---
title: "What the sources say about the Polar Bear | AnimalTracks.wiki"
description: "49 claims from the Polar Bear profile, each beside the words of the source that backs it."
image: "https://animaltracks.wiki/images/animals/polar-bear-1.webp"
canonical: "https://animaltracks.wiki/animals/polar-bear/sources/"
---

# What the sources say about the Polar Bear (*Ursus maritimus*)

> 49 claims from the Polar Bear profile, each beside the words of the source that backs it. A "..." marks a cut in a quote and [brackets] an insertion.

Profile: [Polar Bear](https://animaltracks.wiki/animals/polar-bear/)

## Polar Bear. San Diego Zoo Wildlife Alliance.

https://animals.sandiegozoo.org/animals/polar-bear

| The page says | The source says |
| :--- | :--- |
| a nose that smells seals 20 miles off | A polar bear's nose is so powerful it can smell a seal on the ice 20 miles (32 kilometers) away |
| a polar bear's nose can pick up a seal's scent from 20 miles (32 kilometers) away | A polar bear's nose is so powerful it can smell a seal on the ice 20 miles (32 kilometers) away |
| up to 10 centimeters (4 inches) of fat beneath it | Their 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'.) |
| most experts agree, the longest of the world's eight bear species | Polar bears are the newest of the eight bear species. ... most experts agree that polar bears are the longest bears |
| males can stand over 12 feet (3.7 meters) on their hind legs | males may measure over 12 feet (3.7 meters) when standing on their hind legs |
| Typical adult males weigh 300 to 635 kilograms (660 to 1,400 pounds) | males, most are 660 to 1,400 pounds (300 to 635 kilograms) |
| one enormous bear on record weighed more than 770 kilograms (1,700 pounds) | one enormous polar bear on record weighed more than 1,700 pounds (770 kilograms) |
| Females run smaller, at 150 to 250 kilograms (330 to 550 pounds) | females, most are 330 to 550 pounds (150 to 250 kilograms) |
| a pregnant female can weigh more than 453 kilograms (1,000 pounds) before she dens | pregnant females may weigh more than 1,000 pounds (453 kilograms) before denning |
| Alongside the brown bear, it's one of the two largest carnivores that live on land | Both polar bears and brown bears are big and are the largest land carnivores. |
| sniff out a seal's den under the snow | sniff out a seal's den that has been covered with snow |
| find a breathing hole in the ice up to a mile (1.6 kilometers) away | even find a seal's air hole in the ice up to 1 mile (1.6 kilometers) away |
| it costs a polar bear about twice the energy of most mammals | It costs a polar bear twice as much energy as most other mammals to move about in its Arctic environment. |
| which helps explain why it prefers to sit and wait rather than chase | This helps explain their preference for resting frequently and hunting for seals using sit-and-wait tactics rather than chasing their prey. |
| Underneath the coat sits a layer of fat 5 to 10 centimeters (2 to 4 inches) thick | Their fat can be 2 to 4 inches (5 to 10 centimeters) thick. |
| It is backup energy when food is scarce, and it may also help insulate the bear and keep it afloat | When 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. |
| they have been known to swim more than 100 kilometers (60 miles) without resting | They have been known to swim more than 60 miles (about 100 kilometers) without rest in search of food |
| it costs a polar bear about twice as much energy to get around the Arctic as it does most other mammals | It costs a polar bear twice as much energy as most other mammals to move about in its Arctic environment. |
| They wait motionless for hours beside a seal's breathing hole until it surfaces | Polar 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.) |
| Its scientific name, Ursus maritimus, means sea bear | The taxonomic name for polar bears is Ursus maritimus, which means sea bear |
| which helps explain why polar bears prefer sit-and-wait hunting to chasing | This helps explain their preference for resting frequently and hunting for seals using sit-and-wait tactics rather than chasing their prey. |
| paddling with their broad front feet and steering with their back legs like rudders | using their broad front feet for paddling and their back legs like rudders to steer |
| a bear that can remain motionless for hours above a seal's breathing hole, waiting for a seal to pop up | Polar 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)) |

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

https://sandiegozoowildlifealliance.org/species/polar-bear

| The page says | The source says |
| :--- | :--- |
| the IUCN lists the species as Vulnerable | IUCN Conservation Status: Vulnerable |
| disappearing sea ice is linked to declines in polar bears' body condition, reproduction and survival | Disappearing 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. |

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

https://animaldiversity.org/accounts/Ursus_maritimus/

| The page says | The source says |
| :--- | :--- |
| hollow, see-through fur over jet-black skin | Polar 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.') |
| Jet-black skin under hollow, clear guard hairs | Polar bear skin is black and the fur is actually clear, lacking in pigment. |
| Wild polar bears are estimated to live 25 to 30 years | In the wild polar bears are estimated to live 25 to 30 years. |
| Animal Diversity Web's oldest captive record, a female at the Detroit Zoo, reached 43 years and 10 months | In captivity the oldest recorded lifespan was a female that died at the Detroit Zoo in 1991 at 43 years and 10 months old. |
| waiting motionless for hours beside a seal's breathing hole in the ice until it surfaces | This 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.') |
| Polar bears are excellent swimmers | Polar bears are excellent swimmers |
| Zero 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. | Polar 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.') |
| That much is real biology | Polar 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 fur has zero white pigment, each hair is a hollow, clear tube, and underneath it all is jet-black skin | Polar bear skin is black and the fur is actually clear, lacking in pigment. |
| Polar bears have two ways to hunt, and still-hunting is the one they use most | Polar bears have two hunting strategies. Still-hunting is used predominately. |

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

https://www.fws.gov/species/polar-bear-ursus-maritimus

| The page says | The source says |
| :--- | :--- |
| Mainly ringed and bearded seals, plus walruses, belugas, and scavenged whale carcasses | Polar 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 U.S. Fish and Wildlife Service puts the global population at about 26,000 bears as of 2023, spread across 19 subpopulations | The global polar bear population is estimated to be 26,000 individuals as of 2023 ... Polar bears occur in 19 subpopulations |
| The U.S. Fish & Wildlife Service classifies the polar bear as a marine mammal, protected under the Marine Mammal Protection Act | The 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. |
| it depends largely on sea ice | Largely dependent on sea ice |

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

https://doi.org/10.1364/ao.37.003198

| The page says | The source says |
| :--- | :--- |
| A 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 | New 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)) |
| A 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 | New 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)) |
| fiber-optic cables that guide ultraviolet light | seem to rule out the UV waveguiding proposed by Grojean et al. |

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

https://doi.org/10.1126/science.aan8677

| The page says | The source says |
| :--- | :--- |
| A study that measured the metabolic rates of nine wild bears found their energy use ran 1.6 times higher than scientists had assumed | high 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. |
| leaving more than half the bears studied in an energy deficit | resulted in an energy deficit for more than half of the bears examined |

## 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.

https://doi.org/10.1139/z2012-033

| The page says | The source says |
| :--- | :--- |
| a shrinking sea of ice to swim | Our observations suggest long-distance swimming is a behavioral response to declining summer sea-ice conditions. |
| a study that GPS-tracked 52 adult females over six years | We 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. |
| 50 long-distance swims by 20 bears, averaging 154 kilometers and reaching as far as 687 kilometers, some lasting up to 9.7 days | we 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 researchers suggest the swims are a response to shrinking summer sea ice | Our observations suggest long-distance swimming is a behavioral response to declining summer sea-ice conditions. |
| In the southern Beaufort and Chukchi seas | long-distance swimming (>50 km) by polar bears in the southern Beaufort and Chukchi seas |