Editing Bear (section)

===Reproduction and development{{anchor|Breeding}}===
[[File:Black Bears mating.jpg|thumb|left|American black bears mating at the [[North American Bear Center]]]]

The mating system of bears has variously been described as a form of [[Polygyny in animals|polygyny]], [[Promiscuity#Other animals|promiscuity]] and [[serial monogamy]].<ref>{{cite web |author1=Eide, S. |author2=Miller, S. |title=Brown Bear |publisher=Alaska Department of Fish and Game |url=https://www.adfg.alaska.gov/static/education/wns/brown_bear.pdf |access-date=14 January 2016 |archive-url=https://web.archive.org/web/20130303124834/http://www.adfg.alaska.gov/static/education/wns/brown_bear.pdf |archive-date=2013-03-03 |url-status=live }}</ref><ref name="Ward138">{{Harvnb|Ward|Kynaston|1995|pp=138–141}}</ref><ref name=mammalian>{{cite journal |author=Lariviere, S. |year=2001 |title=Ursus americanus |journal=Mammalian Species |issue=647 |pages=1–11 |url=http://www.science.smith.edu/msi/pdf/647_Ursus_americanus.pdf |doi=10.1644/1545-1410(2001)647<0001:ua>2.0.co;2 |s2cid=198968922  |archive-url=https://web.archive.org/web/20160316025524/http://www.science.smith.edu/msi/pdf/647_Ursus_americanus.pdf |archive-date=2016-03-16 }}</ref> During the breeding season, males take notice of females in their vicinity and females become more tolerant of males. A male bear may visit a female continuously over a period of several days or weeks, depending on the species, to test her reproductive state. During this time period, males try to prevent rivals from interacting with their mate. Courtship may be brief, although in some Asian species, courting pairs may engage in wrestling, hugging, mock fighting and vocalizing. [[Induced ovulation (animals)|Ovulation is induced by mating]], which can last up to 30 minutes depending on the species.<ref name="Ward138"/>

[[File:Cub polar bear is nursing 2.OGG|thumb|[[Polar bear]] mother nursing her cub]]
[[Gestation]] typically lasts six to nine months, including [[delayed implantation]], and litter size numbers up to four cubs.<ref name="Ward144">{{Harvnb|Ward|Kynaston|1995|pp=144–148}}</ref> Giant pandas may give birth to twins but they can only suckle one young and the other is left to die.<ref name="Panda Facts">{{cite web |url=http://www.pandasinternational.org/wptemp/education-2/panda-facts/ |title=Panda Facts |publisher=Pandas International |access-date=26 August 2015  |archive-url=https://web.archive.org/web/20150924063658/http://www.pandasinternational.org/wptemp/education-2/panda-facts/ |archive-date=24 September 2015 }}</ref> In northern living species, birth takes place during winter dormancy. Cubs are born blind and helpless with at most a thin layer of hair, relying on their mother for warmth. The milk of the female bear is rich in fat and antibodies and cubs may suckle for up to a year after they are born. By two to three months, cubs can follow their mother outside the den. They usually follow her on foot, but sloth bear cubs may ride on their mother's back.<ref name="Ward144"/><ref name=Walker>{{cite book |author=Nowak, R. M. |year=2005 |title=Walker's Carnivores of the World |publisher=Johns Hopkins University Press |page=[https://archive.org/details/walkerscarnivore0000nowa/page/114 114] |isbn=978-0-8018-8032-2 |url=https://archive.org/details/walkerscarnivore0000nowa/page/114 }}</ref> Male bears play no role in raising young. [[Infanticide (zoology)|Infanticide]], where an adult male kills the cubs of another, has been recorded in polar bears, brown bears and American black bears but not in other species.<ref>{{Harvnb|Ward|Kynaston|1995|p=132}}</ref> Males kill young to bring the female into [[estrus]].<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|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 |access-date=2017-05-02|archive-url=https://web.archive.org/web/20161221015155/http://bearproject.info/wp-content/uploads/2015/11/2006-A060-Bellemain-Mating-Strategies-in-relation-to-SSI.pdf|archive-date=2016-12-21|url-status=live}}</ref> Cubs may flee and the mother defends them even at the cost of her life.<ref>{{cite journal |author1=Bellemain, E. |author2=Zedrosser, A. |author3=Manel, S. |author4=Waits, L. P. |author5=Taberlet, P. |author6=Swenson, J. E. |year=2005 |pmid=16543170 |pmc=1560043 |title=The dilemma of female mate selection in the brown bear, a species with sexually selected infanticide |journal=Proceedings of the Royal Society of London B: Biological Sciences |volume=273 |issue=1584 |pages=283–291 |doi=10.1098/rspb.2005.3331}}</ref><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 |volume=12 |pages=81–91 |jstor=3873233 |url=https://www.researchgate.net/publication/237374836 |access-date=2017-01-14 |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 |archive-date=2017-11-16 |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=af 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|doi-access=free }}</ref>

In some species, offspring may become independent around the next spring, though some may stay until the female successfully mates again. Bears reach [[sexual maturity]] shortly after they disperse; at around three to six years depending on the species. Male Alaskan brown bears and polar bears may continue to grow until they are 11 years old.<ref name="Ward144"/> Lifespan may also vary between species. The brown bear can live an average of 25 years.<ref>{{cite web|title=Grizzly Bear|date=10 September 2010 |publisher=National Geographic.com|access-date=29 April 2017|url=http://www.nationalgeographic.com/animals/mammals/g/grizzly-bear/|archive-url=https://web.archive.org/web/20170421214527/http://www.nationalgeographic.com/animals/mammals/g/grizzly-bear/|archive-date=2017-04-21|url-status=dead}}</ref>