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What the sources say

Polar BearUrsus maritimus

Every figure, record and mechanism on the Polar Bear profile was written from a source, and this is the working table behind it: 49 claims checked word for word against these sources. The left column is what the page says. The right column is the source's own words, copied, not paraphrased; a ... marks a cut and[brackets] an insertion. Open any source and check it yourself.

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Source
01

San Diego Zoo Wildlife Alliance

Polar Bear. San Diego Zoo Wildlife Alliance.

The page saysa nose that smells seals 20 miles off
The source saysA polar bear's nose is so powerful it can smell a seal on the ice 20 miles (32 kilometers) away
The page saysa polar bear's nose can pick up a seal's scent from 20 miles (32 kilometers) away
The source saysA polar bear's nose is so powerful it can smell a seal on the ice 20 miles (32 kilometers) away
The page saysup to 10 centimeters (4 inches) of fat beneath it
The source saysTheir fat can be 2 to 4 inches (5 to 10 centimeters) thick.Note: SDZWA gives a 2-4 in (5-10 cm) range; stats.superpower states the top of that range as 'up to'.
The page saysmost experts agree, the longest of the world's eight bear species
The source saysPolar bears are the newest of the eight bear species. ... most experts agree that polar bears are the longest bears
The page saysmales can stand over 12 feet (3.7 meters) on their hind legs
The source saysmales may measure over 12 feet (3.7 meters) when standing on their hind legs
The page saysTypical adult males weigh 300 to 635 kilograms (660 to 1,400 pounds)
The source saysmales, most are 660 to 1,400 pounds (300 to 635 kilograms)
The page saysone enormous bear on record weighed more than 770 kilograms (1,700 pounds)
The source saysone enormous polar bear on record weighed more than 1,700 pounds (770 kilograms)
The page saysFemales run smaller, at 150 to 250 kilograms (330 to 550 pounds)
The source saysfemales, most are 330 to 550 pounds (150 to 250 kilograms)
The page saysa pregnant female can weigh more than 453 kilograms (1,000 pounds) before she dens
The source sayspregnant females may weigh more than 1,000 pounds (453 kilograms) before denning
The page saysAlongside the brown bear, it's one of the two largest carnivores that live on land
The source saysBoth polar bears and brown bears are big and are the largest land carnivores.
The page sayssniff out a seal's den under the snow
The source sayssniff out a seal's den that has been covered with snow
The page saysfind a breathing hole in the ice up to a mile (1.6 kilometers) away
The source sayseven find a seal's air hole in the ice up to 1 mile (1.6 kilometers) away
The page saysit costs a polar bear about twice the energy of most mammals
The source saysIt costs a polar bear twice as much energy as most other mammals to move about in its Arctic environment.
The page sayswhich helps explain why it prefers to sit and wait rather than chase
The source saysThis helps explain their preference for resting frequently and hunting for seals using sit-and-wait tactics rather than chasing their prey.
The page saysUnderneath the coat sits a layer of fat 5 to 10 centimeters (2 to 4 inches) thick
The source saysTheir fat can be 2 to 4 inches (5 to 10 centimeters) thick.
The page saysIt is backup energy when food is scarce, and it may also help insulate the bear and keep it afloat
The source saysWhen food is scarce, a polar bear's fat provides backup energy. It may also help insulate their bodies, generate heat in the freezing temperatures, and keep them afloat in water.
The page saysthey have been known to swim more than 100 kilometers (60 miles) without resting
The source saysThey have been known to swim more than 60 miles (about 100 kilometers) without rest in search of food
The page saysit costs a polar bear about twice as much energy to get around the Arctic as it does most other mammals
The source saysIt costs a polar bear twice as much energy as most other mammals to move about in its Arctic environment.
The page saysThey wait motionless for hours beside a seal's breathing hole until it surfaces
The source saysPolar bears can remain motionless for hours above a seal's breathing hole in the ice, just waiting for a seal to pop up.Note: 'for hours' confirmed by sdzwa-polar-bear.
The page saysIts scientific name, Ursus maritimus, means sea bear
The source saysThe taxonomic name for polar bears is Ursus maritimus, which means sea bear
The page sayswhich helps explain why polar bears prefer sit-and-wait hunting to chasing
The source saysThis helps explain their preference for resting frequently and hunting for seals using sit-and-wait tactics rather than chasing their prey.
The page sayspaddling with their broad front feet and steering with their back legs like rudders
The source saysusing their broad front feet for paddling and their back legs like rudders to steer
The page saysa bear that can remain motionless for hours above a seal's breathing hole, waiting for a seal to pop up
The source saysPolar bears can remain motionless for hours above a seal's breathing hole in the ice, just waiting for a seal to pop up.Note: vibe.reason (women artists, round 2)

Source
02

San Diego Zoo Wildlife Alliance

Polar Bears: Icons of the Arctic. San Diego Zoo Wildlife Alliance.

The page saysthe IUCN lists the species as Vulnerable
The source saysIUCN Conservation Status: Vulnerable
The page saysdisappearing sea ice is linked to declines in polar bears' body condition, reproduction and survival
The source saysDisappearing sea ice threatens the survival of the species, and evidence shows that loss of sea ice is correlated with declines in a polar bear's body condition, reproductive success, and survival.

Source
03

Animal Diversity Web, University of Michigan

Ursus maritimus (polar bear). Animal Diversity Web, University of Michigan.

The page sayshollow, see-through fur over jet-black skin
The source saysPolar bear skin is black and the fur is actually clear, lacking in pigment. The white appearance is the result of light being refracted from the clear hair strands.Note: 'hollow' confirmed by sdzwa-polar-bear: 'their hair is really made of clear, hollow tubes filled with air.'
The page saysJet-black skin under hollow, clear guard hairs
The source saysPolar bear skin is black and the fur is actually clear, lacking in pigment.
The page saysWild polar bears are estimated to live 25 to 30 years
The source saysIn the wild polar bears are estimated to live 25 to 30 years.
The page saysAnimal Diversity Web's oldest captive record, a female at the Detroit Zoo, reached 43 years and 10 months
The source saysIn captivity the oldest recorded lifespan was a female that died at the Detroit Zoo in 1991 at 43 years and 10 months old.
The page sayswaiting motionless for hours beside a seal's breathing hole in the ice until it surfaces
The source saysThis involves finding a seal's breathing hole in the ice and waiting for the seal to surface to make the kill.Note: 'for hours' confirmed by sdzwa-polar-bear: 'Polar bears can remain motionless for hours above a seal's breathing hole in the ice, just waiting for a seal to pop up.'
The page saysPolar bears are excellent swimmers
The source saysPolar bears are excellent swimmers
The page saysZero white pigment. Each guard hair is a hollow, clear tube, and what looks like white fur is really light refracting off that structure over jet-black skin underneath.
The source saysPolar bear skin is black and the fur is actually clear, lacking in pigment. The white appearance is the result of light being refracted from the clear hair strands.Note: 'hollow' confirmed by sdzwa-polar-bear: 'their hair is really made of clear, hollow tubes filled with air.'
The page saysThat much is real biology
The source saysPolar bear skin is black and the fur is actually clear, lacking in pigment. The white appearance is the result of light being refracted from the clear hair strands.
The page saysthe fur has zero white pigment, each hair is a hollow, clear tube, and underneath it all is jet-black skin
The source saysPolar bear skin is black and the fur is actually clear, lacking in pigment.
The page saysPolar bears have two ways to hunt, and still-hunting is the one they use most
The source saysPolar bears have two hunting strategies. Still-hunting is used predominately.

Source
04

U.S. Fish & Wildlife Service

Polar Bear (Ursus maritimus). U.S. Fish & Wildlife Service.

The page saysMainly ringed and bearded seals, plus walruses, belugas, and scavenged whale carcasses
The source saysPolar bears prey heavily on ringed seals (Phoca hispida) and, to a lesser extent, bearded seals (Erignathus barbatus). They occasionally take larger animals such as walruses (Odobenus rosmarus) and belugas (Delphinapterus leucas).Note: 'scavenged whale carcasses' confirmed by sdzwa-polar-bear: 'Sometimes several bears scavenge together at a whale carcass or human garbage dump.'
The page saysThe U.S. Fish and Wildlife Service puts the global population at about 26,000 bears as of 2023, spread across 19 subpopulations
The source saysThe global polar bear population is estimated to be 26,000 individuals as of 2023 ... Polar bears occur in 19 subpopulations
The page saysThe U.S. Fish & Wildlife Service classifies the polar bear as a marine mammal, protected under the Marine Mammal Protection Act
The source saysThe polar bear (Ursus maritimus) is the largest of the extant bear species and is classified as a marine mammal. Polar bears are protected under the Endangered Species Act and Marine Mammal Protection Act.
The page saysit depends largely on sea ice
The source saysLargely dependent on sea ice

Source
05

Koon 1998

Koon (1998). Is polar bear hair fiber optic? Applied Optics.

The page saysA 1998 study in Applied Optics measured how fast light fades inside real polar bear hairs, 2 to 8 decibels per millimeter, a loss rate that, with a reanalysis of older data, its author says seems to rule the idea out
The source saysNew direct measurement of high optical attenuation rates in polar bear hairs--2-8 dB/mm in the visible--and reanalysis of the data of Tributsch et al. ... seem to rule out the UV waveguiding proposed by Grojean et al.Note: 1998 and the journal are the reference record (Koon 1998, Applied Optics)
The page saysA 1998 study in Applied Optics measured how much light a polar bear hair loses over distance: 2 to 8 decibels per millimeter in visible light. That loss rate, together with a reanalysis of older data, seems to rule out the idea that the hairs guide ultraviolet light like fiber-optic cables
The source saysNew direct measurement of high optical attenuation rates in polar bear hairs--2-8 dB/mm in the visible--and reanalysis of the data of Tributsch et al. ... seem to rule out the UV waveguiding proposed by Grojean et al.Note: 1998 and the journal are the reference record (Koon 1998, Applied Optics)
The page saysfiber-optic cables that guide ultraviolet light
The source saysseem to rule out the UV waveguiding proposed by Grojean et al.

Source
06

Pagano et al. 2018

Pagano et al. (2018). High-energy, high-fat lifestyle challenges an Arctic apex predator, the polar bear. Science.

The page saysA study that measured the metabolic rates of nine wild bears found their energy use ran 1.6 times higher than scientists had assumed
The source sayshigh metabolic rates (1.6 times greater than previously assumed) ... They monitored the behavior and metabolic rates of nine free-ranging polar bears over 2 years.
The page saysleaving more than half the bears studied in an energy deficit
The source saysresulted in an energy deficit for more than half of the bears examined

Source
07

Pagano et al. 2012

Pagano et al. (2012). Long-distance swimming by polar bears (Ursus maritimus) of the southern Beaufort Sea during years of extensive open water. Canadian Journal of Zoology.

The page saysa shrinking sea of ice to swim
The source saysOur observations suggest long-distance swimming is a behavioral response to declining summer sea-ice conditions.
The page saysa study that GPS-tracked 52 adult females over six years
The source saysWe used movement data from 52 adult female polar bears wearing Global Positioning System (GPS) collars ... During 6 years (2004–2009), we identified 50 long-distance swims by 20 bears.
The page says50 long-distance swims by 20 bears, averaging 154 kilometers and reaching as far as 687 kilometers, some lasting up to 9.7 days
The source sayswe identified 50 long-distance swims by 20 bears. Swim duration and distance ranged from 0.7 to 9.7 days (mean = 3.4 days) and 53.7 to 687.1 km (mean = 154.2 km), respectively.Note: 154 and 687 are the source's 154.2 and 687.1 km rounded to whole kilometers.
The page saysThe researchers suggest the swims are a response to shrinking summer sea ice
The source saysOur observations suggest long-distance swimming is a behavioral response to declining summer sea-ice conditions.
The page saysIn the southern Beaufort and Chukchi seas
The source sayslong-distance swimming (>50 km) by polar bears in the southern Beaufort and Chukchi seas

How the table was made: a writer drafted the profile from these sources and logged each claim with its quote, a reviewer with nothing but this table checked every sentence said no more than its quote, and a script confirmed each quote appears word for word in the source. The method is in the site'sAbout page.