Arctic fox
- The gestation period in the arctic fox lasts 49–57 days, and a litter may include 7–12 or more young — this is the highest number among carnivores.
- The Arctic fox is the only canid with fur on its paw pads, protecting against frostbite.
- Pregnant arctic foxes are able to consume and absorb large amounts of food according to autumn norms without harm to themselves or their offspring. This is related to their polytocity.
- The arctic fox digs complex burrows with many entrances — up to 60–80. It does this in soft ground surrounded by stones that protect the entrances from predators.
- The arctic fox is the only member of the canid family that exhibits pronounced seasonal coloration dimorphism. It is purely white in winter and dull brown in summer.
- One female walked more than 3500 km across the ice in 76 days — a record for the species.
- Winter fur is 1.4 times denser than summer; it starts shivering only at −70 °C.
- Arctic fox families usually live separately, but may form colonies consisting of 2–3 families.
- Raw fish contains the enzyme thiaminase, which breaks down vitamin B1. Long-term consumption of such fish is undesirable, as it may lead to vitamin deficiency in young animals.
- A female arctic fox can become pregnant only during a short period of estrus, which lasts 3–7 days and occurs in the middle of February to the middle of March.
- The arctic fox eats animals caught in traps, including other arctic foxes. On the coast, it often accompanies polar bears and obtains some of the meat from killed seals.
- The arctic fox has a short muzzle and rounded ears that barely protrude from the winter fur, which protects them from frostbite.
- It hears lemmings under up to 70 cm of snow and dives into the drift to catch them.
Age
Arctic foxes have a typical lifespan of from 10 to 14 years, with a maximum recorded lifespan of 21 years and 4 months, and a theoretical lifespan ranging from 8 years and 2 months to 16 years and 4 months; the species reaches sexual maturity from 10 months and 1 week to 1 year of age. The young open their eyes between 1 week and 3 days and 2 weeks and 2 days, and begin walking from 2 weeks and 4 days to 4 weeks of age. During the embryonic stage, the embryo develops inside the mother, receiving nourishment from her and growing rapidly. The pup stage begins after birth, when the young are initially blind and toothless, living in a den and feeding on maternal milk, lasting from 1 day to 1 month and 2 weeks. Following this, the species enters the adult stage, which lasts from 11 months to 7 years, during which time the animal can reproduce and forage for food independently, and its fur changes color seasonally.
Phenotype
The Arctic fox has soft and dense fur to protect its young from the cold, and their eyes open two weeks after birth. Adults possess very thick and warm white fur for camouflage on snow and protection from frost, but also have shorter and sparser brown fur for camouflage among grass and stones. The species has small rounded ears that help conserve body heat, and short legs with dense fur on the soles to prevent freezing on ice. It also possesses a bushy tail used as a blanket during sleep.
Physiology
The Arctic fox’s body height ranges from 35 to 65 centimeters, and its body length varies from 45 to 70 centimeters; the species' mass is between 3.09 and 3.15 kilograms. During the "Embryo" stage, the developing individual has a body mass ranging from 1 to 40 grams and a body length of 5 to 12 centimeters. As a “Pup,” the young have a body mass from 60 grams to 0.8 kilograms and a body length between 20 and 40 centimeters. The “Adult” stage is characterized by a body mass ranging from 3.5 to 5.5 kilograms and a body length of 50 to 70 centimeters.
Habitat
Arctic foxes inhabit elevations of up to 500 meters and are found in flooded meadows where water frequently covers the ground and there is abundant grass, taiga with cold winters and many coniferous trees such as spruce and pine, and tundra characterized by very cold temperatures and short summers with little tree growth and much moss. The species occupies terrestrial landscapes including deserts and semi-deserts, highland tundra, and intertidal zones. The climate features cool summers with temperatures of 15 to 20 degrees Celsius, constant moisture with frequent rains, polar tundra conditions with very cold temperatures and short summers, very cold conditions with abundant snow and ice, and a combination of plentiful rainfall, a cool summer, and snow in winter.
Shelter
Arctic foxes are found on hills or riverbanks within permafrost zones; the species utilizes an excavated underground tunnel or chamber for shelter or nesting. The Arctic fox uses its den for reproduction, rest, and protection from cold. Materials used in the den include berries.
Geography
Arctic foxes are found within the biogeographical realms of Nearctica and Palearctica, inhabiting ecosystems such as the Russian Arctic desert, the Kalaallit Nunaat Arctic steppe, and the Davis Heights tundra.
Feeding
The Arctic fox is a predator that primarily hunts lemmings; during summer, the species also consumes birds, eggs, and insects, while in winter it frequently eats carrion left by polar bears. Its diet includes lemmings, voles, birds, eggs, carrion, berries, rodents, and field mice. The strategy for obtaining food involves active hunting, ambushes, searching for food, and scavenging. Daily food requirements range from 150 grams to 400 grams, and young Arctic foxes consume milk. The species preys on lemmings, grey voles, white ptarmigans, geese, swan geese, divers, smews, scoters, eiders, hares, and waterfowl. In some cultures, the animal is eaten, but it is not considered halal or kosher.
Reproduction
Arctic foxes inhabit and develop on land, away from bodies of water, and their young develop in a nest built on or near the ground, specifically within an underground den where both parents care for them. The species reproduces through live birth, with the female giving birth to between 5 and 12 pups within the den. Gestation lasts 1 month and 3 weeks; the female has litters of 5 to 12 pups. Arctic foxes are monogamous, and both parents provide care for their offspring. The species reproduces through sexual reproduction, always involving fertilization and without generational change. Maturity is reached from 10 months to 1 year, and the interval between reproductions is 1 year.