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Arctic Fox - Alopex lagopus
#1
Arctic Fox - Alopex lagopus


Range and Habitat 

[Image: 20060106193153!Distribution_arctic_fox.jpg]


The arctic fox is the only canid that has successfully made a home exclusively in the Arctic circle. They are found in the tundras of the arctic areas of Eurasia, North America, Iceland, and Greenland. However, their former range was much more extensive. Their remains have been found in many southern European countries like France, Great Britain, Germany, Poland and Switzerland.


Physical Appearance 

Arctic foxes have extremely small, rounded ears, which restrict heat loss, and a very large bushy tail that takes up half the animals length. The soles of their feet are covered entirely with hair to prevent frostbite. Their hair is very thick and dense, and is longer in the winter than the summer. Their thick fur has the highest insulation value of any mammal. 

Two color types (morphs) are known in the arctic fox: the white and the blue color morphs. Within these color morphs is a wide range of coloration. Arctic foxes in their winter phase can be solid white; white with light grey legs and face and a white stripe on the nose; light grey body with dark grey legs and head; dark grey all over; and any range of colors in between. Their colors will change throughout the year as well. When they molt in the summertime, the blue foxes turn a dark chocolate, while the white phase foxes turn greyish with lighter under parts. Foxes living where it is cold all the time generally stay white or a lighter grey, while those living on the coast where it is warmer tend to stay bluish. The blue color morph comprises less than 1% of the continental population, but are more common in western Alaska and on islands.


Diet 
Arctic foxes are highly opportunistic eaters, and will feed on rodents, lemmings, scavenge from wolf kills of bison, walrus carcass, flightless sea birds, and their eggs. They often cache food in holes dug in the ice, to eat later. The arctic foxes' population is directly correlated to the lemming. Both their lives exhibit a four year cycle, with the highest fox numbers peaking with the highest lemming numbers.


Reproduction and Life Cycle 
The arctic fox appears to be monogamous, with pairs staying together a significant amount of time. Mating season is from February to May. After a gestation period of 53 days, the arctic fox gives birth to a litter of 5-10 cubs in an underground den. This underground den is extensive and has many entrances, which may be used for several generations. The male helps in the raising of the young. The cubs emerge from the den at 3 weeks old, but will not accompany their parents on hunting expeditions until they are 8 weeks old. The group will remain together for up to 6 months, with the male cubs dispersing first. 


Behavior 
Arctic foxes are perhaps the only canid that has no fear of man. They have been observed stealing food from camps and bothered men skinning seals. This is rather unusual, because the arctic fox has been persecuted just like any other fox for its fur. So it is surprising that they still come into such close contact with people.

The arctic fox can travel extensively throughout its range, and some have been observed 931 mi. (1500 km) from where they were originally trapped and tagged. It is believed they are also carried by ice floes in the springtime. Arctic foxes have a distinct seasonal movement pattern. They live in the northernmost parts of their range during the spring and summer, and return inland in autumn to mate and raise their young. Arctic foxes also maintain large home ranges, which can be from 3 - 7 sq. mi (8.6 - 18.5 sq. km), and the home ranges rarely overlap. Territory size is influenced by availability of prey. 


Threats 
Snowy owls and golden eagles, as well as polar bears, wolverines, and red foxes all prey on arctic foxes, and humans and their dogs will kill them as well. They have been hunted extensively for their thick white fur in Iceland, and have even been captured and raised on fur farms. Diseases also take their toll, with rabies and distemper being the most common. Overall, the arctic fox is not threatened, and continues to thrive.


Subspecies 
  • Alopex lagopus lagopus 
  • Alopex lagopus beringensis -- Bering Islands 
  • Alopex lagopus fuliginosus -- Iceland 
  • Alopex lagopus groenlandicus -- Greenland 
  • Alopex lagopus hallensis -- Hall Island in the Bering Sea 
  • Alopex lagopus innuitus -- Karogar River, Point Barrow 
  • Alopex lagopus pribilofensis -- St. George Island, Pribilof Islands 
  • Alopex lagopus semenovi -- Mednij Island, one of the Commander Islands in the northeastern former Soviet Union 
  • Alopex lagopus sibiricus 
  • Alopex lagopus spitzbergensis -- Svalbard 
  • Alopex lagopus ungava 

Taxonomic Note 
The species name for the Arctic fox, lagopus, means "hare-footed" in Latin. The genus name, Alopex, means "fox" or "fox-like" in Greek.


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#2
Seasons of the Snow Fox

By John L. Eliot 

Patrolling vast expanses, this wanderer of the far north has adapted to cycles of feast or famine. 

Let a raven drop a bone onto the ice or the aromas from a hunter's cook tent waft from a mile away, and a small white shadow will soon materialize to investigate—an arctic fox. Near Hudson Bay a fox's curious nose pokes around a knifelike ridge of ice. "It is the friendliest and most trusting of the North American foxes, although it is characterized . . . as 'impudent,'" wrote naturalist Barry Lopez.

In winter these small, almost delicate foxes range over huge areas seeking rodents or mammal carcasses. Some cross more than 600 miles (966 kilometers) of pack ice in 40-below-zero conditions. The species expanded in the Arctic at the end of the last warm inter- glacial period, about 120,000 years ago. Evolution equipped them with small ears, short muzzles, and thick fur to minimize heat loss. Their feet are fur-covered, like hares'—hence their scientific name, Alopex lagopus, or "hare-footed fox."

Play or predation? Hunting ringed seal pups born in small caves under the snow in Norway's Svalbard archipelago, a fox rears up, jumps on a den, and dives in head first. Pups often escape from the den into open water. The foxes' keen noses can detect such lairs more than a mile away. Near Hudson Bay, foxes tag along with polar bears in winter to scavenge leftover seal carcasses.

Arctic foxes' most vital food source—or lack thereof—is a little fur ball called the lemming. Problem is, the rodents aren't reliable. "They don't commit mass suicide: That's a myth popularized by an old Walt Disney film," says James D. Roth, an ecologist at the University of Central Florida who has studied Hudson Bay foxes. "But lemmings do follow a natural boom-and-bust cycle. About every four years they're super-abundant, then they crash for one year, and gradually increase until the next peak." With a circumpolar range, arctic foxes probably total several hundred thousand with wide fluctuations because of variations in the lemming populations.

Most arctic foxes turn white in winter, but some have brownish blue fur. Many blue foxes live in coastal areas, where they blend into dark backgrounds. Both color types live in Svalbard, where competition for mates rouses rivals in March.

Some parts of the arctic foxes' range, like Svalbard, have no lemmings, so foxes there feed on seabirds, geese, and their eggs in summer. In winter the opportunist foxes scavenge seal and reindeer carcasses. Compared with Hudson Bay, Svalbard's fox population is more stable. "But because they rely on marine species, they have high concentrations of contaminants like PCBs," says Eva Fuglei, a wildlife biologist at the Norwegian Polar Institute, who is studying the effect of the toxics on the foxes' disease resistance and reproduction

As wildflowers replace ice and snow, young foxes emerge from dens in July. Lemming numbers have a huge impact on litter size. In 2002, when lemmings crashed in much of Canada, photographer Rosing found two sleepy pups in a den of only seven on Victoria Island in the Canadian Arctic. The following year, when lemmings were plentiful, "this den near Churchill had 13 pups", says Rosing, "and it was littered with lemming and bird carcasses." One of the den's adults for ages to feed its young. These foxes have shed their white winter coats for the brown and cream fur of summer. Blue foxes also turn dark brown this time of year.

In good lemming years one female may have up to 20 pups, and local arctic fox populations boom. When lemming numbers plummet, many arctic foxes starve in winter, leading to fewer and smaller litters.

Fox in the goose house: With more than a dozen hungry pups waiting, a female heads home with a mouthful of month-old snow goose. Critical to foxes during lean lemming years, about 100,000 snow geese nest on La Pérouse Bay near Churchill. "I found 72 geese feet in one Churchill den," says ecologist James Roth

When the pups were about two weeks old, their mother moved them one by one to a new den. Heavy rain may have prompted her decision, or she may have sought a cleaner site. Dens are often used by many generations—for as long as 300 years. The burrow complex may spread over 500 square feet (47 square meters) and have a hundred entrances, offering the pups quick escape from predators. Owls and eagles prey on young and adults, as do red foxes, a species from the south that overlaps the arctic foxes' range. Red foxes, which are considerably larger, also compete with arctic foxes for denning sites.

In years when food is abundant, adults feed their young through the summer until autumn, when the pups disperse. In lean years the pups leave the den earlier, to hunt on their own in a land where success is never a sure thing.

Seasons of the Snow Fox
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#3
The Arctic Fox with it's large Neighbor!
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The best looking fox [Image: e5127535.png]
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#4
Red Dog Wrote:
Quote:I always thought they were ALL white till I read this! :-[

The only white mammal which remains white the whole year round is the polar bear.
The artic fox changes colour just like the ptarmigan bird ( probably to adapt to the surrounding).

Additional info:

Canada, 2001
As the seasons change, the Arctic fox changes the color of its coat. In the spring and summer, it has a dark coat, to match the brown dirt in its environment. In the fall and winter, it turns white, to match the surrounding snow.

http://science.howstuffworks.com/animal-camouflage2.htm
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#5
Arctic Fox May Be Left Behind By Warming, Study Suggests


for National Geographic News
April 9, 2007

Contrary to popular opinion, not all cold-loving animals can simply retreat north in the face of global warming. New research into vanished populations of arctic foxes suggests there is no easy escape route. 

Scientists who investigated the fate of arctic foxes living in Europe during the end of the last ice age say the animals most likely died out after becoming isolated by rapidly rising temperatures. 

Since arctic foxes are highly mobile animals, the findings don't bode well for other, slower creatures that are sensitive to climate warming, the Swedish-led study team warned. (Related: "Polar Bears Suffering as Arctic Summers Come Earlier, Study Finds" [September 21, 2006].) 

"What our results show is that Arctic species don't retreat, they just disappear," said zoologist Love Dalén of Stockholm University. 

A team headed by Dalén and Anders Götherström of Uppsala University compared the DNA of arctic foxes in Scandinavia to genetic samples from animals that lived to the south some 20,000 years ago, when the previous ice age was drawing to a close. 

If the prehistoric foxes had retreated north as temperatures rose, their DNA should be reflected in current populations in northern Scandinavia, the study team said. 

But the genetic analysis of fossil bones unearthed in Germany, Belgium, and western Russia indicated no ancestral link to arctic foxes living today. 

Siberian Origins 

The researchers found instead that Swedish and Norwegian populations are descended from foxes that had spread thousands of miles west from eastern Siberia as the northern ice sheets melted. 

"The arctic foxes in mid-latitude Europe became extinct," the team concludes in the current issue of the journal Proceedings of the National Academy of Sciences. "Their genes did not contribute to the make-up of present-day populations." 

Clues to the disappearances may come from the way Scandinavian arctic foxes are responding to current climate change, Dalén said. 

"What we see is that the populations are decreasing, but they aren't really moving," he said. 

Movement is usually driven by high population density and competition for territory. But today numbers are actually falling due to climate-caused impacts, Dalén noted. 

"In a decreasing population, which was likely the case when the Ice Age was gone, probably there were lots of empty territories," he said. 

So instead of moving to more northerly latitudes, the arctic foxes gained altitude, Dalén suggested, taking to higher areas such as the Alps. 

But the killer blow may have been the arrival of red foxes as milder conditions took hold. 

Red Invasion 

"Red foxes, which are twice the size, could suddenly survive in these areas and out-compete the arctic foxes," Dalén said. "The red foxes probably came in and took over the lowland areas, and the arctic foxes got marooned." 

History may already be repeating itself. The recent northward spread of red foxes into polar regions in Europe and North America is being linked to the disappearance of the Arctic species in some regions. 

Conservationists say Scandinavia's arctic fox population, with fewer than 200 individuals remaining, now faces serious threat of extinction. Culling of red foxes has been introduced in arctic fox territories. 

The study team says its findings have far-reaching implications for understanding how species respond and adapt to climate change, suggesting that many animals could be more vulnerable to global warming than previously thought. 

"Arctic species may be unable to track the shifting habitat as the temperature increases," the researchers write. "This may result in losses of genetic variation as local populations become extinct." 

Dalén said similar studies are needed, because the ability of a species to follow climate-caused shifts in habitat isn't properly considered when predicting how the creature might respond to future warming. 

"Personally, I suspect most Arctic species will behave like the arctic fox," he said. "I would be very surprised, for example, if polar bears behaved differently." 

http://news.nationalgeographic.com/news/2007/04/070409-arctic-foxes_2.html 
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#6
Foxes Get Frisky In The Far North: First Genetic Evidence Of Polyandry With Multiple Paternity Found


Science Daily — Bees do it, chimps do it... Now it seems Arctic foxes do it, too. New research looking at the DNA fingerprints of canids in the Far North has revealed that foxes once thought to be monogamous are in fact quite frisky.


From polyandry to multiple paternity and plural breeding, Canadian researchers have gathered DNA evidence from adult foxes and their offspring that proves that some arctic foxes are mixing it up when it comes to mating. 

Until recently, wildlife biologists considered many species of canines--including foxes, wolves and coyotes--to be monogamous. But molecular genetic techniques are starting to reveal complexities in mammalian mating systems that were not apparent from observational studies of animal social behavior. Using a technique called microsatellite DNA fingerprinting, a team of researchers from the University of Alberta in Edmonton and the University of Quebec at Rimouski collected DNA samples from 49 arctic foxes trapped in dens on Bylot Island, Nunavut. 

In three-quarters of the dens, DNA fingerprints showed that the fox cubs were the offspring of a single male and female. But in a quarter of the cases, the arctic foxes proved to be less exclusive, with one litter providing the first genetic evidence of polyandry (females having multiple male mates at one time) with multiple paternity.

Lindsey Carmichael--lead author of the study and a recent graduate from the U of A--says there are various explanations for polyandry and the multiple paternity associated with it. 

"Multiple paternity allows a female to increase the genetic variation contained in a single season's reproductive output," says Carmichael. "This increase in variation might improve the odds that at least one cub in a litter will be optimally adapted to its current environment or better equipped to deal with changes in its environment over time."

The study appears in a recent issue of the Canadian Journal of Zoology.

Note: This story has been adapted from a news release issued by University of Alberta.
http://www.sciencedaily.com/releases/2007/07/070718001620.htm 
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#7
Arctic Foxes Put Eggs in "Cold Storage" for Lean Times

James Owen
for National Geographic News

October 29, 2007

Arctic foxes create "nest eggs" each year to prepare for leaner times, according to a new study. 

Like squirrels gathering nuts for the winter, the small foxes hoard bird eggs in case there's not enough of their favorite prey—the collard lemming—to go around in the spring. 

The stored eggs can last for up to a year after being buried, thanks to the Arctic permafrost and natural preservatives inside the eggs. 

"It appears as if cached eggs are used as a backup for unpredictable changes in lemming numbers," lead study author Gustaf Samelius of Grimsö Wildlife Research Station in Riddarhyttan, Sweden, said in an email. 

"This is a neat adaptation in an environment where food abundance changes dramatically both among seasons and years." 

Samelius added that the study is the first to show the extent to which the carnivores can depend on stored rations. 

Other carnivores are known to store food, the researcher noted, but they generally cache for only a few days and base their diets more on fresh kills. 

"Our results of about 50 percent of the [arctic fox's] diet coming from cached foods might be on the extreme end" compared with other meat-eaters, Samelius said. 

Cold Storage 

Samelius's team based its findings on the behavior of arctic foxes living near Karrak Lake in the Queen Maud Gulf Bird Sanctuary in the territory of Nunavut, Canada, between 2000 and 2004 (see a map of Nunavut). 

Karrak Lake is the summer breeding ground for up to a million snow geese and Ross's geese. The birds' nests supply ample pickings for the region's foxes, which store between 2,000 and 3,000 eggs a year. 

Over the course of their four-year study, which appeared in last month's issue of the Journal of Animal Ecology, the team found that the foxes stored similar numbers of eggs each year. 

But the degree to which the mammals relied on their caches varied with changes in lemming abundance. 

Collard lemming populations fluctuate dramatically over three- to five-year cycles, Samelius said, and the changes are largely unpredictable. 

When lemming numbers were high, the stored eggs made up less than 28 percent of the foxes' springtime diet. 

When the rodents were scarce, the eggs accounted for up to 74 percent of the mammals' food. 

For the foxes, the eggs are a reliable backup system because they are abundant during goose nesting season and are well suited to long-term storage. 

"Eggs are protected by the egg shell, several membranes, as well as chemical properties of the albumen [egg white], preventing microbial activity," Samelius said. 

The cold conditions of the Canadian Arctic also extend the shelf life of stored eggs, according to the study team. 

Chemical Proof 

The new study monitored the arctic foxes' yearly diets using analysis of chemical markers called isotopes in samples of the animals' fur and blood. 

Different levels of carbon and nitrogen isotopes in these samples reflected the different foods the mammals ate in the spring and fall of a given year. 

Vincent Careau is an arctic-fox researcher at the Université de Sherbrooke in Quebec who was not involved with the study. 

He said that the new research offers solid evidence for what many biologists had previously suspected. 

"Many noted the presence of egg shells in fox scats while there was no goose around, meaning that the consumed egg was inevitably recovered from a cache," Careau said, "but these observations remained anecdotic until this study came out." 

How the foxes manage to locate their egg caches after such a long time remains a mystery, Careau added. 

But studies of closely related red foxes and observations of the arctic foxes suggest that the animals use "spatial memory of cache locations and exploratory digging," he said. 

"We also observed foxes spending a lot of time moving eggs from cache to cache," Careau added. 

"This re-caching behavior probably improves memory of cache locations, especially if they progressively bring their eggs into one basket." 

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An arctic fox carries a stolen goose egg to be stored for the winter.

The carnivorous mammals hoard eggs for up to a year to use as a backup source of food during times when their preferred prey, the collard lemming, is scarce, according to a new study.


Here's a video of an Arctic Fox stealing eggs to 'store' - 'The Egg Thief'

http://news.nationalgeographic.com/news/2007/10/071029-arctic-foxes.html
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#8
Interactions between Arctic and Red Foxes in Scandinavia - Predation and Aggression


"ABSTRACT. 
Arctic fox (Alopex lagopus) populations in Scandinavia are small and restricted to alpine regions, while red foxes (Vulpes vulpes) are common throughout both Norway and Sweden. The two species are similar in behaviour and diet, and thus competition between them is likely. This study provides seven observations of aggressive interactions between the two species. One adult arctic fox and one cub were killed by red foxes, one male arctic fox was chased away from his den, one female arctic fox and a cub fled into the den as a red fox approached, four cubs fled into the den as a red fox walked upon it and once a red fox walked upon the arctic fox den when no arctic foxes could be seen. Only on one occasion did an arctic fox succeed in chasing away a red fox. Red fox predation may prove to be limiting to the small arctic fox population in Scandinavia, and arctic foxes can be displaced from good dens and the most productive regions."
http://pubs.aina.ucalgary.ca/arctic/Arctic42-4-354.pdf 
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#9
Arctic fox needs help in Nordic region: report

Tue May 27, 2008 

STOCKHOLM (Reuters) - The arctic fox is inching back from the brink of extinction in the Nordic region, but intensive conservation efforts must continue if the species is to survive in the longer term, a report said on Tuesday.

The Swedish-Finnish-Norwegian Arctic Fox Project has managed to double the number of breeding foxes since starting in 1998, it said in its report.

"We have succeeded in saving the arctic fox and getting the population to grow," said Professor Anders Angerbjorn, who leads the project.

But with about 140 individual animals in Sweden and 215 in the Nordic region, the local population is still considered too limited for long-term survival.

"The stock is still too small for a species that earlier existed over a greater part of the moorlands," the report said.

"Active support measures are needed to increase the arctic fox's ability to meet rising and falling food supply."

The arctic fox, a priority species according to the European Union's Habitat Directive, was nearly wiped out in the Nordic region by hunters in the early 20th century who were after its prized white fur.

Now global warming is adding to the danger, although the global population of the animal exceeds 100,000.

"Our unique Swedish moorland, which is the habitat of arctic foxes and many other unique animals and plant species, could just be a memory if we don't cut carbon dioxide emissions," said Tom Arnbom of the World Wildlife Fund in Sweden.

A warmer climate has, among other things, helped the spread of red foxes, which, at around 10 kg (22 lb), are twice the size of their arctic cousins and compete for food and territory.

A small and fragmented arctic fox population has also decreased genetic variation, while farmed arctic foxes, which differ from their wild relatives, have escaped into the wild and added to problems.

http://www.reuters.com/article/environmentNews/idUSL2790920820080527?pageNumber=1&virtualBrandChannel=0
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#10
Arctic foxes suffer while reds thrive in northern Canada

4 January 2013 Last updated at 03:01 

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Arctic fox sightings in northern Canada are at an unprecedented low this winter, according to wildlife guides.

And, unusually, the number of red foxes has simultaneously surged in the area, on Hudson Bay.

The surprising pattern has prompted observers to question whether the elusive Arctic foxes are being driven out of their dens by invading red relatives.

"It stopped dead, turned and ran," says Tera Ryan, wildlife guide at polar expedition company Churchill Wild, describing the time she witnessed an Arctic fox's reaction to a red fox travelling away in the distance.

"In the Arctic you conserve energy... This was running for fear. He did not want to be seen by that red fox."

Famed for their bright white coats in winter, delicate Arctic foxes (Vulpes lagopus) are not much larger than a domestic cat. Yet with their thick, insulating fur and increased blood circulation they are adapted to thrive in some of the world's most extreme conditions.

Previous studies have indicated that larger and more aggressive red foxes moving northward may outcompete their Arctic cousins for food and even kill the smaller species when the two collide on the same territory.

Arctic fox populations naturally fluctuate from year to year depending on the availability of their main food source, lemmings.

But the wildlife guides at Seal River lodge on Hudson Bay have reported the lowest number of Arctic fox sightings for years, despite what they say is a good year for lemmings.

The team have reported an average of two Arctic foxes spotted near their observation lodge in the same day, whereas "it would not be unusual to see a dozen or more per day in an average year," says Churchill Wild's Mike Reimer.

"Last year we had Arctic foxes everywhere you looked and no coloured foxes. And this year is completely different.

"This year it's coloured foxes... we've got red, silvers, crosses. And we've had the odd Arctic fox try to come in and the coloured [ones] are much more aggressive so they drive them off."

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Red foxes may struggle to cope in harsh winters

But biologist Dr Jim Roth from the University of Manitoba in Winnipeg, Canada says that while it is "possible" a surge in red foxes this season could have a temporary impact on Arctic fox numbers, the dip is more likely to have been caused by another factor such as food resources, disease or parasites.

Dr Roth's annual observations of both Arctic and red fox dens around the Arctic town of Churchill show that the success of the two species is highly correlated.

"However, in 2011 Arctic fox den success was among the lowest ever recorded, while red fox den was among the highest," he says.

Dr Roth concluded that a different prey species such as snowshoe hare may have been abundant in red foxes' forest habitat but was not available to Arctic foxes hunting on the tundra terrain.

Despite this evidence, some experts believe that red foxes gradually moving further north are a major threat to Arctic foxes.

In Russia, reds have been observed taking over Arctic fox dens and scientists have occasionally found Arctic fox remains around some red fox dens.

"Being bigger, the red fox tends to exclude the Arctic fox from its habitat," explains Dr Dominique Berteaux from the University of Quebec, Rimouski (UQAR) in Canada.

"They occupy the same ecological niche and are in direct competition."

However, Dr Roth argues that in general, "changes in food availability and disease" are "more likely to have greater impacts" on Arctic fox numbers.

The change in red fox distribution, with the species pushing further northwards, has been associated with climate change in the Arctic.

Warmer conditions allow red foxes to travel further north as they are more likely to survive without the special adaptations of the Arctic species.

But Dr Berteaux, who has conducted a number of studies into Canada's Arctic foxes, believes we may actually be more directly accountable for the species' movement.

"Red foxes follow humans," he tells BBC Nature.

"In the last 60 years many villages have established in the Arctic and red fox benefit from the dump sites where they scavenge on human garbage."

Dr Bertaux simply summarises that the red foxes "have more food available now than in the past" but his fellow biologists continue to debate the issue.

http://www.bbc.co.uk/nature/20892310 
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#11
Mercury exposure linked to dramatic decline in Arctic foxes


6 May 2013 Last updated at 21:00 GMT 
By Matt McGrath
Environment correspondent, BBC News

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According to the research, the levels of mercury found in Arctic foxes depend on their diets

Scientists say that foxes in Arctic regions who feed on ocean prey are being exposed to dangerous levels of mercury.

On one Russian island where the population of foxes has crashed, the researchers believe the toxin has played a key role in the decline.

They say the findings could have important implications for conservation.

The data is published in the Journal, PLOS ONE.

Mercury levels in the world's oceans have doubled over the past 100 years, according to the UN, with more mercury deposited in the Arctic than on any other part of the planet.

The Arctic Council says there has been a ten-fold increase in the levels of mercury found in top predators in the region over the past 150 years.

Hair of the dog

Now a team of researchers says it has found significant levels of mercury in different populations of Arctic foxes in different environments.

On the small Russian island of Mednyi, part of the Commander Islands chain in the North Pacific Ocean, the foxes survive almost exclusively on sea birds with some also eating seal carcasses.

The island's fox population declined mysteriously in the 1970s, and while the population is currently stable many of them are in poor condition, and have low body weight. They are listed as a critically endangered species with IUCN.

Scientists at one time believed their shrinking numbers were caused by an infection, but they couldn't find the underlying cause.

"We started to look for different pathogens that might underline the cause of the poor condition and high mortality but we couldn't find anything," said Dr Gabor Czirjak from the Leibniz Institute for Zoo and Wildlife Research, a lead author on the new work.

But when they examined hair samples from the foxes and the food the animals eat, they found significant rates of mercury.

"They have high levels, compatible with the food, and it could explain the state of the foxes there," said Dr Czirjak.

[Image: _67440545_c0143973-arctic_fox_pair_playi...aee0cb.jpg]
Arctic foxes change the colour of their fur depending on the season

"We know it is in the marine environment and it is causing exactly the type of symptoms that were found in this population," he added.

The team found a very different result when they compared the Russian foxes to their Icelandic cousins who live inland. These foxes survived on non-marine birds and rodents. They had much lower levels of the poison in their systems.

The scientists say their findings have important lessons for conservation in the Arctic.

"When you make a decision to try and conserve a species then you can make it based on the ecology or the feeding strategies that they use," said Dr Czirjak.

"If we want to preserve the Arctic foxes, it is better to invest in the inland population where we can maintain or sustain in the long term, than in a coastal population where it is really hard to disconnect from the source which is the marine environment."

The study raises some important questions about the how mercury is accumulating in the marine food chain in the Arctic region.

Mercury levels there have for decades been linked to industrial pollution but recent research from Nasa has suggested that declining levels of sea ice in the region could be helping to push up levels of the substance.

Global efforts to contain the poisonous effects of the element received a boost earlier this year when more than 140 countries agreed on a legally binding treaty to curb mercury pollution.

http://www.bbc.co.uk/news/science-environment-22425219




Correlates between Feeding Ecology and Mercury Levels in Historical and Modern Arctic Foxes (Vulpes lagopus)

Abstract

Changes in concentration of pollutants and pathogen distribution can vary among ecotypes (e.g. marine versus terrestrial food resources). This may have important implications for the animals that reside within them. We examined 1) canid pathogen presence in an endangered arctic fox (Vulpes lagopus) population and 2) relative total mercury (THg) level as a function of ecotype (‘coastal’ or ‘inland’) for arctic foxes to test whether the presence of pathogens or heavy metal concentration correlate with population health. The Bering Sea populations on Bering and Mednyi Islands were compared to Icelandic arctic fox populations with respect to inland and coastal ecotypes. Serological and DNA based pathogen screening techniques were used to examine arctic foxes for pathogens. THg was measured by atomic absorption spectrometry from hair samples of historical and modern collected arctic foxes and samples from their prey species (hair and internal organs). Presence of pathogens did not correlate with population decline from Mednyi Island. However, THg concentration correlated strongly with ecotype and was reflected in the THg concentrations detected in available food sources in each ecotype. The highest concentration of THg was found in ecotypes where foxes depended on marine vertebrates for food. Exclusively inland ecotypes had low THg concentrations. The results suggest that absolute exposure to heavy metals may be less important than the feeding ecology and feeding opportunities of top predators such as arctic foxes which may in turn influence population health and stability. A higher risk to wildlife of heavy metal exposure correlates with feeding strategies that rely primarily on a marine based diet.

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0060879 
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#12
From ‘third pole’ to north pole: a Himalayan origin for the arctic fox


Xiaoming Wang, Zhijie Jack Tseng, Qiang Li, Gary T. Takeuchi and Guangpu Xie
Published 11 June 2014 doi: 10.1098/rspb.2014.0893
Proc. R. Soc. B 22 July 2014 vol. 281 no. 1787 20140893

Abstract
The ‘third pole’ of the world is a fitting metaphor for the Himalayan–Tibetan Plateau, in allusion to its vast frozen terrain, rivalling the Arctic and Antarctic, at high altitude but low latitude. Living Tibetan and arctic mammals share adaptations to freezing temperatures such as long and thick winter fur in arctic muskox and Tibetan yak, and for carnivorans, a more predatory niche. Here, we report, to our knowledge, the first evolutionary link between an Early Pliocene (3.60–5.08 Myr ago) fox, Vulpes qiuzhudingi new species, from the Himalaya (Zanda Basin) and Kunlun Mountain (Kunlun Pass Basin) and the modern arctic fox Vulpes lagopus in the polar region. A highly hypercarnivorous dentition of the new fox bears a striking resemblance to that of V. lagopus and substantially predates the previous oldest records of the arctic fox by 3–4 Myr. The low latitude, high-altitude Tibetan Plateau is separated from the nearest modern arctic fox geographical range by at least 2000 km. The apparent connection between an ancestral high-elevation species and its modern polar descendant is consistent with our ‘Out-of-Tibet’ hypothesis postulating that high-altitude Tibet was a training ground for cold-environment adaptations well before the start of the Ice Age.

http://rspb.royalsocietypublishing.org/content/281/1787/20140893.abstract?sid=4efb3653-9a32-49a5-a9b6-44fee29895d0




Extinct Fox Species With Supersharp Teeth Discovered in Tibet
The discovery of the ancient, sharp-toothed predator may support the theory that many polar carnivores originated in Tibet.


[Image: arctic-fox-tibetan-ancestor_80550_990x74...803bc2.jpg]
An arctic fox hides in rye grass in Nunavut, Canada.

PHOTOGRAPH BY PAUL NICKLEN, NATIONAL GEOGRAPHIC CREATIVE

Christine Dell'Amore
National Geographic
PUBLISHED JUNE 10, 2014

An extinct species of "very carnivorous" fox with supersharp teeth once roamed the frigid Tibetan Plateau, a new study says.

The fossils of the newly identified Vulpes qiuzhudingi, which lived 5.3 to 2.6 million years ago, in the Pliocene period, are the oldest arctic fox remains ever found. That could make them the earliest known ancestor of today's arctic fox (Alopex lagopus), which ranges throughout the northern poles. 

The discovery also supports the "out of Tibet" theory, which argues that the plateau acted as a "third Pole" where cold-adapted predators lived until they migrated to new lands at the beginning of the Ice Age.

In 2010, scientists unearthed three jaw fossils—one still studded with teeth—of the ancient predator while digging in Tibet's Zanda Basin and Kunlun Mountains.

"I first uncovered part of the lower molar, and immediately I knew it was some kind of a dog," said study co-author Zhijie Jack Tseng, a paleobiologist at the American Museum of Natural History in New York City.

What Does the Ancient Fox Say?

The fossils were set aside until a few years later, when Tseng and colleagues examined them and discovered the teeth bore a "striking resemblance" to those of the arctic fox, according to the study, published June 10 in the journal Proceedings of the Royal Society B.

For one, the fossils' lower molars lack cusps and are sharper than those of other fox species. This adaptation—which allowed the prehistoric predators to slice into prey—is a clear sign of what's called a "hypercarnivore," or a carnivore that eats only meat. Omnivorous foxes have bumpier, duller molars better suited for chewing plants, he said.

[Image: fox-jaw_zps941d8e9e.jpg]
The teeth of the new fox species Vulpes qiuzhudingi are sharp like those of modern-day arctic foxes.

The extinct fox would've had plenty of meat to choose from: Other fossils found near the remains in Tibet include potential prey species, such as shrews, pikas, voles, and squirrels—all small mammals that today's arctic fox would eat. 

Eating mostly meat makes sense for polar animals, in part because of the taxing demands of living in such icy cold environments and the scarcity of other food sources, Tseng said. That's likely why, in addition to the arctic fox, other northern carnivores, such as polar bears and gray wolves, are highly predatory.

Polar animals in general also tend to be bigger, possibly because beefier animals lose precious heat more slowly than smaller animals do.

That's also the case with the newfound fox, which was likely 20 percent bigger than the modern-day arctic fox. It was about the size of a male red fox (Vulpes vulpes), the biggest known fox species.

Link Olson, a mammal biologist at the University of Alaska Fairbanks, called it an "interesting hypothesis," but he's "not convinced of the close relationship with the arctic fox."

"As the authors briefly note, this could well be yet another example of convergence"—when two species evolve similar adaptations, Olson said by email.

Olson noted that canines' skulls are "notoriously plastic, even among living species; consider how much variation we see in the heads of domestic dog breeds versus cat breeds."

He added that a rigorous analysis, including a closer look at the fox family tree, "would make for a more compelling case."

Out of Tibet?

To Tseng, the discovery of the ancient fox is more proof for the out of Tibet theory. It goes like this: At the end of the Pliocene, about 2.6 million years ago, it was considerably warmer in the Arctic and colder in Tibet, where a host of animals evolved to cope with the elements. 

When global temperatures dropped at the start of the Ice Age, these cold-loving Tibetan animals may have chosen to "step down from the plateau and spread northward toward the vast expanse of Russia, Siberia, and northern Canada, where they became characteristic Ice Age mega-mammals," Tseng said. 

Indeed, Tseng and his colleagues have discovered that other species, such as the extinct woolly rhinoceros, the hyena, the snow leopard, and now the arctic fox, share roots in the Tibetan Plateau.

University of South Carolina cell biologist Adam Hartstone-Rose agrees that the "Out of Tibet" theory is a plausible one, noting that modern-day Tibetan animals—such as the yak—resemble Arctic animals.

"This fox fits in that scheme. Obviously it's a little less sexy than the big carnivores, but it's a neat little thing," said Hartstone-Rose, who has studied extinct foxes but wasn't involved in the new study.

"It's exciting to see as [Tseng's group] fleshes out this theory species by species."

http://news.nationalgeographic.com/news/2014/06/140610-animals-foxes-tibet-new-species-fossils-science/ 
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#13
Arctic Foxes 'Grow' Their Own Gardens
The little carnivores' colorful dens provide veritable oases in the tundra, a new study says.


[Image: 01-arctic-fox-den.adapt.1900.1_zpswd6xtsz2.jpg]
An Arctic fox appears at the entrance of its den in Alaska's Arctic National Wildlife Refuge. 
PHOTOGRAPH BY DANIEL J. COX

By Adam Popescu
PUBLISHED MAY 20, 2016

BARROW, ALASKA The underground homes, often a century old, are topped with gardens exploding with lush dune grass, diamondleaf willows, and yellow wildflowers—a flash of color in an otherwise gray landscape. 

“They’re bright green and everything around them is just brown,” says Brian Person, a wildlife biologist for the North Slope Borough in Barrow, Alaska. “It pops.”

He’s talking about arctic fox dens. 

Person has spent the better part of a decade studying the wide-ranging carnivores' movements throughout northern Alaska. The 6-to-12-pound (3-to-5-kilogram) foxes, which prey mostly on lemmings and small game, are found throughout the circumpolar Arctic, from Alaska and Canada all the way into Europe and Greenland.

He's tracked satellite-collared foxes that have traveled as far east as the Chukchi Sea (map) before doubling back and hopping sea ice until they’ve skirted the coast of neighboring Siberia.

But arctic foxes move too quickly to follow in real time, and Person only receives their GPS location every three days. That makes the colorful fox dwellings the key to better monitoring the population—and how they fit into the Arctic environment.

Peering down from a fixed-wing aircraft, the splashes of green “allow me to estimate just how many dens are out there," he says. 

“These animals are fertilizing and basically growing a garden."

Gardens that create such a stark contrast on the tundra that scientists who recently published the first scientific study on the dens have dubbed the foxes "ecosystem engineers." 

Conducted in 2014 near Churchill, Manitoba, the experiments revealed that the foxes' organic waste supports almost three times as much botanical biomass in summer months as the rest of the tundra. 

How a Fox Garden Grows

During the long, dark Arctic winter, the tundra fades into an opaque world where sky and ground blend into a never-ending haze. 

With temperatures that dip into the double-digit negatives, the only place for the foxes to take shelter and protect young from the elements—and other predators—is deep underground. 

Some dens are over a century old, and the best are elevated: ridges, mounds, riverbanks. But with so much permafrost—frozen ground—and such a flat environment, prime sites can take years to develop.

And since digging new homes wastes valuable energy, real estate is limited—so foxes reuse locations—and in a strange time-share, foxes sometimes steal sites belonging to ground squirrels.

With litters averaging about eight to 10 pups—some as high as 16—the foxes deposit high amounts of nutrients in and around their dens, a combination of urination, defecation, and leftover kills. 

In winter, foxes don’t drink water or eat snow or ice, which lowers their core temperature. Instead they get water from their food, which concentrates nutrients in their urine, making it more potent. 

Tundra Oases

These tundra oases are beyond just being postcard beautiful: They boost the Arctic environment. 

And that means more food options in a place without many, says Jim Roth of the University of Manitoba, a co-author on the recent study.

Greater plant diversity gives herbivores a spot to forage during short summers, he explains. 

“Lots of other species visit these dens,” adds Roth, who has been studying arctic foxes since 1994. “Caribou and other herbivores are attracted to the lush vegetation, and scavengers come looking for goose carcasses.”

Winter Wonder

Arctic fox gardens occur throughout the Arctic, says Person, who isn’t shy about his respect for the animal and its abilities.

In times of plenty, the canids can cache as many as 104 snow goose eggs a day, another unsung nutritional boost to the land—and opportunistic scavengers.

With short ears and snout—which requires less energy to heat—as well as a heavily insulated coat, the species is perfectly adapted to winter, Person says. So well, in fact, that scientists have been unable to get the animals to shiver in laboratory chambers—even when they drop temperatures to -40ºC.

"They’re incredibly efficient. I’ve seen them running and it’s almost like they’re not touching the ground.”

Polar bears may get more attention as the Arctic’s top predator, but an animal a fraction of their size might in fact be pound-for-pound the more impressive beast.

http://news.nationalgeographic.com/2016/05/160520-arctic-foxes-animals-science-alaska/




Tazarve Gharajehdaghipour, James D. Roth, Paul M. Fafard & John H. Markham Arctic foxes as ecosystem engineers: increased soil nutrients lead to increased plant productivity on fox dens Scientific Reports 6, Article number: 24020 (2016) doi:10.1038/srep24020

Abstract
Top predators can provide fundamental ecosystem services such as nutrient cycling, and their impact can be even greater in environments with low nutrients and productivity, such as Arctic tundra. We estimated the effects of Arctic fox (Vulpes lagopus) denning on soil nutrient dynamics and vegetation production near Churchill, Manitoba in June and August 2014. Soils from fox dens contained higher nutrient levels in June (71% more inorganic nitrogen, 1195% more extractable phosphorous) and in August (242% more inorganic nitrogen, 191% more extractable phosphorous) than adjacent control sites. Inorganic nitrogen levels decreased from June to August on both dens and controls, whereas extractable phosphorous increased. Pup production the previous year, which should enhance nutrient deposition (from urine, feces, and decomposing prey), did not affect soil nutrient concentrations, suggesting the impact of Arctic foxes persists >1 year. Dens supported 2.8 times greater vegetation biomass in August, but δ15N values in sea lyme grass (Leymus mollis) were unaffected by denning. By concentrating nutrients on dens Arctic foxes enhance nutrient cycling as an ecosystem service and thus engineer Arctic ecosystems on local scales. The enhanced productivity in patches on the landscape could subsequently affect plant diversity and the dispersion of herbivores on the tundra.

Attached to this post:[Image: attach.png] Arctic_foxes_as_ecosystem_engineers__increased_soil_nutrients_lead_to_increased_plant_productivity_on_fox_dens.pdf (606.53 KB)
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#14
Arctic fox sets new record after walking from Norway to Canada in 76 days

By Bridget Judd
Updated about 5 hours ago
[Image: 11270274-3x2-700x467.jpg]
PHOTO: The Arctic fox was fitted with a GPS tracking device in March 2018. (Supplied: Norwegian Polar Institute)

So you think your New Year's resolution to exercise more is proving gruelling?

Key points:
  • Norwegian researchers GPS-tracked a juvenile fox that covered more than 3,500 kilometres in 76 days, reaching Canada
  • It reached distances of up to 155km a day, which is the fastest movement rate ever recorded for the species
  • Its transmitter stopped working in February and researchers have been unable to track its movements
Spare a thought for one Arctic fox, which travelled from Norway's Svalbard islands to northern Canada in a remarkable journey that left scientists "thunderstruck".
According to researchers at Norway's Polar Institute, the juvenile fox — which was fitted with a GPS tracking device — covered more than 3,500 kilometres in just 76 days, averaging 46km a day.
"We couldn't believe our eyes at first," Eva Fuglei of the Polar Institute told Norway's NRK public broadcaster, according to the BBC.
"We thought perhaps it was dead, or had been carried there on a boat, but there were no boats in the area. We were quite thunderstruck."
The young female was released into the wild on the east coast of Spitsbergen, the largest island of the Svalbard archipelago, which separates mainland Norway and the North Pole, in March last year.

[Image: 11270340-3x2-700x467.jpg]
PHOTO: The fox travelled an average of 46 kilometres per day (file photo). (Supplied: Norwegian Polar Institute)

About three weeks later, researchers tracked the fox to Greenland — 1,512 kilometres away.
It then travelled another 2,000 kilometres to Canada's Ellesmere Island, totalling more than 3,500 kilometres in under three months.
'It shows the exceptional capacity of this little creature'
According to the research findings, published in the Polar Research journal, the fox reached distances of 155km a day while traversing ice sheets in northern Greenland.
That is the "fastest movement rate ever recorded for this species", the report concluded, and was found to be 1.4 times faster than the previous record set by an adult male Arctic fox tracked in Alaska.
"[Winter] is when the Arctic fox often migrates to other geographical areas to find food to survive," Ms Fuglei told NRK.
"But this fox went much further than most others we've tracked before — it just shows the exceptional capacity of this little creature."
Despite its speed, the fox made two breaks in its journey across northern Greenland, according to a graph produced by the Polar Institute.
At one point, its movement rate dropped below 10 kilometres a day for 48 hours.
Scientists believe the juvenile, thought to be under a year old when it embarked on its journey, may have encountered bad weather or stopped to "snap up crustaceans from the open water".
The second leg of the animal's journey into Canada remains more of a mystery, however.
Its transmitter stopped working in February this year, and its fate remains unknown.

[Image: 11270364-3x2-700x467.jpg]
PHOTO: The animal's transmitter stopped working in February this year (file photo). (Supplied: Norwegian Polar Institute)

https://www.abc.net.au/news/2019-07-02/a...gLzB7gkMvs



Abstract
We report the first satellite tracking of natal dispersal by an Arctic fox (Vulpes lagopus) between continents and High-Arctic ecosystems. A young female left Spitsbergen  (Svalbard  Archipelago,  Norway)  on  26  March  2018  and  reached  Ellesmere Island, Nunavut, Canada, 76 days later, after travelling a cumulative distance  of  3506  km,  bringing  her  ca.  1789  km  away  (straight-line  distance)  from her natal area. The total cumulative distance travelled during the entire tracking  period,  starting  when  she  left  her  natal  area  on  1  March  2018  and  ending when she settled on Ellesmere Island on 1 July 2018, was 4415 km. This is among the longest dispersal events ever recorded for an Arctic fox. Crossing extensive stretches of sea ice and glaciers, the female moved at an average rate of 46.3 km/day ± 41.1 SD. The maximum movement rate was 155 km/day and occurred on the ice sheet in northern Greenland. This is the fastest movement rate recorded for this species. The northernmost location recorded was on the sea  ice  off  northern  Greenland  at  a  latitude  of  84.7°N.  The  Arctic  fox  was  of   the blue colour morph typical for coastal environments, where Arctic foxes are adapted to food webs without lemmings but with substantial inputs of marine food resources. The Arctic fox settled on Ellesmere Island in a food web with lemmings, thereby switching ecosystems. Our observation supports evidence of gene flow across Arctic regions, including those seasonally bridged by sea ice, found in studies of the circumpolar genetic structure of Arctic fox populations.

https://polarresearch.net/index.php/pola.../3512/9288
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