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The Arctic's climate is characterized by cold winters and cool summers. Its precipitation mostly comes in the form of snow and is low, with most of the area receiving less than 50 cm (20 in). High winds often stir up snow, creating the illusion of continuous snowfall. Average winter temperatures can be as low as −40 °C (−40 °F), and the coldest recorded temperature is approximately −68 °C (−90 °F). Coastal Arctic climates are moderated by oceanic influences, having generally warmer temperatures and heavier snowfalls than the colder and drier interior areas. The Arctic is affected by current global warming, leading to Arctic sea ice shrinkage, diminished ice in the Greenland ice sheet, and Arctic methane release as the permafrost thaws.

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Mainly an animal of the far north, most of the 15 subspecies live their lives above the northern tree line in the Arctic tundra, they are also found on many arctic islands. There are woodland reindeer in Finland and Siberia in the forests.

reindeer / caribou facts Basics

Average Weight: 60 to 300kg (132 - 660 lbs)

Average Length: 160 to 200 cm long (5.3 - 6.6 feet) plus a short tail of 14 - 20 cm (6 - 8 inches), 80 to 150cm (2.6 - 4.9 feet) tall at the shoulder.

Females are smaller than males, the extent of the difference varies in the different subspecies, domesticated reindeer have shorter legs and are heavier then wild reindeer/caribou.

Breeding Season: Mating is from late September to early November when males compete with each other for access to females. Most encounters between males are dealt with at a distance without contact, though this does happen by locking antlers and pushing when a pair of males both think they are the strongest. A successful male may mate with 15-20 females during this time. The requirement for constant vigilance against other males during the mating season means that dominant males have no time to eat and lose much of their stored reserves. A male may only be able to display this level of dominance for one season in his lifetime when he is large enough at around 6 years old.

Calves are born in May or June. Newborns can follow the mother within about an hour of birth, they start to graze after about 45 days but continue to suckle from their mothers as a supplement for several months.

Estimated world population: - 1 million worldwide, fluctuations that appear to be cyclic over 40-60 years.

Feeding & diet: In the summer months reindeer eat sedges, grasses, herbs, ferns and mosses on the tundra. They will also eat shoots and leaves of trees when available being particularly fond of willow and birch. They have been recorded as being opportunistic carnivores eating lemmings, birds eggs and arctic char (fish).

In the winter months they feed almost exclusively on lichens and fungi which they often gain access to by sweeping snow and ice away with their antlers and/or hooves. Reindeer have the unique adaptation amongst mammals of having a n enzyme called lichenase which enables them to break down tough lichens to release glucose.

Conservation status: Least Concern.

Distribution: Circumpolar including many islands, native to the far north.

Predators: Reindeer are predated upon mainly by wolves which hunt them in packs, particularly in the winter. The calves in the calving season are subject to heavy predation, mainly by golden eagles and sea eagles, but also by wolverine and less commonly brown bears and polar bears.

Distribution range of reindeer / caribou

In Europe these animals are called reindeer only. In North America they are called caribou when wild and reindeer when domesticated.

Reindeer live in areas of Arctic tundra (a cold treeless plain, frequently poorly drained) and the northern boreal forests that make up the southern edge of the tundra. They are herbivores and ruminants meaning they feed on plant material which they ferment with bacteria in a large intestinal chamber called the rumen which is then regurgitated to be chewed again (chewing the cud) before passing further down the intestines.

Reindeer live within families (mothers and calves) within herds of various sizes. Tundra reindeer live in large herds, though they fragment and become smaller in the winter months. Wood reindeer live in groups of no more than 20-30 throughout the year.

What are Reindeer / Caribou like? how do they survive?

The Reindeer is mainly an animal of the far north. Most subspecies live their lives above the northern tree line in the Arctic tundra, they are also found on many arctic islands. There are groups in Finland and Siberia that are regarded as woodland reindeer that are found in the forests in those regions.

Historically reindeer were found across much of Eurasia above the line of latitude of 50Ãƒâ€šÃ‚Â° north. There was much concern a little while ago (2009) about the continuing decline of wild reindeer herds all across their range with global warming being blamed. No link was found however and some of the previously declining populations have begun to stabilise or increase in size again while others that were stable have begun to decline.

Herds are threatened by harvesting by hunters, regional climate trends and by increased development particularly of mining and oil and gas facilities which in their turn bring in more workers who may also hunt recreationally.

Reindeer have a relationship with humans going back thousands of years. As a hardy large herbivore they have been herded for food and to provide the muscle for transport by circumpolar peoples of the north. They are still hunted for food and other materials such as hides, antlers and bone to make tools by a number of Inuit peoples. They are herded in particular by the Sami and Nenets, they are not fully domesticated in the way that sheep and cattle are but are semi-wild roaming on pasture in a process of nomadic herding. There was a herd introduced to the Sub-Antarctic island of South Georgia where 10 animals landed in 1911 to provide food for whalers and sealers had grown to a population of 6,600 by early 2014 when they were all culled due to their impact on native bird life.

Reindeer / caribou Adaptations:

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Reindeer of the Arctic, Facts and Adaptations - Rangifer tarandus, also called caribou

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Mainly an animal of the far north, most of the 15 subspecies live their lives above the northern tree line in the Arctic tundra, they are also found on many arctic islands. There are woodland reindeer in Finland and Siberia in the forests.

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Polar Bear Facts and Adaptations - Ursus maritimus

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Polar bears live and breed entirely in the far north they live their whole lives above the northern tree line in the Arctic. They feed mainly on seals and are regarded more as a marine mammal than a land mammal as they hunt largely at the edge of sea-ice where wind, currents and tides provide open areas of the sea, so attracting their prey.

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Orcas, Sea wolves, Blackfish, Grampus. One of the worlds most formidable predators all the more so as they hunt in packs, orcas are toothed whales related to dolphins.

Orcas/ Killer whales fact Basics

Killerwhales / Orca jumping off the coast of Alaska

Maximum length: 9.8m (32.2ft) males / 8.5m (27.9ft) females

Adult weight: males: 11.1 tonnes max. / females 8.3 tonnes max. 35-50 years

Breeding: Sexual maturity: 12-16 years males / 6-10 years females, Gestation: 12-16 months, Birth length: 2 - 2.5m (6-9ft), Birth weight: 180kg (300lbs)

Dive duration: 20 mins

Feeding: little is know of the diet, different populations seem to have particular favoured prey, in Antarctica seals, minke whales, fish and squid are taken, one group known as Type-C are thought to feed exclusively on fish

Distribution: common in all oceans

Current world population:up to 100,000, the majority (70,000) in Antarctica. Orcas weren't targeted by whalers, threats are interactions with fisheries and from pollution. Not particularly abundant anywhere in its range.

Conservation status: Insufficient data

Killer whales or Orcas are probably the best known of the whales, as large carnivores they have a keen intelligence that enables them to be trained in captivity to do various tricks for rewards and so have been kept in marine aquariums and "Sea-World" type exhibits for many years. They are easily identified with their distinctive black and white patterning.

Killer whales are stocky in appearance compared to most whales which are quite long and slim relative to their length. Males are significantly larger than females (a trait known as "sexual dimorphism") and have a large and prominent dorsal fin (the one in the middle of their back) that can reach 6ft (1.8m) in height, the females dorsal fin is usually less than half this height.

They are Odontocetes or toothed whales and while they are quite small compared to the great baleen whales (Mysticetes) they are at the very top of the Antarctic food chain due partly to their formidable array of teeth, but most of all due to the fact that they often hunt in packs or "pods". Their tastes are wide ranging from krill, squid, fish and sharks to penguins, seals and even the much larger baleen whales.

Orcas are the largest of all carnivores on earth that feed on a wide variety of foods, they are found in almost all oceans, from the tropics to the Arctic and Antarctic where they will go deep into the pack-ice to hunt seals and penguins. They are commonest in coastal waters and in cool temperate and sub polar seas.

They have very sharp stout conical shaped teeth, from 40-48 with equal numbers in each side of the upper and lower jaws. The teeth can be up to 5cm (2") long. When a pod of killer whales is feeding, they will co-ordinate their movements by a continual stream of clicks and calls, though becoming silent in the final approach to intelligent prey such as seals. Ever ready to spot an opportunity, killer whales will even follow ice-breakers at the start of the season as they cut paths through the ice to reach deeper into the ice and perhaps get to seals and penguins that were beyond their reach.

A male killer whale at the rear showing the charcteristic much larger dorsal fin compared to the female in the foreground.

So adventurous and opportunistic are killer whales in this respect, that groups of killer whales are thought to have spent an entire winter living in and around a polynya, an area of open water kept clear by currents and winds while surrounded by miles of closed ice. These killers were unable to return to the open ocean as they would have had to have held their breath under the continuous pack ice for longer than they were able.

In the days of commercial whaling, while Orcas weren't very much hunted themselves (they were much too small a catch to waste an expensive harpoon on), they would often follow the whaling boats and rush at the dead baleen whales that were being flensed or towed alongside the boat ready for flensing and feed on the carcass. As such, they were much disliked by the whalers as they competed for the prey that they had just captured. Not for nothing are these whales called the "wolves of the sea".

Ecology and behaviour

Killer whales are very social animals living in family groups that are determined by the females of the group, so-called matrilineal groups. They form the most stable family groups of any animal species. Different groups have specific hunting techniques and even vocalizations that are passed down over many generations.

It is likely, though not yet proven that there is actually more than one species of killer whale, so distinct are different populations.

Killer whales swimming in McMurdo Sound Antarctica - Photo Donald LeRoi, NOAA Southwest Fisheries Science Center, National Science Foundation

An interesting aspect of the ecology of Orcas discovered from studies of populations off Washington state in the USA and up to Alaska is there are three distinct types that are very similar but differ somewhat in coloration in morphology (the way they look / proportions etc.) but most of all in their behaviour. These three types are known as "Residents", "Transients" and "Offshore", they are discrete populations and little or no mixing between them appears to take place.

Residents - These stay in one location all through their lives and form very stable communities. They tend to be mainly fish eaters which they are thought to catch with the help of echolocation. Their dorsal fins are more rounded at the top compared to the transients that have more pointed dorsal fins.

Transients - Move around more, they tend to feed on marine mammals, mainly seals. They form pods with less members than residents and are not so loyal to a particular pod.

Offshore - The least of all is known about these (as they live mainly offshore) but they form large pods and move following the edge of the continental shelves.

Though these groups have only been studied to any depth in the North Western United States, indications are that the behavioural types exist elsewhere too such as the "Type C" population found in Antarctica.

Type C orcas, identified by the sloping white patch near the eye, this is a calf with an older individual, probably the mother behind it. Type C's are a population that live in the Ross Sea in Antarctica, they are thought to feed almost exclusively on Antarctic cod. In the immediate foreground is a non-native Antartic species getting a whale selfie.

Many Orcas feed on a huge range of prey. More or less - if they find it and catch it, they'll at least have a go at eating it. Different pods of Orcas seem to have different specialties of diet and will specialize in a particular type of prey developing and becoming skilled in the ways to capture that prey. For instance they have been seen:

Co-operatively herding fish such as herring together into tight groups and then slapping them with their tails to stun them. Otherwise a herring would be a lot of effort and a small mouth-full for such a large animal.

Surprising young and unwary sea lions off the coast of Patagonia by chasing after them right into the shallows and then lunging with a great snap of their powerful jaws. Returning to sea after a near stranding in these cases takes quite an effort for the whale.

Attacking the great baleen whales such as blue whale by tearing at and eating the great tongue which itself can be the size of an African elephant. A pod of 40 or so Orcas have been seen engaging in this behaviour attacking a solitary huge adult blue off the coast of California.

Breaking through sea ice from below to surprise seals and penguins, or seeing them on ice-floes and then pushing upwards on the floe to tip the prey into the water. Alternatively two whales may rush at an ice floe which is then washed over by a large wave which dislodge the seal or penguin.

Killer whales are often approachable by boats and are generally inquisitive. They are frequently active at the surface showing such behaviours as lobtailing, flipper-slapping, spyhopping, wave riding and breaching.

Rubbing against a hard surface such as rocks or even other whales is often seen. It is thought to serve as a comfort movement and helps to remove dead skin. Certain rock rubbing areas may be socially important.

Like all whales, sound is very important to killer whales. Researchers have even identified unique sounds and discrete calls that are distinctive to certain pods and family groups, to the extent that killer whale dialects can be identified.

I was a little late on the scene this morning, and thereby witnessed a most extraordinary scene. Some 6 or 7 killer whales, old and young, were skirting the fast floe edge ahead of the ship; they seemed excited and dived rapidly, almost touching the floe. As we watched, they suddenly appeared astern, raising their snouts out of water. I had heard weird stories of these beasts, but had never associated serious danger with them. Close to the water's edge lay the wire stern rope of the ship, and our two Esquimaux dogs were tethered to this. I did not think of connecting the movements of the whales with this fact, and seeing them so close I shouted to Ponting, who was standing abreast of the ship. He seized his camera and ran towards the floe edge to get a close picture of the beasts, which had momentarily disappeared. The next moment the whole floe under him and the dogs heaved up and split into fragments. One could hear the 'booming' noise as the whales rose under the ice and struck it with their backs. Whale after whale rose under the ice, setting it rocking fiercely; luckily Ponting kept his feet and was able to fly to security. By an extraordinary chance also, the splits had been made around and between the dogs, so that neither of them fell into the water. Then it was clear that the whales shared our astonishment, for one after another their huge hideous heads shot vertically into the air through the cracks which they had made. As they reared them to a height of 6 or 8 feet it was possible to see their tawny head markings, their small glistening eyes, and their terrible array of teeth--by far the largest and most terrifying in the world. There cannot be a doubt that they looked up to see what had happened to Ponting and the dogs.

The latter were horribly frightened and strained to their chains, whining; the head of one killer must certainly have been within 5 feet of one of the dogs. After this, whether they thought the game insignificant, or whether they missed Ponting is uncertain, but the terrifying creatures passed on to other hunting grounds, and we were able to rescue the dogs, and what was even more important, our petrol--5 or 6 tons of which was waiting on a piece of ice which was not split away from the main mass.

Of course, we have known well that killer whales continually skirt the edge of the floes and that they would undoubtedly snap up anyone who was unfortunate enough to fall into the water; but the facts that they could display such deliberate cunning, that they were able to break ice of such thickness (at least 2 1/2 feet), and that they could act in unison, were a revelation to us. It is clear that they are endowed with singular intelligence, and in future we shall treat that intelligence with every respect.

Captain Robert Falcon Scott, January 5th 1911, from: Scott's Last Expedition - The Journals of Captain R. F. Scott, R.N., C.V.O.

Orcas or killer whales in Alaska - picture courtesy Christopher Michel - Creative Commons Attribution 2.0 Generic license

All photos above courtesy NOAA unless otherwise stated

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Killer whale - Facts and Adaptations - Orcinus orca in Antarctica

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Orcas, Sea wolves, Blackfish, Grampus. One of the worlds most formidable predators all the more so as they hunt in packs, orcas are toothed whales related to dolphins. Orcas/ Killer whales fact Basics Killerwhales / Orca jumping off the coast of Alaska Maximum length: 9.8m (32.2ft) males / 8.5m (27.9ft) females Adult weight: males: 11.1 tonnes max.

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Medium sized toothed whales with just the single long tusk is present in males and about 15% of females. Animals of the far north and the original unicorns.

narwhal facts Basics

Average Weight: 800 - 1,600 kg (1,800 - 3,500 pounds)

Average Length: 395 to 550 cm long (13 - 18 feet) not including the tusk which is 150 - 310 cm (4.9 - 10.2 feet). Males are slightly larger than females usually it is males that have a tusk.2.6m

Breeding Season: Narwhals breed at the end of the winter out in deep water, gestation lasts for about 14-16 months and the following summer calves are born in shallow water where the whales migrate to in the summer months. They have one calf every 3 years or so and become reproductive after 5 years for females and 8 years for males.

Estimated world population: 75,000

Feeding & diet: A limited range of fish, Greenland halibut, Arctic cod, polar cod, squid and shrimp with occasional others. Other than the tusk narwhals are toothless, no-one has seen them feeding in the wild as it happens in the depths of icy seas but it is thought they ingest their prey with a powerful suck. It is by looking at the stomach contents of dead narwhals that their diet has been determined and also their dive depth as some fish species they feed on are only found below certain depths.

Conservation status: Near threatened.

Distribution: High Arctic Ocean, unlike many other whales they don't migrate away from this region remaining through the winter months. Most are found in the fjords of North Eastern Canada and Western Greenland.

Predators: Killer whales (orcas) and polar bears. The bears may kill them at leads or polynyas in the winter sea ice by reaching them with their sharp claws when they have to surface to breathe at a possibly shrinking open water area. They are also hunted by Inuit around the Arctic as they have been for hundreds, possible thousands of years.

Distribution range of narwhals

What are Narwhals like? how do they survive?

Narwhals are warm blooded air breathing mammals that give birth to live young that suckle on milk. They belong to a group called the Cetaceans that includes the large baleen whales such as blue and humpbacks and also smaller toothed whales like orcas, dolphins and porpoises. Narwhals are medium sized toothed whales although they don't have any teeth other than the tusk, there are vestigial teeth when they are young, but these never erupt and disappear before maturity.

Narwhals are very difficult to study as they are large fast swimming animals that live in very cold seas in very remote parts of the world. It is difficult and costly to get to where they live and difficult and costly to find out much about them when you are there, consequently their biology is not very well known. Inuit people's hunt narwhals for food which provide some specimens that may be studied to provide information about them. They can also be tracked by satellite transmitters attached to their backs.
Narwhals live in groups of 10-100 individuals though can sometimes form much larger groups.
The most obvious and striking feature of narwhals is the tusk. This is an elongated canine tooth and is mainly found in males though around 15% of females also have a tusk albeit shorter and with a less pronounced spiral. The tusk is the left upper canine tooth and has a fairly tight left handed spiral which is thought to keep the tusk straight as it grows rather than curving as in other animals with tusks such as elephants and pigs which would cause problems when swimming. Very occasionally a male will grow two tusks, one from each side though the right tusk also has a left hand spiral rather than being a mirror image as might be expected, around 1 in 500 male narwhals have two tusks. The tusks don't grow out below the lip, they actually grow entirely horizontally in relation to the skull so actually break through the upper lip rather than emerging from the mouth as do other animals tusks.

While the tusk is essentially a tooth it has a structure rather different to that of a typical tooth being sort of inside-out with the outside being porous with the hard usually external enamel layer in the center the opposite way to your teeth. There is a pulp at the very center (like other mammalian teeth) which has blood vessels and nerves and in the order of ten million channels that allow sea-water to enter the tusk.

The purpose of the tusk was for a long time unknown or at least unproven. That only males always have fully developed tusks indicates that there is some element of sexual selection in its function in that the tusk somehow enables males to compete for access to females. There is no evidence to show that male narwhals use the tusks to fence in duels with each other as once thought, though males have been seen touching their tusks with other males in non-combative interactions. It is possible that the tusks are largely for show only when it comes to mate selection like a peacocks tail for instance. It has been suggested that they may be used to break ice or spear prey though there is no evidence for either of these things.

What has relatively recently been found is that the tusks are highly sensitive sense organs thanks to all those tiny little channels. They will be able to detect water pressure (and so depth) temperature and salinity. However discovering the role of the tusk as a sense organ raises as many questions as it answers, if it is so sensitive and so useful, then why don't females always have one? Anything that could aid finding food would be of more value to females than males as they need the extra nutrition during pregnancy and during suckling.
Historically
From Viking times and through to the Middle Ages in Europe narwhal tusks were thought to be the horns of unicorns. Merchants kept their true origin secret and they were sold for huge prices, up to ten times the equivalent weight in gold thanks to their reputed magical powers. They were thought to neutralize any poison and so were used to make drinking goblets, they could also cure melancholia (they couldn't really), powdered unicorn horn was a vital part of a physicians medicine chest.

Queen Elizabeth of England was given a unicorns (narwhals) horn in the 1500's worth Ã‚Â£10,000 at the time, the price of a small castle. They were sometimes used in the thrones and crown jewels of European Royalty.

Narwhal skull with two tusks

Austrian Imperial Crown Jewels - Narwhal tusk staff to sceptre

Narwhal tusk mounted as a unicorn horn - Cieszyn muzeum Poland
Narwhal Adaptations:

Low surface area to volume ratio (anatomical) - Being large means it is easier to stay warm by retaining heat generated by the metabolism, narwhals have a clean shape with only the flippers adding much extra surface area.

Thick blubber layer under the skin for insulation (anatomical and physiological) - Blubber or fat is an excellent source of insulation, it also provides a means of storing food when times are good and there is plenty to eat as well as providing buoyancy. Narwhals live in water that is at a fairly steady temperature around freezing point all year round. Any other mammal other than whales or seals would eventually get too cold and die of hypothermia in these conditions. Whales such as narwhals live their whole lives in frigid water being always able to maintain a constant warm mammalian body temperature. Blubber can make up 40% of a narwhals mass.

Countercurrent heat exchanger in the flippers (anatomical and physiological) - A close arrangement of the arteries entering the flippers and the veins leaving the flippers means that warm blood entering is cooled down by the cold blood leaving. In this manner warmth is contained within the body cavity rather than being lost to the high surface area - low volume of the flipper. In warmer waters and after exertion that generates excess heat that must be lost, the countercurrent exchanger can be made to work less efficiently so allowing the flippers to dump heat into the sea.

Diving physiology (physiological and anatomical) - Whales and seals have a number of adaptations that allow them to dive deep beneath the sea for extended time periods, narwhals can dive to 1,500m (4,900 feet) and stay submerged for up to 25 minutes.

The lungs are collapsed lungs on diving with only the minimum of air held in the respiratory system. This prevents any retained air (or more specifically the nitrogen in that air) from being forced into the blood under pressure at depth and coming out again on resurfacing so resulting in the "bends" which can be damaging or even fatal.

Bradycardia, the slowing down of the heart considerably from the normal rate. Blood is directed only towards the vital organs such as the brain and heart and to the swimming muscles and those associated with catching prey. The rest of the body is largely bypassed for the duration of the dive to retain oxygen for immediately necessary purposes only.

Large amounts of myoglobin in the swimming muscles to store oxygen for use during a dive. Myoglobin is a large protein molecule similar to haemoglobin that carries oxygen in the blood. Haemoglobin gives up its oxygen before myoglobin does, so once the haemoglobin source of oxygen is exhausted, then myoglobin gives up its oxygen to the muscles enabling them to work efficiently for longer. large amounts of myoglobin in diving animals makes their muscle a deep red colour.

Oxygen loading and ridding of carbon dioxide before a deep and long dive. Long deep breaths are taken while at rest before diving to clear dissolved CO2 from the blood and load up haemoglobin and myoglobin with oxygen before the dive to enable a longer period before the next breath.

Smooth streamlined shape to enable easy movement through the water (anatomical) - The tail flippers are held separately from the body (as in many aquatic animals) which means that the tail can act as a unique entity for generating thrust away from the body which has its own hydrodynamic shape. The tail is connected to the body by a narrow region only to allow this.

Nostrils on top of the head forming a blow hole (anatomical) - In common with other Cetaceans narwhals have a blow-hole on top of the head making breathing easier when swimming and surfacing

Migration towards shallower water around coasts in the summer when the females give birth and then further offshore in the winter (behavioural) - In the winter narwhals move offshore into deeper water where they live amongst open water leads, long strips of ice free areas through the thick pack ice or in polynyas, pools of open water kept that way by wind and tide or even the continued movement of the whales living within them.

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Narwhals of the Arctic Facts and Adaptations - Monodon monoceros

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Medium sized toothed whales with just the single long tusk is present in males and about 15% of females. Animals of the far north and the original unicorns. narwhal facts Basics Average Weight: 800 - 1,600 kg (1,800 - 3,500 pounds) Average Length: 395 to 550 cm long (13 - 18 feet) not including the tusk which is 150 - 310 cm (4.9 - 10.2 feet).

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Making a round trip of up to 90 000km a year while weighing about the same as a quarter pound burger and seeing more continuous daylight than any other animal on earth in the north and south polar summers makes this elegant extreme flier one of the most remarkable of all birds.

arctic tern facts Basics

Average Weight: 95 to 120g (3.3 - 4.2 oz),

Average Length: 33 to 39 cm long (13 - 15.5 inches), wingspan 66 - 77 cm (26 - 30 inches).

Breeding Season: April/May in the Arctic summer, when the young have fledged and become independent, they then fly to Antarctica (including the juveniles) where they winter during the Antarctic summer before flying back again to the Arctic to breed the following year.

Estimated world population: 2 million individuals, 500-900,000 breeding pairs in Europe.

Feeding: Opportunistic feeders, they feed on fish and larger zooplankton such as krill especially when in Antarctica. They catch their prey by seeing them from the air, searching and hovering much like a hawk does on the land and then diving to catch them.

Conservation status: Conservation status - a conservation priority in some parts of the range.

Distribution: Circumpolar around the Arctic including many islands, native to the far north usually found in treeless tundra.

Predators: Nests are vulnerable as they are generally on the ground, arctic foxes, polar bears and mink may take eggs and chicks.

picture courtesy
Distribution range of the Arctic Tern, nesting region in red
Andreas Trepte - licensed under CC BY-SA 2.5

What are Arctic Terns like? how do they survive?

The Arctic Tern is a member of a very exclusive animal club, it can be found at different times at both poles. The polar regions are areas of very high seasonal productivity. Very long day length with up to 24 hours daylight in the summer depending on the distance to the pole. This means that photosynthetic productivity (plant growth) is in overdrive, especially in the sea which leads to an abundance of other potential food a little further along the food chain which is then available to larger animals such as birds like terns.

Such is this abundance of seasonal food, it is actually worth the effort for terns to fly the length of the planet to take advantage of the Antarctic summer after spending the Arctic summer having partaken of its own seasonal abundance. They breed in the Arctic and use Antarctica as the wintering grounds (though it is the Antarctic summer!).

The flying abilities of Arctic terns are amongst the most astonishing of any birds. They have a length of a little over 30cm (a foot), a wingspan of less than a meter (about two and a half feet) and a weight of around 100g (3.5oz, or a little less than a quarterpounder burger). Despite this, they have been measured at flying up 90,000 km (nearly 56,000 miles) a year. This has recently be proven by attaching trackers onto birds and is around twice the previously thought distance. The reason is that the birds follow the prevailing wind patterns that carry them along rather than taking the most direct routes.

They stop over in an area of upwelling and high productivity in the North-Atlantic for around 25 days when flying south. It takes them about 3 months on the journey south, but only around 40 days to fly back north again, mainly due to the strength of the prevailing winds.

They arrive in the north in April/May, mate, nest and rear their young. They leave again in July/August to reach Antarctica in November where they stay until February/March. Both the Arctic and the Antarctic have 24 hours daylight in mid-summer and Arctic Terns are in both places in mid summer. They are most probably the animal that experiences the most daylight of any on the planet.

Arctic terns have a very particular and extreme lifestyle, all the more surprising when you realise how small they are, they have a number of anatomical, behavioural and physiological adaptations that allow them to survive successfully.
Arctic Tern Adaptations:

Very high metabolic rate (physiological) - Many polar and cold climate birds deal with cold temperatures by consuming and burning food to generate heat from within. In order to do this they have to consume high energy food that is easily and quickly digestible. The fish and oily krill and other prey that terns feed on provide the readily accessible fuel that enables them to live their fast-paced life.

Dive bomb other animals that approach the nest, aiming at the head (behavioural) - Whether a potential predator or just some big clumsy animal that might trample the nest, eggs and chicks, they all come in for the same treatment. Arctic terns dive repeatedly at any animal (including man) that they think represents a threat. They call out in alarm and repeatedly attack from behind the head so they have maximum disorientation effect and are less likely to be harmed themselves. They keep going as long as they feel threatened and stop when the threat is sufficiently far away. Often you will have no idea where the nest actually is other than somewhere near where you were. A frantic term attack can leave even a polar bear with bloody wounds to the head!

Nests in colonies with other birds (behavioural) - This maximizes the effectiveness of the defensive dive-bombing behaviour with many birds involved at the same time.

Flies from the Arctic to Antarctic and back again every year (behavioural) - Arctic Terns nest in the Arctic during the summer, when their young have fledged and become independent, they then fly to Antarctica (including the juveniles) where they winter during the Antarctic summer before flying back again to the Arctic to breed the following year. They do this to take advantage of food abundances at the peak times of year and to avoid food shortages at other times. They nest and rear their young all around the Arctic, though mainly fly south along an Atlantic route before spreading out again once in Antarctica.

Fantastic fliers - as you might imagine (anatomical and physiological) - Shaped with tail feathers that can be spread wide or pulled into a narrow dart to change aerodynamics in flight for covering distance or hovering and diving while feeding. Hollow bones for lightness. Able to sleep on the wing during migrations. Short legs that aid an aerodynamic shape in the air but make the birds rather clumsy on the ground.

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Arctic Tern Facts and Adaptations - Sterna paradisaea

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Making a round trip of up to 90 000km a year while weighing about the same as a quarter pound burger and seeing more continuous daylight than any other animal on earth in the north and south polar summers makes this elegant extreme flier one of the most remarkable of all birds.

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Arctic Wolf (also sometimes called the Polar Wolf or White Wolf) is an animal of the far north. It lives its whole life above the northern tree line in the Arctic tundra.

arctic wolf facts Basics

Average Weight: 32 to 70kg (70-155 lbs)

Average Length: 100 to 180 cm long (3.2-5.9 feet).

Breeding Pattern: As with other kinds of wolves, only the top ranking alpha and beta females in a pack will be allowed to mate and reproduce. This ensures that possibly scarce food resources at the critical time will not be spread too thinly across too many pups which could lead to the death of all or many of them, up to twelve pups are born at a time.

Arctic wolves may give birth in a den dug into the ground or snow where this is possible, though it is not always the case if the ground is frozen too hard. Ready-made dens in rocks, caves or dug in previous years by other wolves will also be used.

Estimated world population: - 200,000.

Feeding: A wide variety of food sources, the majority is of large herbivores such as moose, caribou, deer, elk, etc. Also smaller prey animals, livestock, carrion, and garbage, opportunistic as are many predators.

Conservation status: Least Concern.

Distribution: North America and Greenland but not extending into mainland Europe or Asia.

Distribution range of the Arctic Wolf

What are Arctic Wolves like? how do they survive?

The Arctic Wolf (also sometimes called the Polar Wolf or White Wolf) is an animal of the far north. It lives its whole life above the northern tree line in the Arctic tundra, roaming across North America and Greenland but not extending into mainland Europe or Asia.

It is a kind of grey wolf, though is no longer thought to be a distinct subspecies, it is the least threatened of all grey wolves and its subspecies populations as they live in isolated regions that rarely bring them into contact or conflict with man.

They survive in some of the coldest places on earth, they have a number of anatomical, behavioural and physiological adaptations that allow them to do this successfully. Arctic wolves live for around 7 to 10 years in the wild.

Arctic Wolf Adaptations:

Small ears to reduce their surface area to volume ratio (anatomical) - Compared to other the grey wolf and other subspecies, arctic wolves have proportionally smaller ears. This means that there is less surface area to lose heat from compared to the larger ears of their more southern cousins.

Thick camouflaged seasonal fur (anatomical) - The coat of the arctic wolf is always thick and highly insulating. It is light in colour, often almost white though can be quite grey too in some individuals. There are inner and outer layers to the fur with the inner being shorter softer hairs for insulation and the outer longer hairs a water and snow-proof layer that gets thicker as the colder weather starts to arrive.

Fur on the paws (anatomical) - to insulate them from snow and ice and also provide for a better grip on slippery surfaces.

Thick layer of body fat (anatomical / physiological) - for insulation and food storage to help survive the winter when food supply may be intermittent.

Countercurrent heat exchanger in the paws (anatomical/physiological) - Along with many other animals including domestic dogs, there is a mechanism in the paws of arctic wolves that keeps them at a lower temperature than the body core so minimizing heat loss via this extremity that is in contact with the ground. Blood entering the paws is used to heat up blood that is leaving, this prevents the core from being cooled by heat loss at the extremities. Similar mechanisms are also found in the feet of birds such as ducks and penguins.

Very large territories with pack territories of 2,500 square kilometers (1,000 square miles) or more. (behavioural) - The size of the territory is related to the amount of food available. Artic wolves will hunt down larger animals such as caribou ad muskoxen in packs and take smaller prey such as arctic hares, lemmings etc. alone. They will form groups of 2 to about 20 individuals or become solo for a time depending on the amount and kind of prey available to them.

Arctic wolves hutting muskoxen

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Arctic Wolf Facts and Adaptations - Canis lupus arctos

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Arctic Wolf (also sometimes called the Polar Wolf or White Wolf) is an animal of the far north. It lives its whole life above the northern tree line in the Arctic tundra. arctic wolf facts Basics Average Weight: 32 to 70kg (70-155 lbs) Average Length: 100 to 180 cm long (3.2-5.9 feet).

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Arctic Hare Facts and Adaptations - Lepus arcticus

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Average Weight: 2.5 to 5.5kg (6-12 lbs), up to 7kg (15.5lb), females tend to be larger than males. Average Length: 48 to 68 cm long (19-28 inches), a short tail of 3-8cm (1-3 inches) Breeding Season: April to mid-September, usually one or two litters per year with 5 to 6 leverets (baby hares) at a time.

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A true animal of the far north, the Arctic fox lives its whole life above the northern tree line in the Arctic tundra.

arctic foxes facts - Basics

Average Weight: 3 to 8kg (6.5-17 lbs) 75 to 110 cm long (2.3-3.5 feet) including a tail of around 30cm (12 inches), 20 to 30cm (9-12 inches) tall at the shoulder, females slightly smaller than males

Breeding Season: Arctic foxes form monogamous pairs through a breeding season (April to May) though often several females will live together in a large and complex den that can be many years old, even centuries. Typically they have litters of 5 to 8 but may be as many as 25, the most of any carnivore. Sometimes young non-breeding foxes will live in the den also and help to raise the pups from the following year.

Estimated world population: - Several hundred thousand, wide fluctuations as a result of varying prey numbers and a rapid ability to reproduce.

Feeding & diet: A wide range of foods, the main prey is lemmings, they will hunt and catch other small animals and will also scavenge food from beneath sea-bird colonies on cliffs and left overs from predators such as polar bears. They will take bird eggs where possible from tundra nesting birds, though are not entirely carnivorous eating berries and seaweed when available.

A family of foxes can get through several dozen lemmings in a day. They will eat young ringed seals when they are vulnerable in the snow den shortly after they are born in the same manner that they attack lemmings beneath the snow, detecting them by sound and then jumping on and punching through the covering snow layer.

Conservation status: Least Concern.

Distribution: The Arctic Fox lives its whole life above the northern tree line in the Arctic tundra, it has found its way to most Arctic islands and is the only mammal native to Iceland. It may be found on the sea-ice in winter as it extends its foraging range. The southern limit of the arctic fox is partially dictated by the presence of red foxes which out-compete arctic foxes in areas where tundra turns to shrubs and trees.

Predators: Polar bears, wolverines, red foxes and golden eagles. They have been and continue to be trapped for their thick winter coats in particular.

Distribution range of the Arctic Fox

What are Arctic Foxes like? What adaptations do they have?

They survive in some of the coldest places on earth which is no mean feat for such a relatively small animal, they have a number of anatomical, behavioural and physiological adaptations that allow them to do this successfully.

Arctic Fox Adaptations:

Thick fur on the tail (anatomical) - The tail acts to provide extra insulation when it is needed. When the fox is active and generating heat it is out of the way, while when the fox curls up to sleep or to keep warm in extreme cold, the tail fur can brought into play for extra wrap around insulation.

Shelter in burrows they dig into the snow during blizzards and very cold weather (behavioral) - A relatively quick and easy way of avoiding the worst of the weather by tunneling beneath the snow to avoid the biting wind and gain extra insulation from the snow. While the temperature in the snow hole is still below freezing, it can be much higher than outside the snow hole.

Very keen sense of hearing (anatomical/physiological) - Though small, the ears of arctic foxes are pointed forwards and so are very directional. They can hear their main prey, lemmings, moving through tunnels they make in the snow allowing the fox to pounce on the area where the sound is coming from without needing to see the prey and with the prey unaware that the fox is about to pounce.

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Arctic Foxes Facts and Adaptations - Vulpes lagopus / Alopex lagopus

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A true animal of the far north, the Arctic fox lives its whole life above the northern tree line in the Arctic tundra.