The Arctic fox ((Aloplex lagopus) Fjellrev (in Norwegian) Fjällräven (in Swedish)) is one of Scandinavia’s most endangered predators here we discuss how they are adapted to their environment and what is being done to help protect them.
Adaptations for living in the cold:
The Arctic fox lives in the Arctic region of the northern hemisphere and is extremely well adapted to the severe weather conditions (it can survive conditions as cold as -50oC!). These adaptations include very thick insulating fur, a special circulatory system in their legs to maintain their body temperature and to stop their feet freezing! They have rounded ears to reduce surface area for heat loss, as well as a short muzzle and short legs which also help reduce heat loss by reducing the fox’s surface area. During the autumn the arctic fox adds to it fat deposits in order to keep it warm throughout the winter and to use as an energy reserve.
The Arctic fox’s coat colour changes from winter to summer to help it remain camouflaged and in the winter the fox grows fur on the bottom of it’s paws which helps it walk on ice and snow as well as helping to keep it’s feet warm! It has excellent hearing in order to hear its prey underneath the snow.
Arctic foxes are able to lower their metabolic rate and their body temperature during winter this helps them to conserve their energy. During times when there is little food availability to increase the Arctic fox’s chances of finding food they can reduce their metabolic rate still further, allowing them to use their energy reserves more slowly.
Arctic foxes usually make their dens in low mounds or eskers in the arctic tundra. The dens are often used by many generations and some can be hundreds of years old! They often have numerous entrances and tunnels covering large areas underground.
The Arctic fox eats mainly lemmings but will also eat hares, voles, sometimes seal pups and will even eat other animals’ leftovers if food is scarce. The Arctic fox uses its excellent hearing to find its food under a covering of snow. When the Arctic fox hears its prey it will jump on the spot to break through the snow to its prey below.
Arctic foxes have a high pitched bark and will hiss and scream but they do not howl. Studies have shown that they can differentiate between members of their families and non members by their barks.
The number of the Arctic fox world wide is very high (several hundred thousand). The population size of the arctic fox is directly linked to the population size of its main food source, the lemming. In abundant lemming years a female can have as many as 10 – 16kits per litter though the average is 6! Where as in years where lemming numbers are low a female may only have a few kits or not reproduce at all.
However populations in Sweden and Norway are critically low and the Arctic fox is threatening to become extinct in both countries. The estimated total number of adults in Norway, Sweden and Finland (Fennoscandia) is thought to only be around 200 individuals.
In the past the main threat to Arctic foxes was hunting for their fur. Whilst the demand for fox fur has decreased and with it to the amount of foxes being hunted Arctic foxes are still hunted today by indigenous people as a game species.
The encroachment of the red fox on the territories of the Arctic fox is another factor affecting the numbers of Arctic fox as the red fox is larger and more aggressive.
There are several projects operating in Sweden and Norway which are working to help increase the numbers of Arctic foxes through the supplementation of food and control of red fox populations.