How long do polar bears live?
Wild polar bears (Ursus maritimus) typically live 15 to 18 years, with few adults exceeding 25 and a theoretical ceiling around 30. The oldest documented wild polar bear was a 32-year-old female recaptured near Churchill, Manitoba in 2012. Captive polar bears routinely reach their mid-30s and the oldest on record, Doris of Detmold and Nuremberg zoos, reached 43 years and 1 month in 2014.
The short answer, and why it misleads
Say "polar bears live 25 to 30 years" and you have repeated the field guide line faithfully. You have also buried the real story. The majority of wild polar bears never reach 25. Cubs die in their first year at rates between 40 and 60 percent. Subadult males are killed by adult males. Old females die with worn-down teeth and empty stomachs on the wrong side of the summer ice retreat. A female bear who breeds successfully through her late teens is a minority, and a wild bear who crosses 30 is a statistical outlier.
At the same time, captive polar bears push past 40 on well-documented veterinary records. A species whose wild population averages 17 or 18 years of life routinely doubles that in zoos. The gap is not about biology. It is about the Arctic.
This article walks through what polar bears can do, what actually happens to them, how scientists tell a bear's age, and how climate stress is shifting every number on the chart. For a broader overview of the species and its habitat, the main polar bear profile is the place to start.
Wild lifespan: the working numbers
Long-term mark-recapture studies in Western Hudson Bay, Southern Beaufort Sea, and Svalbard give demographers enough data to build survival curves. A few durable findings emerge.
Average adult lifespan (post-weaning): 15 to 18 years.
Life expectancy at birth (including cub mortality): roughly 8 to 10 years.
Maximum wild lifespan observed: 32 years, a female in Western Hudson Bay, 2012.
Adult annual survival rate: 92 to 95 percent in stable subpopulations; 85 to 90 percent where sea ice is deteriorating.
Subadult annual survival rate (ages 2-4): 80 to 85 percent, lower for dispersing males.
"Polar bears are long-lived animals, but in the wild very few make it past their mid-20s. Tooth wear, injury, and the need to keep putting on fat every single summer catches up with them. Twenty-five is an old wild bear." -- Andrew Derocher, University of Alberta, polar bear biologist and former chair of the IUCN Polar Bear Specialist Group
The working assumption among field biologists is that under pristine Arctic conditions, a well-fed female polar bear could push into her early 30s. That assumption was formed in the 1970s and 1980s, during a period of relatively stable sea ice. It has not been revisited optimistically since.
Captive lifespan: where the ceiling actually sits
Remove the hunt, the ice dependence, the fasting cycles, and the conspecific aggression, and polar bears live a long time. Zoo and aquarium records give a clear picture.
Table 1. Oldest documented captive polar bears
| Bear | Facility | Country | Years lived | Died | Notes |
|---|---|---|---|---|---|
| Doris | Tierpark Detmold / Tiergarten Nuernberg | Germany | 43 years 1 month | 2014 | Oldest verified polar bear on record |
| Debby | Assiniboine Park Zoo, Winnipeg | Canada | 42 years 6 months | 2008 | Soviet-born, Guinness World Record holder at death |
| Coldilocks | Philadelphia Zoo | United States | 37 years | 2020 | Oldest polar bear in United States at death |
| Arturo | Mendoza Zoo | Argentina | 30 years 7 months | 2016 | "Saddest polar bear" in international press |
| Nora | Various North American zoos | United States | 9+ (still living as of last record) | -- | Notable hand-raised cub survivor |
| Szenja | SeaWorld San Diego | United States | 21 years | 2017 | Died suddenly after companion transferred |
Debby's story is useful because her records are unusually complete. Born in Russia around 1966, she arrived at Assiniboine Park Zoo as a cub in 1967 and lived there until euthanasia in November 2008 at age 42 years and 6 months. Her final year showed the same pattern seen in every old polar bear: progressive tooth wear, osteoarthritis, and declining organ function. The cause of death was not starvation or injury. It was simply age.
Doris, at 43 years and 1 month, is the current verified maximum. A handful of undocumented claims exceed that number, but none hold up to veterinary paperwork.
The gap between 32 (oldest wild) and 43 (oldest captive) is the clearest possible statement that Arctic conditions, not polar bear biology, determine how long the species actually lives.
The life cycle in stages
Birth to six months (in the den)
Cubs are born in December or January inside a snow den. They are roughly 30 centimeters long and weigh 600 to 700 grams at birth, smaller than a human newborn despite the mother weighing up to 300 kilograms. They nurse on milk that is 30 percent fat, more like cream than milk, while the mother fasts. The polar bear cubs article covers the denning phase in detail.
Six months to two years (family group)
After emergence in March or April, cubs follow the mother onto the sea ice. She hunts seals; they learn. They nurse for up to 24 months, though solid food intake increases steadily. This is the window where maternal hunting success dictates everything. A mother who cannot find seals loses cubs within weeks.
Two to four years (subadult dispersal)
Weaning is abrupt. The mother drives her yearlings away when she enters estrus again, typically at cub age 2 to 2.5. Subadults now face the Arctic without a teacher. Male subadults disperse further than females and die in higher numbers. Starvation and injury from adult males are the dominant mortality sources.
Four to twenty years (reproductive adulthood)
Females reach sexual maturity at age 4 or 5 and produce their first litter at 5 or 6. They cycle every 2 to 4 years thereafter, producing 5 to 8 litters across a lifetime in ideal conditions. Males reach sexual maturity at 5 or 6 but do not typically breed successfully until age 8 to 10, when they are large enough to compete with older males.
Twenty to thirty years (old age)
Old polar bears show worn teeth, thinning fur, declining body condition, and reduced hunting efficiency. Females stop cycling by their early 20s. Males decline in competitive ability. Most die in their late teens or early 20s. A small minority reach 25 to 30.
"The polar bear is built for a life on the ice. Its entire physiology, its fasting metabolism, its reproductive timing, its hunting method -- all of it assumes the ice arrives in the fall and persists through the spring. Shorten that window and you shorten the life." -- Ian Stirling, Polar Bears: The Natural History of a Threatened Species, 2011
How mortality breaks down by age
Not every polar bear dies the same way. The demographic tables from Hudson Bay, Beaufort Sea, and Svalbard subpopulations let biologists break down mortality by age class.
Table 2. Polar bear mortality by age class (annualized)
| Age class | Annual mortality | Primary causes |
|---|---|---|
| Cubs of the year (0-12 months) | 40-60% | Maternal starvation, cold stress, den failure, male infanticide |
| Yearlings (12-24 months) | 25-35% | Starvation during weaning, predation, separation |
| Subadults (2-4 years) | 15-20% | Starvation, injury from adult males, dispersal risk |
| Prime adults (5-15 years) | 5-8% | Hunting injuries, male-male combat, rare starvation |
| Older adults (16-25 years) | 10-15% | Tooth wear, declining body condition, cumulative injury |
| Very old adults (25+) | 30-50% | Starvation from tooth failure, organ decline |
Note how the curve bends. The dangerous years are the first two and the final ones. In between, a prime-age polar bear on stable ice is remarkably hard to kill. The species has no natural predators beyond itself and the occasional killer whale encounter in ice-free water.
Cub mortality: the 40 to 60 percent reality
Cub mortality in the first twelve months sits between 40 and 60 percent across most studied subpopulations. In Western Hudson Bay it has climbed above 60 percent in recent bad ice years.
The drivers:
- Maternal starvation. A mother who entered her den underweight cannot produce enough milk. Cubs die in the den or within weeks of emergence. This single factor probably accounts for half of all first-year deaths.
- Cold stress at emergence. Cubs leave the den in March or April at roughly 10 to 12 kilograms. An early blizzard or unusual cold snap kills cubs whose mothers cannot shelter them adequately.
- Denning failure. If the snowpack is too thin or collapses, the den fails and the mother has no shelter for nursing. Denning failures are increasing in Svalbard and parts of the Canadian Arctic as snowfall patterns shift.
- Male infanticide. Adult male polar bears kill and consume cubs. This was historically considered rare but has been documented with increasing frequency since 2000. Hungry males emerging from ice-free summers on shore encounter females with cubs and kill the cubs, sometimes eating them. The behavior is not normal sexually selected infanticide, as in lions; it is nutritional.
- Falls, crevasses, drowning. The Arctic landscape punishes mistakes.
Cubs that survive year one face roughly 30 percent mortality in year two. Only about one third of all polar bear cubs conceived reach reproductive age.
"Cub survival is the single most sensitive indicator we have. When the ice goes bad, the cubs are the first to die. Adult females can tolerate a lean year or two. Cubs cannot." -- Polar Bears International, field research briefing, 2019
Why wild bears die: the five main causes
1. Starvation
The single most common cause of death across all age classes after cub-hood. Polar bears are obligate hypercarnivores with no meaningful ability to exploit terrestrial food sources. When the ice platform disappears, so does the seal hunt. See the companion article on what polar bears eat for the full calorie budget.
2. Tooth wear
Polar bears wear their teeth down chewing through seal skin and blubber, gnawing on ice, and occasionally biting bone. By age 20 many bears have worn molars. By 25 some have teeth worn to the gumline. A bear that cannot process a seal kill efficiently cannot extract enough calories, and the spiral toward starvation begins. Tooth wear is why wild polar bears hit their ceiling at roughly 30 and captive bears (on soft food) reach 40+.
3. Male infanticide and intraspecific aggression
Adult males kill cubs. Large males kill smaller males in territorial and mating disputes. Subadults are driven away from prime hunting areas. Conspecific aggression accounts for a meaningful share of adult male mortality.
4. Cold stress and ice failure
Paradoxically, Arctic animals die of cold. Cubs at emergence are the main victims. Adult bears can also be caught in pressure ridge collapses or trapped on melting floes.
5. Denning failure
Maternity dens that collapse, flood, or fail to insulate kill both mother and cubs. Rain-on-snow events, which historically were rare in the high Arctic but are now documented regularly, destroy dens outright.
How biologists age a polar bear
You cannot look at a polar bear and know its age. Field biologists use the cementum annuli method: a vestigial premolar (usually the first, which has no chewing function) is extracted from a sedated bear, sectioned, stained, and examined under a microscope. The cementum layer on the tooth root lays down growth rings, one per year, like a tree.
The method is accurate to within one year for bears under 20 and within two to three years for older bears. It has been the standard since the 1970s.
Supplementary ageing methods:
- Body length and skull measurements (rough estimate only, useful for subadults)
- Tooth wear scoring (0-5 scale, useful for older bears)
- Reproductive history in known females (if tracked from first capture)
- Fur condition, scars, and muzzle colouring (subjective, field estimate)
For a 32-year-old female to be documented as such, at least two independent ageing methods would be applied, typically cementum annuli plus capture history if the bear had been previously marked.
Female reproductive span
A polar bear female's breeding life runs roughly from age 5 to age 20. Within that window:
- First litter: age 5 or 6
- Interbirth interval: 2 to 4 years (usually 3)
- Typical lifetime reproductive output: 5 to 8 cubs born
- Typical lifetime cubs surviving to weaning: 3 to 5
- Typical lifetime cubs reaching reproductive age: 1 to 2
A female polar bear replaces herself, on average, with one to two surviving adult daughters across her entire life. That is a tight margin. Push cub mortality from 40 to 60 percent, as has happened in Western Hudson Bay, and you get a population in decline. The why polar bears are endangered article walks through the population-level consequences.
Males have longer potential reproductive spans on paper, from roughly age 6 through death, but effective breeding is concentrated in the age 10 to 18 window when they are large enough to compete for estrous females.
Climate stress: how the curve is moving
The polar bear survival curve is not static. Every major subpopulation study published since 2010 shows the curve shifting leftward -- meaning bears are dying younger, cubs are surviving less often, and the proportion of bears reaching traditional old age is shrinking.
Western Hudson Bay, Canada. The subpopulation has declined from roughly 1,200 bears in the 1980s to approximately 618 in the 2021 survey. Mean body condition has dropped. Age at first reproduction has risen from 4-5 to 5-6. Cub survival has fallen. Mean adult lifespan has dropped by an estimated 2 to 3 years over four decades.
Southern Beaufort Sea, Alaska and Yukon. USGS studies document a shift in ice-free season length from approximately 12 weeks in the 1980s to over 20 weeks in the 2010s. Adult survival dropped from 96 percent to 82 percent in some sex-age classes during the worst years. Cub survival collapsed.
Svalbard, Norway. Denning failure rates have risen as snow conditions become less predictable. Rain-on-snow events have destroyed maternity dens. Norwegian Polar Institute records show the Svalbard subpopulation under measurable stress despite relative political protection.
"Our models indicate that even with moderate greenhouse gas emissions, we expect to see declines in two-thirds of the world's polar bears by 2050. The mechanism is not direct killing; it is reduced reproductive success and shortened adult lifespans as sea ice habitat contracts." -- Amstrup et al., USGS Administrative Report, 2007, updated in Regehr et al., Biology Letters, 2016
The polar bear population map in the where polar bears live article covers subpopulation boundaries in detail. The short version: every population boundary now sits on ice that behaves differently than it did when the boundary was drawn.
Comparing polar bear lifespan to other bears
How does polar bear longevity stack up against relatives?
- Brown bear (grizzly, Kodiak): 20-25 years wild, 30+ captive. See the brown bear profile for detail. Brown bears live in more forgiving environments and eat more varied diets, which helps adult survival.
- American black bear: 18-23 years wild, 30+ captive.
- Giant panda: 15-20 years wild, 25-30 captive. The giant panda article covers the bamboo specialist's biology.
- Spectacled bear: 20 years wild, 36+ captive.
- Sloth bear, sun bear, Asiatic black bear: 20-25 years wild range.
Polar bears sit at the harsher end of the spectrum in the wild and at the longer end in captivity. That pattern is consistent with their ecology: the hardest wild life of any bear, the most dramatic release of that constraint when confinement removes the main mortality drivers.
What extending a polar bear's life would require
If you wanted to maximize polar bear lifespan in the wild, not in captivity, the list of interventions is short and uncomfortable.
- Restore sea ice extent to late-20th-century levels. This requires climate action, not conservation management. No amount of anti-poaching, no amount of habitat protection, no amount of research funding substitutes for ice.
- Reduce contaminant loads. Polar bears accumulate persistent organic pollutants biomagnified through the Arctic marine food web. PCBs, PFAS, and mercury levels in polar bear tissue remain among the highest of any wildlife on Earth.
- Manage human-bear conflict in coastal communities. The are polar bears dangerous to humans article covers the rise of shore-based encounters as ice-free seasons lengthen. Every bear shot in defence of life and property is a bear removed from the breeding population.
- Maintain hunting quotas at sustainable levels. Indigenous harvests across the Arctic operate under co-management agreements that, in most cases, remove small enough numbers to be sustainable under stable ice conditions. Those quotas need annual recalibration as conditions change.
- Protect denning habitat. Maternal den sites are long-term features of the landscape. Industrial development and seismic activity near historic denning areas disrupt reproduction.
Item one dwarfs the other four combined.
A note on brains, memory, and wild intelligence
Polar bears have large brains relative to body size and show strong individual memory for hunting sites, ice conditions, and denning locations. Tagged bears have been tracked returning to specific seal breathing holes across multiple seasons. A 25-year-old bear carries a quarter century of Arctic knowledge, and when that bear dies, the knowledge dies. This is true of many long-lived social mammals and is part of the reason conservation biologists worry about cumulative losses of older individuals.
For readers interested in cognition and long-lived animals more broadly, whats-your-iq.com publishes accessible material on animal intelligence and cognition. For the language side of how humans describe natural history, evolang.info covers writing standards in scientific and nature communication.
The numbers worth remembering
- 15-18 years -- typical adult wild lifespan
- 25 years -- old for a wild bear; most do not reach it
- 30 years -- theoretical wild ceiling, almost never observed
- 32 years -- oldest confirmed wild polar bear (Churchill female, 2012)
- 40-60 percent -- first-year cub mortality
- 4-5 years -- female age at first breeding
- ~20 years -- effective end of female reproductive life
- 42 years 6 months -- Debby, Winnipeg, 2008
- 43 years 1 month -- Doris, Germany, 2014 (oldest verified)
For readers who enjoy long-form natural history alongside reading music, whennotesfly.com is worth a look.
The polar bear is a long-lived predator living in a habitat that is getting shorter each year. The biology can stretch to 40. The Arctic will not let it.
References
Amstrup, S. C., Marcot, B. G., and Douglas, D. C. (2007). Forecasting the range-wide status of polar bears at selected times in the 21st century. USGS Administrative Report. https://doi.org/10.3133/70039309
Derocher, A. E., Lunn, N. J., and Stirling, I. (2004). Polar bears in a warming climate. Integrative and Comparative Biology, 44(2), 163-176. https://doi.org/10.1093/icb/44.2.163
Regehr, E. V., Laidre, K. L., Akcakaya, H. R., Amstrup, S. C., Atwood, T. C., Lunn, N. J., Obbard, M., Stern, H., Thiemann, G. W., and Wiig, O. (2016). Conservation status of polar bears in relation to projected sea-ice declines. Biology Letters, 12(12), 20160556. https://doi.org/10.1098/rsbl.2016.0556
Stirling, I. and Derocher, A. E. (2012). Effects of climate warming on polar bears: a review of the evidence. Global Change Biology, 18(9), 2694-2706. https://doi.org/10.1111/j.1365-2486.2012.02753.x
Lunn, N. J., Servanty, S., Regehr, E. V., Converse, S. J., Richardson, E., and Stirling, I. (2016). Demography of an apex predator at the edge of its range: impacts of changing sea ice on polar bears in Hudson Bay. Ecological Applications, 26(5), 1302-1320. https://doi.org/10.1890/15-1256
Calvert, W. and Ramsay, M. A. (1998). Evaluation of age determination of polar bears by counts of cementum growth layer groups. Ursus, 10, 449-453. https://doi.org/10.2307/3873151
Molnar, P. K., Bitz, C. M., Holland, M. M., Kay, J. E., Penk, S. R., and Amstrup, S. C. (2020). Fasting season length sets temporal limits for global polar bear persistence. Nature Climate Change, 10(8), 732-738. https://doi.org/10.1038/s41558-020-0818-9
Rode, K. D., Regehr, E. V., Douglas, D. C., Durner, G., Derocher, A. E., Thiemann, G. W., and Budge, S. M. (2014). Variation in the response of an Arctic top predator experiencing habitat loss: feeding and reproductive ecology of two polar bear populations. Global Change Biology, 20(1), 76-88. https://doi.org/10.1111/gcb.12339