Hijab

 

Endangered Species

 

Endangered Species

what dose Endangered  mean?

  1. Endangered means that the  animal is in jeopardy  of dying  out as a species.
  2. when a species of animal completely dies out, they become extinct, never to live again.

3.being Endangered  means that more and more  animals are dying and less and less are being born.

How dose a species become Endangered?  

✴habitats changes

✴people moving in to animals habitats

✴land being taken over for farming

✴land and habitats are changed from pollution

✴climate altered by release of greenhouse gases

 

 

Snow Petrels – Pagadroma nivea

Snow petrels are pure white birds with jet black beaks and eyes. They are the size of a pigeon and arguably the most beautiful of all the Antarctic birds.

SNOW PETREL BASICS

Snow petrel

Weight: 240 to 460g, it is a characteristic of snow petrels that there can be a large range of sizes amongst individuals.

Length: 30 – 40 cm, wingspan: 75 – 95 cm

Breeding Season: Nests are made and eggs laid from October to November, the chicks fledge and leave the nest 41 – 45 days later, snow petrels can live for up to 20 years.

Estimated world population: – More than 4,000,000 individuals.

Feeding: A varied seafood diet of krill, fish and squid that are usually taken very close to the surface, though shallow dives are also undertaken. They will also feed on carrion where it is available.

Conservation status: Least concern.

Distribution
: Circumpolar, usually found near to pack ice and even continuous ice as long as there are open water leads to feed at. Breeds mainly on the Antarctic continent and surrounding islands, it is the most southerly breeding bird species, breeding even further south than the Emperor penguin. Snow petrel have even been seen at the south pole.

Predators: Antarctic (south polar) skuas, though weather conditions especially snow blocking nesting sites cause much greater loss of eggs and chicks.

  What are snow petrels like?

Snow petrel

In their appearance and behaviour snow petrels symbolize the very essence of the deep south. They are the purest of white and despite their diminutive size are as tough as animal needs to be to survive and even thrive in low temperatures and with a frequently high wind chill. They are frequently encountered in their hundreds, rarely in thousands, they tend to be spread out over a wide nesting area rather than being close together in large discrete colonies as are other Antarctic species.

They feed largely on krill and must always be near to the sea in order to feed.They are found therefore particularly along coasts and along the Antarctic peninsula.

The flying pair of birds in the picture are are a courting couple. In the Antarctic spring the males go looking for mates, and the females put them through their paces to assess their suitability and tenacity.

The courtship ritual consists initially of a male snow petrel following a female as she flies around the nesting area which is frequently a rocky outcrop or cliff with suitable ledges or nest holes. The female then leads him around the cliffs in a high speed aerial ballet, climbing and diving, flying almost into the cliff face at full speed before changing direction with an imperceptible twist of the wing at the last moment.

Snow petrelThe poor beleaguered male not only has to match this aeronautical master class, but he has to do it as close as possible to the female and without a script, gauging her every move while proving himself her equal at rapid flying. Many would be suitors seem to give up and get left behind, certainly in the early days. In this picture the male is calling to the female during a relatively relaxed moment.

Photographing flying snow petrels requires a lens on fixed focus, bright light, fast shutter, small aperture, and much cursing. Even then, it all happens so quickly that you don’t really know what you’ve got until you can look at the picture on a bigger screen.

  Why are these snow petrels hiding down a hole?

Snow petrelUnusually for Antarctic birds, snow petrels seem to apply some thought to the practicalities of a nest site. This pair are at the entrance to their nest which has been made in a natural crevice amongst some large broken-up rocks. This is a frequent choice for a nest site though not always available or in plentiful supply as snow petrels nest very far south and such crevices are frequently snowed or iced up.

Attempting to approach a nest (as I did on many occasions when helping in a long term programme on nesting success) brings out the worst in snow petrels. A well aimed stream of foul smelling, bright pink, oily, semi-digested krill mixed with oily stomach secretions would come in your direction as their (admirably unpleasant) defence mechanism. As small birds, nesting in crevices gets them out of the wind so reducing their risk of chilling in the wind and also protects them from nest raiding birds such as skuas. Antarctic has no land based nest raiding mammals such as cats or rats.

Snow petrels have been known to nest far inland on the Antarctic continent, 325 km. from the nearest sea that they must travel to in order to feed. They must nest on rock and in these cases choose “nunataks” isolated outcrops of tall rock ridges and mountains that protrude above the surrounding ice from the bed rock.

  Isn’t it cold and windy sitting out on the sea ice?

Snow petrelSnow petrels are birds of the Antarctic, they don’t migrate as such but move further north in winter as the cold weather sets in. Research in recent years has shown that the Antarctic ocean beneath the winter ice is surprisingly rich in life – a fact that it seems these birds have known about for some time.

They frequently arrive surprisingly far south in the winter in ridiculously low temperatures and high winds for such small creatures and rest overnight on totally exposed sea-ice, as here. Any spring and summer shelter is blocked up by now by blown snow. The reason they venture south in such adverse conditions would seem to be in order to take advantage of the abundance beneath the ice and the relative rarity of summer competitors.

  Why are these snow petrels hanging around the edge of this tide crack?

That these birds are prepared to undergo so much to find their food is testament to the nutritional value of that food – krill. Here snow petrels (and in the first photograph a crabeater seal too) are taking advantage of a tide crack to fish through in the case of the birds and to breathe at in the case of the seal who will be busy fishing for krill under the ice. A tide crack is a long narrow open lead of water that stretches between two points such as nearby islands or exposed rocks. It arises when the tide rises and falls, when the tide rises the crack opens when it falls, the crack closes. Such tide cracks can easily stretch for several kilometres, but never being more than about 50cm wide. 

The snow petrels space themselves out along the tide crack and sit patiently waiting for a krill to swim by at which point they jump out and hover just above the surface to take the tasty morsel.

Snow petrel
Snow petrel

 

Arctic Animals: 37 Photos of Snow-White wildlife

Arctic Animals:37 Photos of snow-white wildlife

Dramatic curving horns are the most notable feature of Dall sheep, a species native to northwestern North America that are almost entirely white in color. They’re primarily found in the subarctic mountain ranges of Alaska, the Yukon territory, the MacKenzie Mountains and the Northwest Territories.

Many of them are sheltered within the Arctic National Wildlife Refuge in Alaska. Year-round residents of the Refuge, Dall sheep live high on ridges and steep mountain slopes, using the rugged terrain to escape predators like wolves, golden eagles, bears and humans. These herbivores have adapted to the scarce food availability their frigid environment by maturing slowly, with low reproductive rates, to save their energy.

According to the Arctic National Wildlife Refuge, “Dall sheep walk a survival tightrope, although they do it rather effectively. They have lived since the Pleistocene in places such as the Arctic Refuge.”

Arctic Tern

With an annual migration covering 44,300 miles – the longest regular migration of any known animal on earth – the Arctic Tern certainly gets around. It goes from the Arctic circle as far south as Massachusetts over the course of the year. Mostly gray and white with black crowns and red beaks, Arctic Terns are medium-sized birds with wingspans of about 30 inches. Many of them can live up to thirty years.

Each individual tern has its own special social call that is distinguishable to the other terns, allowing them to identify individuals. They mate for life in most cases and will defend their nests fiercely against predators, even attacking humans by striking the top or back of the head with their beaks.

Arctic Gyrfalcon

The Gyrfalcon is the largest of the falcon species, and breeds all over the Arctic coasts of North America, Greenland and Northern Europe. Its plumage varies greatly from dark brown and black to almost solid white. White form Gyrfalcons are the only predominately white falcons in existence, and tend to be located in Greenland.

Gyrfalcons breed fuzzy white nestlings on bare cliffs, often in the abandoned nests of other birds like ravens and golden eagles. They’re very aggressive toward any creatures that come too near their nests, dive-bombing brown bears. Their primary threat is humans, mostly in the form of either car collisions and hunting. They can live to be up to 20 years old. While the species was considered ‘near-threatened’ from the mid-20th century to 1994 due to poisoning from pesticides, they have since made a comeback, and are no longer considered rare.

ARCTIC ANIMALS

navigation bar Polar bears

Polar bears are found around the polar region; spends time along the southern edge of the arctic pack ice. Their habitats are on pack ice, open water and on land. Male polar bear weigh 400-450kg and female polar bear weigh 300-350kg. Their diet includes seals, birds from sea and icy land. Their body contains blubber. This insulate them from the cold climate. Their lifespan is up to 25 years. The population of polar bear is around 40,000. Polar bear`s future depends on the protection of Arctic environments (windy, ice, snowy lands) from pollution.

navigation bar Penguins

There are no penguins in the northern hemisphere. They are found in the southern hemisphere. Penguins live from the sea ice along the edges of antarctica, up to thr equator. Penguins are birds that do not fly and swims well. Some penguins lives in very cold ice and snowy places. They finds their food mostly from the sea, such as fish. Some penguins spend most time of their lives in the water. And some spends most o their time on the snowy land. They lay their eggs on the land. To survive in this cold snowy climate, they have a thick layer of fat below their skin for insulation.

navigation bar Arctic fox

Arctic fox are found in the fur north areas of North America, Iceland, Greenland. The colour of the animal is gray or white. They are carnivores, eats eggs, birds, fish, small mammals. They have thick insulating fur. They protect themselves by hiding in the snow. Their lifespan is between 3-10 years. They are adapted to live in the cold climate. Arctic foxes metabolic rate starts to increase at minus 50 degree celcius. Therefore they can tolerate snowy climate.

navigation bar Musk ox

Musk ox are found on the tundra of Canada, Alaska, Greenland and some Arctic islands. Their diet includes grasses, willow leaves, lichens. They are 4-5 ft tall and weighs 230 – 360 kg. The fur of the musk ox is 3-4 inches thick. The muskox fur coat and hooves acts as insulation in the cold weather. They have long outer hair. Under this hair, they have wooly qiviut. It is naturally occurs fibre at up to 10 times warmer than sheep wool. Their lifespan is just over 20 years.

navigation bar    Wolverine

 

Wolverine is the largest member of the weasel family. Wolverine is found in the Northern United States, Alasa, Canada. Their diet includes, eggs, small mammals, rats, birds. The male wolverine weigh 36 pounds and female weight 25 pounds. Their thick fur insulates them in the cold climate. Their lifespan is up to 22 years in captivity.

 

I HOP YOU ENJOYED IT

Image Map used on Bear's face

Snow and Animals

Snow and Animals

It can be difficult for animals to live in places that receive large amounts of snow, such as in the high latitudes and at high elevations. Snowy places tend to receive less sunlight, which decreases temperatures and makes it hard for animals to stay warm. Deep snow can also be difficult to move around in; animals must spend more time and energy walking through it or finding food beneath it.

Adaptations

Some animals have adapted to co-exist with the cold. Deer, elk, bison, and other grazing animals use their hooves and muzzles to clear snow away from plants they need to eat to survive. To help retain warmth throughout the winter, they also grow thicker, shaggier coats, which they shed in the spring when the weather becomes warm again.

Other animals, like the snowshoe hare, develop ways to travel on top of deep snow. Snowshoe hares have large hind feet, and they can spread their toes to act like snowshoes, which helps them walk on the surface of deep snow without falling through. Similarly, the ptarmigan, a bird common to the Rocky Mountains, saves energy by walking on top of the snow with its feather-covered feet.

The pika, another Rocky Mountain native, dries little bundles of hay in the fall, then brings this food under the snow to spend the winter. The Arctic fox, which must deal with the cold, snowy conditions of the Arctic all year, grows thick fur all the way down to the bottoms of its paws. It has a stocky body, short legs, and small ears, all of which conserve body heat.

During cold periods, frogs, snakes, and other amphibians and reptiles slow their body processes almost to a stop, using up their energy very slowly. Some insects have adapted a lifecycle that follows the seasons. They grow and reproduce during the summer months, then die in the fall, leaving their offspring in protective cocoons that will open the following spring.

 

Hibernation

Deep snow can prevent some animals from finding food, but it also acts like a blanket, keeping the ground beneath it warmer than the surrounding air temperature. Some animals take advantage of snow’s insulation, and cope with the cold season by building in a protective den or burrow and going into a deep, long sleep, a process called hibernation. Bears and groundhogs, for instance, build up fat reserves in the fall so they can survive hibernating through the snowy winter months, usually not waking again until spring.

Migration

Some animals simply leave snowy, cold regions during the toughest seasons. Arctic terns, for example, spend the No

rthern Hemisphere summer in the Arctic, and then migrate to Antarctica for the Southern Hemisphere summer, traveling about 39,000 kilometers (24,000 miles) round-trip each year. Migration can also happen over shorter distances: Deer and elk in the Rocky Mountains of the United States tend to migrate down into valleys during the winter.

The timing of spring snowmelt and autumn snowfall also affects migration. Many migratory water birds take advantage of the 24-hour sunlight and extensive food supplies available during the Arctic summertime. But the timing of birds’ breeding and nesting depends on when particular regions in the Arctic become snow-free each spring. Some populations nest in Greenland, where snow melts later in the spring season, and there is a smaller window of opportunity for the species migrating there. Arctic areas of Europe, Asia, and Alaska, however, have recently experienced earlier springtime thawing, resulting in more snow-free patches and longer summer seasons for migrating birds.

A herd of caribou walking single-file through the snow

During winter, animals often must contend with deep snow, which makes movement difficult. These caribou are walking in single file; a lead animal will break a trail through the snow, and the rest of the herd follows in its tracks.
An elk digs through the snow to graze

Elk and other grazing animals often have to dig through snow to graze during winter.
Willow ptarmigan in the snow

The ptarmigan’s feathered feet act as snowshoes, distributing its weight and preventing it from sinking into the snow.

I HOP YOU LEARNT LOTS OF NEW THING ABOUT SNOW ANIMALS

from satarra

The Snowy Owl

The Snowy Owl

Description:   They are called snowy owls because their colouring is almost pure white when they are full grown. The feet of snowy owls are covered with feathers and have extra thick pads.

Vision:   Snowy owls have incredible vision. They can see from high up in the sky and swoop down silently to capture their prey. Like all owls they have good night vision.

Diet:  They stay in the Arctic during the winter unless their food sources are scarce. If they leave the arctic in the winter they overwinter in northern Greenland, the Canadian islands, or North America.

Newborn winter owl

 

Arctic Fox

 

              Arctic Fox

The arctic fox also called as white fox, snow fox or polar fox is small in stature with a species name Vulpes Lagopus. It is seen in the Northern Hemisphere arctic regions and is a common animal in the Arctic Tundra biome. The arctic fox is adapted to live in cold climates and has a thick fur, which is brown in summer and takes white hue in winter. The average size is 85.3cm body length. The body is round in shape facilitating minimal escape of heat from the body.

Introduction :

Arctic fox usually eat small animals they find like voles, fish, birds and seal pups. Berries, carrion and seaweed are also eaten by them. They are monogamous breeders and stay in groups always. They reside in underground complex structured dens.

The arctic fox lives in a circumpolar area or the area that includes the entire arctic region. Greenland, Alaska, Canada, Svalbard and Russia and also parts of Iceland and Scandinavia are the places that arctic foxes are seen commonly in. They are properly conserved in all these areas except the Scandinavian mainland area, where they are an endangered species. The total number of arctic foxes in Finland, Sweden and Norway come to only 120 adults.

Appearance :

As the arctic fox lives in frigid and cool places, the appearance is adapted for living in extremely cold conditions. It has a thick and deep fur, paws that help in heat exchange by countercurrent to retain the body core temperature and also is endowed with an appropriate supply of fat in the body.

The surface area and volume ratio is low due to the round shape, short muzzle, short legs, and thickset ears. Due to less area of exposure the heat that escapes is very low. Furry paws enable the arctic fox to search for prey in the snow. The keen sense of hearing helps it locate the prey and catch them. The fur can change colors according to the season. In summer it is brown, while in winter it takes a white color to blend with the surrounding snow.

Diet :

The food for arctic fox is generally the small animals like hares, owls, voles, lemmings, carrion and eggs. Lemmings form its most common food. Dozens of lemmings can be consumed by a family of foxes in a day. In the April and May months, the arctic fox preys on seal pups, which are helpless and confined to snow dens. Fish found below the ice sheets are also good food sources for arctic foxes. Berries and seaweeds are also eaten by arctic foxes making them omnivorous in nature. In the presence of huge left over food after the family has consumed, the food is buried by them and in times of scarcity, they scavenge the leftovers and also feed on the feces of animals like polar bears.

Breeding :

The breeding season for arctic fox starts from early part of September to the early part of May. The gestation time is 52 days and the litters are usually 5 to 8 in number, but some can litter as high as 25. Both the parents help in raising the young ones. The females exit from the family and join with their own gender, while the male stays with the family.

The arctic fox is monogamous in nature and litters are created during early summer. Large dens are used to raise the young ones. The dens are complicated structures having many generations of foxes in them. The young ones help the parents to look after the small kits. The young ones are brown, but turn white when they grow up. The color changes to brown in summer and returns to white in winter.

Predators :

Arctic foxes are usually preyed upon by larger animals like the polar bear. Humans kill arctic foxes for their fur and some indulge in trophy hunting too. Farmers kill the foxes as they attack the sheep and livestock.

Life Cycles & Lifestyle :

The dens are not usually used by arctic foxes except during the breeding season. The natal den is constructed and is usually seen in bank area of snow or on a ridge side, or sometimes in a rock pile. A den has four or twelve openings and some older dens have nearly hundred openings. Some are even present for many centuries.

Twelve pups is the average litter size and the birth weight is 57g. Most kits have a poor rate of survival. During food scarcity, the stronger kits feed on the weak siblings and sometimes the parents abandon the young kits too. Wolves, eagles and grizzly bears also prey on the young kits. The weaning is over in the fourth week, while adulthood is reached at the tenth month.

The population can undergo a ten or even twenty fold increase and also a hundred percent reduction by the end of a particular cycle. The decline in numbers forces them to migrate to greener areas. Though in captivity foxes can live up to 15 years, this is not the case in the wild. Predation, human hunting and harsh survival conditions lead to a high mortality rate.

Facts :

The arctic fox is the solitary land mammal seen in Iceland, probably due to the migration during the ice age. The population of arctic foxes is dependent on the prey population, especially the voles and lemmings. The arctic fox is becoming extinct and giving way to the more dominant red fox. This is due to the climate changes, when the camouflage factor of the lighter coat is reduced by the decreasing snow cover. The red foxes usually kill the arctic foxes and the kits in areas where their presence is overlapped. Now red fox is the top predator in the area.

Habitat :

Arctic foxes live in the arctic region that include Greenland, Iceland, Alaska, Canada, Russia and other location in the northern hemisphere. It is the only mammal to inhabit Iceland. They live in dens dug on hill sides, cliff sides or on riverbanks. The arctic foxes live in treeless areas at temperatures that range between 76 and 68 degrees Fahrenheit

Pics, Images, Photos and Pictures of The Arctic Fox :

Arctic Fox Arctic Fox Arctic Fox Arctic Fox Arctic Fox Arctic Fox Arctic Fox
Behavior :

The adaptations present in the arctic foxes helps them to live in extreme conditions. Studies reveal that the foxes can identify the barks of members and those that do not belong to the family. Barking is their only means of communication. The arctic females are nomadic inside the territory, while the male fox’s range is typically larger than the female.

From Satarra

Snow leopards

 

 

Basic Facts About Snow Leopards

The snow leopard, known for its beautiful, thick fur, has a white, yellowish or soft gray coat with ringed spots of black on brown. The markings help camouflage it from prey. With their thick coats, heavy fur-lined tails and paws covered with fur, snow leopards are perfectly adapted to the cold and dry habitats in which they live.

Diet

Snow leopards primarily hunt wild sheep and goats. Snow leopards are also known to eat smaller animals like rodents, hares and game birds.

Population

Did You Know?

Snow leopards have very large paws that act as snowshoes and keep them from sinking into the snow. Their paws are also completely fur-covered, protecting them from the cold.

Very rare in most of their range, an estimated 3,500 to 7,000 snow leopards are left in the wild, with 600 – 700 in zoos around the world. Exact numbers in the wild have not been determined due to the snow leopard’s shy nature.

Range

Snow leopards are found at altitudes between 9,800 and 17,000 feet in the high, rugged mountains of Central Asia. Their range spans from Afghanistan to Kazakstan and Russia in the north to India and China in the east. China contains about 60% of snow leopard habitat. They have already disappeared from certain parts of Mongolia, which is part of their historic range.

Behaviour

Snow leopards prefer to inhabit steep cliff areas, rocky outcrops and ravines. Such habitats provide them with the camouflage they need to ambush unsuspecting prey. They stalk their prey and usually spring from a distance of 20 – 50 feet. Their long and powerful hind limbs help snow leopards leap up to 30 feet, which is six times their body length.

Did You Know?

Snow leopards have light green or gray eyes, unusual for big cats, who usually have yellow or gold eyes.

Mostly active at dawn and dusk, snow leopards are rarely seen in the wild. Unlike other big cats, snow leopards are unable to roar. Solitary in nature, they pair only during the breeding season.

Reproduction

Mating Season: Between January and mid-March.
Gestation: period 3-3 ½ months.
Litter size: 2-3 cubs.

Females give birth in rocky dens lined with their fur. The young follow their mother on hunts at three months and remain with her through their first winter.

Snow leopard

The snow leopard is a large cat native to the mountain ranges of Central and South Asia. It is listed as endangered on the IUCN Red List of Threatened Species because as of 2003, the size of the global population was estimated at 4,080–6,590 adults, of which fewer than 2,500 individuals may reproduce in the wild.
  • Scientific name: Panthera uncia
  • Biological classification: species
  • Belongs to: uncia

Polar bear

 

 

How big are polar bears?

Polar bears are the largest carnivorous land mammals on Earth. They are about 7-8 feet long measured from nose to the tip of their very short tail. Male polar bears are much larger than the females. A large male can weigh more than 1,700 pounds, while a large female is about half that size (up to 1,000 pounds). Bears can weigh about 50 percent more after a successful hunting season than they do at the start of the next; most of this additional weight is accumulated fat. A newborn polar bear weighs only about 1.5 pounds which is very small compared to the weight of its mother.

What do polar bears eat?

Unlike other bear species, polar bears are almost exclusively meat eaters (carnivorous). They mainly eat ringed seals, but also bearded seals. They also eat walruses, other species of seals and whale carcasses. Polar bears will search out bird eggs and other food sources but none of these are abundant enough to sustain the large body mass and dense populations of polar bears.

How do polar bears hunt seals?

Polar bears hunt seals by waiting for them to come to the surface of sea ice to breathe. When the seal nears the surface, the polar bear will bite or grab the seal and pull it onto land to feed.

Another vitally important food source in most areas are seal pups that are born and live in dens in the arctic ice. The polar bear identifies these dens by smell and other markers and pounces though the roof of the den to capture the young seals. In Hudson Bay, the availability of seal pups in the spring is increasingly limited by earlier melting of ice . In the Arctic, polar bears are at the top of the food chain; they eat everything and nothing (but native hunters) eats them.

 

How long do polar bears live?

Polar bears in the wild can live to be 30 years of age, but this is rare. Most adults die before they reach 25 years.

What is a polar bear’s typical habitat?

Polar bears walking through icy waters

Polar bears depend on the sea ice, which forms above the open waters where their seal prey lives. They will spend time on land when sea ice is not available (most pregnant polar bear females make their dens on shore near the coast).

Polar bears are excellent swimmers and they will travel long distances between shore and the sea ice if necessary. However, if a storm kicks up during these increasingly long swims (caused by the warming ocean) they can drown. These long swims and storms are also often difficult for cubs. During periods of ice breakup, polar bears frequently swim between floating ice islands.

Permanent, multi-year ice that doesn’t ever melt is more important to polar bears than the annual ice that melts and reforms every year; this multi-year ice is increasingly rare, but will likely persist for longer in the island archipelago of northwestern Canada than in Alaska or off the northern coast of Russia.

Where do polar bears live?

Most polar bears occur north of the Arctic Circle to the North Pole. There are some populations south of the Arctic Circle in Hudson Bay, Manitoba, Canada. Polar bears live in Alaska, Canada, Russia, Greenland and some northern islands owned by Norway like Svalbard.

How do polar bears communicate and associate with each other?

Polar bears tend to live solitary lives except when mating, when a female is raising her cubs forming a family group, or when many bears are attracted to a food source like a beached whale. Young polar bears spending the summer ashore on the Hudson Bay coast will frequently play with each other, most commonly with their siblings. When necessary or playing, polar bears communicate with each other with grunts, growls, roars or squeals.

Polar bears near Churchill on the coast of Hudson Bay are even known to play with chained sled dogs without killing them, which they could easily do.

Polar bear

What are the reproductive habits of polar bears?

Polar bears breed in the late spring as the temperatures begin to rise in the Arctic. Like other bear species, however, they don’t really become pregnant at the time of breeding as the tiny embryo (or blastocyst) will not implant in the female’s uterus until fall when true gestation starts. This is called delayed implantation and allows a female bear to physiologically assess her condition prior to starting gestation and the process of birthing, nursing and carrying for her offspring for the next three years. The period of actual gestation following implantation to the birth of cubs is only about 60 days.

In the Hudson Bay population, where the reproductive biology of polar bears has been most extensively studied, it appears that a polar bear female carrying a blastocyst must achieve a body weight of at least 490 pounds to have the blastocyst implant and start gestation. If this threshold is not achieved, the blastocyst will reabsorb, the female will continue to hunt seals all winter, attempting to be fatter a year later and able to carry off a successful pregnancy.

In the beginning of the winter, a pregnant female will dig a den in a snow bank and begin the process of gestation that leads to the birth of her cubs. Depending on the area, pregnant females may enter dens anytime between early October and December. Time of exit from dens occurs between late February and April. Most females dig their dens in a snow bank on land, but some also den on the floating sea ice. In Hudson Bay, females may dig a den in the earth instead, but they use areas where the snow will build up and provide insulation. In the middle of winter in some of the coldest places on Earth, female polar bears give birth to cubs. Litter size is most commonly two cubs but sometimes litters can be one, three or, very rarely, four cubs.

Female polar bears in the Hudson Bay area spend remarkable periods of time fasting, the longest known of any mammal species. This fasting period before denning and in dens averages about 180-186 days. In Hudson Bay, pregnant females can successfully fast for as long as 240 days. The long period of fasting makes this species especially vulnerable to environmental changes like a warming climate that reduces the amount of time they have available to build up the fat reserves they need to survive both fasting and to bring off a successful pregnancy.

Polar bear mom cleaning cub

When the cubs are born they are completely dependent on their mother. They stay in the den nursing on her rich milk until spring, when they emerge and start exploring the world as their mother heads out to the ice to catch the seals she needs to replenish the weight she’s lost during her period of fasting. Over the next two years the cubs will learn from their mother how to catch seals themselves and to develop the other skills needed to survive and grow to adult size. Typically, cubs will stay with their mother until they are two-and-a-half years old but in some cases they will stay for a year more or a year less. If the mother is able to replenish her fat reserves sufficiently she can produce a litter of cubs that survive until weaning every three years. When food declines in abundance, there is a longer period between successive successful litters and litter sizes are smaller

Polar bears

The polar bear is a carnivorous bear whose native range lies largely within the Arctic Circle, encompassing the Arctic Ocean, its surrounding seas and surrounding land masses. It is a large bear, approximately the same size as the omnivorous Kodiak bear. A boar weighs around 350–700 kg, while a sow is about half that size. Although it is the s…

The polar bear is a carnivorous bear whose native range lies largely within the Arctic Circle, encompassing the Arctic Ocean, its surrounding seas and surrounding land masses. It is a large bear, approximately the same size as the omnivorous Kodiak bear. A boar weighs around 350–700 kg, while a sow is about half that size. Although it is the sister species of the brown bear, it has evolved to occupy a narrower ecological niche, with many body characteristics adapted for cold temperatures, for moving across snow, ice, and open water, and for hunting the seals which make up most of its diet. Although most polar bears are born on land, they spend most of their time at sea. Their scientific name means “maritime bear”, and derives from this fact. Polar bears hunt their preferred food of seals from the edge of sea ice, often living off fat reserves when no sea ice is present.
  • Weight: 331 – 551 lb (Female) · 849 – 904 lb on average (Male)
  • Scientific name: Ursus maritimus
  • Height: 4 – 5.2 ft · 4.4 ft on average (Male)
  • Length: 5.9 – 7.9 ft (Female) · 7.9 – 9.8 ft (Male)
  • Speed: 3.5 mph on average (Walk) · 6.2 mph (Swimming)
  • Tail length: 0.2 – 0.4 ft