“Diet: The most important time for a polar bear is during the months of April through July when the ringed seals are abundant. Polar bears must take advantage of the good hunting to prepare for the times when their stored body fat is the key to survival. This is the time of the year when they replenish their body fat. A polar bear has to solve two physiological problems; maintaining their body temperature in a cold climate, and being able to store enough energy to last between meals that could be days or even months apart. Ringed seals form the basis of their diet during these months. They usually kill a seal every 5-6 days. Polar bears can consume up to 150 lbs. of food at one sitting due to the fact that their stomachs are very large. As a result of this, they can go weeks without eating.
During April - July, polar bears will usually eat only the skin and blubber of seals. If they kill a newborn pup, they most likely will not eat it. During the summer months, polar bears will also eat carrion, small pieces of seaweed, grasses, crowberries, lemmings or voles. They also hunt beluga whales and walruses.” (Science Castle)
During April - July, polar bears will usually eat only the skin and blubber of seals. If they kill a newborn pup, they most likely will not eat it. During the summer months, polar bears will also eat carrion, small pieces of seaweed, grasses, crowberries, lemmings or voles. They also hunt beluga whales and walruses.” (Science Castle)
“Summer on land is a difficult time for polar bears. Relying on the fat gained during winter hunting to see them through the more difficult hunting of summer when pack ice melts. Unfortunately, summer is becoming even deadlier, with pack ice melting earlier, melting farther, and arriving later in the winter.
When summer comes to Svalbard the ice pack melts and polar bear are stuck on land. Their metabolism slows down and they enter a kind of walking hibernation. They rely on the reserves of fat generated from a winter of hunting seals to sustain them through the summer months. Polar bear are at their most dangerous to humans at this time of year… wouldn’t you be if you were starving?
Not only are polar bears more dangerous to humans at this time of year, but the odds of running into one have been increasing in conjunction with melting ice. The less ice, the more likely polar bears are to be on land, and near human habitations.
Being stranded with fewer food choices for longer periods during summer is becoming a problem for migratory birds as well. Barnacle Geese that nest on Svalbard during summer are increasingly a target for polar bears. Even though their eggs are small in comparison to a bear’s usual meal for a bearded seal, they’re easy food. And the slow-to-reproduce birds are losing thousands of eggs to hungry bears.
Of the more than 500 nests holding eggs on the island this summer, fewer than 40 were successful–with the majority of those producing only one or two chicks. Just 60 years ago, the goose population on Svalbard had dipped below 300. After decades of conservation work, the population has climbed above 30,000. This most recent threat, however, could jeopardize that seemingly robust number.
When pack ice melt presents problems for bears, the effects trickle out to other species as well.
In the summer, when the ice is melted, the opportunity to catch seals is few and far between, which is another reason why bears enter this fasting period in late summer and fall. If they didn’t catch enough seals in winter, they won’t have enough fat to sustain them — and with ice melting sooner and arriving later, it’s a serious problem.
A few weeks into summer the ice pack begins to melt, bear need to swim further to find ice to hunt seal. Eventually the ice is too far for them to reach so they retreat to shore.
Some of the most heartbreaking images are that of polar bears without any ice to rest on. The record-breaking swims have become news headlines. Earlier this year, a bear was seen to swim 426 miles over 9 days without a single rest. This uses up their valuable fat reserves, which they can little afford to waste on long swims.
Even mother bears have been spotted swimming with their cubs on their backs, a situation that is both good and bad — good, because it shows adaptive behavior that could help cubs’ odds of surviving the swims, but bad for the obvious reason that it saps a mother’s strength and her own fat reserves, which can in turn reduce a cub’s chances of making it to adulthood.” (Heimbuch)
When summer comes to Svalbard the ice pack melts and polar bear are stuck on land. Their metabolism slows down and they enter a kind of walking hibernation. They rely on the reserves of fat generated from a winter of hunting seals to sustain them through the summer months. Polar bear are at their most dangerous to humans at this time of year… wouldn’t you be if you were starving?
Not only are polar bears more dangerous to humans at this time of year, but the odds of running into one have been increasing in conjunction with melting ice. The less ice, the more likely polar bears are to be on land, and near human habitations.
Being stranded with fewer food choices for longer periods during summer is becoming a problem for migratory birds as well. Barnacle Geese that nest on Svalbard during summer are increasingly a target for polar bears. Even though their eggs are small in comparison to a bear’s usual meal for a bearded seal, they’re easy food. And the slow-to-reproduce birds are losing thousands of eggs to hungry bears.
Of the more than 500 nests holding eggs on the island this summer, fewer than 40 were successful–with the majority of those producing only one or two chicks. Just 60 years ago, the goose population on Svalbard had dipped below 300. After decades of conservation work, the population has climbed above 30,000. This most recent threat, however, could jeopardize that seemingly robust number.
When pack ice melt presents problems for bears, the effects trickle out to other species as well.
In the summer, when the ice is melted, the opportunity to catch seals is few and far between, which is another reason why bears enter this fasting period in late summer and fall. If they didn’t catch enough seals in winter, they won’t have enough fat to sustain them — and with ice melting sooner and arriving later, it’s a serious problem.
A few weeks into summer the ice pack begins to melt, bear need to swim further to find ice to hunt seal. Eventually the ice is too far for them to reach so they retreat to shore.
Some of the most heartbreaking images are that of polar bears without any ice to rest on. The record-breaking swims have become news headlines. Earlier this year, a bear was seen to swim 426 miles over 9 days without a single rest. This uses up their valuable fat reserves, which they can little afford to waste on long swims.
Even mother bears have been spotted swimming with their cubs on their backs, a situation that is both good and bad — good, because it shows adaptive behavior that could help cubs’ odds of surviving the swims, but bad for the obvious reason that it saps a mother’s strength and her own fat reserves, which can in turn reduce a cub’s chances of making it to adulthood.” (Heimbuch)
“Polar bears are coming ashore earlier in western Hudson Bay. The ice breaks up around June 25th now as opposed to July 15th. However, polar bears actually come ashore about three weeks after ‘break-up’. Break-up occurs in early July while most bears do not come ashore until the end of July, sometimes even August. Conversely, they go out on the ice about one or two weeks earlier than what is considered freeze-up (usually leaving around November 14 whereas freezeup is considered November 21).
Realistically, this means they are on land for about 15 weeks. During this time, they mostly remain in a state of ‘walking hibernation’. Their system slows down and consumes less energy. However, this does not mean that they are fasting. They eat Lyme grass, berries, peat, kelp and whatever they can find. Researchers at the La Perouse Bay Snow Goose Camp have watched young bears and mothers with cubs routinely hunt snow geese, basically chasing them up against willow bushes, stomping on a few of them and then sitting down for a nice meal of goose guts.
Of course, none of these meals compare to a good and fat seal pup and, therefore, an early break-up remains critical to survival and to continued cub production. Scientists believe that an early break-up of even one week will translate to a 3-8% reduction in the annual survival rate, primarily affecting old bears and lone sub-adults. Researchers believe that warming springs are primarily due to the effects of global climate change.
It is important to get back on the ice but life is still tough out there. Hunting is sparse through the winter months and polar bears still spend much of their time in a state of walking hibernation or even hunkered down, waiting out severe weather. Polar bears in western Hudson Bay do not reach their lowest weights until March, so when you think about it, the polar bears we see in ‘bear season’ are really still in modest condition.
Bears do not do the majority of their hunting until spring, pretty much starting in April when the ringed seal pup birthing season starts. Seal pups are about 50% fat and an easy meal for polar bears. In fact, about 80% of a bear’s diet consists of ringed seals under one year of age.” (Eliasson)
Realistically, this means they are on land for about 15 weeks. During this time, they mostly remain in a state of ‘walking hibernation’. Their system slows down and consumes less energy. However, this does not mean that they are fasting. They eat Lyme grass, berries, peat, kelp and whatever they can find. Researchers at the La Perouse Bay Snow Goose Camp have watched young bears and mothers with cubs routinely hunt snow geese, basically chasing them up against willow bushes, stomping on a few of them and then sitting down for a nice meal of goose guts.
Of course, none of these meals compare to a good and fat seal pup and, therefore, an early break-up remains critical to survival and to continued cub production. Scientists believe that an early break-up of even one week will translate to a 3-8% reduction in the annual survival rate, primarily affecting old bears and lone sub-adults. Researchers believe that warming springs are primarily due to the effects of global climate change.
It is important to get back on the ice but life is still tough out there. Hunting is sparse through the winter months and polar bears still spend much of their time in a state of walking hibernation or even hunkered down, waiting out severe weather. Polar bears in western Hudson Bay do not reach their lowest weights until March, so when you think about it, the polar bears we see in ‘bear season’ are really still in modest condition.
Bears do not do the majority of their hunting until spring, pretty much starting in April when the ringed seal pup birthing season starts. Seal pups are about 50% fat and an easy meal for polar bears. In fact, about 80% of a bear’s diet consists of ringed seals under one year of age.” (Eliasson)
Works Cited
Eliasson, Kelsey. Polar Bears of Churchill - Polar Bear Facts. 2006. 31 January 2012 <http://www.polarbearalley.com/polar-bears-of-churchill-population.html>.
Heimbuch, Jaymi. Witnessing Summer Starvation Among Polar Bears (Pics) : Feeding The Headlines. 29 August 2011. 31 January 2012 <http://www.feedingtheheadlines.com/2011/08/29/witnessing-summer-starvation-among-polar-bears-pics/>.
Science Castle. *Polar Bear*. 2012. 31 January 2012 http://sciencecastle.com/sc/index.php/animalspecies/showspecies/31.
Eliasson, Kelsey. Polar Bears of Churchill - Polar Bear Facts. 2006. 31 January 2012 <http://www.polarbearalley.com/polar-bears-of-churchill-population.html>.
Heimbuch, Jaymi. Witnessing Summer Starvation Among Polar Bears (Pics) : Feeding The Headlines. 29 August 2011. 31 January 2012 <http://www.feedingtheheadlines.com/2011/08/29/witnessing-summer-starvation-among-polar-bears-pics/>.
Science Castle. *Polar Bear*. 2012. 31 January 2012 http://sciencecastle.com/sc/index.php/animalspecies/showspecies/31.