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What the sources say

Arctic FoxVulpes lagopus

Every figure, record and mechanism on the Arctic Fox profile was written from a source, and this is the working table behind it: 51 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

Alaska Department of Fish and Game

Arctic Fox. Alaska Department of Fish and Game.

The page saysMainly lemmings and tundra voles in summer, plus nesting seabirds, berries, eggs and scavenged remains, including seals killed by polar bears in winter
The source saysIn summer, arctic foxes feed primarily on small mammals, including lemmings and tundra voles. Foxes denning near rocky cliffs along the seacoast often depend heavily on nesting seabirds such as auklets, puffins, and murres. ... Arctic foxes are omnivorous, and sometimes eat berries, eggs, and scavenged remains of other animals. Many foxes venture out onto the sea ice during winter to feed on remains of seals killed by polar bears.Note: seabirds are scoped to cliff-denning foxes in the body
The page saysThe arctic fox (Vulpes lagopus) has short legs, a short body, short ears and dense winter fur, which make it look stocky next to its slightly larger relative, the red fox.
The source saysTheir short legs and body, short ears, and dense winter fur give them a stocky appearance compared to their slightly larger relative, the red fox
The page saysFully grown arctic foxes weigh 6 to 10 pounds (2.7 to 4.5 kg) and average 43 inches (109 cm) long, including a tail of about 15 inches (38 cm).
The source saysFully grown arctic foxes weigh from 6 to 10 pounds. They average 43 inches (109 cm) in length including the tail, which is about 15 inches (38 cm) long.Note: 2.7 to 4.5 kg converted from 6 to 10 lb (2.72 to 4.54 kg); AnAge lists an adult weight of 5,200 g from older compilations; ADFG is the current anchor
The page saysIn summer they feed mainly on lemmings and tundra voles, and foxes denning near seaside cliffs often depend heavily on nesting seabirds such as puffins.
The source saysIn summer, arctic foxes feed primarily on small mammals, including lemmings and tundra voles. Foxes denning near rocky cliffs along the seacoast often depend heavily on nesting seabirds such as auklets, puffins, and murres.
The page saysThey sometimes eat berries, eggs and scavenged remains, too.
The source saysArctic foxes are omnivorous, and sometimes eat berries, eggs, and scavenged remains of other animals.
The page saysArctic foxes molt twice a year.
The source saysArctic foxes molt twice each year.
The page saysWhite foxes start shedding their long winter fur in early April, and by late June the face, legs and upper body wear short brown summer fur.
The source saysThe white foxes begin to shed their long winter fur in early April. By late June the face, legs, and upper parts of the body are covered with short, brown summer fur.
The page saysThe switch back runs through September and October, and by November the white winter coat is complete.
The source saysThe change to winter pelage occurs in September and October. By November the luxurious white winter coat is complete.
The page saysIn winter, many arctic foxes venture onto the sea ice to feed on the remains of seals killed by polar bears.
The source saysMany foxes venture out onto the sea ice during winter to feed on remains of seals killed by polar bears.
The page saysIn winter, dense fur sheathes the arctic fox's paws, which sets it apart from other canids. That is where its scientific name comes from: lagopus means "rabbit-footed."
The source saysThe arctic fox's paws are sheathed in dense fur during the winter, unlike other canids, giving it the name "lagopus" (which means "rabbit footed").
The page saysRabbit-Footed by Name
The source saysgiving it the name "lagopus" (which means "rabbit footed")
The page saystags: carnivore
The source saysIn summer, arctic foxes feed primarily on small mammals, including lemmings and tundra voles.
The page saystags: burrower
The source saysThey extend from six to 12 feet underground. Enlarged ground squirrel burrows with several entrances are often used as dens.

Source
02

Animal Diversity Web, University of Michigan

Vulpes lagopus (Arctic fox). Animal Diversity Web, University of Michigan.

The page saysTreeless Arctic tundra, usually in coastal areas, across Eurasia, North America, Greenland and Iceland
The source saysArctic foxes are found in the treeless tundra extending through the arctic regions of Eurasia, North America, Greenland, and Iceland. ... Arctic foxes are found mainly in arctic and alpine tundra, usually in coastal areas.Note: ADW is 2007 but is the only range source in the pack; ADFG's range line is Alaska only
The page saysThey live in the treeless tundra of Eurasia, North America, Greenland and Iceland, usually in coastal areas.
The source saysArctic foxes are found in the treeless tundra extending through the arctic regions of Eurasia, North America, Greenland, and Iceland. ... Arctic foxes are found mainly in arctic and alpine tundra, usually in coastal areas.
The page saystags: arctic-tundra
The source saysArctic foxes are found in the treeless tundra extending through the arctic regions of Eurasia, North America, Greenland, and Iceland.
The page saystags: alpine
The source saysArctic foxes are found mainly in arctic and alpine tundra, usually in coastal areas.

Source
03

AnAge: The Animal Ageing and Longevity Database, Build 15 2023

AnAge entry for Vulpes lagopus. AnAge: The Animal Ageing and Longevity Database, Build 15, 2023.

The page saysIn captivity, arctic foxes have lived as long as 16.3 years.
The source saysMaximum longevity 16.3 years (captivity)Note: replaces ADFG's '16 years (captivity average)', which matches AnAge's maximum and cannot be an average

Source
04

Tietgen et al. 2021

Tietgen et al. (2021). Fur colour in the Arctic fox: genetic architecture and consequences for fitness. Proceedings of the Royal Society B: Biological Sciences.

The page saysa coat color set by one gene
The source sayswe identified the MC1R gene as the sole causal gene underlying Arctic fox Vulpes lagopus fur colourNote: 'one gene' for 'sole causal gene'
The page saysBlue foxes stay dark brown or charcoal all year, just slightly lighter in winter.
The source saysThe blue morph is uniformly dark brown or charcoal year-round, with a slightly lighter coloration during winter.
The page saysWhite foxes make up over 90% of the world's arctic foxes.
The source saysThe white colour morph makes up over 90% of the global Arctic fox population
The page saysA 2021 study of Scandinavian arctic foxes
The source saysArctic fox data used in this study originate from population monitoring [ 41 ] and the captive breeding programmeNote: the preceding paragraph names the Scandinavian peninsula population and its captive breeding programme; the study years are 2007-2019
The page saysnamed one gene, MC1R, as the only cause of the difference.
The source sayswe identified the MC1R gene as the sole causal gene underlying Arctic fox Vulpes lagopus fur colour
The page saysIts white version is recessive and its blue version dominant: 878 of 882 foxes with two white copies were white, and 230 of 243 with at least one blue copy were blue.
The source saysthe C allele represented a recessive white fur colour allele, and T a dominant blue fur colour allele (878 of 882 CC individuals were white, 221 of 234 TC individuals were blue and nine of nine TT individuals were blueNote: 230 of 243 = TC 221/234 plus TT 9/9
The page saysWhite foxes make up over 90% of the world's arctic foxes
The source saysThe white colour morph makes up over 90% of the global Arctic fox population
The page saysthe blue morph stays dark brown or charcoal all year, just slightly lighter in winter
The source saysThe blue morph is uniformly dark brown or charcoal year-round, with a slightly lighter coloration during winter.
The page saysOne gene, MC1R, sets the color
The source sayswe identified the MC1R gene as the sole causal gene underlying Arctic fox Vulpes lagopus fur colour
The page saysin a 2021 study, 878 of 882 foxes with two copies of its recessive white version were white, and 230 of 243 with at least one copy of its dominant blue version were blue.
The source saysthe C allele represented a recessive white fur colour allele, and T a dominant blue fur colour allele (878 of 882 CC individuals were white, 221 of 234 TC individuals were blue and nine of nine TT individuals were blueNote: 230 of 243 = TC 221/234 plus TT 9/9

Source
05

Henshaw, Underwood & Casey 1972

Henshaw, Underwood & Casey (1972). Peripheral Thermoregulation: Foot Temperature in Two Arctic Canines. Science.

The page saysFeet kept just above the point where living tissue freezes
The source saysArctic foxes and gray wolves maintain their foot temperature just above the tissue freezing point (about -1 degrees C)when standing on extremely cold snow, or when the foot is immersed in a -35 degrees C bath in the laboratory.
The page saysFeet held just above the point where living tissue freezes
The source saysArctic foxes and gray wolves maintain their foot temperature just above the tissue freezing point (about -1 degrees C)when standing on extremely cold snow, or when the foot is immersed in a -35 degrees C bath in the laboratory.
The page saysA 1972 study found that arctic foxes keep their feet just above the point where living tissue freezes, about -1°C, whether standing on extremely cold snow or with a foot dunked in a -35°C bath in the lab.
The source saysArctic foxes and gray wolves maintain their foot temperature just above the tissue freezing point (about -1 degrees C)when standing on extremely cold snow, or when the foot is immersed in a -35 degrees C bath in the laboratory.
The page saysWarm blood shunted through a network of blood vessels in the skin of the foot pad carried more than 99% of the heat the pad surface lost.
The source saysSelective shunting of blood-borne body heat through a cutaneous vascular plexus in the foot pad accounted for more than 99 percent of measured heat loss from the pad surface.
The page saysKeeping that heat exchange in the skin touching the cold ground, rather than throughout the pad, gives maximum energy efficiency, the researchers wrote.
The source saysMaximum energetic efficiency is achieved because the unit of heat exchange is located in the pad surface which contacts the cold substrate rather than throughout the pad.
The page saysA 1972 study found arctic foxes keep their feet just above the point where living tissue freezes, about -1°C, whether standing on extremely cold snow or with a foot in a -35°C lab bath.
The source saysArctic foxes and gray wolves maintain their foot temperature just above the tissue freezing point (about -1 degrees C)when standing on extremely cold snow, or when the foot is immersed in a -35 degrees C bath in the laboratory.
The page saysWarm blood shunted through a network of blood vessels in the skin of the foot pad carried more than 99% of the heat the pad surface lost.
The source saysSelective shunting of blood-borne body heat through a cutaneous vascular plexus in the foot pad accounted for more than 99 percent of measured heat loss from the pad surface.
The page saystags: cold-tolerant
The source saysSelective shunting of blood-borne body heat through a cutaneous vascular plexus in the foot pad accounted for more than 99 percent of measured heat loss from the pad surface.

Source
06

Prestrud 1991

Prestrud (1991). Adaptation by the Arctic Fox (Alopex lagopus) to the Polar Winter.

The page saysa body that needs no extra energy to stay warm even at -40°C
The source saysThe lower critical temperature is below -40 degrees C, and consequently increased metabolic rate to maintain homeothermy is not needed under natural temperature conditions.Note: LCT below -40 means no raised metabolism at -40
The page saysThat short, rounded shape, short muzzle included, helps it lose less heat.
The source saysShort muzzle, ears and legs, a short, rounded body and probably a counter-current vascular heat exchange in the legs contribute to reduce heat loss.
The page saysThe rest of the fox leans on its fur.
The source saysThe arctic fox ( Alopex lagopus ) adapts to the low polar winter temperatures as a result of the excellent insulative properties of its fur.
The page saysA 1991 review called it the best insulating fur of any mammal.
The source saysAmong mammals, the arctic fox has the best insulative fur of all.Note: dated in the sentence: a 1991 ranking
The page saysThe fox's lower critical temperature, the point below which a body must burn extra energy to stay warm, is under -40°C, so it doesn't need that extra burn in the temperatures it meets in the wild.
The source saysThe lower critical temperature is below -40 degrees C, and consequently increased metabolic rate to maintain homeothermy is not needed under natural temperature conditions.
The page saysa fox whose fur insulates so well that its body needs no extra energy to stay warm even at -40°C
The source saysThe lower critical temperature is below -40 degrees C, and consequently increased metabolic rate to maintain homeothermy is not needed under

Source
07

Lai, Bêty & Berteaux 2015

Lai, Bêty & Berteaux (2015). Spatio–temporal hotspots of satellite–tracked arctic foxes reveal a large detection range in a mammalian predator. Movement Ecology.

The page sayssatellite-tracked treks of up to 40 kilometers to hotspots on the sea ice
The source saysby detecting hotspots of fox activity on the sea ice. ... Foxes often traveled more than 10 km, and up to 40 km, to reach hotspots
The page saysSatellite tracking of foxes on Canada's Bylot Island showed how far they will go.
The source saysSummary of the winter tracking records of 26 arctic foxes from Bylot Island, Nunavut, Canada.
The page saysThey often traveled more than 10 kilometers, and up to 40, to reach hotspots on the sea ice where they were likely scavenging marine mammal carcasses.
The source saysthese solitary foragers occasionally used the sea ice where they sometimes formed spatio–temporal hotspots, likely scavenging on marine mammal carcasses. We detected 35 movements by 13 individuals forming five hotspots. Foxes often traveled more than 10 km, and up to 40 km, to reach hotspots
The page saysEach hotspot lasted one to two weeks and drew up to 12 foxes
The source saysto reach hotspots, which lasted one–two weeks and could gather up to 12 individuals.
The page sayswith as many as nine there on the same day
The source saysFour to 12 foxes visited a given hotspot, with a maximum of nine foxes present on the same day at Hotspot–1
The page saysAfter 30 of the 35 visits, the fox was back inside its home range the next day.
The source saysIn 30 times out of 35 (85.7 %), foxes were back inside their home range the day after leaving a hotspot
The page saysSatellite-tracked foxes on Canada's Bylot Island often traveled more than 10 kilometers, and up to 40, to reach hotspots on the sea ice where they were likely scavenging marine mammal carcasses.
The source saysthese solitary foragers occasionally used the sea ice where they sometimes formed spatio–temporal hotspots, likely scavenging on marine mammal carcasses. ... Foxes often traveled more than 10 km, and up to 40 km, to reach hotspots
The page saysEach hotspot lasted one to two weeks and drew up to 12 foxes.
The source saysFoxes often traveled more than 10 km, and up to 40 km, to reach hotspots, which lasted one–two weeks and could gather up to 12 individuals.

Source
08

Angerbjörn & Norén 2025

Angerbjörn & Norén (2025). Vulpes lagopus. The IUCN Red List of Threatened Species 2025: e.T899A223595394.

The page saysLeast Concern
The source saysIUCN Red List category: Least Concern (LC).Note: read through GBIF's copy of the Red List, iucnredlist.org refuses scripts; 2025 publication of the 2023 assessment

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.