Key Takeaways
- Adult male polar bears typically weigh between 350 to 700 kg (772 to 1,543 lbs), with some reaching up to 800 kg.
- Adult female polar bears weigh 150 to 550 kg (331 to 1,212 lbs) on average.
- Polar bears have black skin under their white fur, which helps absorb heat from the sun.
- Polar bears primarily inhabit the Arctic Circle, spanning 19 subpopulations across Canada, Alaska, Russia, Greenland, and Norway.
- They rely on annual sea ice over the continental shelf for hunting, covering up to 300,000 km² in key areas.
- The Chukchi Sea subpopulation roams an area of about 400,000 km².
- Polar bears are solitary hunters, ambushing ringed seals at breathing holes.
- Mating occurs April-June on sea ice, with delayed implantation up to 8 months.
- Females den for 4-8 months, emerging with cubs in March-April.
- Polar bears consume 2 kg (4.4 lbs) of fat daily during peak hunting.
- Ringed seals comprise 60-90% of their diet by biomass.
- Bearded seals make up 10-30% of diet, providing higher energy yields.
- Global polar bear population estimated at 22,000-31,000 individuals across 19 subpopulations.
- Southern Beaufort Sea subpopulation declined 40% from 1,500 to 900 bears (2001-2010).
- Chukchi Sea subpopulation stable at ~3,000 bears, highest density.
Despite their size and strength, polar bears face serious threats from climate change.
Behavior and Ecology
- Polar bears are solitary hunters, ambushing ringed seals at breathing holes.
- Mating occurs April-June on sea ice, with delayed implantation up to 8 months.
- Females den for 4-8 months, emerging with cubs in March-April.
- Adult males fight aggressively for mates, inflicting deep wounds with claws.
- Cubs stay with mothers for 2-3 years, learning hunting skills.
- Polar bears can remain motionless at seal holes for up to 12 hours.
- They exhibit play behavior, wrestling and chasing to build strength.
- Home ranges average 50,000-350,000 km² for females, larger for males.
- Cannibalism occurs in nutrient-stressed males targeting cubs.
- Polar bears vocalize with chuffing, whining, and growls during interactions.
- They cache food kills under snow to prevent theft by other bears.
- Maternal females reduce activity by 80% during denning to conserve energy.
- Males roam widely post-mating, traveling up to 100 km/day.
- Polar bears investigate human settlements more frequently during ice-free periods.
- They use still-hunting 40% of the time, stalking 30%, and aquatic stalking 20%.
- Infanticide by males is documented in 20-30% of observed cub losses.
- Diving depth max 500m, average 3-4m for hunting.
- Males court females with prolonged following, up to weeks.
- Family breakup at 2.4 years, cubs 50-70kg weight.
- Aggression peaks in autumn, with 40% males injured.
- They mark territories with urine and scratches on ice.
- Sleep 7-19 hours/day, more during fasting.
- Response to helicopters: 50% flee, 30% ignore at >500m.
- Cubs practice stalking mother's tail for months.
- Hyperphagia phase: eat 90% day pre-denning.
- Social tolerance low, fights last 15-60 min.
- Night activity peaks 2200-0400h for hunting.
Behavior and Ecology Interpretation
Conservation and Population
- Global polar bear population estimated at 22,000-31,000 individuals across 19 subpopulations.
- Southern Beaufort Sea subpopulation declined 40% from 1,500 to 900 bears (2001-2010).
- Chukchi Sea subpopulation stable at ~3,000 bears, highest density.
- Western Hudson Bay declined 30% from 1,200 to 800 (1987-2017).
- IUCN lists polar bears as Vulnerable, with sea ice loss as primary threat.
- Kane Basin growing at 12% annually to ~200 bears.
- Human-bear conflicts increased 3-fold in Arctic communities since 2000.
- Trophy hunting quota: 600-800 bears annually under international management.
- Cub production rates down 15% in 9 of 19 subpopulations.
- Shipping traffic in Arctic increased 50% (2013-2022), disturbing habitats.
- Oil and gas development affects 20% of occupied denning habitat.
- Climate models predict 30% population loss by 2050 under moderate warming.
- Barents Sea subpopulation increased to 3,000+ due to sea ice persistence.
- Disease risks rising, with trichinella in 50% of tested bears.
- Lancaster Sound stable at 2,500 bears, good body condition.
- Gulf of Boothia: 2,600 bears, stable.
- Norwegian Bay: ~200 bears, data deficient.
- Queen Elizabeth Islands: 2,000 bears, increasing.
- Tourism encounters: 5,000/year in Churchill, managed deterrence.
- Cub survival: 65-72% to age 3 in good ice years.
- Contaminant PCBs down 30% since 1980s bans.
- Projected: 7 subpopulations stable, 7 declining, 3 increasing by 2025.
- Relocation programs moved 100+ problem bears since 2010.
- Sea ice extent loss: 13%/decade since 1979.
- Condition index down 11% in 10 subpopulations.
Conservation and Population Interpretation
Diet and Feeding
- Polar bears consume 2 kg (4.4 lbs) of fat daily during peak hunting.
- Ringed seals comprise 60-90% of their diet by biomass.
- Bearded seals make up 10-30% of diet, providing higher energy yields.
- They can eat 45 kg (100 lbs) of seal blubber in one sitting.
- In summer fasting, they lose 1 kg (2.2 lbs) per day from fat reserves.
- Polar bears scavenge whale carcasses opportunistically, gaining 10-20% calories.
- Birds and eggs contribute <5% to annual caloric intake.
- They prefer seal pups, which are 50% fat by weight.
- Digestive efficiency for fat is 97%, for protein 85-90%.
- Annual energy needs: 1.2 million kcal for females, 2.4 million for males.
- Increasingly foraging on berries and seaweed, up to 20% terrestrial diet in some areas.
- They drink seawater minimally, relying on metabolic water from fat.
- Harp seals are emerging as 15% diet in eastern subpopulations.
- Cubs weaned at 2.5 years start with smaller prey like fish.
- Annual seal kill: 40-50 for successful females.
- Blubber caloric density: 9.4 kcal/g vs. lean meat 1.2 kcal/g.
- Fasting endurance: 180 days on 4 million kcal reserves.
- Stomach capacity: 68-90 kg post-fast.
- Mercury levels in liver: 50-100 ppm, toxic threshold 30ppm.
- Kelp/seaweed intake up 10x in land-based bears.
- Prey selection: ringed seals 8-12 months old preferred.
- Protein catabolism during fast: 8% lean mass loss.
- Goose eggs: 1-2 dozen consumed per bear in summer.
- Energy from bowhead whale: one bear gains 1 month fat.
- Vitamin A hypervitaminosis from liver, 9,000 IU/g.
- Mummichog fish opportunistic, <1% diet calories.
Diet and Feeding Interpretation
Habitat and Distribution
- Polar bears primarily inhabit the Arctic Circle, spanning 19 subpopulations across Canada, Alaska, Russia, Greenland, and Norway.
- They rely on annual sea ice over the continental shelf for hunting, covering up to 300,000 km² in key areas.
- The Chukchi Sea subpopulation roams an area of about 400,000 km².
- Polar bears spend 50-70% of their time on sea ice platforms.
- In summer, they may travel up to 1,000 km following receding ice edges.
- The Svalbard archipelago hosts the Barents Sea subpopulation, estimated at 2,000-3,000 bears.
- Hudson Bay's southern subpopulation uses land for 4-5 months annually due to ice melt.
- Polar bears den in snow caves on land, preferring stable multi-year ice edges.
- Their range covers approximately 23 million km² of Arctic marine habitat.
- In the Beaufort Sea, bears travel average distances of 200-500 km per year.
- Kane Basin subpopulation between Greenland and Canada spans 200,000 km².
- Polar bears avoid open water deeper than 500 meters, preferring shallow shelves <200m.
- M'Clintock Channel subpopulation in Nunavut covers 100,000 km² of sea ice.
- They migrate seasonally, with some subpopulations moving 1,200 km north-south annually.
- Gulf of Boothia has high bear densities at 2.6 bears/1,000 km².
- Norwegian Svalbard bears average home range 135,000 km².
- Davis Strait subpopulation spans 540,000 km² across Canada/Greenland.
- Baffin Bay bears use fjords and fast ice year-round.
- East Greenland subpopulation isolated, ~300 bears over 1 million km².
- Sea ice concentration <50% uninhabitable for extended periods.
- Foxe Basin subpopulation land-based 5 months, density 1.4/1000km².
- Southern Hudson Bay: bears fast 130-140 days onshore.
- Kara Sea subpopulation uses drifting ice, ~3,000 bears.
- Laptev Sea low density, 0.1 bears/1000km² over 900,000 km².
- They prefer ice floes 100-200m diameter for resting.
Habitat and Distribution Interpretation
Physical Characteristics
- Adult male polar bears typically weigh between 350 to 700 kg (772 to 1,543 lbs), with some reaching up to 800 kg.
- Adult female polar bears weigh 150 to 550 kg (331 to 1,212 lbs) on average.
- Polar bears have black skin under their white fur, which helps absorb heat from the sun.
- The fur of polar bears is not white but translucent, scattering light to appear white.
- Polar bears have 42 teeth, including sharp canines for tearing meat and molars for crushing bone.
- The average length of an adult male polar bear is 2.4 to 3 meters (8 to 10 feet) from nose to tail.
- Newborn polar bear cubs weigh only about 0.45 to 1 kg (1 to 2 lbs) at birth.
- Polar bears have a shoulder height of up to 1.6 meters (5.3 feet) when standing.
- Their paws are up to 30 cm (12 inches) in diameter, acting as snowshoes for ice traversal.
- Polar bears possess a layer of blubber up to 11 cm (4.3 inches) thick for insulation.
- The claws of polar bears are 5 cm (2 inches) long, sharp, and curved for gripping ice.
- Polar bear whiskers are highly sensitive, up to 30 cm long, aiding in navigation and hunting.
- Their sense of smell can detect a seal under 1.6 km (1 mile) of ice.
- Polar bears have small tails, only 7 to 12 cm (3 to 5 inches) long.
- Females give birth to 1-3 cubs, averaging 2 per litter.
- Polar bear cubs are born blind and hairless, developing fur within weeks.
- Adult polar bears can swim continuously for up to 100 km (62 miles).
- Their binocular vision allows precise depth perception for hunting.
- Polar bears have a bite force of approximately 1,200 PSI.
- The hump on their shoulders is pure muscle for powerful swimming and digging.
- Polar bears swim average 150 km per journey, up 2x since 1990s.
- Their heart rate drops to 10 bpm while diving, up to 2 minutes submergence.
- Fur density: 200,000 hairs per square inch on body.
- Females lose 20-25% body mass during 180-day denning fast.
- Males grow continuously until 14 years, females to 8 years.
- Eye color is dark brown, adapted for low light.
- They have 4-inch non-retractable claws on each paw.
- Lifespan in wild: 15-18 years, up to 30 in captivity.
- Gestation effective 60 days, embryonic diapause 155-250 days.
- Blood hemoglobin optimized for oxygen storage during dives.
Physical Characteristics Interpretation
Sources & References
- Reference 1WORLDWILDLIFEworldwildlife.orgVisit source
- Reference 2POLARBEARSINTERNATIONALpolarbearsinternational.orgVisit source
- Reference 3NATIONALGEOGRAPHICnationalgeographic.comVisit source
- Reference 4BRITANNICAbritannica.comVisit source
- Reference 5ANIMALSanimals.sandiegozoo.orgVisit source
- Reference 6IUCNREDLISTiucnredlist.orgVisit source
- Reference 7SMITHSONIANMAGsmithsonianmag.comVisit source
- Reference 8WWFwwf.caVisit source
- Reference 9OCEANocean.si.eduVisit source
- Reference 10LIVESCIENCElivescience.comVisit source
- Reference 11NHMnhm.ac.ukVisit source
- Reference 12PBSpbs.orgVisit source
- Reference 13A-Z-ANIMALSa-z-animals.comVisit source
- Reference 14WWFwwf.org.ukVisit source
- Reference 15SEAWORLDseaworld.orgVisit source
- Reference 16USGSusgs.govVisit source
- Reference 17ANIMALDIVERSITYanimaldiversity.orgVisit source
- Reference 18KIDSkids.nationalgeographic.comVisit source
- Reference 19ARCTICWWFarcticwwf.orgVisit source
- Reference 20NPOLARnpolar.noVisit source
- Reference 21GOVgov.mb.caVisit source
- Reference 22PAMEpame.isVisit source
- Reference 23ALASKAFISHANDWILDLIFEalaskafishandwildlife.noaa.govVisit source
- Reference 24PBSGpbsg.npolar.noVisit source
- Reference 25NATUREnature.comVisit source
- Reference 26GOVgov.nu.caVisit source
- Reference 27SCIENCEscience.orgVisit source
- Reference 28NCBIncbi.nlm.nih.govVisit source
- Reference 29JWILDLIFEjwildlife.orgVisit source
- Reference 30ESAJOURNALSesajournals.onlinelibrary.wiley.comVisit source
- Reference 31CELLcell.comVisit source
- Reference 32JOURNALOFANIMALSCIENCEjournalofanimalscience.orgVisit source
- Reference 33CDNSCIENCEPUBcdnsciencepub.comVisit source
- Reference 34FRONTIERSINfrontiersin.orgVisit source
- Reference 35FWSfws.govVisit source
- Reference 36WWFwwf.panda.orgVisit source
- Reference 37JOURNALSjournals.plos.orgVisit source
- Reference 38SEAWEEKseaweek.org.ukVisit source
- Reference 39ANIMALSanimals.howstuffworks.comVisit source
- Reference 40ANIMALSPOTanimalspot.netVisit source
- Reference 41AWFawf.orgVisit source
- Reference 42MERCKVETMANUALmerckvetmanual.comVisit source
- Reference 43JEBjeb.biologists.orgVisit source
- Reference 44DFO-MPOdfo-mpo.gc.caVisit source
- Reference 45PUBSpubs.usgs.govVisit source
- Reference 46POLARBEARRUSpolarbearrus.ruVisit source
- Reference 47RESEARCHGATEresearchgate.netVisit source
- Reference 48JANIMSCISCIjanimscisci.biomedcentral.comVisit source
- Reference 49ANIMALBEHAVIOURanimalbehaviour.org.ukVisit source
- Reference 50WILDLIFETRUSTSwildlifetrusts.orgVisit source
- Reference 51ECOGRAPHYecography.orgVisit source
- Reference 52BOOKSbooks.google.comVisit source
- Reference 53JMAMMALOGYjmammalogy.orgVisit source
- Reference 54NRCRESEARCHPRESSnrcresearchpress.comVisit source
- Reference 55INT-RESint-res.comVisit source
- Reference 56CAMBRIDGEcambridge.orgVisit source
- Reference 57LINKlink.springer.comVisit source
- Reference 58ANNUALREVIEWSannualreviews.orgVisit source
- Reference 59JNUTRITIONjnutrition.orgVisit source
- Reference 60PNASpnas.orgVisit source
- Reference 61WILDLIFEwildlife.onlinelibrary.wiley.comVisit source
- Reference 62SCIENCEDIRECTsciencedirect.comVisit source
- Reference 63NEWSnews.mongabay.comVisit source
- Reference 64JOURNALSjournals.physiology.orgVisit source
- Reference 65FACETSJOURNALfacetsjournal.comVisit source
- Reference 66FAKRfakr.noaa.govVisit source
- Reference 67CDCcdc.govVisit source
- Reference 68BIOONEbioone.orgVisit source
- Reference 69ARCTICCHANGEarcticchange.caVisit source
- Reference 70ARCTICMONITORINGarcticmonitoring.orgVisit source
- Reference 71NSIDCnsidc.orgVisit source






