: ecology and conservation. University of Chicago Press. Chicago, Illinois, . Eurasian lynx (Lynx lynx), the largest type of lynx and the only one to regularly take large prey, is similarly an habitual victim of kleptoparasitism to brown bears throughout Eurasia. Brown bears also co-exist with leopards (Panthera pardus) (in very small remnant wild parts of the Middle East, Jammu and Kashmir, northeastern China and the Primorsky Krai) and snow leopards (Panthera uncia) in several areas of northern central Asia and the Tibetan Plateau). Although the brown bears' interactions with these big cats are little-known, they probably have similar relationships as grizzly bears do with cougars in North America. Snow leopards and Tibetan blue bears are verified, however, to be a threat to one another's cubs.Mallon, D. (1984). The snow leopard in Ladakh. International pedigree book of snow leopards, 4, 23–37.Xu, A. (2007) Status, conservation and some ecological aspects of sympatric Tibetan brown bear and snow leopard on the Qinghai-Tibetan Plateau, China. PhD thesis, Northeast Normal University, Changchun, China. Smaller carnivorous animals are dominated by brown bears and generally avoid direct interactions with them, unless attempting to steal scraps of food. Species which utilize underground or rock dens tend to be more vulnerable to predatory attacks by brown bears. Several mustelids, including badgers, are not infrequently preyed upon and seemingly even arboreal martens may be attacked (especially if unhealthy or caught in furbearer traps). In North America, both species of otter (North American river and sea) have been known to be ambushed by brown bears when on land.COSEWIC. (2012). COSEWIC assessment and status report on the Grizzly Bear Ursus arctos in Canada . Committee on the Status of Endangered Wildlife in Canada. Ottawa. On the contrary, wolverines (Gulo gulo) are known to have been persistent enough to fend off a grizzly bear as much as 10 times their weight from a kill. In some rare cases, wolverines have lost their lives to grizzly bears and wolverines in Denali National Park will reportedly try to avoid encounters with grizzlies. Beyond wolves, other canids may occasionally be killed around their den, most likely pups or kits, or adults if overly incautious near a carrion site, including coyotes (Canis latrans), multiple species of foxes and raccoon dogs (Nyctereutes procyonoides).Sillero-Zubiri, C., Hoffmann, M., & Macdonald, D. W. (Eds.). (2004). Canids: foxes, wolves, jackals and dogs: status survey and conservation action. IUCN. Medium-sized cats may also be rarely killed by brown bears.IUCN/SSC Cat Specialist Group, Kristin Nowell, Peter Jackson. (1996). Wild Cats: Status survey and conservation action plan. Cambridge, UK: IUCN Publication Services Unit. Seals are on rare occasions killed by brown bears, including eyewitness accounts of Russian bears ambushing spotted (Phoca largha) and harbor seals (Phoca vitulina). Consumption of ringed (Pusa hispida) and bearded seal (Erignathus barbatus) has been reported in the Mackenzie river delta, presumably via predation or scavenging of polar bear kills, as pinnipeds are not usually encountered as carrion from land.National Oceanic and Atmospheric Administration (2009). Status Review of the Spotted Seal (Phoca largha). NMFS-AFSC-200. Springfield, VA: Department of Commerce. Brown bears usually dominate other bear species in areas where they coexist. Due to their smaller size, American black bears (Ursus americanus) are at a competitive disadvantage to brown bears in open, unforested areas. Although displacement of American black bears by brown bears has been documented, actual interspecific killing of American black bears by brown bears has only occasionally been reported. Confrontation is mostly avoided due to the American black bear's diurnal habits and preference for heavily forested areas, as opposed to the brown bear's largely nocturnal habits and preference for open spaces. Where they do not live in close proximity to grizzly bears, and especially where found near human habitations, American black bears may become, to a larger extent, nocturnal. Brown bears may also kill Asian black bears, though the latter species probably largely avoids conflicts with the brown bear due to similar habits and habitat preferences to the American black species. Brown bears will eat the fruit dropped from trees by the Asian black bear, as they themselves are too large and cumbersome to climb.The Intellectual observer: review of natural history, microscopic research, and recreative science, Groombridge, 1865 Improbably, in the Himalayas, brown bears are reportedly intimidated by Asian black bears in confrontations. However, the Himalayan black bears are reportedly more aggressive towards humans than the Himalayan brown bear, and the latter is one of the smaller types of brown bear, though still somewhat larger than the Asian black bear. In Siberia, the opposite is true, and Asian black bears are not known to attack people, but brown bears are. Both species of black bear seem to be most vulnerable to predatory attacks by brown bears when the latter species leaves hibernation sooner in early spring and ambushes the smaller ursids in their dens. There has been a recent increase in interactions between brown bears and polar bears (Ursus maritimus), theorized to be caused by climate change. Brown bears have been seen moving increasingly northward into territories formerly claimed by polar bears. Despite averaging somewhat smaller sizes, brown bears tend to dominate polar bears in disputes over carcasses,O'Hara, Dough (24 April 2005) Polar bears, grizzlies increasingly gather on North Slope. Anchorage Daily News. and dead polar bear cubs have been found in brown bear dens. Large herbivores, such as moose, bison and muskox may have an intolerance of brown bears due to their possible threat to vulnerable members of their herds or themselves; moose regularly charge grizzly bears in their calf's defense, but seldom are the bears killed. Bison have been known to fatally injure lone grizzly bears in battles, and even a mountain goat (Oreamnos americanus) was observed to do so with its horns, although herbivores are rarely a serious danger to brown bears. A reconstruction of the cave bear, a close relative of the brown bear that coexisted throughout its evolutionary history

The link

https://www.gbif.org/species/113276597
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Switzerland Spalea Offline
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" It was a year ago this month that we captured this incredible, although graphic, video of a black bear attacking a sounder of pigs, only to have the lead sow return into frame and run off the bear in attempt to save her screaming piglet from the veritable jaws of death. Since then, this video has been viewed well over 1 million times and remains the most remarkable behavioral capture ever recorded by our traps on Tejon. It cannot be overstated how unlikely it is to capture such a dramatic encounter within the finite frame and capture window of our camera traps. Although this predatory behavior is well known in black bears there remains very few recordings of them actively hunting in this way. Despite its violent imagery and disturbing sound, this video is a remarkable testament of the strength and agility of the black bear as a top predator as well as the fearlessness and maternal instinct of the sow as a mother and group leader."


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Romania ApexKing17 Offline
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Two adult male elks killed by one black bear


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https://www.jstor.org/stable/1378446?cookieSet=1&seq=1
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Coexistence in a Crowded World: Brown Bears and Livestock Depredation
By Kimberly Rigano
Introduction
People have a history of exploiting carnivore populations. Humans view carnivores as dangerous thieves. In reality, humans and carnivores are just species which happen to share similar needs for high calorie diets and large amounts of land bringing us into competition with one another. This competition often involves food resources and in particular livestock. Bears are particularly large predators with voracious appetites. Conflict between bears and humans is a worldwide problem occurring in “hotspots” where anthropogenic attractants and bear habitat overlap. Conflict is actually increasing in many areas where bears were once eliminated and have now been reintroduced or are expanding their populations. This is in part due to re-growth of forested areas throughout North America providing increased bear habitat. Conflict involving livestock depredation may also be attributed to modern livestock management. People no longer practice traditional methods of livestock management and as a society have effectively forgotten how to coexist with bears.
What is Causing Bears to Attack Livestock?
Bears are omnivores meaning that they will eat a variety of foods from plant matter to insects and meat. They are also hibernators and must consume huge amounts of food during the fall to gain enough weight to survive winter. During this time they can gain over 3 lbs each day (6). Because bears have such high resource demands, it may appear that bears kill livestock out of necessity to fulfill their daily energy requirements. However, in most areas, their diet consists of over 90% vegetation, and depredation does not correlate with the abundance of natural resources indicating that bears do not attack livestock because they are lacking natural sources of food. Data on livestock losses in Europe show that depredation is not the result of large carnivore populations either, as the small population of 25 to 55 bears in Norway kill more livestock than the more than 2,000 bears in Sweden (4).
Instead, attacks on agricultural animals are related to livestock management. Bone yards where ranchers deposit carcasses are the main attractant associated with bear conflict. Certain livestock operations are also more high risk than others. In almost every country where bears and sheep exist together, sheep account for the majority of livestock killed by bears. Sheep are smaller and more vulnerable than cattle with their only defense being their strong flocking instincts. Lambing and calving areas also have high probabilities of bear predation because newly born animals are easy prey. Other livestock management characteristics correlated with high predation rates include animals which are untended for long periods and those that are left out at night when the majority of bear attacks occur.
Another major factor associated with predation is habitat. Most depredation events occur near forest cover with permanent sources of water because this is ideal bear habitat which often overlaps with livestock grazing. In Norway, high levels of depredation are correlated with a large number of sheep grazed near forested areas overnight (4). In the Himalayan Mountains, the majority of sheep are killed during the fall hyperphagic period when bears have an insatiable appetite to gain weight before hibernation. However, the fall was also when sheep were moved into higher elevation alpine meadows where bears in this region reside. Depredation was also associated with lack of human presence (2). In many countries in Europe, people have abandoned their traditional lifestyles of living with and protecting livestock. Today, bear populations are on the rise, especially in Europe and specific areas of the U.S. such as the Northern Continental Divide Ecosystem in Idaho and Montana and Yellowstone National Park, but people remain resistant to changes in livestock management.
Is Depredation a Learned Behavior?
Livestock are an easily accessible food source compared to their wild counterparts. Thus, when bears come in contact with livestock, they often kill more animals than they can eat leaving carcasses behind. Bears are opportunistic feeders, so this is normal adaptive behavior for them as it is advantageous to kill multiple animals at once when predation is easy. This occurs less in the wild because multiple kills are typically difficult with wild ungulates (6). Near Yellowstone, all bears that had access to sheep attacked them. Of the 37 bears collared, only four returned to the same areas at the same time of year after predating livestock (5). All bears that killed livestock exhibited normal foraging behavior similar to that of other bears. This indicates that killing livestock is not a unique behavior that’s only learned by a few problem bears. Livestock depredation is the result of easy foraging opportunities.
There is evidence to suggest that bears do learn some foraging behaviors from their mother. However, in Yellowstone, yearling offspring of problem bears that were then separated from their mother were not more likely to kill livestock than cubs of non-conflict bears, so this is not a behavior acquired during the first year of life. Also, bear depredation is usually concentrated in a few hotspots, and predation rate does not decrease when a few problem bears are removed (6). This indicates that predation is more strongly correlated to habitat attributes. Males are implicated in depredation events more than females. This may be due to the tendency for males to travel more and the greater likelihood for them to come into contact with livestock. There also may be something intrinsic about male behavior that causes them to attack livestock such as boldness or aggression. Yet, few studies have been done on personality differences between conflict and non-conflict bears. Larger male body size and dietary requirements also may cause them to search for food with more protein than females. All bears that attacked full-grown cattle outside of Yellowstone were adult males (5). Bears of all age classes killed sheep, but juveniles exhibited less caution in doing so and were caught and killed more often as a result. One yearling and juvenile male in Wyoming together killed over 30 sheep in one night (6). Adult bears typically kill one or two sheep on the outer edges of the herd and are thus better at avoiding herders. Bears may learn to improve their ability to kill livestock without getting caught. This may mean that juveniles do not necessarily predate livestock at a higher rate; they may just get caught more.

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Implications
One of the most significant implications of livestock depredation is that it decreases public support for bear conservation which can impact on the probability of survival for bear populations. In fact, plans to reintroduce bears to the Bitterroot Mountains in Idaho were abandoned due to public opposition. For ranchers and livestock owners, hostility toward carnivores, and in particular bears, originates from financial losses incurred by bear predation. Bears do not actually account for a large percentage of overall livestock losses, typically less than 1%, but locally losses can be significant. In Montana, 75% of documented conflict events occurred in “hotspots” that comprised only 8% of the study area (10). On the Upper Green River Cattle Allotment in western Wyoming, uncompensated financial impacts from 1995–2004 due to grizzly bear attacks on calves were $222,500 (9). In the Targhee National Forest twice as many sheep were lost as a result of herding practices as those killed in bear attacks, and yet most livestock managers believe carnivores pose the greatest threat to their animals (5).
Depredation also results in the death of bears when individuals are killed by ranchers as well as legally by the Fish and Wildlife service. Thus, conflict over livestock is a significant source of mortality for brown bears especially in the small, isolated populations such as those that exist in the lower 48 states. Approximately 7% of all human‐caused grizzly bear mortalities between 1998 and 2011 in the Northern Continental Divide Ecosystem were due to management removal actions associated with livestock depredations. At least 51 of 89 management removals were due to attractants such as carcasses that could have been avoided (7). These high removal rates do not always prevent livestock depredation and often result in individual bears being killed that were not involved in the conflict.
Ways to Prevent Livestock Depredation

Change Bear Behavior
Because bears are threatened in the continental U.S., it is important to find nonlethal methods to prevent livestock depredation. Translocating bears involved in livestock attacks to another area may be effective, but may not be desirable as it is stressful for the bear and results in the removal of a reproductively fit individual from the population. Data also indicates that this may not be feasible in areas such as those around Yellowstone where most individuals attack sheep when given the opportunity. Electric fences are expensive and break if not properly maintained. Also, they’re not compatible with sheep grazing because herders have to move their animals throughout the year. Electric fences also produce undesirable effects such as injury and isolation of other wildlife.
Guard dogs can be effective when trained correctly. Properly guarded livestock in the Cantabrian Mountains in Spain and Abruzzo, Italy suffered lower losses than unguarded animals (6). Annual savings due to the use of a livestock protection dog for ranchers from 16 states and 2 Canadian provinces were anywhere from $180 to $14,447 (3). Unfortunately, most of these programs provide livestock owners with puppies, and  herders may not have the expertise or the time required for effective training. This can result in aggressive dogs which are a danger to the livestock they were supposed to protect. Aversion techniques using light or noise have been tried but are nearly impossible with bears because they have to be applied right after the behavior and must be highly variable as bears habituate to these stimuli.

*This image is copyright of its original author

Change Livestock Management
A more effective way to prevent depredation is to change the way humans manage livestock. This includes minimizing bone yards and sheep grazing as this has been shown to be incompatible with large carnivore populations. The majority of bear predation occurs at night, so bringing livestock into enclosures or barns at night may reduce attacks. However, these enclosures need to be bear-proof as bears can cause considerable damage if they are able to get into pens causing the sheep to panic and die as a result of crowding and suffocation (4). There is also increased risk when humans are minimally involved with the herds. In the Himalayan Mountains, predation increases when sheep and cattle are left to graze near bear habitat untended for 3 to 5 months (2). Therefore, increased human presence could help reduce conflict. An alternative to protecting livestock within bear habitat is to move high risk operations such as sheep grazing and lambing and calving areas away from key bear habitat. This would involve moving livestock from forested areas as well as rivers and streams. The combination of using off-site water sources along with limiting attractants successfully reduced livestock depredation by bears in Montana (7). However, this requires livestock managers to provide artificial sources of shade for their animals and transport water from off-site locations and may not be realistic for managers with smaller plots of land or in protected areas where grazing is regulated. In areas within one-third of a mile from the electrical grid, an electrical pump is a feasible, cost effective option for transporting water. For 100 cattle, initial costs plus annual electricity was estimated at just under $1000. For areas farther from the electricity, more costly methods are required. A solar powered system to provide water for 100 cattle will cost up to $10000 plus labor to install (8).
Another way to prevent predation without demanding more of livestock managers is to make the livestock themselves more self-sufficient. Flerds may be an effective methods. Flerds are a grazing group of mixed species. Typically, pairing cattle with sheep or another vulnerable animal has been used to prevent predation. The concept of mixed stocking has been around since humans started managing grazers, and research on it began over a hundred years ago.Yet, its use in predation prevention with large carnivores was first proposed in the mid-1980s. The process of creating a flerd involves penning lambs with young cattle to create a bond. In initial trials in New Mexico, no sheep were killed as a result of predation after 30 days of penning with cattle while the rate of predation on non-bonded sheep was 1 every 5 days. A longer initial housing period will result in a stronger bond; however, sheep have become bonded to cattle in as little as 14 days (1). The sheep remain with the cattle at all times and will follow the movements of any cattle, not just those that they were originally housed with. Thus, after the initial housing period where feed is the main cost, this is a relatively easy management strategy. One or more bonded ewes can be used to facilitate the bonding of additional sheep. It is ideal to form a core flerd and then add single individuals to it over time. This system works because of the strong influence of peer behavior on sheep, goats, and other small ruminants.
Flerds have also been shown to improve foraging efficiency of individuals and increase vegetation heterogeneity since species have variable diets and utilize different parts of the land. Sheep will graze in areas that cattle will not thus utilizing a greater proportion of the pasture. Flerds also spread themselves more uniformly over the pasture than single species grazing groups. Initial start-up costs and time requirements involved in creating a flerd may be high, but long-term management declines. Less fencing can be used as cattle require fewer wires to contain them. This benefits wildlife by creating fewer barriers and livestock managers by bringing down costs. Over a quarter mile of fencing, adding two extra wires can cost an additional $66. When miles of fencing are required, savings can be significant (1).

*This image is copyright of its original author

Summary
Bear attacks on livestock account for a small percentage of total livestock losses. However, depredation events are increasing in areas where bear populations are expanding their range, and livestock depredation greatly reduces public support for bear conservation. It also results in high mortality in some areas where bears involved in depredation are killed by humans and thus represents a serious threat to survival. Data indicates that livestock predation is not a learned behavior, but is instead the result of an innate tendency for bears to exploit easy foraging opportunities. Livestock at high risk of bear attacks include sheep grazed in key bear habitat as well as animals which are left untended for long periods of time and left in open pastures as night. Changing the behavior of a wild carnivore is difficult, so techniques which alter livestock management may be more effective measures of preventing depredation. These include enclosing livestock and moving them away from bear habitat. Flerds may represent a revolutionary idea for preventing depredation.

https://appliedbehavior.wordpress.com/behavior-projects/bear-livestock/
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Predator-prey relationships between rocky mountain elk and black bears in northern New Mexico

Abstract
We conducted a 4-year study (2009–2012) evaluating the role of predation and nutrition in limiting the productivity of an elk (Cervus elaphus) population in northern New Mexico. In the years leading up to the initiation of the study, we observed low (<25:100) calf:cow ratios, suggesting calf recruitment was lower than desired. We sought to identify the reason for low recruitment by assessing the role of predation and nutrition in the population. We captured and fixed ear-tag radio transmitters to 245 elk calves (126M, 119F) to determine cause specific mortality. We quantified summer calf survival using Program MARK and annual survival using Cox Proportional Hazards models. During the second half of our study, we implemented spring black bear (Ursus americanus) harvest that included supplemental take by New Mexico Department of Game and Fish personnel and evaluated the response in calf survival. Across all years of our study we quantified how risk of mortality varied for juvenile elk both spatially and temporally by comparing the landscape surrounding black bear and mountain lion predation sites to sites where elk calves were captured. Simultaneously, we captured 9 black bears in 2011 and 2012 and equipped them with Global Positioning System (GPS) collars to quantify patterns of landscape use. Global positioning collars deployed on black bears obtained multiple locations per day and we evaluated bear habitat use in relation to presence of elk calves on the landscape. We also assessed the nutritional condition of adult female elk by quantifying herd-wide percent ingesta-free body fat (IFBF) and pregnancy rates. To achieve this, sport hunters harvested adult female elk from autumn through winter 2009–2012. We estimated autumn ingesta-free body fat (IFBF) using the Kistner subset score when possible (n = 1,130) or the kidney fat mass method (n = 284) when the Kistner score was not possible. We developed a set of models to explain IFBF of females through autumn and winter. The primary cause of death for calves across all years was black bear predation (57 of 140 non-anthropogenic mortalities). Predation was the primary cause of death for juveniles during their first 3 weeks of life, resulting in 84 of 92 non-anthropogenic mortalities. During this time, black bears were the primary predator (n = 49), but coyotes (Canis latrans, n = 26) and mountain lions (Puma concolor, n = 4) were also predators. Black bear and mountain lion predation sites had higher percent canopy cover (64%, 95% CI=0.531–0.741) than capture sites (19%, 95% CI=0.152–0.220). For every 1% increase in canopy cover, a site was approximately 2 times more likely to be a black bear or mountain lion predation site than a capture site. We suspect that increased predation pressure in the forest edge environment likely influenced selective pressure on maternal elk to choose more open habitats postpartum because they were less risky for juvenile elk early in life. Annual calf survival was greater when spring black bear harvest was moderate to heavy (0.44–0.47) compared to low (0.33–0.35). For every additional bear harvested in spring, radio-tagged elk calves were 2.6% more likely to survive the summer. Though black bear predation is typically considered an additive form of mortality, when we only considered Ursid predation patterns we observed this predation on calves to be dependent on the size of the calf (P = 0.0403, P = 0.00251). This size-dependent predation suggests that ursid predation on elk calves may not have been entirely additive during our study. Black bears fixed with GPS-collars used a variety of vegetation types, demonstrating the generalist nature of black bears in New Mexico. Despite having a small sample size of GPS-collared bears during the calving season (n = 4), we found that black bears tended to have smaller home ranges that overlapped the calving area to a greater extent during the calving season compared to other seasons. This suggests that it is possible that black bears are keying in on elk calves during the calving period. Adult female elk were harvested by sport hunters from October through March 2009– 2012 (n = 1,808). Across years and age classes 82% (SE = 1%) of females were pregnant. Pregnancy rate was greatest for prime aged (2–14 years) females (88%, SE = 1%) and lower for young (<2 years, 11%, SE = 4%) and senescent (>14 years, 47%, SE = 5%) females (χ2 = 267.3, P < 0.001). Our herd-wide estimate of autumn IFBF was 11.41% (SE = 0.19) but varied by age class, pregnancy status, and lactation status. Prime-aged females that were pregnant had greater autumn IFBF (12.51%, SE = 0.51%) than females that were not pregnant (9.95%, SE = 0.21; F1,725 = 88.09; P < 0.001). Ingesta-free body fat decreased as winter progressed (F1,1408 = 58.37; P<0.001), with body fat being an average of 1.29% lower during winter than autumn, but this also depended upon age class and lactation status. We found that IFBF was best explained by a model incorporating both environmental (winter severity and harvest unit) and biological (pregnancy status, lactation status, herd-wide calf survival, and age) covariates. The range of variables deemed significant underscores the importance of considering multiple factors that may influence a large herbivore population and IFBF of adult females in particular. Simple models (those with a single predictor variable) performed worse than models that were more complex, suggesting that IFBF is influenced by a combination of environmental and biological factors. Low calf recruitment despite adequate condition and nutrition of adult females in the study area suggested that substantial black bear predation was limiting population productivity. Despite observing black bear predation that may have been partially compensatory, when spring bear harvest was heavy calves were 1.5 (95% CI = 0.97–2.32) times more likely to die compared to when black bears were heavily harvested (P = 0.068). Results from our study suggest that productivity could be increased by implementing a spring black bear harvest strategy, targeting hunting or removal efforts near calving areas. However, we were unable to sustain higher spring black bear harvest with hunter effort alone. We recommend that a combination of analysis of IFBF on hunter harvested adult female elk and an assessment of cause-specific neonatal survival can be used to assess the limiting nature of predation and nutrition in many settings.

https://www.researchgate.net/publication/314079225_Predator-prey_relationships_between_rocky_mountain_elk_and_black_bears_in_northern_New_Mexico
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Account from the book, Man meets grizzly : encounters in the wild from Lewis and Clark to modern times


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Grizzly bear killed a bison bull and ate him



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https://archive.org/details/manmeetsgrizzlye00youn/page/60/mode/2up
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Finland Shadow Offline
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Small looking bear and big moose... at 1:10 picture quality gets better




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( This post was last modified: 04-01-2020, 05:13 PM by Shadow )

Photo from Sweden, brown bear chasing bull moose, July 2019. It´s not too often that people are able to film or take photos from these cases.


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Text from article, translated to English:

" Here the bear hunts moose in front of Ludwig's camera: "Shock experience"

UPDATED AUGUST 1, 2019 PUBLISHED JULY 31, 2019

Ludvig Emmoth had placed a tile camera near his cabin outside Gällivare to find out if there were moose in the area - but the forest turned out to have more inhabitants.

It was Monday that Gällivarebon Ludvig Emmoth placed a tile camera in the hunting fields around his cabin a mile west of Gällivare. The reason was that salt stones were previously placed to attract moose to the area - and with a tile camera you could confirm if there are moose.

The camera is connected to Ludwig's and his dad's phones and on Wednesday morning a text message came that something was stuck on the camera at 02.18.

- I thought it was a fox or a reindeer, but then I saw that it was a bear chasing a large moose bull, says Ludvig Emmoth.

"A shock experience"

Just an hour before the photo was taken, Ludvig Emmoth and some others had been in the cabin and chopped wood and fixed it.
- It was a bit of a shock experience.

He says that there have been bears in the area before, but that more and more tracks and droppings have appeared in recent years.
[i]Does this affect the moose hunt?[/i]

- There are some shared opinions about it. Some people think that where there is a bear, there are moose, but others see it on the contrary.

"Some will find it difficult to pick berries"

He says that he and his dad received a huge response to the image after sharing it on social media.

- We have a lot of family, relatives and friends who tend to be there in the cabin and some may think it is difficult to pick berries there now.
- But it will probably be an eye opener now, that there is a bear living in the areas.[color=var(--color-grey-darkest)]"[/color]

[color=var(--color-grey-darkest)]https://www.svt.se/nyheter/lokalt/norrbotten/har-jagar-bjornen-alg-mitt-framfor-ludvigs-kamera-chockupplevelse[/color]
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