Study: Polar bears may survive ice melt, with or without seals

New calculations indicate that land-based food sources like caribou, snow geese, and eggs might provide enough calories for bears to avoid starvation

Two polar bears were photographed near the coast of the Western Hudson Bay, where researchers have shown bears are consuming land-based foods during ice-free periods. CREDIT © AMNH/R. Rockwell

Two polar bears were photographed near the coast of the Western Hudson Bay, where researchers have shown bears are consuming land-based foods during ice-free periods. CREDIT © AMNH/R. Rockwell

From the AMERICAN MUSEUM OF NATURAL HISTORY

As climate change accelerates ice melt in the Arctic, polar bears may find caribou and snow geese replacing seals as an important food source, shows a recent study published in the journal PLOS ONE. The research, by Linda Gormezano and Robert Rockwell at the American Museum of Natural History, is based on new computations incorporating caloric energy from terrestrial food sources and indicates that the bears’ extended stays on land may not be as grim as previously suggested.

“Polar bears are opportunists and have been documented consuming various types and combinations of land-based food since the earliest natural history records,” said Rockwell, a research associate in the Museum’s Department of Ornithology who has been studying the Arctic ecology of the Western Hudson Bay for nearly 50 years. “Analysis of polar bear scats and first-hand observations have shown us that subadult polar bears, family groups, and even some adult males are already eating plants and animals during the ice-free period.”

Previous studies have predicted mass polar bear starvation by 2068, when annual ice breakup is expected to separate the bears from their sea-ice hunting grounds for a consecutive 180 days each year–creating ice-free seasons that will last two months longer than those in the 1980s. But those estimates assumed no energetic input from land food sources.

Gormezano and Rockwell computed the energy required to offset any increased starvation and then determined the caloric value of snow geese, their eggs, and caribou that live near the coast of the Western Hudson Bay. They found that there likely are more than enough calories available on land to feed hungry polar bears during the lengthening ice-free seasons.

Although the exact energetic cost for a bear to hunt geese and caribou is uncertain, polar bears in Manitoba have been reported ambushing caribou with the same energetically low-cost techniques they typically use to hunt seals. The similar size of these two prey species means that bears would need to hunt for caribou only as often as they would usually hunt for seals, the researchers say.

“If caribou herds continue to forage near the coast of Western Hudson Bay when bears come to shore earlier each year, they are likely to become a crucial component of the bears’ summertime diet,” Rockwell said.

The eggs of snow geese are another food source for bears, and the energetic cost of obtaining eggs in ground nests is exceedingly low, the researchers say. With adequate food sources available, snow geese are known to endure polar bear egg predation without detrimental effects to the population.

Scientific consensus holds that the rapidly melting circumpolar ice reserves will increasingly prevent polar bears from hunting the seals on which they currently depend. Nevertheless, these observations of one population along the Western Hudson Bay show that bears marooned on land might, where the conditions are right, stave off starvation by turning to alternate food sources.

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65 thoughts on “Study: Polar bears may survive ice melt, with or without seals

  1. Wouldn’t the seals also follow the shoreline IF it shrinks , or do they have one specific area of ocean that they stay within ????

    • Omnivores: who knew??? Next paper: “Risk of Polar Bears getting Hypothermia Mitigated by Insulation”, research suggests. Said Professor Greenback, lead author of the multinational team of fifty scientific brainboxes: “It’s, like, amazing. They have this stuff we have decided to dub ‘white fur’ and it seems to reduce heat losses. With further research funding we may be able to prove this principle. This has implications for mankind: plumbers might, for example, clad water pipes in white fur.” It is hoped that the Nobel Prize committee is aware of this groundbreaking work.

  2. Apparently, the snow-geese are going to be just fine,too.
    ” With adequate food sources available, snow geese are known to endure polar bear egg predation without detrimental effects to the population.”
    I’m a bit concerned about the vegetation, though; the bears in the pic seem to have seriously over-grazed their broccoli patch.

    • consider also Svarlbard, where, we were told some years ago, Barnacle geese numbers had increased after decades of protection to the point that they had swamped suitable nesting areas.
      I seem to remember reports of polar bears eating young and eggs there in the past, having found the supply of young etonian climate change students too irregular to become a staple part of their omnivore diet.

      • They waxed hopeful when the arctic was invaded by sailboats, rowboats and cross ice adventurers going out to see how the bears were doing.

  3. Isn’t it interesting that the greenies always want to save a species, but only so another species can kill them. The delta smelt need to be saved to feed the salmon, frogs need to be saved to feed the birds, and baby seals can’t be clubbed because they need to be ripped apart, by tooth and claw, alive, to feed polar bears. How compassionate those greenies are.

    • hoyt
      The watermelons seem to wish to eliminate any possibility of a further supply of young Etonians (even Winston Churchill only went to Harrow), by stopping anyone but their watermelon elite giving their kids an advantage.
      And Eton is an advantage.
      Auto

  4. This is not their first rodeo. Polar bears have survived all the climate changes since there were polar bears which is over 100,000 years, and nothing about the current climate is unique in any way. That time frame, by the way, means there was a time when there were no polar bears. The fact that they are still here makes their ability to survive change self evident. Their numbers are still growing. Only climate scientists don’t get that. They are highly mobile opportunists that will eat anything on the menu. I put this right up there with exposed tree stumps at the snout of retreating glaciers as evidence of serial climate scientist ignorance. One could conclude they never personally do field work, preferring to write bad models for data witnessed first hand by others.

    • … One could conclude they never personally do field work, preferring to write bad models for data witnessed first hand by others.

      One of the most prominent worriers-about-polar-bears-and-global-warming is Ian Stirling. I’ve met him in the field on several occasions. He’s done lots of field work. As far as I can tell, he is a first rate scientist. wiki He will tell you that polar bears eat seals and how they hunt them. He thus extrapolates that, if the ice melts due to global warming they won’t be able to get seals and will thus starve.
      Dr. Stirling knows what he knows. However, he has no experience with prolonged periods of warming. We have had a warmer climate in the arctic during the Bronze Age, Roman, and Medieval warm periods. The ice conditions were probably quite different. In fact, the Vikings may have circumnavigated Greenland. link
      It’s quite possible to do lots of field work (and be an acknowledged expert) and still be wrong. The problem arises when people extrapolate beyond what they actually know.

      • Does he know where the seals are going to go when there’s no pack ice? Seems like they’re going to have to hit the beach where a lot of hungry polar bears are hanging out with their brown bear cousins or learn to look like orcas.

    • “Polar bears have survived all the climate changes since there were polar bears which is over 100,000 years”
      From our friend Dr. Susan J. Crockford at polarbearscience.com:
      “Estimates of when polar bears began to split from brown bears continue to change as geneticists look further into the polar bear genome. Recent studies suggest that polar bears split from a common brown bear ancestor 350,000-6 million years ago.” –http://www.polarbearsinternational.org/about-polar-bears/essentials/evolution
      “Estimates of polar bear age over the last 4 years (there were also some before that), counting down from the most recent:
      8. Liu et al. 2014 < 500 thousand years ago [this post]
      7. Cronin et al. 2014 1.2 million years ago
      6. Cahill et al. 2013 ~600 thousand years ago (“similar to Hailer et al. 2012”)
      5. Miller et al. 2012 ~4-5 milliion years ago
      4. Hailer et al. 2012 ~600 thousand years ago
      3. Davison et al. 2011 ~160 thousand years ago
      2. Edwards et al. 2011 ~120 thousand years ago
      1. Lindqvist et al. 2010 ~134 thousand years ago
      http://polarbearscience.com/2014/05/10/evolution-by-geneticsts-again-yet-another-date-for-when-polar-bears-arose/
      Note that the more recent studies have much longer spans the earlier ones. By way of contrast, "Over the past 740,000 years there have been eight glacial cycles."
      wikipedia.org Quaternary_glaciation
      The previous interglacial the Eemian began about 130,000 years ago and ended about 115,000 years ago, and was warmer than anything so far observed in the Holocene. wikipedia.org Eemian
      The most reasonable inference is that the current inter glacial is not the Polar Bears first rodeo.

    • We should relocate a few (neutered) dozen of the many thousands of them to the Florida Everglades where they can kill off the infestation of anaconda and boa constrictors there. When the snakes run out of gators and birds to feed on they’re going to start crawling into boats, homes, and cabins to make snacks of people. Bears are too big to eat and big enough to rip a snake to shreds and will die off from old age, finally – win win. What could go wrong?

    • Indeed. A top of food chain predator, omnivore, and scavenger smart enough and tough enough to live in the arctic climate apparently not near as fragile an these armchair experts have been bellowing about for years. Polar bears will do fine no matter how many global warming meetings, including Paris, armchair alarmists will hold around the world.

  5. 2068!!!!????
    Oh well, most of us will be long gone in 53 years.
    Must be a very exact program to nail things down to a specific year 5 decades from now.
    “In the year 2025 ….”
    Aquarius.

  6. There’s more than one way to go extinct. Polar Bears adapted to life on the ice in the first place during the ice ages and split off from grizzly bears. They can still mate with grizzlies creating blonde “pizzlies” and gradually reintegrate back into the grizzly population from whence they came, becoming extinct through “miscegenation”. Something that ecologists are discovering happens in nature more often than they like to admit.

  7. The Arctic sea ice is always going to be there as long as the Earth’s axis is tilted so that the Arctic gets little to no sunlight in the winter months as has occurred for the last 4.4 billion years running now.

  8. But if there is no sea–ice, then surely the seals will give birth on land (like other seals). As it is the young seals that mostly feed the bears, then where is the loss of primary food?

    • Rocky You are correct. These experts have no common sense. Seals are not fish and have to spend a lot of their time out of the water. With no ice the seals and the bears will both be on land. If the seals, with flippers, and the bears, with four feet, are both on land who do you think could run faster? In Churchill these omnivores have no issue eating our garbage. What part of that observed trait would lead a PHD equipped expert to conclude that Polar Bears only eat seals

  9. They want another Ice Age and we are at the tail end of a typical Interglacial so this wish for another Ice Age will be granted, most likely.

  10. Ok, so when an intelligent and resourceful omnivore’s primary food-source runs low, they might eat something else instead.
    Well who would have thunk it. Did they get a prize for this?
    R

    • ralf
      A prize?
      A Nobel prize.
      Apparently.
      See, oh, I dunno, maybe a scientist – sensu lato, perhaps – with one or more names beginning with – as an example only, of course – M – Mike (the phonetic in the NATO phonetic alphabet).
      Auto
      Alpha Uniform Tango Oscar

  11. I wonder why they forgot to reassure their readers that, not only would poley bears survive if the ice were to recede, their population size has increased approximately five-fold during this supposed period of unprecedented warming and rapid ice-melt.
    Perhaps they omitted that information on purpose in order to avoid straying from the doom-and-gloom narrative, in which case their paper might be just a fig leaf for another of their failed predictions.

  12. My Dad shot a polar bear in 1951 outside Resolute Bay.
    The bear was trying to eat him and his Inuit companions.
    The Inuits ended up eating the bear and sleeping in the bear skin.

  13. With Churchill, Manitoba population of polar bears surviving after the Hudson’s Bay ice goes out a month or more before the arctic ice and forms a month or more later, ordinary folk have known the bear would survive any serious reduction in ice in the arctic. This is one of those such self evident truths that it is sickening to see ‘scientists’ proclaim the obvious. Another obvious thing that these ‘experts’ didn’t consider is that if the arctic warms, then the forest encroaches on the shores and brings no end of creatures right to their doorstep. They can eat seals that have come ashore as I’ve clarioned for several years, their prey now a linear hunting ground instead of three dimensional. They could even live in the woods most of the time and eventually re-mate with grizzlies. Heck, I’m only a geologist and engineer, but I seem to have come across enough data to make myself a polar bear expert as a hobby.

  14. That polar bears eat land resources has been known since the dawn of polar bear observation.
    They have evolved specializations that help them prey upon ringed seals, other pinnipeds and marine mammals, but that doesn’t mean they can’t still eat the same things that their grizzly bear ancestors ate.

  15. Few biologist understand climate change, but many assume the propaganda to be true. their observations are then subject to confirmation bias. Climate changes! Adapt or face extinction. Polar bears seem to get this better than these biologists. Since most of the current interglacial was warmer than now, polar bears should be able to survive well into the next glacial period. And we will probably learn to like polar bear steaks cooked over a nice grill in our igloos above the frozen city of Chicago.

  16. Just so I understand: If man kills baby seals, that’s a horrible thing, but if polar bears DON’T kill baby seals, that’s a horrible thing too. Now, if the polar bears are not killing enough seals for the environment, can we let the baby seal clubbing recommence to balance things out?

  17. I would say humans are the most fortunate and we can influence our faith, but the animals have to adapt or they will have no other way. At least, we can try to do something…….

  18. If the polar bears get really hungry. then they can always snack on a few of the Global Warming Tourists visiting the area in search of signs of melting ice,

  19. Question
    Year after year the summer temps in the Arctic do not vary significantly vs the average but the remainder of the year large variations that tend to be above the average. Any idea why?
    Not a good case for global temp rise when the max temps are uniform.

  20. my prediction-If the arctic melts we wont need to protect polar bears at all. The seals will have to use the land as a base, so they will be easier to catch then ever. They use the shores sometimes now anyway, so it is a safe prediction. Polar bear numbers will soar now that finding food is much easier, just follow the coast until you find them. So in the end we will end up reinstating heavier levels of hunting to keep polar bears in check.

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