polar fox
| polar fox | ||||||||||||
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Arctic fox in winter fur |
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| Scientific name | ||||||||||||
| Vulpes lagopus | ||||||||||||
| ( Linnaeus , 1758) |
The arctic fox or ice fox ( Vulpes lagopus , synonym Alopex lagopus ) is a species of fox that is native to the northern polar region.
features
The scientific name means "rabbit-footed fox " because its paws are covered with thick fur like those of the polar hare . Its shape identifies it as a typical fox, but its head and snout shape appear more compact than that of the red fox, for example . The average length, including the approximately 35 centimeters long tail, measures between 65 and 90 centimeters. The shoulder height is around 30 centimeters, the weight around 5 kilograms. The females are only slightly smaller than the males.
The arctic fox is the only wild dog that the seasons the color of its fur changes . In summer the head, back, tail and legs are brown, the flanks and belly are light beige hairy. This fur cover, which is particularly pronounced in July and August and is shorter compared to winter fur, offers perfect camouflage in the tundra .
While the summer fur of all arctic foxes is similar, two very different color versions appear in the winter fur phase - a white and a blue variant. Accordingly, a distinction is made between “white fox” and “blue fox”. The white fox wears a pure white fur in winter. The colors of the winter blue fox fur, on the other hand, vary from light gray to dark blue and even black; There are differences from litter to litter and also geographically.
In the Canadian territory of Nunavut and the Northwest Territories , the white variant clearly predominates, while the blue variant only accounts for about one percent of the population in the interior and up to five percent in the coastal area and on the Arctic islands. In contrast, the blue variant is predominant on the Aleutian Islands and the Pribilof Islands of Alaska. In the south of Greenland the proportions are roughly the same. In general, the blue variant should be dominant , but the white foxes are likely to prevail in natural selection due to their better camouflage in snowy landscapes.
The relatively short snout, the very small ears and the rather short legs are an example of Allen’s rule and, in addition to the warming fur with a thick undercoat, are essential properties to defy the extreme arctic conditions all year round. The white winter fur, however, makes the hair appear longer than it really is. With around 70 percent undercoat, however, it has unusually good thermal insulation properties. It has been experimentally determined that the arctic fox can survive temperatures as low as −80 ° C. The fur has the best insulating properties of all mammals. Even at very low temperatures, the metabolic rate does not increase. The hairy soles of the feet (Linnes: Lagopus, the hare-footed ones) also contribute to this. By autumn, fat storage can increase weight by up to 50 percent, on the one hand for insulation and on the other hand as an energy reserve. Evolution developed further ways of saving energy: a lowerable resting metabolic rate and a lowering of the core body temperature; this also reduces the need for food intake. Surprisingly, it turned out that the energy expenditure when running is lower in winter than in summer. The tooth formula is 3 / 3-1 / 1-4 / 4-2 / 3 = 42
Arctic fox, white morph in winter fur, Iceland
In transition skin
In summer fur
Distribution area
The arctic fox is circumpolar north of the tree line and is widespread in Northern Europe ( Scandinavia , Spitsbergen , Iceland ), Northern Russia ( Siberia ), Northern Canada , Alaska ( United States ) and Greenland . Its habitat is mainly the tundra, but arctic foxes even live on the pack ice of the Arctic Ocean ; in search of food, arctic foxes occasionally penetrate south into boreal zones . In general, arctic foxes are very agile and, in search of a new territory, can cover large stretches over land and sea ice and also colonize more distant islands . There are reports that individual arctic foxes have traveled distances of over 3500 km. So he colonized Iceland through the frozen pack ice during cooler climates like the Little Ice Age .
nutrition
Like most foxes , the arctic fox is a predator and omnivore, but the size of the population is still mainly dependent on the fluctuating supply of rodents, in particular on the voles belonging to the lemmings . Depending on the region, the main prey of the arctic fox includes the mountain lemming ( Lemmus lemmus ), the collar lemming ( Dicrostonyx torquatus ), the Siberian lemming ( Lemmus sibiricus ), the swamp mouse ( Microtus oeconomus ) and the gray bank vole ( Myodes rufocanus ). The arctic fox is able to detect rodent nests and their tunnel-like entrances with the help of its very good sense of smell even through thick layers of snow; by digging up at lightning speed it secures its food even in the dead of winter. In summer he hunts the lemmings in the open tundra.
Also in the arctic breeding birds and their eggs and chicks an important part of the diet then represent the arctic fox. Search with coastal living arctic foxes the beaches of stranded carcasses , remains of fish and shell molluscs from. As companions of polar bears and arctic wolves , they attack the remains of their prey . In times of overabundance, supplies are hidden for periods of hunger. As a survivor, the arctic fox is also a scavenger and in times of need does not disdain any animal or vegetable substance as food. It then eats insects and berries , including ground squirrels , arctic hares , ptarmigan , and even the excrement of other animals is destroyed.
Reproduction and rearing of the young
The arctic foxes build a burrow in late winter for the birth and rearing of their young. They are looking for clay or sand hills that are not directly influenced by permafrost on river banks, lakes or in elevated areas, where they can dig a complex tunnel system with up to eight entrances. Because of the difficulty of finding suitable places, such structures are used for many generations, sometimes for 500 years. It has been proven that the lack of suitable terrain forces even other animal species such as arctic wolves to use ancient burrows abandoned by arctic foxes.
Arctic foxes are monogamous and stay together as a couple for life. Together they take part in the rearing of the young and defend their territory. Sometimes yearlings also help with rearing. There are permanent groups of up to six adults on Mednyi Island. Complicated social systems have sometimes been found on other islands too. The size of the home ranges depends on the food supply and is between 15 and 36 square kilometers.
The young are conceived in March or April. If the previous winter was particularly hard, then there will be delays or complete failure of the fertilization process. Once a year the female throws three to nine, sometimes more young. Since the gestation period is around 50 days, they are usually born between mid-May and mid-June. The size of the litter depends heavily on the food supply and climatic conditions. Mothers living on the coast have smaller litters on average than those living inland. The newborns are tiny and still very clumsy. They are born blind, deaf, and toothless, and they wear soft, dark brown fur hair that grows rapidly and increasingly lighter. After three to four weeks, the young foxes venture out of the birth cavity, after about six weeks they are weaned. At this age they are very playful. Around the middle of August, they were first rejected by their father and a little later by their mother. They spend the winter scattered and on their own. The boys are sexually mature around ten months after birth.
Natural enemies and diseases
In general, the arctic fox has a life expectancy of around four years. Natural enemies, apart from humans, are mainly the arctic wolf and occasionally the polar bear , to whom they keep their distance. Probably because of the increasing global warming , larger red foxes invade the previous area of distribution of the arctic fox and (occasionally) prey on arctic foxes. When threatened, the arctic fox usually flees, but it also knows how to defend itself violently.
The rabies is the most common fatal disease. Encephalitis and distemper can also have lethal effects, especially in years of high occurrence. Most arctic foxes are infested with ectoparasites and endoparasites : the arctic fox is a definitive host of the fox tapeworm , and it is not uncommon for it to be attacked by mange mites.
Systematics
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Phylogenetic classification of the genus Vulpes
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The first scientific description of the arctic fox comes from Carl von Linné in 1758, where he included the fox in the 10th edition of his Systema Naturae . The arctic fox was placed in its own genus Alopex for a long time . However, DNA analysis showed that it must be phylogenetically classified within the genus Vulpes .
On the basis of morphological and molecular biological data, it was developed by Binninda-Emonds et al. In 1999 it was classified as a sister species of the kit fox ( V. macrotis ) and compared with a taxon made up of steppe fox ( V. corsac ) and Tibetan fox ( V. ferrilata ) on the one hand, and red fox ( V. vulpes ) and Rüppell fox ( V. rueppelli ) as sister groups on the other . The North American Swift fox ( V. velox ), which was formerly considered a subspecies of the kit fox and is now considered a sister species of the arctic fox, was not considered in this study .
Up to eight subspecies are discussed:
- V. l. lagopus in most of the distribution area
- V. l. beringensis Bering Island
- V. l. foragorapusis Greenland
- V. l. fuliginosus Iceland
- V. l. pribilofensis Pribilof Islands
- V. l. semennovi Medny Island
Arctic fox skins as a commercial object
In the 19th and first third of the 20th century there was intensive trade in the valuable arctic fox winter pelts; they formed the main object of exchange between Eskimos and Europeans . Meanwhile, arctic fox populations in North America, Siberia and Greenland are considered to be more or less normal and stable again, unlike in Scandinavia and Iceland, where the arctic fox has become rare. The arctic fox is still considered to be a fur supplier in the Northwest Territories and in the Nunavut Territory; the hunting season lasts from the beginning of November to the beginning of April.
Duration
The total population of the arctic fox is given by the IUCN as "several hundred thousand animals". The arctic fox is not considered endangered ("least concern"). However, in an IUCN report from December 2009 for the UN Climate Change Conference in Copenhagen, it is assumed that the arctic fox is one of the animal species most threatened by global warming .
Individual evidence
- ↑ a b c d Anders Angerbörn, Pall Hersteinsson: Wild dogs . Ed .: Udo Gansloßer, Claudio Silleo-Zubiri. Filander Verlag, 2006, ISBN 3-930831-63-5 , The Arctic Fox , p. 121 ff .
- ^ A. Mellows, R. Barnett et al. a .: The impact of past climate change on genetic variation and population connectivity in the Icelandic arctic fox. In: Proceedings. Biological sciences / The Royal Society. Volume 279, Number 1747, November 2012, pp. 4568-4573, ISSN 1471-2954 . doi : 10.1098 / rspb.2012.1796 . PMID 22977155 . PMC 3479732 (free full text).
- ↑ Don Gutoski: A tale of two foxes (photo), nhm.ac.uk, 2015, accessed October 14, 2015.
- ↑ a b O. R. Bininda-Emonds, JL Gittleman, A. Purvis: Building large trees by combining phylogenetic information: a complete phylogeny of the extant Carnivora (Mammalia). In: Biological reviews of the Cambridge Philosophical Society. Volume 74, Number 2, May 1999, pp. 143-175, ISSN 1464-7931 . PMID 10396181 . (Review).
- ↑ a b Jan Zrzavý, Věra Řičánková: Phylogeny of Recent Canidae (Mammalia, Carnivora): Relative Reliability and Utility of Morphological and Molecular datasets. In: Zoologica Scripta Volume 33, No. 4, July 2004, pp. 311-333, doi : 10.1111 / j.0300-3256.2004.00152.x .
- ↑ a b Don E. Wilson & DeeAnn M. Reeder (eds.): 11509 Vulpes lagopus ( Memento of March 4, 2016 in the Internet Archive ) in Mammal Species of the World. A Taxonomic and Geographic Reference (3rd ed).
- ↑ Vulpes lagopus in the endangered Red List species the IUCN 2006. Posted by: Angerbjörn et al , 2004. Retrieved on 11 May, 2006.
- ↑ Climate change: arctic fox and koala bear threatened. In: fr-online.de. December 14, 2009, accessed December 18, 2014 .
literature
- Thomas Riepe: Foxes - Our secret neighbors ; Wagner Verlag (2006). ISBN 3-938623-68-3 .
- Norbert Rosing : In the realm of the polar bear ; Tecklenborg Verlag, Steinfurt 2006 (chapter on arctic foxes p. 85 ff.), ISBN 3-934427-99-5 .
- Northwest Territories, Department of Resources, Wildlife and Economic Development: Arctic and Red Foxes of the Northwest Territories ; 1st ed., Yellowknife 1991, ISBN 0-7708-7186-0 .
Web links
- Vulpes lagopus in the endangered Red List species the IUCN 2006. Posted by: Angerbjörn et al , 2004. Retrieved on 11 May, 2006.
- Arctic Fox - Adapted Arctic Resident Website of the WWF