Overview

Comprehensive Description

Arctic Wolf Comprehensive Description

In the early twentieth century the Arctic wolf was recognized as a subspecies, distinct from the grey wolf, based on the Arctic wolf’s distinctive outer appearance. In the twenty-first century, however, the Arctic wolf’s status as a subspecies has come under scrutiny with genetic testing. A study was conducted by Chambers that tested the Arctic wolf’s autosomal microsatellite DNA and mtDNA. The results of the study concluded that the Arctic wolf was genetically very similar to the grey wolf (no difference in the Arctic wolf’s haplotype, or genes inherited from a progenitor). Chambers deduced that based on this evidence, the Arctic wolf must have more recently colonized its current range. Given this new information, the Arctic wolf could not be considered a subspecies (Chambers 2012). Later on, a peer review known as NCAES found errors in the research, like merging of separate subspecies and incorrect assumptions about distribution, which consequently cast doubt on the validity of the study’s conclusion. The Arctic wolf is not recognized as a legitimate subspecies by ESA (the Endangered Species Act) and has been classified as not threatened according to their specific guidelines (NCEAS 2014).

Arctic wolves are concentrated along the northern and eastern coastline of Greenland, as well as the northernmost parts of North America. Most of their native habitat is covered in snow year round, though there are regions that become snow free between June and August. The lack of snow allows plantlife to thrive in certain areas, which in turn sustains certain wildlife such as musk-oxen, Peary caribou, and Arctic hares. These various species comprise the majority of the Arctic wolf’s diet, and their continued existence is crucial to the Arctic wolf’s survival (Mech 2007). The Arctic wolf’s main predators are humans, polar bears, and other wolves. The wolf subspecies is most threatened by climate change and poaching (Bioexpedition 2013). The harsh and remote habitat causes the Arctic wolf to have fewer pups, and therefore to have smaller pack sizes as compared to other wolves (Petersen 2012). The closest human settlement to the Arctic wolves’ range is governed by the Inuit village (formerly Eskimo), Grise Fiord. Any current human settlements are for the most part fairly recent, which means that human interaction with the Arctic wolf is also a more recent phenomenon (Mech 2007). The wolf packs tend to frequent the same dens or nearby dens each summer even though they are nomadic. Arctic wolf packs on average consist of about seven to eight related members (Bioexpedition 2013). Pack behavior is determined by pack hierarchy, including mating patterns and feeding (which wolves eat in what order) (Dewey 2009).

The Arctic wolf is also commonly referred to as the white wolf, polar wolf, and snow wolf. The subspecies is characterized by its white coat, as well as its comparatively smaller size. It has short legs and a smaller snout (Bioexpedition 2013), and it’s ears are smaller and more rounded than the grey wolf’s ears. Male Arctic wolves are generally larger than female Arctic wolves, though both are heavy bodied (Dewey 2009). Fully grown wolves have 42 teeth and eat their prey in its entirety--including the bones (Bioexpedition 2013). Arctic wolves also have two layers of fur, both of which serve as an evolutionary adaptation to keep the Arctic wolf warm and dry in its severe environment. The inner layer thickens right before the coldest winter months, and the external layer is waterproof. The Arctic wolves’ jaws are also specially adapted to tear through the flesh of their prey, and an Arctic wolf can eat up to twenty pounds of meat in one sitting (White Wolf Sanctuary 2011). Arctic wolves breed once a year between January and March. In a pack only the alpha male and beta female breed. In the case that the alpha male or beta female die, they are oftentimes replaced by other members of the pack, which then become the “new” alpha and beta leaders (Dewey 2009). After mating occurs, the gestation period lasts for 53 to 61 days (the pups are born within a few months), and do not open their eyes until the 10th day. They are born a brownish color and later develop a whiter coat of fur (Bioexpedition 2013). One mating episode can generate anywhere between five and fourteen wolves, with an average of seven per mating episode (Dewey 2009). After three months the offspring officially join the pack (White Wolf Sanctuary 2011). After six months pups are capable of traveling with the pack (Bioexpedition 2013). Pups reach sexual maturity after two to three years, and the average lifespan is five to six years, though the Arctic wolf can live up to thirteen in the wild and fifteen in captivity (Dewey 2009).

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Distribution

endemic to a single nation

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National Distribution

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

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The Arctic wolves had originally lived in the northern hemisphere, north of 15o N latitude . Currently they can be found along the northern edge of North America and along the eastern and northern edges of Greenland. Some wolves can be found as far south as northern Minnesota or Wood Buffalo National Park in northern Alberta (Mech 2007). The majority of Arctic wolves live in Alaska. Those found in Canada and Greenland are in danger of extinction--their numbers have drastically dropped due to loss of habitat and low food supply. The recent settlements of people within their territory have not helped their numbers either. In Alaska, the temperatures are too low for it to be hospitable to humans (Wolf Worlds 2014). Occasionally the Arctic wolves migrate southward. If temperatures fall, prey such as the caribou may migrate south in order to find food. The wolves follow the caribou because they are a major food source for the Arctic wolf. Wolf packs cover great ranges, up to hundreds of miles. This is due to the scarcity of growing plants and scattered prey. Because each pack’s territory is so large, their territories may overlap (Cosmosmith 2014). Their habitats can be described as tundra or taiga. The very cold temperatures cause the ground to be frozen for much of the year. Due to the extreme cold temperatures of the region where the Arctic wolves live, they have some adaptations that differ from their more southern counterparts, such as the grey wolf. The Arctic wolf has thicker fur and smaller ears, which is part of an adaptive strategy used to retain heat. Padded paws allow them to better grip the almost permanently frozen and icy ground. There are different theories that explain how the Arctic wolf evolved and its current distribution. One theory is that the Ice Age forced some wolves into the Arctic region, and these wolves eventually evolved to become the Arctic wolves. Because Arctic wolves are not necessarily recognized as a subspecies of the grey wolf, its range is sometimes combined with that of the grey wolf. However, these two types of wolves have distinct distributions that may overlap slightly but are generally very separate. Arctic wolves, for one, live much farther north than the grey wolves. Their physical adaptations are different in order to survive the much colder temperatures as well as the snow and ice. Their coloring is often different as well, but coloring alone does not constitute enough difference to make one a subspecies. Some Arctic wolves are more grey than white but they still remain Arctic rather than grey wolves. The similarities between the Arctic and grey wolves lend credence to the theory that Arctic wolves were once grey wolves that ended up farther north and had to adapt to the harsher conditions (Wolf Worlds 2014).

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Ecology

Habitat

The Arctic wolves’ habitat is nearly always covered by snow and ice. However, some parts become snow free during the summer time around June to August. The retraction of the snow supports enough plants to feed the wolves’ prey such as Arctic hares, muskoxen, and Peary caribou (Mech 2007). Arctic wolves do not eat much apart from these prey, but if they can catch and kill other animals, they will eat them. The region in which they live is not hospitable to many animals; therefore the Arctic wolf’s diet is rather limited (Wolfs World 2014). Arctic wolves are the top predator in these situations and are near the top of the food chain. Humans are the primary hunters of wolves, though the Arctic wolf can be killed by other wolves that are not part of their pack. Occasionally pups are attacked by other animals, but fully grown wolves, which live in packs, generally do not have a problem with predators (especially due to their isolated habitat). Arctic wolves hunt in packs with numbers ranging from two to thirty-six wolves, depending on the region and the prey available. Larger packs make it easier to take down large prey. Lone wolves are much more likely to hunt smaller animals. Additionally, the wolves sometimes steal prey from other animals (Dewey 2002). It is therefore true that the number of Arctic wolves are directly linked to the abundance of prey caught. The number of Arctic wolves in a region declines if the number of prey also declines. Prey numbers are linked to factors such as plant growth, so decreased plant growth depresses prey numbers. In turn, plants are affected by temperature, snow, and ice cover. A particularly cold year with proliferate snow and ice will greatly inhibit plant growth, which in turn lowers the amount of prey available and the amount of Arctic wolves that can survive (given limited food sources). This cycle shows the dependence of wolves on the local climate. Even though the wolves can survive extreme cold and harsh weather conditions like snow and ice, they are affected by changes to their environment. If their habitat is altered, this could limit the abundance of their food source and result in increased competition among the Arctic wolf packs, decreasing their population overall. A slightly warmer year with more plant growth and an increase in prey populations would support a greater number of Arctic wolves. Sometimes, the prey migrates south in colder years, and so the wolves follow and therefore expand their territory southward. The nomadic nature of their prey encourages the Arctic wolf to also be nomadic to survive, and therefore serves as an evolutionary adaptation. Depending on where they live and the amount of prey available, the wolves can vary greatly in size. They can be anywhere from 75 to 125 pounds, with a length of three to six feet (White Wolf Sanctuary 2010). The subspecies’ habitat is very cold but the wolves are capable of withstanding the extremely low temperatures based on evolutionary adaptations, such as properties of their fur. The Arctic wolf can also live well in parts where it is dark during both the night and day (Wolfs World 2014). The High Arctic, where the wolves have historically lived, has been mostly unsettled by people until the last 100 years or so. Recent settlements include an Inuit village, weather stations, and a military base. As a result of living free of humans for many years, Arctic wolves do not have the same fear of humans as their southern counterparts (Mech 2007).

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Life History and Behavior

Behavior

The Arctic wolf has had limited contact with humans historically and therefore has never been seriously hunted by humans. This limited contact means that the Arctic wolf is largely unafraid of humans. In more recent times humans have been able to have close encounters with the Arctic wolf, with limited accounts of wolf brutality (Mech 2007).

The majority of the Arctic wolf’s daily activities involves movement toward or away from a den. The subspecies is nomadic during the fall, winter, and spring. The subspecies exhibits aggressive behavior against alien wolves (typically the alpha male leads, though females may also be involved). Pups might follow their parents if they move away from the den, though the mother will then carry or lead the pup(s) back. When waking up, the female Arctic wolf oftentimes nudges the male to encourage him to become active and begin foraging. In some cases, the male might ignore the female and go back to sleep, after which the female might alert him by howling loudly. Eventually the male (five to thirty minutes later) goes out to hunt, departing from the den with the female, whereafter the female returns to the den alone because she does not participate in foraging activities. When traveling, the male lines up behind the female in the case that she was in estrus, so as to ward off other males and increase his chance of reproducing with her (because of physical proximity). High-ranking males at the head of the pack usually press for attack (U.S. Department of Interior 2013). Females prepare for pups by digging the den that will become the litter’s  primary residence (Dewey 2009). Generally females spend more time with pups and put more effort toward pup rearing. Any of the other pack members can play with the pups, and pitch in to take care of the newborns. The breeding pair take care of their offspring for the most part, which includes activities like feeding. The male provides the female and pups with the most food after the pups are first born (duration of a few weeks), though other members of the pack can pitch in. During that time the female relies on the male for the majority of her food and her pups’ food. Once the male has hunted, he either drops the food in front of the female or regurgitates the food in his stomach.

Arctic wolf packs have a family hierarchy, where the parents lead the daily activities of the pack and utilize a division-of-labor amongst all individuals. In this system the female typically functions to take care of pups and monitor defense, and the male is responsible for hunting and supplying active amounts of food for the pack (U.S. Department of Interior 2013). The pack is organized and dominance is asserted with specific postures and facial expressions (Dewey 2009). Arctic wolves communicate primarily through howling as a way of indicating their location, to coordinate group hunts, and to signify to other  packs where their territory boundaries are. The alpha male may mark the ground with his scent as another way of indicating his pack’s territory (Dewey 2009).

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Evolution and Systematics

Functional Adaptations

Arctic wolves possess two layers of fur (outer layer is white, inner layer is dark grey) to ensure maximum heat trapping (Wolf conservation center 2013). The outer layer is used to repel sunlight and water (to prevent damage of the inner layers) and to provide camouflage in the Arctic. The inner layer is the actual insulator (the dark color ensures absorption of heat) and keeps the animal at a comfortable temperature, but also has a layer of dry air to repel water (to keep it from being trapped). The shorter nose, ears, and legs ensure reduction in surface area to volume ratio, thus preventing exposure to the cold Arctic winds, which could reduce the Arctic wolf’s adaptive ability (Mech 2007). To reflect this the Arctic wolf is also shorter and smaller than the grey wolf (to compare, the grey wolf two to three feet tall and 4.5 to 6.5 feet long, while the Arctic wolf is only five feet long at max) (WWF 2014). The shorter length of the legs (which usually causes slower movement) does not seem to affect the Arctic wolf’s ability to hunt. The hairy pads of the Arctic wolf also ensures good traction and maximum movement across the snow to increase the subspecies’ ability to catch prey like caribou and muskoxen (although long hairs in the pads may also cause rain and snow to be trapped and cause damage). The tail of the Arctic wolf is also long (almost two feet), which allows the wolf to wrap its nose, and thus protect it from cold when sleeping (Wolf conservation center 2013). These adaptations allow the Arctic wolf to survive temperatures as low as -70 degrees Fahrenheit, or -57 degrees Celsius (Wolfquest 2014).

Also worth noting is the fact Arctic wolves engage in pack hunting as a form of adaptation. Like many predators Arctic wolves are faced with an “all or nothing” reality; they must hunt and get fresh meat or starve, hence the need for pack hunting to maximize their chances (Wolf Country 2014). This allows conservation of energy (especially in cold weather) and makes up for the Arctic wolf’s reduced speed caused by shorter legs. Their hunting tactics are in a way similar to grey wolves. First the wolf packs wander around (sometimes splitting up to explore brushes or even choosing ridges to survey the land below) and then follow tracks and odor to prey (while being upwind to receive the most amount of scent). The target, usually weak or helpless, is chosen when the Arctic wolves stampede the herd and detect the ones least able to react or move. Strangely though, wolves tend to leave prey that stand their ground and go after fleeing prey instead (Mech 2008), whereafter the wolves approach downwind to avoid being detected. They finish the job by attacking the rump or nose, thereby killing the prey by shock or bleeding. The wolves tend to eat organs and rump before muscles and flesh, unlike humans (evolved to eat as much as possible, and to eat the most easily devoured foods) (Wolf Country 2014). However, it is noteworthy that Arctic wolf packs contain far less wolves per pack and so have to coordinate more carefully with less margin for error, as it is hard to replenish genetic losses.

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Conservation

Conservation Status

National NatureServe Conservation Status

Canada

Rounded National Status Rank: NNR - Unranked

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NatureServe Conservation Status

Rounded Global Status Rank: TNR - Not Yet Ranked

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The Arctic wolf is currently listed as “not threatened” under the ESA and COSEWIC. COSEWIC lists species as threatened only if the species is a legitimate species or subspecies that is native to Canada and has occurred regularly inside Canada itself. In addition, there are other criteria that observe reduction in numbers (that are reversible and can be stopped), reduction in mature members, and range or distribution of population (COSEWIC 2005). Because the Arctic wolf is not considered a subspecies but is categorized as the grey wolf, it passes being a native occurring species but is not recognized as a subspecies nor as a subspecies with a small distribution. An attempt was made by Chambers et. al to analyze whether the Arctic wolf was in fact a subspecies; from the amount of unique haplotypes and alleles found on microsatellite DNA the researchers concluded that the Arctic wolf was not, and was just grey wolves with differing colors (Chambers 2012). However, a final review for the Endangered Species Act noted that the 2012 research was flawed. Chambers, the review noted, observed only microsatellite and mitochondrial DNA to see the differences while also assuming isolated populations. The reality was that wolf populations are not isolated and that the data could fit ecological changes (especially once structural analysis was done which showed distinguishable genetic groupings). The research also ignored the time; wolves have only begun re establishment in the last 10,000 to 15,000 years, so the results would not be greatly different (NCEAS 2014).

Outside of this though, the Arctic wolf is not considered under threat due to proximity from human contact. Nunavut, the province Arctic wolves have found, considers it legal to actively hunt (Nunavut Department of Environment), while other provinces like British Columbia consider wolves pests to be culled in population (BC 2014). The biggest threats to the Arctic wolf is climate change and habitat destruction (these two go hand in hand). The Arctic wolf is reliant on its prey of snowshoe hares and muskoxen, which could spell trouble for the Arctic wolf as the prey begins to dwindle due to climate change (Mech Annual 2007). Also, industry such as shale mining as well as gas and oil are slowly heading towards the Arctic to find more resources (Struzik 2014). If increased contact is made with Arctic wolves and humans, this may spell trouble for the Arctic wolf populations, as Arctic wolves don’t have large packs and do not fear humans, and so could be easily suffer large loss in population (a population that is already fairly small) (Mech 2007). With reduction in population, genetic diversity could become an issue, as the population would have a harder time finding each other; this is especially a problem, as there are lot more lone wolves than packs in the Arctic, so finding mates and forming packs become harder (Petersen 2012). Also, the destruction of habitat may cause the wolves to have a harder time hunting their prey (prey such as muskox and snowshoe hare would also dwindle, reducing the amount of food available). If this is the case, it could cause trouble for the Arctic ecosystem in the area, as Arctic wolves are predators that control populations of herd animals in the Arctic.

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Wikipedia

Arctic wolf

"White wolf" redirects here. For other uses, see White Wolf (disambiguation).

The Arctic wolf (Canis lupus arctos), also known as the Melville Island wolf[1] is a possible subspecies of gray wolf native to the Canadian Arctic Archipelago, from Melville Island to Ellesmere Island.[1] It is a medium-sized subspecies, distinguished from the northwestern wolf by its smaller size, its whiter coloration, its narrower braincase,[2] and larger carnassials.[3] Since 1930, there has been a progressive reduction in size in Arctic wolf skulls, which is likely the result of wolf-dog hybridization.[3]

Contrary to its mainland counterparts, the Arctic wolf has never been seriously hunted or pursued, as the high Arctic holds few human settlements. As a result, the Arctic wolf is relatively unafraid of people, and can be coaxed to approach people in some areas.[4] It has occasionally acted aggressively toward humans. Otto Sverdrup wrote that during the Fram expedition, a pair of wolves attacked one of his team-mates, who defended himself with a skiing pole.[5] In 1977, a pair of scientists were approached by six wolves on Ellesmere Island, with one animal leaping at one of the scientists and grazing a cheek. A number of incidents involving aggressive wolves have occurred in Alert, Nunavut, where the wolves have lived in close proximity to the local weather station for decades and become habituated to humans.[6]

The Arctic wolf was first described as a distinct subspecies by British zoologist Reginald Pocock in 1935, after having examined a single skull from Melville Island.[3] As of 2005,[7] the Arctic wolf is still recognized as a distinct subspecies by MSW3. However, studies undertaken on Arctic wolf autosomal microsatellite DNA and mtDNA data indicate that the Arctic wolf has no unique haplotypes, thus indicating that its colonization of the Arctic Archipelago from the North American mainland was relatively recent, and thus not sufficient to warrant subspecies status.[8] However, the research of Chambers et al. (2012) that dismissed the Arctic wolf's genetic integrity became controversial, forcing the USF&WS to commission a peer review of it, known as NCAES (2014).[9] This peer review highlighted numerous flaws in the research such as the erroneous merging of the coastal BC island wolves with the inland Canis lupus nubilus as well as suggesting that gray wolves never lived in the eastern third of the US, etc, and thus concluded unanimously that the Chambers' review "is not accepted as consensus scientific opinion or best available science".

References[edit]

  1. ^ a b Mech, L. David (1981), The Wolf: The Ecology and Behaviour of an Endangered Species, University of Minnesota Press, p. 352, ISBN 0-8166-1026-6
  2. ^ Goldman, E. A. (1964). Classification of wolves. In The Wolves of North America Part 2. Young, S. P. & Goldman, E. A. (Eds.) New York: Dover Publs. p. 430.
  3. ^ a b c Clutton-Brock, J., A. C. Kitchener, & J. M. Lynch. (1994) Changes in the skull morphology of the Arctic wolf, Canis lupus arctos, during the twentieth century. Journal of Zoology (London) 233:19–36.
  4. ^ Mech, L. D., Arctic Wolves and Their Prey, National Oceanic and Atmospheric Administration, May 30, 2007
  5. ^ Sverdrup, O. N., (1918), New land; four years in the Arctic regions, Vol. I, London Longmans, Green, pp. 431-432
  6. ^ Linnell, J.D.C., et al (2002), The Fear of Wolves: A Review of Wolf Attacks on Humans, NINA, pp. 29-31, ISBN 82-426-1292-7
  7. ^ Wozencraft, W. C. (2005). "Order Carnivora". In Wilson, D. E.; Reeder, D. M. Mammal Species of the World (3rd ed.). Johns Hopkins University Press. ISBN 978-0-8018-8221-0. OCLC 62265494. 
  8. ^ Chambers SM, Fain SR, Fazio B, Amaral M (2012). "An account of the taxonomy of North American wolves from morphological and genetic analyses". North American Fauna 77: 1–67. doi:10.3996/nafa.77.0001. Retrieved 2013-07-02. 
  9. ^ http://www.fws.gov/home/wolfrecovery/pdf/Final_Review_of_Proposed_rule_regarding_wolves2014.pdf

Further reading[edit]

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