Editing Polar bear (section)

===Mortality===
Polar bears can live up to 30 years.<ref name="DeMaster1981"/> The bear's long lifespan and ability to consistently produce young offsets cub deaths in a population. Some cubs die in the dens or the womb if the female is not in good condition. Nevertheless, the female has a chance to produce a surviving litter the next spring if she can eat better in the coming year. Cubs will eventually starve if their mothers cannot kill enough prey.{{sfn|Stirling|2011|pp=204–207}} Cubs also face threats from [[wolves]]<ref>{{cite journal|last1=Richardson|first1=E. S.|last2=Andriashek|first2=D.|year=2006|title=Wolf (''Canis lupus'') predation of a polar bear (''Ursus maritimus'') cub on the sea ice off northwestern Banks Island, Northwest Territories, Canada|journal=Arctic|volume=59|issue=3|pages=322–324|doi=10.14430/arctic318|doi-access=free}}</ref> and adult male bears. Males [[infanticide (zoology)|kill cubs]] to bring their mother back into estrus but also kill young outside the breeding season for food.<ref name=Taylor1985>{{cite journal|last1=Taylor|first1=M.|last2=Larsen|first2=T.|last3=Schweinsburg|first3=R. E.|year=1985|title=Observations of intraspecific aggression and cannibalism in polar bears (''Ursus maritimus'')|journal=Arctic|volume=38|issue=4|pages=303–309|doi=10.14430/arctic2149|doi-access=free}}</ref> A female and her cubs can flee from the slower male. If the male can get close to a cub, the mother may try to fight him off, sometimes at the cost of her life.{{sfn|Stirling|2011|p=212}}

Subadult bears, who are independent but not quite mature, have a particularly rough time as they are not as successful hunters as adults. Even when they do succeed, their kill will likely be stolen by a larger bear. Hence subadults have to scavenge and are often underweight and at risk of starvation. At adulthood, polar bears have a high survival rate, though adult males suffer injuries from fights over mates.{{sfn|Stirling|2011|pp=207–208}} Polar bears are especially susceptible to ''[[Trichinella]]'', a parasitic [[roundworm]] they contract through cannibalism.<ref>{{cite journal |last1=Larsen |first1=Thor |last2=Kjos-Hanssen |first2=Bjørn |year=1983 |title=''Trichinella'' sp. in polar bears from Svalbard, in relation to hide length and age |volume=1 |issue=1 |pages=89–96 |doi=10.1111/j.1751-8369.1983.tb00734.x |journal=Polar Research|doi-broken-date=1 November 2024 |bibcode=1983PolRe...1...89L |s2cid=208525641 }}</ref>