Editing Polar bear (section)

===Diet and hunting===
[[File:Polar bear (Ursus maritimus) with its prey.jpg|thumb|right|Bear feeding on a [[bearded seal]]]]
The polar bear is a [[hypercarnivore]],<ref name=Sacco2004/> and the most carnivorous species of bear.<ref name=Slater2010/> It is an [[apex predator]] of the Arctic,{{sfn|Stirling|2011|p=155}} preying on [[Ice seal|ice-living seals]] and consuming their energy-rich [[blubber]].{{sfn|Derocher|2012|p=69}} The most commonly taken species is the [[ringed seal]], but they also prey on [[bearded seal]]s and [[harp seal]]s.<ref name="DeMaster1981"/> Ringed seals are ideal prey as they are abundant and small enough to be overpowered by even small bears.{{sfn|Stirling|2011|pp=155–156}} Bearded seal adults are larger and are more likely to break free from an attacking bear, hence adult male bears are more successful in hunting them. Less common prey are [[hooded seal]]s, [[spotted seal]]s, [[ribbon seal]]s and the more temperate-living [[harbor seal|harbour seal]]s.{{sfn|Derocher|2012|pp=73, 76–77}} Polar bears, mostly adult males, will occasionally hunt [[walrus]]es both on land and ice. They mainly target young walruses, as adults, with their thick skin and long tusks, are too large and formidable.{{sfn|Stirling|2011|p=161}}

Besides seals, bears will prey on [[cetacea]]n species such as [[beluga whale]]s and [[narwhal]]s, as well as [[reindeer]], birds and their eggs, fish and [[marine invertebrates]].{{sfn|Derocher|2012|pp=80–88}} They rarely eat plant material as their digestive system is too specialized for animal matter,<ref>{{cite journal |last1=Ramsay |first1=M. A. |last2=Hobson |first2=K. A. |date=May 1991 |title=Polar bears make little use of terrestrial food webs: evidence from stable-carbon isotope analysis |volume=86 |issue=4 |pages=598–600 |doi=10.1007/BF00318328 |pmid=28313343 |journal=Oecologia|bibcode=1991Oecol..86..598R |s2cid=32221744 }}</ref> though they have been recorded eating berries, moss, grass and [[seaweed]].{{sfn|Derocher|2012|pp=88–89}} In their southern range, especially near Hudson Bay and James Bay, polar bears endure all summer without sea ice to hunt from and must subsist more on terrestrial foods.<ref name="ReferenceB">{{cite journal |last1=Russell |first1=Richard H. |title=The food habits of polar bears of James Bay and Southwest Hudson Bay in summer and autumn |journal=Arctic |date=1975|volume=28 |issue=2 |pages=117–129 |doi=10.14430/arctic2823 |doi-access=free }}</ref> Fat reserves allow polar bears to survive for months without eating.{{sfn|Ellis|2009|p=89}} [[Cannibalism]] is known to occur in the species.<ref name=Taylor1985/>

Polar bears hunt their prey in several different ways. When a bear spots a seal [[Hauling-out|hauling out]] on the sea ice, it slowly stalks it with the head and neck lowered, possibly to make its dark nose and eyes less noticeable. As it gets closer, the bear crouches more and eventually charges at a high speed, attempting to catch the seal before it can escape into its ice hole. Some stalking bears need to move through water; traversing through water cavities in the ice when approaching the seal or swimming towards a seal on an ice floe. The polar bear can stay underwater with its nose exposed. When it gets close enough, the animal lunges from the water to attack.{{sfn|Stirling|2011|pp=170–171}}

During a limited time in spring, polar bears will search for ringed seal pups in their birth lairs underneath the ice. Once a bear catches the scent of a hiding pup and pinpoints its location, it approaches the den quietly to not alert it. It uses its front feet to smash through the ice and then pokes its head in to catch the pup before it can escape. A ringed seal's lair can be more than {{cvt|1|m}} below the surface of the ice and thus more massive bears are better equipped for breaking in. Some bears may simply stay still near a breathing hole or other spot near the water and [[sit-and-wait predators|wait]] for prey to come by.{{sfn|Derocher|2012|pp=127–129, 131}} This can last hours and when a seal surfaces the bear will try to pull it out with its paws and claws.{{sfn|Ellis|2009|p=91}} This tactic is the primary hunting method from winter to early spring.<ref name="DeMaster1981"/>
[[File:Polar Bear ANWR 10.jpg|thumb|left|Bear with whale carcass]]
Bears hunt walrus groups by provoking them into stampeding and then look for young that have been crushed or separated from their mothers during the turmoil.{{sfn|Stirling|2011|p=161}} There are reports of bears trying to kill or injure walruses by throwing rocks and pieces of ice on them.<ref>{{cite journal|last1=Stirling|first1=I.|last2=Laidre|first2=K. L.|last3=Born|first3=E. W.|year=2021|title=Do wild polar bears (''Ursus maritimus'') use tools when hunting walruses (''Odobenus rosmarus'')?|journal=Arctic|volume=74|issue=2|pages=175–187|doi=10.14430/arctic72532|s2cid=236227117|doi-access=free}}</ref> Belugas and narwhals are vulnerable to bear attacks when they are stranded in shallow water or stuck in isolated breathing holes in the ice.{{sfn|Derocher|2012|pp=80–83}} When stalking reindeer, polar bears will hide in vegetation before an ambush.<ref name="Brook">{{cite journal |last1=Brook |first1=R. K. |last2=Richardson |first2=E. S. |year=2002 |title=Observations of polar bear predatory behaviour toward caribou |journal=Arctic |volume=55 |issue=2 |pages=193–196 |doi=10.14430/arctic703|doi-access=free }}</ref> On some occasions, bears may try to catch prey in open water, swimming underneath a seal or [[aquatic bird]]. Seals in particular, however, are more agile than bears in the water.{{sfn|Derocher|2012|pp=84–85, 132}} Polar bears rely on raw power when trying to kill their prey, and will employ bites and paw swipes.<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> They have the strength to pull a mid-sized seal out of the water or haul a beluga carcass for quite some distance.{{sfn|Ellis|2009|p=112}} Polar bears only occasionally [[Hoarding (animal behavior)|store]] food for later—burying it under snow—and only in the short term.<ref>{{cite journal|last1=Stirling|first1=I.|last2=Laidre|first2=K. L.|last3=Derocher|first3=A. E.|last4=Van Meurs|first4=R.|year=2020|title=The ecological and behavioral significance of short-term food caching in polar bears (''Ursus maritimus'')|journal=Arctic Science|volume=6|issue=1|pages=41–52|doi=10.1139/as-2019-0008|s2cid=209575444}}</ref>

[[Arctic fox]]es routinely follow polar bears and scavenge scraps from their kills. The bears usually tolerate them but will charge a fox that gets too close when they are feeding. Polar bears themselves will scavenge. Subadult bears will eat remains left behind by others. Females with cubs often abandon a carcass when they see an adult male approaching, though are less likely to if they have not eaten in a long time.{{sfn|Stirling|2011|pp=191–193}} Whale carcasses are a valuable food source, particularly on land and after the sea ice melts, and attract several bears.<ref name=Derocher1990/> In one area in northeastern Alaska, polar bears have been recorded competing with [[grizzly bear]]s for whale carcasses. Despite their smaller size, grizzlies are more aggressive and polar bears are likely to yield to them in confrontations.<ref>{{cite journal|last1=Miller|first1=S.|last2=Wilder|first2=J.|last3=Wilson|first3=R. R.|year=2015|title=Polar bear–grizzly bear interactions during the autumn open-water period in Alaska|journal=Journal of Mammalogy|volume=96|issue=6|pages=1317–1325|doi=10.1093/jmammal/gyv140|doi-access=free}}</ref> Polar bears will also scavenge at garbage dumps during ice-free periods.<ref>{{cite journal|last1=Lunn|first1=N. J.|last2=Stirling|first2=I.|year=1985|title=The significance of supplemental food to polar bears during the ice-free period of Hudson Bay|journal=Canadian Journal of Zoology|volume=63|issue=10|pages=2291–2297|doi=10.1139/z85-340|bibcode=1985CaJZ...63.2291L }}</ref>