Editing Brown bear (section)

==Behavior and life history==
[[File:Ursus arctos - Norway.jpg|thumb|upright|Like all bears, brown bears can stand on their hindlegs and walk for a few steps in this position, usually motivated to do so by curiosity, hunger or alarm]]

A 2014 study revealed that brown bears peaked in activity around the morning and early evening hours.<ref>{{Cite journal |last1=Ordiz |first1=Andrés |last2=Kindberg |first2=Jonas |last3=Sæbø |first3=Solve |last4=Swenson |first4=Jon E. |last5=Støen |first5=Ole-Gunnar |date=2014-05-01 |title=Brown bear circadian behavior reveals human environmental encroachment |url=https://www.sciencedirect.com/science/article/pii/S0006320714001141 |journal=Biological Conservation |volume=173 |pages=1–9 |doi=10.1016/j.biocon.2014.03.006 |bibcode=2014BCons.173....1O |issn=0006-3207}}</ref> Although activity can happen day or night, bears that live in locations where they are apt to interact with humans are more likely to be fully nocturnal.<ref>{{cite journal|author1=Klinka, D. R. |author2=Reimchen, T. E. |title=Nocturnal and diurnal foraging behaviour of brown bears (''Ursus arctos'') on a salmon stream in coastal British Columbia|journal=Canadian Journal of Zoology|volume=80|issue=#8|pages=1317−1322 |doi=10.1139/z02-123|url=http://web.uvic.ca/~reimlab/noctdibrbear.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://web.uvic.ca/~reimlab/noctdibrbear.pdf |archive-date=2022-10-09 |url-status=live|year=2002|bibcode=2002CaJZ...80.1317K }}</ref> 
In areas with little interaction, many adult bears are primarily [[crepuscular]], while yearlings and newly independent bears appear to be most active throughout the day.<ref>{{cite journal |author1=Moe, T. F. |author2=Kindberg, J. |author3=Jansson, I. |author4=Swenson, J. E. |title=Importance of diel behaviour when studying habitat selection: examples from female Scandinavian brown bears (''Ursus arctos'') |journal=Canadian Journal of Zoology |volume=85 |issue=#4 |pages=518−525 |doi=10.1139/Z07-034 |url=https://www.researchgate.net/publication/237154208 |year=2007 |bibcode=2007CaJZ...85..518M |access-date=12 December 2016 |archive-date=15 June 2020 |archive-url=https://web.archive.org/web/20200615041957/https://www.researchgate.net/publication/237154208_Importance_of_diel_behaviour_when_studying_habitat_selection_Examples_from_female_Scandinavian_brown_bears_Ursus_arctos |url-status=live }}</ref><ref>{{cite journal|author1=Kaczensky, P. |author2=Huber, D. |author3=Knauer, F. |author4=Roth, H. |author5=Wagner, A. |author6=Kusak, J. |title=Activity patterns of brown bears (''Ursus arctos'') in Slovenia and Croatia|journal=Journal of Zoology |volume=269|issue=#4|pages=474−485 |doi=10.1111/j.1469-7998.2006.00114.x|year=2006}}</ref> From summer through autumn, a brown bear can double its weight from what it was in the spring, gaining up to {{Convert|180|kg|lb|abbr=on}} of fat, on which it relies to make it through winter, when it becomes lethargic.<ref>{{cite journal|author1=Kingsley, M. C. S. |author2=Nagy, J. A. |author3=Russell, R. H. |s2cid=90555276 |title=Patterns of weight gain and loss for grizzly bears in northern Canada|journal=Bears: Their Biology and Management |volume=5 |pages=174–178|jstor=3872535|doi=10.2307/3872535|year=1983}}</ref><ref>{{cite journal|author1=Hissa, R. |author2=Hohtola, E. |author3=Tuomala-Saramäki, T. |author4=Laine, T. |author15= Kallio, H. |title=Seasonal changes in fatty acids and leptin contents in the plasma of the European brown bear (''Ursus arctos arctos'')|journal= Annales Zoologici Fennici |pages=215–224|jstor=23735612|volume=35|issue=#4|year=1998}}</ref> Although they are not full [[Hibernation|hibernators]] and can be woken easily, both sexes prefer to [[Maternity den|den]] in a protected spot during the winter months.<ref>{{cite journal|author1=Farley, S. D. |author2=Robbins, C. T. |title=Lactation, hibernation, and mass dynamics of American black bears and grizzly bears|journal=Canadian Journal of Zoology |volume=73 |issue=#12|pages=2216−2222 |doi=10.1139/z95-262|year=1995|bibcode=1995CaJZ...73.2216F }}</ref> Hibernation dens may be located at any spot that provides cover from the elements and that can accommodate their bodies, such as a cave, crevice, cavernous tree roots, or hollow logs.<ref>{{cite journal|author1=Evans, A. L. |author2=Sahlén, V. |author3=Støen, O. G. |author4=Fahlman, Å. |author5=Brunberg, S. |author6=Madslien, K. |author7=Forbert, O. |author8=Swenson, J. E. |author9=Arnemo, J. M. |title=Capture, anesthesia, and disturbance of free-ranging brown bears (''Ursus arctos'') during hibernation|journal=PLOS ONE |volume=7 |issue=#7 |page=e40520 |doi=10.1371/journal.pone.0040520 |pmid=22815757 |pmc=3398017|year=2012|bibcode=2012PLoSO...740520E|doi-access=free }}</ref>

Brown bears have one of the largest brains of any extant carnivoran relative to their body size and have been shown to engage in tool use, which requires advanced cognitive abilities.<ref>{{cite journal|author1=Deecke, V. B. |title=Tool-use in the brown bear (''Ursus arctos'')|journal=Animal Cognition|volume=15|issue=#4|pages=725–730|pmid=22367156|year=2012|doi=10.1007/s10071-012-0475-0|s2cid=9076161|url=http://insight.cumbria.ac.uk/id/eprint/1687/1/Deecke_ToolUseInTheBrownBear.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://insight.cumbria.ac.uk/id/eprint/1687/1/Deecke_ToolUseInTheBrownBear.pdf |archive-date=2022-10-09 |url-status=live}}</ref> This species is mostly solitary, although bears may gather in large numbers at major food sources (e.g., open garbage dumps or rivers containing spawning [[salmon]]) and form social hierarchies based on age and size.<ref name=":2">{{cite journal | last1 = Egbert | first1 = Allan L. | last2 = Stokes | first2 = Allen W. | url = http://www.bearbiology.com/fileadmin/tpl/Downloads/URSUS/Vol_3/Egbert_Stokes_Egbert_Vol_3.pdf | volume = 3 | pages = 41–56 | jstor = 3872753 | last3 = Egbert | first3 = A. L. | title = The Social Behaviour of Brown Bears on an Alaskan Salmon Stream | journal = Bears: Their Biology and Management | date = 16 September 1976 | doi = 10.2307/3872753 | access-date = 29 April 2011 | archive-date = 17 July 2015 | archive-url = https://web.archive.org/web/20150717075022/http://www.bearbiology.com/fileadmin/tpl/Downloads/URSUS/Vol_3/Egbert_Stokes_Egbert_Vol_3.pdf | url-status = dead }}</ref><ref>{{cite book|author=Sandell, M. |year=1989|chapter=The mating tactics and spacing patterns of solitary carnivores|title=Carnivore behavior, ecology, and evolution |pages= 164–182|publisher= Springer |isbn=978-1-4613-0855-3|doi=10.1007/978-1-4613-0855-3_7}}</ref> Adult male bears are particularly aggressive and are avoided by adolescent and subadult males, both at concentrated feeding opportunities and chance encounters. Females with cubs rival adult males in aggression and are much more intolerant of other bears than single females. Young adolescent males tend to be least aggressive and have been observed in nonantagonistic interactions with each other.<ref>{{cite journal|author1=Gau, R. J. |author2=McLoughlin, P. D. |author3=Case, R. |author4=Cluff, H. D. |author5=Mulders, R. |author6=Messier, F.|year=2004|title=Movements of subadult male grizzly bears, ''Ursus arctos'', in the central Canadian arctic|journal=The Canadian Field-Naturalist|volume=118|issue=#2|pages=239–242|doi=10.22621/cfn.v118i2.920|doi-access=free}}</ref><ref name= Dahle>{{cite journal|author1=Dahle, B. |author2=Swenson, J. E. |s2cid=67818528 |title=Seasonal range size in relation to reproductive strategies in brown bears ''Ursus arctos''|journal=Journal of Animal Ecology|volume=72|issue=#4|pages=660–667|doi=10.1046/j.1365-2656.2003.00737.x|jstor=3505643|year=2003|pmid=30893970 |bibcode=2003JAnEc..72..660D |doi-access=free}}</ref> [[Dominance (ethology)|Dominance]] between bears is asserted by making a frontal orientation, showing off canine teeth, muzzle twisting, and neck stretching, to which a subordinate will respond with a lateral orientation, by turning away and dropping the head, and by sitting or lying down.<ref name=":2" /> During combat, bears use their paws to strike their opponents in the chest or shoulders and bite the head or neck.<ref name=Egbert/>

===Communication===
{{listen
 |filename    = Yellowstone sound library - Grizzly Bear Eating - 003.mp3
 |title        = Brown bear sounds
 |description  = Brown bear sounds including huffing, jaw popping and growling
 |format       = [[Vorbis]]
 |filename2   = Yellowstone sound library - Grizzly Bear Eating - 002.mp3
 |title2       = Brown bear roars
 |description2 = Brown bears roaring over a carcass
 |format2      = [[Vorbis]]
}}

Several different facial expressions have been documented in brown bears. The "relaxed-face" is made during everyday activities, a face where the ears pointed to the sides and the mouth closed or slackly open. During social play, bears make "relaxed open-mouth face" in which the mouth is open, with a curled upper lip and hanging lower lip, and the ears alert and shifting. When looking at another animal at a distance, the bear makes an "alert face" as the ears are cocked and alert, the eyes wide open with the mouth is closed or only open slightly. The "tense closed mouth face" is made with the ears laid back and the mouth closed, and occurs when the bear feels threatened. When approached by another individual, the animal makes a "puckered-lip face" with a protruding upper lip and ears that go from cocked and alert when at a certain distance to laid back when closer or when retreating. The "jaw gape face" consists of an open mouth with visible lower canines and hanging lips while the "biting face" is similar to the "relaxed open-mouth face" except the ears are flattened and the eyes are wide enough to expose the [[sclera]]. Both the "jaw gape face" and the "biting face" are made when the bear is aggressive and can quickly switch between them.<ref name=Egbert>{{cite thesis |author=Egbert, A. L. |pages=30–35, 46 |year=1978 |title=The Social Behavior of Brown Bears at McNeil River, Alaska |publisher=[[Utah State University]] |degree=[[Doctor of Philosophy|Ph.D.]] |url=https://digitalcommons.usu.edu/etd/2101/ |access-date=25 April 2021 |archive-date=2 February 2024 |archive-url=https://web.archive.org/web/20240202162031/https://digitalcommons.usu.edu/etd/2101/ |url-status=live }}</ref>

Brown bears also produce various vocalizations. Huffing occurs when the animal is tense, while woofing is made when alarmed. Both sounds are produced by exhalations, though huffing is harsher and is made continuously (approximately twice per second). [[growling|Growls]] and [[roar]]s are made when aggressive. Growling is "harsh" and "[[guttural]]" and can range from a simple ''grrr'' to a rumble. A rumbling growl can escalate to a roar when the bear is charging. Roaring is described as "thunderous" and can travel {{convert|2|km|abbr=on}}. Mothers and cubs wanting physical contact will bawl, which is heard as ''waugh!, waugh!''.<ref name=Egbert/>

===Home ranges===
Brown bears usually inhabit vast home ranges; however, they are not highly territorial. Several adult bears roam freely over the same vicinity without contention, unless rights to a fertile female or food sources are being contested.<ref name="pasitschniak-arts1993mamsp"></ref><ref name= Dahle/> Despite their lack of traditional territorial behavior, adult males seem to have a "personal zone" within which other bears are not tolerated if they are seen.<ref name="Pearson">Pearson, A. M. (1975). ''The northern interior grizzly bear Ursus arctos L. '' Information Canada. p. 86</ref> Males always wander further than females, due to such behavior giving increasing access to both females and food sources. Females have the advantage of inhabiting smaller territories, which decreases the likelihood of encounters with male bears who may endanger their cubs.<ref name="pasitschniak-arts1993mamsp"></ref><ref name= Bellemain>{{cite journal|doi=10.1111/j.1439-0310.2006.01152.x|title=Mating Strategies in Relation to Sexually Selected Infanticide in a Non-Social Carnivore: The Brown Bear|url=http://bearproject.info/wp-content/uploads/2015/11/2006-A060-Bellemain-Mating-Strategies-in-relation-to-SSI.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://bearproject.info/wp-content/uploads/2015/11/2006-A060-Bellemain-Mating-Strategies-in-relation-to-SSI.pdf |archive-date=2022-10-09 |url-status=live|journal=Ethology|volume=112|issue=#3|pages=238–246|year=2006|last1=Bellemain|first1=Eva|last2=Swenson|first2=Jon E.|last3=Taberlet|first3=Pierre|bibcode=2006Ethol.112..238B }}</ref>

In areas where food is abundant, such as coastal Alaska, home ranges for females and males are up to {{convert|24|km2|sqmi|abbr=on}} and {{convert|89|km2|sqmi|abbr=on}}, respectively. Similarly, in [[British Columbia]], bears of the two sexes travel in relatively compact home ranges of {{convert|115|and|318|km2|sqmi|abbr=on}}. In [[Yellowstone National Park]], home ranges for females are up to {{convert|281|km2|sqmi|abbr=on}} and up to {{convert|874|km2|sqmi|abbr=on}} for males. In [[Romania]], the largest home range was recorded for adult males ({{convert|3,143|km2|sqmi|abbr=on|disp=semicolon}}).<ref>{{Cite journal|last1=Pop|first1=Ioan Mihai|last2=Bereczky|first2=Leonardo|last3=Chiriac|first3=Silviu|last4=Iosif|first4=Ruben|last5=Nita|first5=Andreea|last6=Popescu|first6=Viorel Dan|last7=Rozylowicz|first7=Laurențiu|title=Movement ecology of brown bears (Ursus arctos) in the Romanian Eastern Carpathians|journal=Nature Conservation|volume=26|pages=15–31|doi=10.3897/natureconservation.26.22955|issn=1314-3301|year=2018|doi-access=free}}</ref> In the central Arctic of Canada, where food sources are quite scarce, home ranges range up to {{convert|2434|km2|sqmi|abbr=on}} for females and {{convert|8171|km2|sqmi|abbr=on}} for males.<ref name= Novak>Novak, M., Baker, J. A., Obbard, M. E.; Malloch, B. (1987). ''Wild furbearer management and conservation in North America''. Ontario Ministry of Natural Resources.</ref><ref name= Dahle/>

===Reproduction===
[[File:Ähtärin karhut 24.jpg|thumb|Pair of mating brown bears at the [[Ähtäri Zoo]] in [[Ähtäri]], Finland]]

The [[mating season]] occurs from mid-May to early July, shifting to later in the year the farther north the bears are found.<ref>{{cite journal|author1=Herrero, S. |author2=Hamer, D. |year=1977|title=Courtship and copulation of a pair of grizzly bears, with comments on reproductive plasticity and strategy|jstor=1379352|doi=10.2307/1379352|journal=Journal of Mammalogy|volume= 58|issue=#3|pages=441–444}}</ref> Brown bears are [[polygynandry|polygynandrous]], remaining with the same mate for a couple of days to a couple of weeks and mating multiply during the mating season. Outside of this narrow time frame, adult male and female brown bears show no sexual interest in each other.<ref name="pasitschniak-arts1993mamsp"></ref><ref name= Steyaert>{{cite journal|author1=Steyaert, S. M. |author2=Endrestol, A. |author3=Hacklaender, K. |author4=Swenson, J. E. |author5=Zedrosser, A. |year=2012|title=The mating system of the brown bear ''Ursus arctos''|doi=10.1111/j.1365-2907.2011.00184.x|journal= Mammal Review|volume= 42|issue=#1|pages=12–34|bibcode=2012MamRv..42...12S }}</ref> Females mature sexually between the ages of four and eight.<ref name= Craighead/> Males first mate about a year later, when they are large and strong enough to compete with other males for mating rights.<ref name= White>{{cite journal|author1=White, D. J. |author2=Berardinelli, J. G. |author3=Aune, K. E. |year=1998|title=Reproductive characteristics of the male grizzly bear in the continental United States|jstor=3873161|journal=Ursus |volume=10|pages=497–501}}</ref> Males will try to mate with as many females as they can; usually a successful male will mate with two females in a span of one to three weeks.<ref name="Walker"/><ref name= White/> Similarly, adult female brown bears can mate with up to four, sometimes even eight, males while in oestrus (heat), potentially mating with two in a single day.<ref name= Ambarl>{{cite journal|author=Ambarlı, H. |title=Litter size and basic diet of brown bears (''Ursus arctos'', Carnivora) in northeastern Turkey|journal=Mammalia|volume=80|issue=2|doi=10.1515/mammalia-2014-0111|year=2016|s2cid=87968464}}</ref> Females come into [[oestrus]] every three to four years, with an outside range of 2.4 to 5.7 years. The [[urine marking]]s of a female in oestrus can attract several males via scent.<ref>{{cite journal|author1=Halloran, D. W. |author2=Pearson, A. M. |year=1972|title=Blood chemistry of the brown bear (''Ursus arctos'') from southwestern Yukon Territory, Canada|doi=10.1139/z72-112|pmid=5038730|journal=Canadian Journal of Zoology|volume= 50|issue=#6|pages=827–833|bibcode=1972CaJZ...50..827H }}</ref> Dominant males may try to sequester a female for her entire oestrus period of approximately two weeks, but usually are unable to retain her for the entire time.<ref name= Feldhamer/><ref name= Bellemain/> [[copulation (zoology)|Copulation]] is prolonged and lasts for over 20 minutes.<ref name= Feldhamer/><ref>{{cite journal|author1=Craighead, J. J. |author2=Hornocker, M. G. |author3=Craighead, F. C. Jr |year=1969|title=Reproductive biology of young female grizzly bears|journal= J. Reprod. Fertil. |volume=Suppl. 6|pages= 447–475}}</ref>

[[File:Grizzly Bear- Sow and cubs (5728173840).jpg|thumb|left|Grizzly bear cubs often imitate their mothers closely.|alt=A mother bear standing next to her cubs]]

Males take no part in raising cubs – parenting is left entirely to the females.<ref name= Dahle/><ref>{{Cite book |last=Corbet |first=Gordon Barclay |url=https://books.google.com/books?id=GD4_AAAAYAAJ |title=The Terrestrial Mammals of Western Europe |date=1966 |publisher=Foulis |location=London, UK |pages=52–55 |language=en}}</ref> Through the process of [[delayed implantation]], a female's fertilized egg divides and floats freely in the uterus for six months. During winter dormancy, the fetus attaches to the [[uterus|uterine]] wall. The cubs are born eight weeks later, while the mother sleeps. If the mother does not gain enough weight to survive through the winter while gestating, the embryo does not implant and is reabsorbed into the body.<ref name="Craighead">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. pp. 21–56</ref><ref>{{cite journal |name-list-style=amp |author1=Tsubota, T. |author2=Kanagawa, H. |s2cid=84359252 |year=1993|title=Morphological Characteristics of the Ovary, Uterus and Embryo during the Delayed Implantation Period in the Hokkaido Brown Bear (''Ursus arctos yesoensis'')|journal=Journal of Reproduction and Development|volume= 39|issue=#4|pages=325–331|doi=10.1262/jrd.39.325|doi-access=free}}</ref><ref>{{cite journal |name-list-style=amp |author1=Hensel, R. J. |author2=Troyer, W. A. |author3=Erickson, A. W. |year=1969|title=Reproduction in the female brown bear|jstor=3799836|journal=The Journal of Wildlife Management|pages= 357–365|volume=33|issue=#2 |doi=10.2307/3799836}}</ref> Litters consist of as many as six cubs, though litters of one to three are more typical.<ref>{{cite journal|url=http://www.bearbiology.com/fileadmin/tpl/Downloads/IBN_Newsletters/IBN_May_2005.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.bearbiology.com/fileadmin/tpl/Downloads/IBN_Newsletters/IBN_May_2005.pdf |archive-date=2022-10-09 |url-status=live |author1=Pazetnov, V. A. |author2=Pazetnov, S. V. |name-list-style=amp |year=2005|title=Female brown bear with six cubs|journal= International Bear News |volume=14|issue=#2|page=17}}</ref> The size of a litter depends on factors such as geographic location and food supply.<ref name= Steyaert></ref> At birth, cubs are blind, toothless and hairless and may weigh {{convert|350|to|510|g|lb|abbr=on}}. There are records of females sometimes adopting stray cubs or even trading or kidnapping cubs when they emerge from hibernation (a larger female may claim cubs from a smaller one).<ref name="Hunter"/><ref>{{cite journal|author1=Erickson, A. W. |author2=Miller, L. H. |year=1963|title=Cub adoption in the brown bear|journal=Journal of Mammalogy|volume= 44 |issue=#4 |pages=584–585 |doi=10.2307/1377153 |jstor=1377153}}</ref><ref>{{cite journal|url=https://pubs.er.usgs.gov/publication/1012856|author1=Barnes, V. Jr|author2=Smith, R.|year=1993|title=Cub adoption by brown bears (''Ursus arctos middendorffi'') on Kodiak Island, Alaska|journal=Canadian Field-Naturalist|volume=107|issue=3 |pages=365–367|doi=10.5962/p.357155 |access-date=12 December 2016|archive-date=20 December 2016|archive-url=https://web.archive.org/web/20161220042307/https://pubs.er.usgs.gov/publication/1012856|url-status=live|doi-access=free}}</ref> Older and larger females within a population tend to give birth to larger litters.<ref>{{cite journal|author=Stringham, S. F. |year=1990|title=Grizzly bear reproductive rate relative to body size|journal=Bears: Their Biology and Management|volume=8|pages= 433–443|doi=10.2307/3872948|url=https://www.bearbiology.com/fileadmin/tpl/Downloads/URSUS/Vol_8/Stringham_Grizzly_8.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://www.bearbiology.com/fileadmin/tpl/Downloads/URSUS/Vol_8/Stringham_Grizzly_8.pdf |archive-date=2022-10-09 |url-status=live|jstor=3872948}}</ref> The cubs feed on their mother's milk until spring or early summer, depending on climate conditions. At this time, the cubs weigh {{convert|7|to|9|kg|lb|abbr=on}} and have developed enough to follow and forage for solid food with their mother over long distances.<ref name="pasitschniak-arts1993mamsp"></ref><ref>{{cite journal|author1=Dahle, B. |author2=Zedrosser, A. |author3=Swenson, J. E. |year=2006|title=Correlates with body size and mass in yearling brown bears (''Ursus arctos'')|doi=10.1111/j.1469-7998.2006.00127.x|journal=Journal of Zoology|volume= 269|issue=#3|pages=273–283}}</ref>

[[File:Kuusamo, Finland - Bears3.jpg|thumb|Brown bear cub in Finland]]

The cubs are dependent on the mother and a close bond is formed. During the dependency stage, the cubs learn (rather than inherit as instincts from birth) survival techniques, such as which foods have the highest nutritional value and where to obtain them; how to hunt, fish, and defend themselves; and where to den.<ref name= Novak/> Increased brain size in large carnivores has been positively linked to whether a given species is solitary, as is the brown bear, or raises offspring communally. Thus, the relatively large, well-developed brain of a female brown bear is presumably key in teaching behavior.<ref>{{cite journal|pmid=8202515|pmc=44022 |author=Gittleman, J. L. |year=1994|title=Female brain size and parental care in carnivores|journal=Proceedings of the National Academy of Sciences|volume=91|issue=#12|pages=5495–5497|bibcode=1994PNAS...91.5495G|doi=10.1073/pnas.91.12.5495|doi-access=free }}</ref> The cubs learn by following and imitating their mother's actions during the period they are with her.<ref name="Hunter" /> Cubs remain with their mother for an average of 2.5 years in North America, and gain independence from as early as 1.5 years of age to as late as 4.5 years.<ref name= Feldhamer/> The stage at which independence is attained may generally be earlier in some parts of [[Eurasia]], as the latest date which mother and cubs were together was 2.3 years. Most families separated in under two years in a study in [[Hokkaido]], and in Sweden most yearlings were their own.<ref name=mano>{{cite journal|author1=Mano, T. |author2=Tsubota, T. |year=2002|title=Reproductive characteristics of brown bears on the Oshima peninsula, Hokkaido, Japan|jstor=1383508|doi=10.1644/1545-1542(2002)083<1026:RCOBBO>2.0.CO;2|journal=Journal of Mammalogy|volume= 83|issue=#4|pages=1026–1034|doi-access=free}}</ref><ref>{{cite journal|author1=Dahle, B. |author2=Swenson, J. E. |year=2003|title=Family breakup in brown bears: are young forced to leave?|doi=10.1644/1545-1542(2003)084<0536:FBIBBA>2.0.CO;2|journal= Journal of Mammalogy|volume= 84|issue=#2|pages=536–540|doi-access=free}}</ref> Brown bears practice [[Infanticide (zoology)|infanticide]], as an adult male bear may kill the cubs of another.<ref name= Bellemain/> When an adult male brown bear kills a cub, it is usually because he is trying to bring the female into oestrus, as she will enter that state within two to four days after the death of her cubs.<ref name= Bellemain/> Cubs may flee up a tree when they see a strange male bear approaching. The mother often successfully defends them, even though the male may be twice as heavy as she. However, females have been known to die in such confrontations.<ref name= Bellemain/><ref>{{cite journal|author1=Swenson, J. E.|author2=Dahle, B.|author3=Sandegren, F.|year=2001|title=Intraspecific predation in Scandinavian brown bears older than cubs-of-the-year|journal=Ursus|pages=81–91|jstor=3873233|url=https://www.researchgate.net/publication/237374836|volume=12|access-date=12 December 2016|archive-date=16 November 2017|archive-url=https://web.archive.org/web/20171116185901/https://www.researchgate.net/publication/237374836_Intraspecific_predation_in_Scandinavian_brown_bears_older_than_cubs-of-year|url-status=live}}</ref><ref name="Mörner">{{cite journal|author1=Mörner, T. |author2=Eriksson, H. |author3=Bröjer, C. |author4=Nilsson, K. |author5=Uhlhorn, H. |author6=Ågren, E.  |author7=Segerstad, C. H. |author8=Jansson, D. S. |author9=Gavier-Widén, D. |year=2005|title=Diseases and mortality in free-ranging brown bear (''Ursus arctos''), gray wolf (''Canis lupus''), and wolverine (''Gulo gulo'') in Sweden|journal=Journal of Wildlife Diseases|volume= 41|issue=#2|pages=298–303|pmid=16107663|doi=10.7589/0090-3558-41.2.298|s2cid=43774546 |doi-access=free}}</ref>

===Dietary habits===
{{Main|Dietary biology of the brown bear}}
[[File:Brooks Falls Katmai National Park.jpg|thumb|upright|Brown bear hunting [[salmon]]]]

The brown bear is one of the most [[omnivorous]] animals and has been recorded as consuming the greatest variety of foods of any bear.<ref name="Hunter"/> Despite their reputation, most brown bears are not highly carnivorous, as they derive up to 90% of their dietary [[food energy]] from vegetable matter.<ref>{{cite web|url=http://www.dced.state.ak.us/oed/student_info/learn/bearwatching.htm |archive-url=https://web.archive.org/web/20090415202025/http://www.dced.state.ak.us/oed/student_info/learn/bearwatching.htm |archive-date=15 April 2009 |title=Alaska is bear territory!|work=Alaska Office of Economic Development |publisher=Dced.state.ak.us |access-date=10 October 2009}}</ref> They often feed on a variety of plant life, including [[Berry|berries]], grasses, [[flower]]s, [[acorn]]s, and [[pine cone]]s, as well as fungi such as [[mushroom]]s.<ref name="pasitschniak-arts1993mamsp"></ref> Among all bears, brown bears are uniquely equipped to dig for tough foods such as [[root]]s, [[bulb]]s,<ref name="Ursus arctos Brown bear">{{Cite web|url=https://animaldiversity.org/accounts/Ursus_arctos/|title=Ursus arctos (Brown bear)|website=[[Animal Diversity Web]]|access-date=28 May 2021|archive-date=13 May 2021|archive-url=https://web.archive.org/web/20210513130048/http://animaldiversity.org/accounts/Ursus_arctos/|url-status=live}}</ref> and [[Shoot (botany)|shoot]]s. They use their long, strong claws to dig out earth to reach roots and their powerful jaws to bite through them.<ref name="pasitschniak-arts1993mamsp"></ref> In spring, winter-provided carrion, grasses, shoots, [[Carex|sedges]], [[moss]],<ref name="Ursus arctos Brown bear"/> and [[forb]]s are the dietary mainstays for brown bears internationally.<ref name="Hunter"/> 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.<ref name="Hunter"/>

[[File:A grizzly bear digs for food along the park road near the Sable Pass closure sign on Sept. 1, 2019. (6f96b20b-a076-46dc-be8f-c867d144305f).JPG|thumb|Brown bear digging for squirrels|left]]

They will also commonly consume animal matter, which in summer and autumn may regularly be in the form of insects, [[larvae]], and [[Larva|grubs]], including [[beehive]]s. Bears in Yellowstone eat an enormous number of [[moth]]s during the summer, sometimes as many as 40,000 [[army cutworm]] moths in a single day, and may derive up to half of their annual food energy from these insects.<ref>{{cite web|url=http://www.yellowstonepark.com/MoreToKnow/ShowNewsDetails.aspx?newsid=163 |archive-url=https://web.archive.org/web/20100715011549/http://www.yellowstonepark.com/moretoknow/shownewsdetails.aspx?newsid=163 |url-status=dead |archive-date=15 July 2010 |title=Yellowstone Grizzly Bears Eat 40,000 Moths a Day In August |publisher=Yellowstonepark.com |date=21 June 2011}}</ref> Brown bears living near coastal regions will regularly eat crabs and [[clam]]s. In Alaska, bears along the beaches of estuaries regularly dig through the sand for clams.<ref name="brown"/> This species may eat birds and their [[Egg (biology)|egg]]s, including almost entirely ground- or rock-nesting species.<ref name="brown"/> The diet may be supplemented by [[rodent]]s or similar small [[mammal]]s, including [[marmot]]s, [[ground squirrel]]s, [[Mouse|mice]], rats, [[lemming]]s, and [[vole]]s.<ref name="pasitschniak-arts1993mamsp"></ref> With particular regularity, bears in [[Denali National Park]] will wait at burrows of [[Arctic ground squirrel]]s, hoping to pick off a few of those {{convert|1|kg|lb|abbr=on}} rodents.<ref name="Brown">{{cite web |last=Brown |first=Susan A. |title=Inherited behavior traits of the domesticated ferret |url=http://www.weaselwords.com/page/ferret_art036.php |date=17 January 2010 |orig-date=2002 |archive-url=https://web.archive.org/web/20091004091445/http://www.weaselwords.com/page/ferret_art036.php |archive-date=4 October 2009 |url-status=live |magazine=Off the Paw |issue=November/December 2002 |via=WeaselWords.com |access-date=16 October 2024}}</ref>

In the Kamchatka peninsula and several parts of coastal Alaska, brown bears feed mostly on spawning [[salmon]], whose nutrition and abundance explain the enormous size of the bears in those areas. 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 water, 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 salmon spawning, when there is usually a glut of fish to feed on, may eat only the most nutrious parts of the salmon (including the eggs and head) and then indifferently leave the rest of the carcass to scavengers, which can include [[red fox]]es, [[bald eagle]]s, [[common raven]]s, and [[gull]]s. Despite their normally solitary habits, brown bears will gather closely in numbers at good spawning sites. The largest and most powerful males claim the most fruitful fishing spots and will sometimes fight over the rights to them.<ref name="brown"/>

[[File:Moose mom with calves and a bear, Deanli National Park.png|thumb|A cow moose with calves being approached by an inland brown bear, [[Denali National Park]], Alaska]]

Beyond the regular predation of salmon, most brown bears are not particularly active predators.<ref name="brown"/> While perhaps a majority of bears of the species will charge at large prey at one 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.<ref name="brown"/> On the other hand, some brown bears are quite self-assured predators who habitually pursue and catch large prey. Such bears are usually taught how to hunt by their mothers from an early age.<ref name="brown"/> Large mammals preyed on can include various [[ungulate]] species such as [[elk]], [[moose]], [[Reindeer|caribou]], [[muskox]]en, and [[wild boar]].<ref name="pasitschniak-arts1993mamsp"></ref> When brown bears attack these large animals, they usually target young or infirm ones, which are easier to catch. Typically when hunting (especially young prey), the bear pins its prey to the ground and then immediately tears at and eats it alive.<ref>{{cite journal | last1=French |first1= S. P. |last2= French |first2=M. G. |title=Predatory behavior of grizzly bears feeding on elk calves in Yellowstone National Park, 1986–1988 |year= 1990 |journal=International Conf. Bear Res. And Manage | volume= 8|pages= 335–341|url=http://www.bearbiology.com/fileadmin/tpl/Downloads/URSUS/Vol_8/French_French_8.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.bearbiology.com/fileadmin/tpl/Downloads/URSUS/Vol_8/French_French_8.pdf |archive-date=2022-10-09 |url-status=live | doi=10.2307/3872937|jstor= 3872937 }}</ref> It will also bite or swipe some prey to stun it enough to knock it over for consumption.<ref name= Macdonald>{{cite book|year=1993|title=Mammals of Europe|publisher=Princeton University Press|location=New Jersey|page=[https://archive.org/details/mammalsofeurope00macd/page/107 107]|isbn=978-0-691-09160-0|author1=Macdonald, D. W.|author2=Barrett, P.|url=https://archive.org/details/mammalsofeurope00macd/page/107}}</ref> In general, large mammalian prey is killed with raw strength and bears do not display the specialized killing methods of felids and canids.<ref name=Sacco2004>{{cite journal|last1=Sacco|first1=T|last2=Van Valkenburgh|first2=B|year=2004|title=Ecomorphological indicators of feeding behaviour in the bears (Carnivora: Ursidae)|journal=Journal of Zoology|volume=263|issue=1|pages=41–54|doi=10.1017/S0952836904004856}}</ref> To pick out young or infirm individuals, bears will charge at herds so the more vulnerable, and thus slower-moving, individuals will become apparent. Brown bears may ambush young animals by finding them via scent.<ref name="pasitschniak-arts1993mamsp"></ref>

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.<ref name= Macdonald/> 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.<ref name="pasitschniak-arts1993mamsp"></ref> On rare occasions, while confronting fully-grown, 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.<ref name="brown"/> They feed on [[carrion]], and use their size to intimidate other predators – such as [[Wolf|wolves]], [[cougar]]s, tigers, and [[American black bear]]s – away from their kills. Carrion is especially important in the early spring (when the bears are emerging from hibernation), much of it comprising winter-killed big game.<ref name="pasitschniak-arts1993mamsp"></ref> Cannibalism is not unheard of, though predation is not normally believed to be the primary motivation when brown bears attack each other.<ref name="brown"/>

When forced to live in close proximity with humans and their domesticated animals, bears may potentially predate any type of domestic animal. Among these, domestic cattle are sometimes exploited as prey. Cattle are bitten on the neck, back, or head, and then the abdominal cavity is opened for eating.<ref name="pasitschniak-arts1993mamsp"></ref> Plants and fruit farmed by humans are readily consumed as well, including [[Maize|corn]], wheat, [[sorghum]], melons, and any form of [[Berry|berries]].<ref name="brown"/> They may feed on domestic [[Beekeeping|bee yards]], readily consuming both honey and the brood (grubs and pupae) of the [[honey bee]] colony.<ref name="brown"/> Human foods and trash are 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.<ref name="brown"/>

===Relations with other predators===
[[File:Wolfbear.jpg|thumb|Brown bear being followed by a [[wolf]]]]

Adult bears are generally immune to predatory attacks except from large [[Siberian tiger|Siberian (Amur) tigers]] and other bears. Following a decrease of ungulate populations from 1944 to 1959, 32 cases of Siberian tigers attacking both [[Ussuri brown bear]]s (''Ursus arctos lasiotus'') and [[Ussuri black bear]]s (''U. thibetanus ussuricus'') were recorded in the [[Russian Far East]], and bear hairs were found in several tiger scat samples. Tigers attack black bears less often than brown bears, since the brown bears live in more open habitats and are not able to climb trees. In the same time period, four cases of brown bears killing female tigers and young cubs were reported, both in disputes over prey and in self-defense.<ref name="soviet"/> In rare cases, when Amur tigers prey on brown bears, they usually target young and sub-adult bears, besides small female adults taken outside their dens, generally when lethargic from [[hibernation]].<ref name=FBW>{{cite book| author=Fraser, A. F. |year=2012 |title=Feline Behaviour and Welfare |publisher=CABI| pages=72–77 |isbn=978-1-84593-926-7}}</ref> Predation by tigers on denned brown bears was not detected during a study carried out between 1993 and 2002.<ref name="Denning">{{cite journal |author=Seryodkin, I. V. |author2=Kostyria, A. V. |author3=Goodrich, J. M. |author4=Miquelle, D. G. |author5=Smirnov, E. N. |author6=Kerley, L. L. |author7=Hornocker, M. G. |name-list-style=amp |url=http://www.wcsrussia.org/DesktopModules/Bring2mind/DMX/Download.aspx?EntryId=3313&PortalId=32&DownloadMethod=attachment |year=2003 |title=Denning ecology of brown bears and Asiatic black bears in the Russian Far East |journal=Ursus |volume=14 |issue=2 |page=159 |access-date=15 September 2014 |archive-date=17 August 2011 |archive-url=https://web.archive.org/web/20110817151324/http://www.wcsrussia.org/DesktopModules/Bring2mind/DMX/Download.aspx?EntryId=3313&PortalId=32&DownloadMethod=attachment |url-status=dead }}</ref> Ussuri brown bears, along with the smaller black bears constitute 2.1% of the Siberian tiger's annual diet, of which 1.4% are brown bears.<ref name=Seryodkin2>{{cite book |author=Seryodkin, I. V. |author2=Goodrich, J. M. |author3=Kostyrya, A. V. |author4=Schleyer, B. O. |author5=Smirnov, E. N. |author6=Kerley, L. L. |author7=Miquelle, D. G. |name-list-style=amp |year=2005 |chapter=Глава 19. Взаимоотношения амурского тигра с бурым и гималайским медведями [Chapter 19. Relationship of Amur tigers with brown and Himalayan black bear] |editor1=Miquelle, D. G. |editor2=Smirnov, E. N. |editor3=Goodrich, J. M. |title=Tigers of Sikhote-Alin Zapovednik: Ecology and Conservation |location=Vladivostok, Russia |publisher=PSP |pages=156–163 |language=ru |chapter-url=https://translate.google.com/translate?hl=en&sl=ru&u=http://www.wcsrussia.org/Publications/TigerMonograph/tabid/2082/language/en-US/default.aspx&ei=yhlkSsf9KeOgjAf4r7zvDw&sa=X&oi=translate&resnum=3&ct=result&prev=/search%3Fq%3Dwcs%2Brussia%2Btiger%2Bmonograph%26hl%3Den%26safe%3Doff%26sa%3DG |access-date=19 March 2023 |archive-date=18 October 2020 |archive-url=https://web.archive.org/web/20201018234449/http://translate.google.com/translate?hl=en&sl=ru&u=http%3A%2F%2Fwww.wcsrussia.org%2FPublications%2FTigerMonograph%2Ftabid%2F2082%2Flanguage%2Fen-US%2Fdefault.aspx&ei=yhlkSsf9KeOgjAf4r7zvDw&sa=X&oi=translate&resnum=3&ct=result&prev=%2Fsearch%3Fq%3Dwcs%2Brussia%2Btiger%2Bmonograph%26hl%3Den%26safe%3Doff%26sa%3DG |url-status=live }}</ref><ref name="Seryodkin_PhD">{{cite thesis |url=http://uml.wl.dvgu.ru/rscv.php?id=74 |title=The ecology, behavior, management and conservation status of brown bears in Sikhote-Alin |language=ru |author=Seryodkin, I. |year=2006 |type=PhD |publisher=Far Eastern National University |location=Vladivostok, Russia |pages=61–73 |url-status=dead |archive-url=https://web.archive.org/web/20131224090426/http://uml.wl.dvgu.ru/rscv.php?id=74 |archive-date=2013-12-24}}</ref>

[[File:Zoltán, a Farkasember 1.jpg|thumb|Brown bear and wolf pack squabbling over a carcass]]

Brown bears regularly intimidate [[wolf|wolves]] to drive them away from their kills. In [[Yellowstone National Park]], 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." Despite the animosity between the two species, most confrontations at kill sites or large carcasses end without bloodshed on either side. Though conflict over carcasses is common, on rare occasions the two predators tolerate each other at the same kill. To date, there is a single recorded case of fully-grown wolves being killed by a grizzly bear.<ref>{{cite journal|volume=122 |issue=1 |year=2008 |title= Gray Wolves, ''Canis lupus'', Killed by Cougars, ''Puma concolor'', and a Grizzly Bear, ''Ursus arctos'', in Montana, Alberta, and Wyoming |author1= Jimenez, Michael D. |author2=Asher, Valpa J. |author3=Bergman, Carita |author4=Bangs, Edward E. |author5=Woodruff, Susannah P. |journal=The Canadian Field-Naturalist |page=76|doi=10.22621/cfn.v122i1.550 |doi-access=free }} [http://mountainlion.org/US/WY/WY%20R%20Jimenez%20et%20al%202008%20Gray%20Wolves%20Killed%20by%20Cougars%20and%20Grizzly%20Bears%20in%20Montana,%20Alberta,%20and%20Wyoming%20-%20Canadian%20Field%20Naturalist.pdf PDF] {{Webarchive|url=https://web.archive.org/web/20210119030500/https://mountainlion.org/US/WY/WY%20R%20Jimenez%20et%20al%202008%20Gray%20Wolves%20Killed%20by%20Cougars%20and%20Grizzly%20Bears%20in%20Montana,%20Alberta,%20and%20Wyoming%20-%20Canadian%20Field%20Naturalist.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://mountainlion.org/US/WY/WY%20R%20Jimenez%20et%20al%202008%20Gray%20Wolves%20Killed%20by%20Cougars%20and%20Grizzly%20Bears%20in%20Montana,%20Alberta,%20and%20Wyoming%20-%20Canadian%20Field%20Naturalist.pdf |archive-date=2022-10-09 |url-status=live |date=19 January 2021 }}.</ref> Given the opportunity, however, both species will prey on the other's cubs.<ref>{{cite web |author=Downey, Betsy |title=Personal Encounter. Wolf-Grizzly interaction in Yellowstone National Park |publisher=[[International Wolf Center]] |url=http://www.wolf.org/wolves/news/iwmag/2006/spring/personalencounter.pdf |archive-url=https://web.archive.org/web/20080227175714/http://www.wolf.org/wolves/news/iwmag/2006/spring/personalencounter.pdf |archive-date=27 February 2008 }}</ref> In some areas, grizzly bears regularly displace [[cougar]]s from their kills.<ref>{{cite journal|jstor=3873109|title=Encounter Competition between Bears and Cougars: Some Ecological Implications|author1=Murphy, Kerry M. |author2=Felzien, Gregory S. |author3=Hornocker, Maurice G. |author4=Ruth, Toni K. |journal=Ursus|volume=10 |year=1998|pages=55–60}}</ref> Cougars kill small bear cubs on rare occasions, but there was only one report of a bear killing a cougar, of unknown age and condition, between 1993 and 1996.<ref>[http://www.arlis.org/docs/vol1/52386062/ursus_arctos_001.html ADW: Ursus arctos: Information] {{Webarchive|url=https://web.archive.org/web/20130512163707/http://www.arlis.org/docs/vol1/52386062/ursus_arctos_001.html |date=12 May 2013 }}. Arlis.org. Retrieved 9 August 2012.</ref><ref>{{Cite book |last1=Hornocker |first1=Maurice |url=https://books.google.com/books?id=ZSDUxT3fSYEC&q=editions:wf3LntQ6js8C |title=Cougar: Ecology and Conservation |last2=Negri |first2=Sharon |date=2009-12-15 |publisher=University of Chicago Press |isbn=978-0-226-35347-0 |pages=163–174 |language=en}}</ref> 

Brown bears usually dominate other bear species in areas where they coexist. Due to their smaller size, [[American black bear]]s are at a competitive disadvantage to grizzly bears in open, unforested areas. Although displacement of black bears by grizzly bears has been documented, actual killing of black bears by grizzlies has only occasionally been reported. Confrontation is mostly avoided due to the black bear's diurnal habits and preference for heavily forested areas, as opposed to the grizzly's largely nocturnal habits and preference for open spaces.<ref>{{cite journal |url=http://www.nps.gov/yell/naturescience/upload/predation.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.nps.gov/yell/naturescience/upload/predation.pdf |archive-date=2022-10-09 |url-status=live|title=Probable grizzly bear predation on an American black bear in Yellowstone National Park |author1=Gunther, Kerry A. |author2=Biel, Mark J. |author3=Anderson, Neil |author4=Watts, Lisette |year=2002 |journal=[[Ursus (journal)|Ursus]] |volume=13 |pages=372–374}}</ref> Brown bears may also kill [[Asian black bear]]s, though the latter species probably largely avoids conflicts with the brown bear, due to similar habits and habitat preferences to the American black species.<ref name="denning">{{cite journal|url=http://www.bearbiology.com/fileadmin/tpl/Downloads/URSUS/Vol_14_2/Seryodkin_14_2.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.bearbiology.com/fileadmin/tpl/Downloads/URSUS/Vol_14_2/Seryodkin_14_2.pdf |archive-date=2022-10-09 |url-status=live |title=Denning ecology of brown bears and Asiatic black bears in the Russian Far East|jstor=3873015|author=Seryodkin, Ivan V.|journal=Ursus|volume=14|issue= 2 |year=2003|pages=153–161|last2=Kostyria|first2=A. V.|last3=Goodrich|first3=J. M.|last4=Miquelle|first4=D. G.|last5=Smirnov|first5=E. N.|last6=Kerley|first6=L. L.|last7=Quigley|first7=H. B.|last8=Hornocker|first8=M. G. }}</ref> As of the 21st century, there has been an increase in interactions between brown bears and [[polar bear]]s, theorized to be caused by [[climate change]]. Brown and grizzly bears have been seen moving increasingly northward into territories formerly claimed by polar bears. They tend to dominate polar bears in disputes over carcasses,<ref>Dough O'Hara [https://web.archive.org/web/20081120030414/http://dwb.adn.com/front/story/6415667p-6294323c.html Polar bears, grizzlies increasingly gather on North Slope]. Anchorage Daily News. 24 April 2005</ref> and dead polar bear cubs have been found in brown bear dens.<ref>{{cite web |url=https://abcnews.go.com/Technology/DyeHard/Story?id=582243&page=3 |title=ABC News: Grizzlies Encroaching on Polar Bear Country |work=ABC News |access-date=10 October 2009 |archive-date=5 August 2017 |archive-url=https://web.archive.org/web/20170805152310/http://abcnews.go.com/Technology/DyeHard/Story?id=582243&page=3 |url-status=live }}</ref>

===Longevity and mortality===
{{multiple image |align=right |direction=vertical |width=
 |image1=BärenspurP1050395.jpg |caption1=Front [[paw]] imprint
 |image2=Grizzly rear paw print.jpg |caption2=Rear paw imprint
}}

The brown bear has a naturally long life. Wild females have been observed reproducing at 28 years, which is the oldest known age for reproduction of any [[Bear|ursid]] in the wild. The peak reproductive age for females ranges from four to 20 years old.<ref name="Hunter"/><ref>{{cite journal|author1=Schwartz, C. C. |author2=Keating, K. A. |author3=Reynolds III, H. V. |author4=Barnes, V. G. Jr|author5=Sellers, R. A. |author6=Swenson, J. E. |author7=Miller, S. D. |author8=McLellan, B. |author9=Keay, J. |author10=McCann, R. |author11=Gibeau, M. |author12=Wakkinen, W. F. |author13=Mace, R. D. |author14=Kasworm, W. |author15=Smith, R. |author16=Herrero, S. |year=2003|title=Reproductive maturation and senescence in the female brown bear|journal= Ursus|pages= 109–119|jstor=3873012|volume=14|issue=#2}}</ref> The lifespan of both sexes within minimally hunted populations is estimated at an average of 25 years. The oldest recorded wild individual was nearly 37 years old.<ref>{{Cite book |last=Macdonald |first=David David Whyte |url=https://books.google.com/books?id=VRMxmAEACAAJ |title=The New Encyclopedia of Mammals |date=2001| entry= Bear family|publisher=Oxford University Press, Incorporated |isbn=978-0-19-850823-6 |language=en}}</ref> In captivity, the oldest recorded female was around 40 years old, while males have been known to live up to 47 years.<ref name="pasitschniak-arts1993mamsp"></ref><ref name= Walker/>

While male bears potentially live longer in captivity, female grizzly bears have a greater annual survival rate than males within wild populations, per a study done in the [[Greater Yellowstone Ecosystem]].<ref>{{cite journal|author1=Schwartz, C. C. |author2=Haroldson, M. A. |author3=White, G. C. |author4=Harris, R. B. |author5=Cherry, S. |author6=Keating, K. A. |author7=Moody, D. |author8=Servheen, C. |title=Temporal, Spatial, and Environmental Influences on the Demographics of Grizzly Bears in the Greater Yellowstone Ecosystem |journal=Wildlife Monographs|volume=161|pages=1–68|doi=10.2193/0084-0173(2006)161[1:TSAEIO]2.0.CO;2|year=2006|s2cid=85600938 }}</ref> Annual mortality for bears of any age is estimated at 10% in most protected areas.<ref name="Hunter"/> Around 13% to 44% of cubs die within their first year.<ref name="pasitschniak-arts1993mamsp"></ref> Beyond predation by large predators – including [[Wolf|wolves]], Siberian tigers, and other brown bears – starvation and accidents also claim the lives of cubs. Studies have indicated that the most prevalent cause of mortality for first-year cubs is malnutrition.<ref name="pasitschniak-arts1993mamsp"></ref>

Brown bears are susceptible to parasites such as [[Fluke (flatworm)|fluke]]s, [[ticks]], [[tapeworms]], [[roundworm]]s, and [[Mallophaga|biting lice]].<ref>{{Cite journal |last1=Rogers |first1=Lynn L. |last2=Rogers |first2=Susanne M. |date=1976 |title=Parasites of Bears: A Review |url=http://dx.doi.org/10.2307/3872791 |journal=Bears: Their Biology and Management |volume=3 |pages=411–430 |doi=10.2307/3872791 |jstor=3872791 |issn=1936-0614}}</ref><ref>{{Cite journal |last=J. Brglez |first=S. Valentinclc |date=1968 |title=Parasites of brown bear, Ursus arctos L. |url=https://www.cabidigitallibrary.org/doi/full/10.5555/19720802813 |journal=Acta Veterinaria (Beograd) |volume=18 |issue=6 |pages=379–384}}</ref> It is thought that brown bears may catch [[Canine distemper|canine distemper virus]] (CDV) from other [[caniform]]s such as [[stray dog]]s and wolves.<ref>{{Cite journal |last1=Di Francesco |first1=Cristina Esmeralda |last2=Gentile |first2=Leonardo |last3=Di Pirro |first3=Vincenza |last4=Ladiana |first4=Lara |last5=Tagliabue |first5=Silvia |last6=Marsilio |first6=Fulvio |date=2015-01-01 |title=Serologic Evidence for Selected Infectious Diseases in Marsican Brown Bears (''Ursus arctos marsicanus'') in Italy (2004–09) |url=http://dx.doi.org/10.7589/2014-01-021 |journal=Journal of Wildlife Diseases |volume=51 |issue=1 |pages=209–213 |doi=10.7589/2014-01-021 |pmid=25375945 |issn=0090-3558}}</ref> A captive individual allegedly succumbed to [[Aujeszky's disease]].<ref>{{Cite journal |last1=Mörner |first1=Torsten |last2=Eriksson |first2=Hanna |last3=Bröjer |first3=Caroline |last4=Nilsson |first4=Kristina |last5=Uhlhorn |first5=Henrik |last6=Ågren |first6=Erik |last7=Segerstad |first7=Carl Hård af |last8=Jansson |first8=Désirée S. |last9=Gavier-Widén |first9=Dolores |date=April 2005 |title=Diseases and mortality in free-ranging brown bear (''Ursus arctos''), gray wolf (''Canis lupus''), and wolverine (''Gulo gulo'') in Sweden |url=http://dx.doi.org/10.7589/0090-3558-41.2.298 |journal=Journal of Wildlife Diseases |volume=41 |issue=2 |pages=298–303 |doi=10.7589/0090-3558-41.2.298 |pmid=16107663 |issn=0090-3558}}</ref>

=== Hibernation physiology ===
A study conducted by the Brown Bear Research Project did a [[Proteomics|proteomic]] analysis of the brown bear's blood, organs, and tissues to pinpoint proteins and [[peptide]]s that either increased or decreased in expression in the winter and summer months. One major finding was that the presence of the plasma protein [[sex hormone-binding globulin]] (SHBG) increased by 45 times during the brown bear's hibernation period. Although scientists do not yet understand the role of SHBG in maintaining the brown bear's health, some believe these findings could potentially help in understanding and preventing human diseases that come from a sedentary lifestyle.<ref name=":1">{{Cite journal |last1=Fröbert |first1=O. |last2=Frøbert |first2=A. M. |last3=Kindberg |first3=J. |last4=Arnemo |first4=J. M. |last5=Overgaard |first5=M. T. |date=March 2020 |title=The brown bear as a translational model for sedentary lifestyle-related diseases |journal=Journal of Internal Medicine |language=en |volume=287 |issue=3 |pages=263–270 |doi=10.1111/joim.12983 |pmid=31595572 |issn=0954-6820|doi-access=free |hdl=11250/2642746 |hdl-access=free }}</ref>