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Post by brobear on Dec 31, 2019 17:55:45 GMT -5
bearwithus.org/8-bears-of-the-world/?fbclid=IwAR0kx4pDGjKN6r4l6K07C1ahnw_BM7-4Aq0qkx4ygqX9QdxmD8D1F-tysuI 2-Brown Bear – Ursus Arctos – Several subspecies. The Brown Bear can be found in Alaska, western Canada,and parts of Washington, Montana and Wyoming. Small individual populations are scattered throughout parts of Europe and Asia. Russia has a healthy population of brown bears currently. Brown bears range in colour from almost black, brown to very light brown or blonde. Size varies greatly depending on geographic location and general food availability. The largest bears, the “Big Browns” exist along the coast of Alaska and Russia growing to very large sizes rivaling that of the Polar Bear. The interior bears of the North American Rocky Mountains (Grizzly Bear) and the mountains of Europe tend to be much smaller. The really big bears (1500pounds/700kg and bigger) are now very rare.Credit -text- Mike McIntosh, photographs of brown bears – Charlie Russell-www.cloudline.ca .
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Post by brobear on Feb 27, 2020 14:52:47 GMT -5
bioweb.uwlax.edu/bio203/f2013/hackfort_dawn/classification.htm Classification Domain: Eukarya Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Carnivoria Family: Ursidae Genus: Ursus Species: Ursus arctos Eukarya The grizzly bear is in the domain Eukarya. It is classified in this domain because it is a Eukaryote. All Eukaryotes have cells, a nucleus, and other membrane bound organelles (Wallace, 1997). Animalia They are in the kingdom Animalia because they are eukaryotic, multicellular, heterotrophic, motile, and they lack rigid cell walls (Wallace, 1997). Chordata They are in the phylum Chordata because they are deuterostomes (develop anus-first) and they possess a notochord and a tail (Wallace, 1997). Mammalia Grizzly bears are in the class Mammalia because they have hair, three middle ear bones, sweat glands (and mammary glands if they are females), a four-chambered heart and a neocortex. The neocortex is a portion of the brain located in the outer layers of the cerebral cortex involved in reasoning, sensory perception, thought and language (Wallace, 1997). Carnivoria They are in the order Carnivoria because they are flesh-eating organisms with sharp teeth and claws (Wallace, 1997). Ursidae They are in the family Ursidae because they are caniforms (dog-like carnivorians) with long snouts and non-retractile claws (Wallace, 1997). Ursus They are in classified in the genus Ursus, because they are a type of bear with large bodies, long hair, and short legs and tails (Wallace, 1997). Ursus arctos The scientific name for the grizzly bear, Ursus arctos, comes from the Latin word, ursus, meaning bear and the Greek word, arctos, also meaning bear (Wallace, 1997). The closet relative to the grizzly bear is the polar bear. The grizzly and the polar bear are sister taxa. Sister taxa simply mean that they are the closest living relatives of each other. The phylogenetic tree below is based on the Ursidae family. The members of the Ursidae family are all caniforms, as stated earlier. Polar bears recently diverged from grizzly bears, approximately 4-5 million years ago (Phylogeny, 2011).
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Post by brobear on Mar 9, 2020 1:21:17 GMT -5
www.gbif.org/species/113276597 Ursus arctos Linnaeus, 1758 DESCRIPTION Brown bear claws are longer and less curved than those of black bears Color of brown bears Brown bear on a rock Brown bears are often not fully brown. They have long, thick fur, with a moderately long mane at the back of the neck which varies somewhat across the types.Swenson, J. E. (2000). Action plan for the conservation of the brown bear in Europe (Ursus arctos) (No. 18-114). Council of Europe. In India, brown bears can be reddish with silver-tipped hairs, while in China brown bears are bicolored, with a yellowish-brown or whitish collar across the neck, chest and shoulders. Even within well-defined subspecies, individuals may show highly variable hues of brown. North American grizzlies can be dark brown (almost black) to cream (almost white) or yellowish-brown and often have darker-colored legs. The common name "grizzly" stems from their typical coloration, with the hairs on their back usually being brownish-black at the base and whitish-cream at the tips, giving them their distinctive "grizzled" color. Apart from the cinnamon subspecies of the American black bear (U. americanus cinnamonum), the brown bear is the only modern bear species to typically appear truly brown. The winter fur is very thick and long, especially in northern subspecies, and can reach 11 to at the withers. The winter hairs are thin, yet rough to the touch. The summer fur is much shorter and sparser and its length and density varies geographically. Claws and feet Front paws of a brown bear Brown bears have very large and curved claws, those present on the forelimbs being longer than those on the hind limbs. They may reach 5 to and may measure 7 to along the curve.Heptner, "Sirenia and carnivora (Sea cows; Wolves and Bears)" They are generally dark with a light tip, with some forms having completely light claws. Brown bear claws are longer and straighter than those of American black bears (Ursus americanus).Bear Anatomy and Physiology from Gary Brown's The Great Bear Almanac, Lyons & Burford, Publishers, 1993 The claws are blunt, while those of a black bear are sharp. Due to their claw structure, in addition to their excessive weight, adult brown bears cannot typically climb trees as can both species of black bear, although in rare cases adult female brown bears have been seen in trees.Seryodkin, I. V. (2016). Behavior of Brown Bears During Feeding in the Sikhote-Alin. Achievements in the Life Sciences. The claws of a polar bear are also quite different, being notably shorter but broader with a strong curve and sharper point, presumably both as an aid to traveling over ice (sometimes nearly vertically) and procuring active prey.Stirling, I., & Guravich, D. (1998). Polar bears. University of Michigan Press. The paws of the brown bear are quite large. The rear feet of adult bears have been found to typically measure 21 to long, while the forefeet tend to measure about 40% less in length. All four feet in average sized brown bears tend to be about 17.5 to in width. In large coastal or Kodiak bear males, the hindfoot may measure up to 40 cm in length, 28.5 cm in width, while outsized Kodiak bears having had confirmed measurements of up to 46 cm along their rear foot.Whitaker, J. O., & Elman, R. (1996). National Audubon Society Field Guide to North American Mammals (p. 992). New York: Knopf. Brown bears are the only extant bears with a hump at the top of their shoulder, which is made entirely of muscle, this feature having developed presumably for imparting more force in digging, which is habitual during foraging for most bears of the species and also used heavily in den construction prior to hibernation.Novak, M., Baker, J.A., Obbard, M.E. & Malloch, B. (1987). Wild furbearer management and conservation in North America. Ontario Ministry of Natural Resources. Cranial morphology and size Brown bear skull Adults have massive, heavily built concave skulls, which are large in proportion to the body. The forehead is high and rises steeply. The projections of the skull are well developed when compared to those of Asian black bears (Ursus thibetanus): the latter have sagittal crests not exceeding more than 19–20% of the total length of the skull, while the former have sagittal crests comprising up to 40–41% of the skull's length. Skull projections are more weakly developed in females than in males. The braincase is relatively small and elongated. There is a great deal of geographical variation in the skull, and presents itself chiefly in dimensions. Grizzlies, for example, tend to have flatter profiles than European and coastal American brown bears. Skull lengths of Russian brown bears tend to be 31.5 to for males, and 27.5 to for females. The width of the zygomatic arches in males is 17.5 to, and 14.7 to in females. Brown bears have very strong teeth: the incisors are relatively big and the canine teeth are large, the lower ones being strongly curved. The first three molars of the upper jaw are underdeveloped and single crowned with one root. The second upper molar is smaller than the others, and is usually absent in adults. It is usually lost at an early age, leaving no trace of the alveolus in the jaw. The first three molars of the lower jaw are very weak, and are often lost at an early age. The teeth of brown bears reflect their dietary plasticity and are broadly similar to other bears, excluding the two most herbivorous living bears, the giant panda (Ailuropoda melanoleuca) and the spectacled bear (Tremarctos ornatus), which have blunt, small premolars (ideal for grinding down fibrous plants) compared to the jagged premolars of ursid bears that at least seasonally often rely on flesh as a food source. The teeth are reliably larger than American black bears, but average smaller in molar length than polar bears. Brown bears have the broadest skull of any extant ursine bear; only the aforementioned most herbivorous living bears exceed them in relative breadth of the skull. Another extant ursine bear, the sloth bear (Melursus ursinus), has a proportionately longer skull than the brown bear and can match the skull length of even large brown bear subtypes, presumably as an aid for foraging heavily on insect colonies for which a long muzzle is helpful as an evolved feature in several unrelated mammalian groups. Body size Brown bears are highly variable in size. Eurasian brown bears often fall around the middle to low sizes for the species. The brown bear is the most variable in size of modern bears. The typical size depends upon which population it is from, and most accepted subtypes vary widely in size. This is in part due to sexual dimorphism, as male brown bears average at least 30% larger in most subtypes. Individual bears also vary in size seasonally, weighing the least in spring due to lack of foraging during hibernation, and the most in late fall, after a period of hyperphagia to put on additional weight to prepare for hibernation. Therefore, a bear may need to be weighed in both spring and fall to get an idea of its mean annual weight. The normal range of physical dimensions for a brown bear is a head-and-body length of 1.4 to and a shoulder height of 70 to. The tail is relatively short, as in all bears, ranging from 6 to in length.Parker, S. P. (1990). Grzimek's encyclopedia of mammals. McGraw-Hill, New York. (set).Nowak, R. M. (1999). Walker's mammals of the world (Vol. 1). JHU Press. The smallest brown bears, females during spring among barren-ground populations, can weigh so little as to roughly match the body mass of males of the smallest living bear species, the sun bear (Helarctos malayanus), while the largest coastal populations attain sizes broadly similar to those of the largest living bear species, the polar bear. Interior brown bears are generally smaller than is often perceived, being around the same weight as an average lion, at an estimate average of 180 kg in males and 135 kg in females, whereas adults of the coastal populations weigh about twice as much. The average weight of adult male bears from 19 populations, from around the world and various subspecies (including both large- and small-bodied subspecies), was found to 217 kg while adult females from 24 populations were found to average 152 kg.
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Post by brobear on Mar 9, 2020 1:22:07 GMT -5
Continued... Ecotypes or regional populations Brown bear size, most often measured in body mass, is highly variable and is correlated to extent of food access. Therefore, bears who range in ecozones that include have access to openings, cover and moisture or water tend to average larger whereas those bears that range into ecozones with enclosed forested areas or arid, sparsely vegetated regions, both of which tend to be sub-optimal foraging habitat for brown bears, average smaller. The brown bear in northern Europe (i.e. Scandinavia, eastern Europe, western Russia), Yellowstone National Park or interior Alaska seasonally weigh on average between 115 and, from mean low adult female weights in spring to male bear mean high weights in fall. Brown bears from the Yukon Delta, interior British Columbia, Jasper National Park and southern Europe (i.e. Spain, the Balkans) can weigh from 55 to on average. These mass variations represent only two widespread subspecies, the grizzly bear in North America and the Eurasian brown bear in Europe. Due to the lack of genetic variation within subspecies, the environmental conditions in a given area likely plays the largest part in such weight variations. The grizzly is especially variable in size, as grizzlies from the largest populations, i.e. interior Alaska, with the heaviest weights recorded in Nelchina, Alaska, nearly three times heavier in males than the smallest grizzlies from Alberta, Canada's Jasper National Park. Between the sexes, the grizzlies of Nelchina average around 207 kg, whereas the Jasper grizzlies averaged about 74 kg. The enclosed taiga habitat of Jasper presumably is sub-optimal foraging habitat for grizzlies, requiring them to range widely and feed sparsely, thus reducing body weights and putting bears at risk of starvation, while in surfaces areas in the tundra and prairie are apparently ideal for feeding. Even elsewhere in Alberta, weights averaging more than twice those of Jasper grizzlies have been recorded.Mundy, K. R. D., & Flook, D. R. (1973). Background for managing grizzly bears in the national parks of Canada. Information Canada. p. 34 A gradual diminishment in body size is noted in grizzly bears from the sub-Arctic zone, from the Brooks Range to the Mackenzie Mountains, presumably because food becomes much sparser in such regions, although perhaps the most northerly recorded grizzly bears ever, in the Northwest Territories, was a large and healthy male weighing 320 kg, more than twice as much as an average male weighs near the Arctic Circle. Data from Eurasia similarly indicates a diminished body mass in sub-Arctic brown bears, based on the weights of bears from northern Finland and Yakutia. Head-and-body length in grizzly bears averages from 1.8 to while in Eurasian brown bears it similarly averages from 1.7 to.Mallinson, J. (1978). The Shadow of Extinction: Europe's Threatened Mammals. Macmillan, London. Adult shoulder height averaged 95.2 cm in Yellowstone (for any bear measured five or more years old) and a median of 98.5 cm (for adults only 10 or more years old) in Slovakia.Rigg, R., & Adamec, M. (2007). "Status, ecology and management of the brown bear (Ursus arctos) in Slovakia". Slovak Wildlife Society, Liptovský Hrádok. Standing on its hindlegs, a posture only assumed occasionally, typically-sized brown bears can reportedly range from 1.83 to in standing height. Exceptionally large inland specimens have been reported in several parts of North America, Europe, Russia and even Hokkaido. The largest recorded grizzlies from Yellowstone and Washington State both weighed approximately 500 kg and eastern European bears have been weighed in Slovakia and Bulgaria of up to 400 kg, about double the average weight for male bears in these regions. Among the grizzly and Eurasian brown bear subspecies, the largest reportedly shot from each being 680 kg and 481 kg, respectively. The latter bear, from western Russia, reportedly measured just under 2.5 m in head-and-body length. An Ussuri brown bear of Hokkaido, a relatively small-bodied population, in the snow
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Post by brobear on Mar 9, 2020 1:22:56 GMT -5
Continued... In Eurasia, the size of bears roughly increases from the west to the east, with the largest bears there native to eastern Russia.Vereschagin, N. K. (1976). "The brown bear in Eurasia, particularly the Soviet Union", in Bears: Their Biology and Management, pp. 327–335. Even in the nominate subspecies size increases in the eastern limits, with mature male bears in Arkhangelsk Oblast and Bashkortostan commonly exceeding 300 kg.Loskutov, A. V., Pavlov, M. P., & Puchkovsky, S. V. (1993). "Brown bear. Volzhsko-Kamsky region", pp. 91–135 in Vaisfeld and Chestin.Vaisfeld, M. A. (1993). "The north-east of European Russia", pp. 37–51 in Vaisfeld and Chestin. Other bears of intermediate size may occur in inland populations of Russia. Much like the grizzly and Eurasian brown bear, populations of the Ussuri brown bear (U. a. lasiotus) and the East Siberian brown bear (U. a. collaris) may vary widely in size. In some cases, the big adult males of these populations may have matched the Kodiak bear in size. East Siberian brown bears from outside the sub-Arctic and mainland Ussuri brown bears average about the same size as the largest-bodied populations of grizzly bear, i.e. those of similar latitude in Alaska, and have been credited with weights ranging from 100 to throughout the seasons.Stroganov, S. U. (1969). Carnivorous mammals of Siberia. Jerusalem, Israel: Israel Program for Scientific Translations. p. 522. On the other hand, the Ussuri brown bears found in the insular population of Hokkaido are usually quite small, usually weighing less than 150 kg, exactly half the weight reported for male Ussuri brown bears from Khabarovsk Krai. This is due presumably to the enclosed mixed forest habitat of Hokkaido.Yudin, V.G. (1993). "The Brown Bear" in Vaisfeld and Chestin A similarly diminished size has been reported in East Siberian brown bears from Yakutia, as even adult males average around 145 kg, thus about 40% less than the average weight of male bears of this subtype from central Siberia and the Chukchi Peninsula. In linear measurements and mean body mass, several subspecies may vie for the title of smallest subtype, although thus far their reported body masses broadly overlaps with those of the smaller-bodied populations of Eurasian brown and grizzly bears. Leopold (1959) described the now-extinct Mexican grizzly bear that, according to Rausch (1963), as the smallest subtype of grizzly bear in North America, although the exact parameters of its body size are not known today. Bears from the Syrian subspecies (U. a. syriacus) will reportedly weigh around 100 to in adulthood.Hamdinea, W., Thévenotb, M., & Michauxc, J. (1998). Recent history of the brown bear in the Maghreb. The Himalayan brown bear (U. a. isabellinus) is another rival for the smallest subspecies, in Pakistan this subtype averages about 70 kg in females and 135 kg in males. Himalayan brown bear females were cited with an average head-and-body length of merely 1.4 m.Prater, S. H., & Barruel, P. (1971). The book of Indian animals (Vol. 3). Bombay: Bombay Natural History Society. Brown bears of the compact Gobi Desert population, which is not usually listed as a distinct subspecies in recent decades, weigh around 90 to between the sexes, so are similar in weight to bears from the Himalayas and even heavier than grizzlies from Jasper National Park. However, the Gobi bear has been reported to measure as small as 1 m in head-and-body length, which, if accurate, would make them the smallest known brown bear in linear dimensions.Balint, P. J., & Steinberg, J. A. (2003). "Conservation case study of the Gobi bear", pp. 238–257 in Mongolia Today: Science, Culture, Environment, and Development. Psychology Press. . These smallest brown bear subtypes are characteristically found in "barren-ground" type habitats, i.e. sub-desert in bears from the Syrian subspecies and the Gobi subtype and arid alpine meadow in Himalayan brown bears. Considering pinnipeds and polar bears to be marine, the Kodiak bear is the largest(Overview page ) of the living, land-based, mammalian predators.
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Post by brobear on Mar 9, 2020 1:24:10 GMT -5
Continued...
The largest subspecies are the Kodiak bear (U. a. middendorffi) and the questionably-distinct peninsular or coastal brown bear (U. a. gyas). Also the extinct California grizzly bear (U. a. californicus) was rather large. Once mature, the typical female Kodiak bear can range in body mass from 120 to and from sexual maturity onward males range from 168 to.Troyer, W.A. & Hensel, R.J. (1969). The Brown Bear of Kodiak Island. Kodiak National Wildlife Refuge Report. U.S. Fish and Wildlife Service. Kodiak, Alaska, USA.Henkelmann, A. (2011). Predictive modeling of Alaskan brown bears (Ursus arctos): assessing future climate impacts with open access online software. PhD thesis, Lincoln University, New Zealand 21. According to the Guinness Book of World Records the average male Kodiak bear is 2.44 m in total length (head-to-tail) and has a shoulder height of 1.33 m. When averaged between their spring low and fall high weights from both localities, males from Kodiak island and coastal Alaska weighed from 312 to with a mean body mass of 357 kg while the same figures in females were 202 to with a mean body mass of 224 kg.LeFranc, M.N. (1987). Grizzly bear compendium. Washington, DC, USA: Interagency Grizzly Bear Committee. By the time they reach or exceed eight to nine years of age, male Kodiak bears tend to be much larger than newly mature six-year-old males, potentially tripling their average weight within three years' time, and can expect to average between 360 and. The reported mean adult body masses for both sexes of the polar bear are very similar to the peninsular giant and Kodiak bears. Due to their roughly corresponding body sizes, the two subtypes and the species can both legitimately be considered the largest living member of the bear family Ursidae and largest extant terrestrial carnivores. The largest widely accepted size for a wild Kodiak bear, as well as for a brown bear, was for a bear killed in English Bay on Kodiak Island in fall 1894 as several measurements were made of this bear, including a body mass of 751 kg, and a hind foot and a voucher skull were examined and verified by the Guinness Book of World Records.Carwardine, M. (2008). Animal Records. Sterling Publishing Company, Inc. Claims have been made of larger brown bears, but these appear to be poorly documented and unverified and some, even if recited by reputable authors, may be dubious hunters' claims. The largest variety of brown bear from Eurasia is the Kamchatka brown bear (U. a. beringianus). In the Kamchatka brown bears from past decades, old males have been known to reach body mass of 500 - by fall, putting the subtypes well within Kodiak bear sizes and leading it to be considered the largest of the extant Russian subtypes. However, a diminishment in body size of U. a. berigianus has been noted, mostly likely in correlation with overhunting. In the 1960s and 1970s, most adult Kamchatka brown bears weighed merely between 150 and, however, mean weights of mature male bears have been reported as averaging 350 to in 2005.
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Post by brobear on Mar 9, 2020 1:25:29 GMT -5
Continued... DIETARY HABITS Brown bear feeding on salmon
The brown bear is one of the most omnivorous animals in the world and has been recorded consuming the greatest variety of foods of any bear. Throughout life, this species is regularly curious about the potential of eating virtually any organism or object that they encounter. Certainly no other animal in their given ecosystems, short perhaps of other bear species and humans, can claim to feed on as broad a range of dietary opportunities. Food that is both abundant and easily obtained is preferred. Their jaw structure has evolved to fit their dietary habits. Their diet varies enormously throughout their differing areas based on opportunity. In spring, winter-provided carrion, grasses, shoots, sedges and forbs are the dietary mainstays for brown bears from almost every part of their distribution. Fruits, including berries, become increasingly important during summer and early autumn. Roots and bulbs become critical in autumn for some inland bear populations if fruit crops are poor. The dietary variability is illustrated in the western United States, as meat made up 51% of the average year-around diet for grizzly bears from Yellowstone National Park, while it made up only 11% of the year-around diet for grizzlies from Glacier National Park a few hundred miles to the north.
Plants and fungi Despite their reputation, most brown bears are not highly carnivorous, as they derive up to 90% of their dietary food energy from vegetable matter. Brown bears often feed on a variety of plant life, including berries, grasses, flowers, acorns (Quercus ssp.) and pine cones as well as mosses and fungi such as mushrooms. In total, over 200 plant species have been identified in their foods. Arguably the most herbivorous diets have come from the warmer temperate parts of Eurasia as more than 90% of the diet may be herbivorous. These include countries and regions such as Spain, Slovakia, most of the Balkans including Greece, Turkey, the Himalayas and presumably the Middle East. In many inland portions of North America the diet of grizzly bears is between 80 and 90% plant-based, but animal meat can be much more important in some areas.Murie, A. (2012). The grizzlies of Mount McKinley. University of Washington Press. It has been found that being restricted to a largely vegetarian diet puts constraints on the growth and size of bears who live off of them, largely because their digestive systems do not process plants as well as animal fats and proteins. Among all living bears, brown bears are uniquely equipped to dig for tough foods, such as roots and shoots. They use their long, strong claws to dig out earth to reach the roots and their powerful jaws to bite through them. For the most part, the consumed plant life in spring, predominantly roots immediately post-hibernation and grasses later in spring, is not highly nutritious for bears and mainly staves off hunger and starvation until more nutritious food is available. Brown bears have difficulty digesting large quantities of tough, fibrous foods. Hedysarum roots are among the most commonly eaten foods from throughout the range and can become important substitutes if stable foods such as fruits become unavailable. Corms and bulbs are important when available, as they are one of the greater sources of protein in plant life, as are hard masts such as acorns. Brown bears are restricted in their access to hard masts compared to American and Asian black bears because of the limited climbing abilities of grown bears and therefore are confined largely to masts fallen to the ground, pirated from other creatures or within a reach of about 3 m that the bears can stretch to with their paws extended and standing on their hindlegs. Hard masts can become the most important food (although consumed mainly in late summer and fall) where available in large quantities such as on Hokkaido, Italy and Spain. One of the most important foods in the Rocky Mountains region of the United States is the whitebark pine nut (Pinus albicaulis), which is attained perhaps a majority of the time by raiding the once-abundant caches of American red squirrels (Tamiasciurus hudsonicus) rather than direct foraging. The decline of whitebark pine nuts due to the inadvertent introduction by man of the invasive, virulent fungi Cronartium ribicola has in turn required grizzlies to seek alternative food sources, many of which are carnivorous. In a Greek food study, soft masts were found to outrank hard masts as a food source, with about a quarter of the year-around diet consisting of the legume Medicago. A grizzly bear sow and her two cubs foraging in a field for wild blueberries
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Post by brobear on Mar 9, 2020 1:26:32 GMT -5
Continued...
Fruits and berries are indispensable for brown bears in most areas as a high-energy food stuff for bears, which is necessary to survive the hibernation cycle. The variety of fruits consumed is high, with most of the well-known, wild fruiting plants in temperate North America and Eurasia attracting brown bears in late summer and fall.Ewer, R. F. (1973). The carnivores. Cornell University Press. Among the most prominent fruits found in their foods from through the range include many Prunus species including prunes and cherries, crowberries (Empetrum nigrum), pears (Pyrus ssp.), crabapples (Malus ssp.), brambles (Rubus fruticosus), raspberries (Rubus idaeus), bearberries (Arctostaphylos ssp.) (reportedly named for bears' fondness for them), blueberries (Vaccinium ssp.), lingonberries (Vaccinium vitis-idaea) and huckleberries (Vaccinium parvifolium). Fruit appears to become more secondary in the diet in areas where hard masts and animal protein are abundant in late summer and fall, as these more protein-rich foods appear to be more nutritious for bears than carbohydrate-rich fruits are, despite their fondness for fruit. Even where fruit are commonly eaten, other foods must be eaten to meet nutritional requirements. It is estimated that a small female brown bear may need to eat nearly 30,000 berries each day in late summer/fall in order to subsist on a purely fruit-based diet.
Invertebrates Brown bears will also commonly consume animal matter, which in summer and autumn may regularly be in the form of insects, larvae such as grubs and including beehives. Most insects eaten are of the highly social variety found in colonial nests, which provide a likely greater quantity of food, although they will also tear apart rotten logs on the forest floor, turn over rocks or simply dig in soft earth in attempts to consume individual invertebrates such as bugs, beetles and earthworms. Honey bees and wasps are important supplemental foods in Eurasia from the furthest west of their range, in Spain, to the furthest east, in Hokkaido. Bears in Yellowstone and Montana eat an enormous number of moths during the summer, sometimes consuming as many as 40,000 army cutworm moths (Euxoa auxiliaris) in a single day, and may derive up to half of their annual food energy from these insects. In Europe, a variety of species of ants have been found to factor heavily into the diet in some areas such as Scandinavia and eastern Europe. In Slovenia, for example, up to 25% of the dry mass consumed by brown bears was ants. Locally heavy consumption of ants has been reported in North America as well, as in west-central Alberta, 49% of scat contained ants. Brown bears mainly feed on ants with a passive response to the colony being dug out and low levels of formic acid, therefore carpenter ants (Camponotus ssp.), which are accessed through rotten logs rather than underground colonies, are preferred where available. Other important insect aggregations that brown bears feed heavily on in some regions include ladybird beetles and caddisfly. Brown bears living near coastal regions will regularly eat crabs and clams. In Alaska's Katmai National Park and Preserve, brown bears along the beaches of estuaries regularly dig through the sand for soft-shell clam (Mya arenaria) and Pacific razor clam (Siliqua patula), providing a more nutritious source of dietary energy in spring than plant life before fish become available there. The zarigani (Cambaroides japonicus), a type of crayfish, of Hokkaido is also an important, protein-rich dietary supplement for brown bears there.
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Post by brobear on Mar 9, 2020 1:27:25 GMT -5
Continued...
Fish A freshly-caught salmon is a very nutritious meal for a young Alaska Peninsula brown bear
By far the closest dietary relationship between brown bears and fish occurs between the salmon and trout of the genus Oncorhynchus, particularly in coastal areas, but also in some inland areas of North America. In the Kamchatka peninsula and several parts of coastal Alaska, including Kodiak Island, brown bears feed largely on spawning salmon, whose nutrition and abundance explain the enormous size of the bears in these areas. Sockeye salmon (O. nerka) and pink salmon (O. gorbuscha) are the two most commonly preyed upon, but many coho (O. kisutch), Chinook (O. tshawytscha), masu (O. masou) and chum salmon (O. keta) are also taken.Quinn, T. P. (2011). The behavior and ecology of Pacific salmon and trout. UBC press. Even in the coastal ranges of the Pacific, a diverse omnivorous diet is eaten, with the salmon spawning reliably providing food only in late summer and early fall. Exceptionally, salmon may come to inland rivers as early as June in the Brooks River when other coastal Alaskan bears are in their dietary "lean period" and provide food for bears sooner than normal. On Kodiak island, it appears the availability of alternative food sources is high, as berry crops are often profuse, marine organisms often wash up and ungulates both wild and domesticated are available. The fishing techniques of bears are well-documented. They often congregate around falls when the salmon are forced to breach the water, at which point the bears will try to catch the fish in mid-air (often with their mouths). They will also wade into shallow waters, hoping to pin a slippery salmon with their claws. While they may eat almost all the parts of the fish, bears at the peak of spawning, when there is usually a glut of fish to feed on, may eat only the most nutritious parts of the salmon (including the eggs (if the salmon is female) and the head) and then indifferently leave the rest of the carcass to scavengers, which can include red foxes (Vulpes vulpes), bald eagles (Haliaeetus leucocephalus), common ravens (Corvus corax) and gulls. Despite their normally solitary habits, brown bears will gather rather closely in numbers at good spawning sites. The largest and most powerful males claim the most fruitful fishing spots and bears (especially males) will sometimes fight over the rights to a prime fishing spot. Despite their aggressive defensive abilities, female brown bears usually select sub-optimal fishing spots to avoid male bears that could potentially threaten their cubs. One other key relationship occurs between brown bears and Oncorhynchus species occurs with the grizzly bear and the cutthroat trout (O. clarki) in the Rockies such as around Yellowstone. Here this species was consumed in considerable numbers although, like the whitebark pine nut, this food source has declined due to invasive species introduced by man, i.e. invasive trout species which are outcompeting cutthroat trout.Koel, T. M., Bigelow, P. E., Doepke, P. D., Ertel, B. D., & Mahony, D. L. (2005). Nonnative lake trout result in Yellowstone cutthroat trout decline and impacts to bears and anglers. Fisheries, 30(11), 10–19. The now-extinct California grizzly bear was also a fairly specialized Onocorhynchus predator in California's mountain streams and rivers, principally of rainbow trout (O. mykiss). Outside of Pacific-based salmonids, predatory relationships between brown bears and fish are uncommon. Predation on broad whitefish (Coregonus nasus) and longnose suckers (Catostomus catostomus) has been reported in sub-Arctic Canada and northern pike (Esox lucius) and grayling (Thymallus thymallus) in Siberia, plus other older records of brown bears hunting miscellaneous freshwater fish in Eurasia.
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Post by brobear on Mar 9, 2020 1:30:06 GMT -5
Continued... 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. A perhaps surprisingly high balance of mammalian foods consists of rodents or similar smallish mammals, as about half of the species consumed by brown bears weigh less than 10 kg on average. These may include hares (Lepus ssp.), pikas (Ochotona ssp.), marmots (Marmota ssp.), ground squirrels, chipmunks, mice, rats, lemmings and voles. Due to their propensity for digging, brown bears are able to smell out active subterranean burrows of these small mammals and either wait quietly or furiously dig away until the animals are either displaced and lunged at or are cornered in their burrows. Given that most small burrowing mammals found in cool temperate zones enter hibernation, they may be eaten most often when the brown bears exit hibernation earlier, as befits their larger size, allowing them to catch animals in torpor that may otherwise be too agile. Not only do they consume the small mammals, but they also feed on their caches, as has been recorded in grizzly bears attacking voles and northern pocket gophers (Thomomys talpoides). In some areas, caches may be the primary target when bears dig at these animal's burrows, as may be the case with Siberian chipmunks (Eutamias sibiricus), whose hoards can contain up to 20 kg of food, with the chipmunks themselves only being caught occasionally. With particular regularity, tundra-dwelling grizzlies will wait at burrows of Arctic ground squirrels (Spermophilus parryii) hoping to pick off a few of the 750 g rodents. Ground squirrel hunting is most successful in September and October, when early snow may impede the rodents' rocky escape routes. In Denali National Park, Arctic ground squirrels represent about 8% of the year-round diet of grizzly bears and are the most consistent source of animal protein for grizzlies there. An even more important dietary relationship with a small mammal occurs in the Tibetan blue bear, which is apparently the most completely carnivorous brown bear type, foraging most regularly for plateau pikas (Ochotona curzoniae), a species about one-sixth the weight of an Arctic ground squirrel. As many as 25 pikas have been found in a single bear's stomach and in Changtang, 60% of the diet consisted of pikas.Chapman, J. A., & Flux, J. E. (1990). Rabbits, hares and pikas: status survey and conservation action plan. IUCN. Where plateau pikas are absent, as in the Mustang region of Nepal, Himalayan marmots (Marmota himalayana) become the dietary staple of the bear, occurring in about half of nearly 1,000 scats. Large rodents such as beavers (Castor spp.) and North American porcupines (Erethizon dorsatum) are rare prey items, mostly due to differing habitat preferences, as well as the obvious defenses of the latter.Edwards, M. (2005). Ecology of Grizzly Bears (Ursus arctos) in the Mackenzie Delta oil and gas development area . University of Alberta, Department of Biological Sciences. Up to five species of cetaceans have been recorded as a food source in the coastal regions of Alaska, the Central Arctic and (formerly) California when beached. In most of their range, brown bears regularly feed on ungulates. In many cases, this important food source is obtained as carrion. Carrion is mostly eaten in spring, when winter snow and ice conditions (including snowslides) and starvation claim many ungulate lives. As carcasses are often solidly frozen when encountered, brown bears may sit on them to thaw them sufficiently for consumption. While perhaps a majority of bears of the species will charge at ungulates at some point in their lives, many predation attempts start with the bear clumsily and half-heartedly pursuing the prey and end with the prey escaping alive. On the other hand, some brown bears are quite self-assured predators who habitually pursue and catch large prey items, mainly ungulates. Such bears are usually taught how to hunt by their mothers from an early age. They are the most regular predator of ungulates among extant bear species. The extent of hunting behavior differs by region. For example, in Slovenia, ungulate meat was four times more likely to be obtained as carrion than through hunting, while on the contrary in east-central Alaska, live hunting of ungulates was four times more likely than scavenging of carrion. The extent of carnivory in brown bears has been proven to increase at northern latitudes. When brown bears attack these large animals, they usually target young or infirm ones, as they are easier to catch. Successful hunts usually occur after a short rush and ambush, but they may chase down prey in the open and will try to separate mother and young. Prey is usually killed when the bear grabs the rib cage over the back and delivers a bite to the back of the head, neck, face or nose. The bear may also pin its prey (usually young) to the ground and then immediately tear and eat it alive. Despite being characterized as unskilled predators with minimally-refined hunting skills, most individual bears who are routine ungulate predators have shown the ability to vary their hunting strategy and have hunting success rates comparable to other large, solitary carnivorans. Brown bears will on occasion bite or swipe at some prey in order to stun it enough to knock it over for consumption. To pick out young or infirm individuals, bears will charge at herds so the slower-moving and more vulnerable individuals will be made apparent. Brown bears may also ambush young animals by finding them via scent. Despite being characterized as a danger primarily to young, spring neonatal ungulates in the first couple of days of life, when they have undeveloped legs and cannot run at full speed, young ungulates may be pursued well into summer or fall after they have developed running abilities. Most attacks on adult ungulates occur when the prey has some variety of physical disadvantage. When emerging from hibernation, brown bears, whose broad paws allow them to walk over most ice and snow, may pursue large prey such as moose, whose hooves cannot support them on encrusted snow. Similarly, predatory attacks on large prey sometimes occur at riverbeds, when it is more difficult for the prey specimen to run away due to muddy or slippery soil. On rare occasions, most importantly when confronting unusually large, fully-grown and dangerous prey, bears kill them by hitting with their powerful forearms, which can break the necks and backs of large creatures such as adult moose and adult bison. A grizzly bear feasts on a bison carcass in Yellowstone.
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Post by brobear on Mar 9, 2020 1:33:22 GMT -5
Quote: Similarly, predatory attacks on large prey sometimes occur at riverbeds, when it is more difficult for the prey specimen to run away due to muddy or slippery soil. On rare occasions, most importantly when confronting unusually large, fully-grown and dangerous prey, bears kill them by hitting with their powerful forearms, which can break the necks and backs of large creatures such as adult moose and adult bison. A grizzly bear feasts on a bison carcass in Yellowstone.
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Post by brobear on Mar 9, 2020 1:34:16 GMT -5
Continued... 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.
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Post by brobear on Mar 9, 2020 1:35:32 GMT -5
Continued... Other vertebrates This species may eat birds and their eggs, including almost entirely ground- or rock-nesting species. Although not typically able to capture a healthy grown bird, eggs, nestlings and fledglings of large bird species can be very attractive to brown bears. Species attacked have ranged can be any size available from Aleutian terns (Onychoprion aleuticus) to trumpeter and whooper swans (Cygnus buccinator and C. cygnus). Most recorded avian prey have consisted of geese and sea ducks nesting in the lower Arctic Circle, followed by coveys of galliforms, as these birds place their nests in shallow water and on the ground as well as raise their chicks in such areas, so they are relatively more vulnerable. Large birds of prey, including sea eagles, gyrfalcons (Falco rusticolus) and golden eagles (Aquila chrysaetos), are sometimes exploited as prey if nesting in rock formations that are accessible on foot, and eagles and falcons may furiously dive at bears near their nests.Kochert, M.N., K. Steenhof, C.L. McIntyre, and E.H. Craig. (2002). "Golden Eagle (Aquila chrysaetos)". In: A. Poole, [Ed.], The birds of North America online, No. 684. Cornell Laboratory of Ornithology, Ithaca, NY. Due to their inhabitance of cooler temperate areas, reptiles and amphibians are rarely a food source and have been verified as prey only in a few cases: frogs in the Italian Alps, rat snakes in Hokkaido, grass lizards in the Amur territory and tortoises in Greece.
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Post by brobear on Mar 9, 2020 1:36:45 GMT -5
Quote: Due to their inhabitance of cooler temperate areas, reptiles and amphibians are rarely a food source and have been verified as prey only in a few cases: frogs in the Italian Alps, rat snakes in Hokkaido, grass lizards in the Amur territory and tortoises in Greece.
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Post by brobear on Mar 9, 2020 1:37:30 GMT -5
Continued... Domestic animal food sources When forced to live in close proximity with humans and their domesticated animals, bears may potentially prey on any type of domestic animal. Most type of livestock have been domesticated for millennia and have little to no anti-predator defenses. Therefore, brown bears are somewhat more likely to attack healthy adult domestic animals than they are healthy adult wild animals. Among domestic and farm animals, European cattle (Bos primigenius taurus) are sometimes exploited as prey. Cattle are bitten on the neck, back or head and then the abdominal cavity is opened for eating. In Norway, free-ranging domestic sheep (Ovis aries) are numerous and the local brown bears derive 65–87% of their dietary energy in late summer from sheep. Because of the aforementioned vulnerability, examination of Norwegian sheep remains suggest many of the sheep consumed there are adults that were killed by the bears rather than merely scavenged and thus some local farmers received partial compensation for their stock losses. In nearby northern Sweden, free-ranging sheep are not present and the bear derive their food predominantly from natural sources. Domestic horses (Equus ferus caballus), domestic goats (Capra aegagrus hircus), domestic pigs (Sus scrofa domesticus), domestic chickens (Gallus gallus domesticus) and domestic dogs (Canis lupus familaris) may be opportunistically killed in several parts of the brown bear's range as well.Ozolins, J. (2003). Action plan for the conservation of brown bear (Ursus arctos) in Latvia. State Forest Research Institute ‘‘Silava’’, Salaspils, Latvia. Plants and fruit farmed by humans are readily consumed as well, including corn (Zea mays), wheat (Triticum spp.), apples (Malus pumila), sorghum (Sorghum ssp.), melons and many species of berries. They will also feed at domestic bee farms, readily consuming both honey and the contents of the honey bee colony. Human food and trash or refuse is eaten when possible. When an open garbage dump was kept in Yellowstone, brown bears were one of the most voracious and regular scavengers. The dump was closed after both brown and American black bears came to associate humans with food and lost their natural fear of them. In other areas, such as Alaska, dumps may continue to be an attractant for brown bears.
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Post by brobear on Mar 9, 2020 1:38:12 GMT -5
Continued... 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 kills. In 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.
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Post by brobear on Mar 9, 2020 1:41:01 GMT -5
Continued... 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.
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Post by brobear on Mar 9, 2020 1:42:52 GMT -5
Continued... Paleo-ecology and interactions In the roughly 0.9 million years of its existence, brown bears have had to contend with multiple competing species, a majority of which went extinct at the end of the Pleistocene Era. In its much longer history in Eurasia, brown bears diverged from the two species of cave bear, the cave bear (U. spelaeus) and the Pleistocene small cave bear (U. rossicus), two species that it existed alongside in what is now Europe for the larger species and Central Asia and Siberia for the smaller species.Kurtén, B. (1995). The cave bear story: life and death of a vanished animal. Columbia University Press. The cave bears were similar in size to the larger forms of brown bear and polar bear alive today in terms of length, but were bulkier, with much higher-density skeletal remains and presumably rather heavier than the modern brown bear, with the cave bear about the same length as a modern Kodiak bear, but projected to be some 30% heavier.Kurtén, B. (1955). Sex dimorphism and size trends in the cave bear, Ursus spelaeus Rosenmüller and Heinroth. Pleistocene-era brown bears appear to have been somewhat larger and more carnivorous than most modern forms based on skull dimensions. The cave bears are usually deemed to have been highly herbivorous to a greater extent than the brown bear, based on examinations of stable isotopes and dental morphology. Recent studies, however, have shown that cave bears could have opportunistically adapted to a fairly omnivorous diet and consumed many herbivore carcasses. Despite this, the dietary differences and differing habitat preferences (caves, of course, being much more habitually used by the cave bears rather than by the brown bear) allowed the three Ursus to persist at the same time in different parts of Eurasia. A more dangerous competitor was encountered by brown bears upon crossing the Bering Land Bridge about 100,000 years ago in the form of the giant short-faced bear (Arctodus simus), a long-legged bear that was estimated to have weighed about twice as much on average than a modern Kodiak bear. Although at one time deemed a hyper-carnivorous predator that used its long legs to run down large prey, more recent studies have indicated that, like the modern brown bear, it was an omnivorous opportunist that probably scavenged many meals and presumably used its size and great height to intimidate large predators from kills. Until it declined along with its food sources, dwindling into extinction, the giant short-faced bear presumably prevented the brown bear from spreading south, mainly through competition but also, to some extent, predation. A single fossil ulna some 70,000-years-old found in Great Britain, deemed to come from an extremely large sub-adult Pleistocene polar bear (Ursus maritimus tyrannus), was projected to be the largest known form of the genus Ursus. However, this cannot be ruled out as an extinct population of brown bear, based on the inconclusiveness of the only known fossil. Other carnivorans during the Pleistocene that, based on their large size, were possibly occasional predators of early brown bears (at least females and cubs), were primarily big cats, including the cave lion (Panthera spelaea) and the saber-toothed cat Machairodus in Eurasia and, perhaps rarely, in southern Beringia (i.e. in northwestern North America) the American lion (Panthera atrox), the saber-toothed cat Smilodon and the scimitar-toothed cat Homotherium. Interactions with these large cats were probably not highly disparate from those that continue today between brown bears and the Siberian tiger. Unlike most of these species, the brown bear was able to survive the Quaternary extinction event that concluded the Ice Age. Presumably, this was due to its greater dietary and habitat plasticity and its adoption of a more extensively herbivorous diet, as most temperate zone herbivores that may have provided meals for more specialized large land carnivores went extinct, as the warming climate killed off their food source. It is likely that humans have caused the extinction and fragmentation of bear populations and their habitats since prehistoric times. It has been shown, for instance, that bear populations from the Greater Caucasus and the Lesser Caucasus Mountains, separated by the densely populated Transcaucasian Depression, have been matrilineally isolated since the early Holocene Era, i.e., after permanent human settlements appeared throughout the area. While hunting by early humans was a (previously underestimated) factor in many of the Quaternary extinction events, a perhaps stronger factor in the survival of this species compared to many other northern Pleistocene bears is the brown bear's stronger genetic diversity. In comparison, the cave bear appeared to enter a genetic bottleneck that started a population decline some 25,000 years before the species' extinction.
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Post by brobear on Mar 9, 2020 1:43:37 GMT -5
Continued... DISTRIBUTION Brown bears were once native to much of Asia, some parts of the Atlas Mountains of Africa and perhaps most of Europe and North America, but are now extinct in some areas and their populations have greatly decreased in other areas. There are approximately 200,000 brown bears left in the world. The largest populations are in Russia with 120,000, the United States with 32,500, Canada with around 25,000 and Romania with around 5,000. The brown bear currently occurs in the countries of Afghanistan, Albania, Andorra (recently reoccupied), Armenia, Azerbaijan, Belarus, Bhutan (possibly extinct), Bosnia and Herzegovina, Bulgaria, Canada, China, Croatia, Czech Republic (possibly only vagrants), Estonia, Finland, France, Georgia, Greece, India, Iran, Iraq, Italy, Japan, Kazakhstan, Kyrgyzstan, Latvia (extinct before World War II; possibly vagrants from Estonia or Russia after World War II), North Macedonia, Mongolia, Montenegro, India, Nepal, North Korea, Norway, Pakistan, Poland, Romania, Russia, Serbia, Slovakia, Slovenia, Spain, Sweden, Tajikistan, Turkey, Turkmenistan, Ukraine, the United States and Uzbekistan. Brown bear at Brooks Falls in Katmai National Park
North America The brown bear is usually called the grizzly bear in North America. It once ranged throughout much of the western part of the continent.Bears in the Mountain National Parks. Grizzly Bears. Parks Canada
Canada As many as 20,000 brown bears range throughout Yukon, the Northwest Territories, British Columbia and in the majority of Alberta. Canada has one of the most stable brown bear populations today. They reach their current eastern limits of their distribution in North America in a majority of Nunavut, northeastern Saskatchewan and northern Manitoba, where they range as far east as the west coast of the Hudson Bay from around Rankin Inlet south to Southern Indian Lake.
United States The brown bear has lost 98% of its habitat in the lower 48 states. About 95% of the brown bear population in the United States is in Alaska, though in the lower 48 states, they are repopulating gradually but steadily along the Rockies and the western Great Plains.Servheen, C. (1999). "Status and management of the grizzly bear in the lower 48 United States". C. Servheen, S. Herrero, and B. Peyton, compilers. Bears—status survey and conservation plan. IUCN/SSC Bear and Polar Bear Specialist Groups. IUCN, Gland, Switzerland and Cambridge, UK, pp. 50–54. The Alaskan population is estimated at 32,000 individuals. The largest populations of brown bears in the lower 48 states are found in the 23,300 square kilometre Greater Yellowstone Ecosystem and the 24,800-square kilometre Northern Continental Divide Ecosystem. The Greater Yellowstone Ecosystem of northwest Wyoming is estimated to hold about 674–839 grizzly bears, followed slightly by the Northern Continental Divide Ecosystem of northwest Montana with about 765 animals, the Cabinet-Yaak Ecosystem of northwest Montana and northeast Idaho with about 42–65 animals, the Selkirk Ecosystem of northeast Washington and northwest Idaho with only about 40–50 animals, and (even less) the North Cascades Ecosystem of north-central Washington with about five to 10 animals.Almack, J. A. (1993). "North Cascades grizzly bear ecosystem evaluation: final report". Interagency Grizzly Bear Committee (USA).Craighead, J. J., Sumner, J. S., & Mitchell, J. A. (1995). "The grizzly bears of Yellowstone: their ecology in the Yellowstone ecosystem, 1959–1992". Island Press. Group of brown bears at Brooks Falls.
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Post by brobear on Mar 9, 2020 1:44:31 GMT -5
Continued... These five ecosystems combine for a total of a maximum 1,729 wild grizzlies still persisting in the contiguous United States. Unfortunately, these populations are isolated from each other, inhibiting any genetic flow between ecosystems and creating low genetic diversity in remaining populations which can have negative long-term effects. This isolation poses one of the greatest threats to the future survival of the grizzly bear in the contiguous United States. Although there is no record of their existence in the United States east of the Rocky Mountain and Great Plains regions (except for a relic population in the Ungava Peninsula which survived until the dawn of the 20th century) in human history, fossil records from Kentucky do in fact show that grizzly bears once roamed in eastern North America.
Mexico Although many people believe some brown bears may be present in Mexico, they are almost certainly extinct there. The last Mexican grizzly bear was shot in 1976. Prior to the 1976 record, none have been seen since at least 1962.
Europe Bear watching hut in Alutaguse, Estonia. There are around 700 bears in Estonia and they are especially numerous in the Alutaguse forests.
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