A 200-kilogram caribou provides protein-rich food to polar bears and they can afford to spend days in summer without eating. habitat. Arctic explorers. On average, polar bears on all fours are 3.5 to 5 feet (1 to 1.5 meters) tall, but when standing on its hind legs, an adult male polar bear may reach more than 10 feet (3 m). Behavioral predictions based on optimal foraging models that assume an energy-maximizing strategy have been challenged on both theoretical and empirical grounds. This is flat-out wrong: sea ice declines have been minimal in spring.  The earliest breakup dates since 1991 for Western Hudson Bay, where this research was done, have been mid-June (according to the most recent study by Cherry et al. While they also did some observational work watching bears chase geese (reported in Iles et al., 2013; see abstract below), the primary scientific contribution was the scat analysis. – Polar Bear Giving Birth, Polar Bear Cubs Facts – Interesting Facts about Baby Polar Bears, Polar Bear Penis – Polar Bear Genitalia and Testes Growth. It will also eat berries, seaweed, insects and larvae, [one story picked up the goose population increase and another revealed the caribou population increase, but none that I saw caught both]. This error appears to have come from authors, Robert Rockwell and Linda Gormezano, as I show below. In addition, the AMNH press release makes this erroneous statement that was picked up by every media outlet I saw except one (either exactly as written or reworded slightly): “Climate warming is reducing the availability of their ice habitat, especially in the spring when polar bears gain most of their annual fat reserves by consuming seal pups before coming ashore for the summer.” [my bold]. “polar bears in the warming Arctic are turning to alternate food sources.”. A … Unfortunately, many bears have learned to eat at garbage dumps. Polar bears eat mostly fat and meat, including seals and other marine mammals. Polar bears can lose thousands of calories a day. Scientists suggest that polar bears rarely preyed on snow geese and caribou in the early 20th century because ice froze early each year which makes easier for bears to hunt seals. ), while the animals are also expanding their summer range toward the coast (Abraham and Thompson 1998), thus increasing increasing potential interactions with arriving bears (Fig. Do polar bears eat fish? It that deliberately misleading or just sloppy wording? But as far as we know, polar bears always done this. Spring in the Arctic is March-May; summer is June-August. Polar bears are at the top of the food chain in the Arctic. Gormezano, L.J. Although these are nutritious foods for other species, polar bears are adapted to prey on marine mammals found on or near the sea ice. http://onlinelibrary.wiley.com/doi/10.1111/1365-2656.12050/abstract. Sorry, your blog cannot share posts by email. The principle study conducted by Rockwell and Gormezano (reported in two papers, Gormezano and Rockwell, 2013a and 2013b, abstracts below) involved identification of plant and animal parts found in polar bear fecal samples (bear poop, aka “scat”). Recent research on polar bear diets by Robert Rockwell and Linda Gormezano, it says, suggests that an increase in the consumption of caribou and snow geese since 1968 is a sign that the polar bears are nutritionally stressed due to recent sea ice changes in spring (blamed on global warming) but may be adapting by changing their summer/fall diet. Polar bears need an average of 2 kg (4.4 lb.) This photo was included in virtually all media reports and in Gormezano and Rockwell (2013a:3518, Fig. The claim made by Rockwell in the press release that their research results indicate polar bears are “more resilient [to global warming] than previously thought” is grandstanding nonsense. However, feeding on a seal will actually give the bear far more calories than it needs in a day. By 1990, the colony had expanded to more than 22,500 pairs.”, See also the recent article: “Too many geese big honking problem for North: scientists” (Bob Weber, The Globe and Mail, June 23, 2013). Polar bears are indeed resilient to changing sea ice conditions but not because of the odd bits of terrestrial foods they eat during the summer. [open access] pdf here. Furthermore, Arctic is not the place where plants usually grow so polar bears will ever rely on vegetation. Rockwell. Only 2000 pairs nested at LaPerouse Bay in 1968. Caribou numbers have been increasing steadily (30- to 50-fold) since (Williams and Heard 1986; C. Jonkel, S. Kearney, and R. Brook, pers. However recent changes in climate forced polar bears to survive on offshore land animals. Terrestrial predation by polar bears: not just a wild goose chase. lemmings are eaten by arctic foxes, brown bears and snowy owls. So, it must take a lot of penguins to fill one up, right? In the 1960s, fewer than a hundred caribou were estimated for the population north of the Nelson River (C. Jonkel, S. Kearney, pers. Rockwell, R.F. Generally no, the caribou herds live farther south then the Polar Bears do. Polar bears are also the largest species of bear. Similarly the isolated population in the western Hudson Bay is thought to survive on alternate food sources. Either way, the fact that the press release repeats it is especially unfortunate. The snow goose population increase is considered an Arctic ecological disaster in the making. Polar bears Freedom and Viktor frolic in the water at the Ouwehands Zoo in Rhenen, The Netherlands, 23 January 2014. and Rockwell, R.F. 2013. Ecology and Evolution 3: 3509-3523. They can also feed on items like bird eggs, caribou, or small mammals. Previously white bears didn’t seem to bother with the presence of animals such as caribou because they’ve had enough of seals in winter. Polar bears are forced to hunt on land and thus they prey on caribou. DOI: 10.1186/1472-6785-13-51. Overall, the press release and resulting media reports seem to be further examples of hyping global warming at the expense of the actual science involved and I have to agree with Andrew Derocher’s interpretation of the significance of terrestrial food items for polar bears. The study also proves that bears are now beginning to rely on caribou which is a primary prey in ice-free months. Post was not sent - check your email addresses! Do Polar Bears Eat Caribou? Black man detained while jogging offered police job. Under current climate trends, spring ice breakup in Hudson Bay is advancing rapidly, leaving polar bears (Ursus maritimus) less time to hunt seals during the spring when they accumulate the majority of their annual fat reserves. In addition, in the abstract of that paper (copied in full in the reference section below), Gormezano and Rockwell also make this ridiculous statement: Under current climate trends, spring ice breakup in Hudson Bay is advancing rapidly, leaving polar bears (Ursus maritimus) less time to hunt seals during the spring when they accumulate the majority of their annual fat reserves. Gormezano and R.F. While the two terrestrial diets broadly overlap, polar bears currently appear to be exploiting increasingly abundant resources such as caribou (Rangifer tarandus) and snow geese (Chen caerulescens caerulescens) and newly available resources such as eggs. [in press] draft copy is open access. [my bold]. Polar bears rely sea ice to find and catch most of their prey. Endangered Species Act because their sea ice habitat is shrinking, apparently due to global warming. Arctic Char Polar Bears eat Caribou for Kids. Polar bears likely eat several terrestrial and marine species when the ice disappears. One of the predators is a polar bear that seems to rule the Arctic land in the midsummer. 2009). 2013; L.J. ; Polar bears are surplus killers.It has been reported that polar bear killed two seals at a time while feeding on another seal. Defining how the terrestrial diet might have changed since the onset of rapid climate change is an important step in understanding how polar bears may be reacting to climate change. Sometimes however they do feed on plants but it’s extremely rare and quite unusual in their diet. The increased co-occurrence of polar bears and the now plentiful caribou and snow geese facilitate opportunities for both predation as well as scavenging kills made by other predators (e.g., wolves, Canis lupus, [Brook and Richardson 2002]; grizzly bears, Ursus arctos, [Rockwell et al. DOI: 10.1007/s00300-013-1341-5. 'So much for honor': College boat party scares locals On top of that, the misrepresentation of the sea ice breakup phenomenon in Hudson Bay is more than disappointing — with misinformation like this, it’s no wonder the public gets confused. Journal of Animal Ecology 82: 912-921. obs.). Polar bear, great white northern bear found throughout the Arctic region. Unlike other bear species, polar bears do not eat plants—probably not in a way other bears do. The increased co‐occurrence of polar bears and the now plentiful caribou and snow geese facilitate opportunities for both predation as well as scavenging of kills made by other predators (e.g., wolves, Canis lupus, [Brook and Richardson 2002]; grizzly bears, Ursus arctos, [Rockwell et al. DOI: 10.1002/ece3.740. Abstract (provisional) We characterized the current terrestrial diet of polar bears in western Hudson Bay by evaluating the contents of passively sampled scat and comparing it to a similar study conducted 40 years ago. Although polar bears (Ursus maritimus) are specialist predators of seal pups on the Arctic ice pack, the use of terrestrial food sources during the ice-free period has received increased attention in recent years in light of climate predictions. Polar bears especially like to feed on arctic charr. Further, consuming high rates of certain vegetation and land-based animals that may yield immediate energetic gains could, instead, provide other benefits such as fulfilling vitamin/mineral requirements, diluting toxins and assessing new foods for potential switching. In the text of the article, the authors do not even cite a reference to support this mis-characterization of sea ice breakup as a spring event: on pg 3516 they state: “If the trend in earlier spring breakup in Hudson Bay continues, polar bears will spend more time on shore during the summer…“. The caribou (Rangifer tarandus caribou) is a large North American animal. As the ice disappears, so do the crucial platforms that polar bears use to hunt seals, Stirling says. description. and Rockwell, R.F. The reason behind this behavioral shift is not known. How do polar bears survive their Arctic habitat? The food habits of polar bears of James Bay and southwest Hudson Bay in summer and autumn. The scientists at the American Museum of Natural History suggest that polar bears seem to be increasingly rely on caribou in the past 40 years. However, the AMNH press release fails to mention – as the papers it publicizes certainly do – that Western Hudson Bay populations of caribou and snow geese have increased exponentially since a similar polar bear diet study was done in 1968/69. However, it has not been demonstrated that consumption of any of these terrestrial foods assists in polar bear survival. Arctic hares are eaten by brown bears, kittiwakes, and snowy owls. Foraging and Eating. As it turns out the warmer months stay longer than before. Asked by Wiki User. In the summer they the will eat leaves of willows, sedges, flowering tundra plants, and mushrooms. Musk oxes are eaten by arctic wolves. And everything we can see from what bears eat when they are on land is it has a very, very minimal energetic return relative to the cost.” [my bold]. The two bears were reunited after three years. Russell, R.H. 1975. In other words, there were hardly any caribou or geese around back in the late 60s — little wonder polar bears weren’t eating any. They compared their results to a previous scat study done in 1968 and 1969 by Richard Russell (Russell 1975). Just how many penguins do polar bears eat? The polar bear is a species of bear which lives around the Arctic circle. The bears have also taken advantage of a caribou bonanza: Surveys in the research area in the 1960s found about 100 caribou, whereas nowadays there are between 3,000 and 5,000 Gormezano said. [FYI, I’ve done lots of this kind of scat work myself — not for polar bears, but for seals, sea lions and river otters — so I know what it entails]. 2013b. Despite what the press release implies, they found that the consumption of geese and caribou was pretty minimal relative to other terrestrial foods consumed in summer and fall while on shore: marine algae and Lyme grass were the most frequently consumed items (Gormezano and Rockwell, 2013b). The claim that the recent consumption of caribou, snow goose and other items by polar bears could be an adaptive response to “nutritional stress” [another way of suggesting that “polar bears are starving“], caused by reduced sea ice in spring, is not supported by their data. tundra. Polar bears largely eat ringed and bearded seals, but depending upon their location, they may eat harp, hooded and ribbon seal. “The question is: Does is it do them any good? Larger land mammals such as caribou and muskox are difficult to catch, as polar bears overheat quickly due to their thick coats, but they stand a better chance when targeting a young or sickly animal. Background Credit: Copyright American Museum of Natural History/R. and sparse groups of <50 animals were counted further south (Abraham and Thompson 1998). 2011), with the highest increase and geographic expansion being on the Cape Churchill Peninsula (Rockwell et al. The caribou’s range extends to Alaska where it meets apex predators of the Arctic Ocean. Newborn polar bears eat much less and would be able to eat about 1 kilo a day. 2013) and for the last few years breakup has occurred in July. [my bold], As pointed out above, sea ice breakup in Hudson Bay is not a spring phenomenon — breakup occurs from early to mid-summer, and the timing of it has varied widely in recent years. Our results suggest that polar bears are foraging opportunistically in a manner consistent with maximizing intake while minimizing energy expenditure associated with movement. | Polar Bear Diet & Eating Habits, Largest Polar Bear on Record –Biggest Polar Bear Ever, Polar Bear vs Tiger – Siberian Tiger vs Polar Bear, How Many Claws Does a Polar Bear have? Many researchers (in fact, the leading authorities in the field) are extremely concerned that adaptive behaviors and alternative food sources will not sustain polar bears in their present size or number. Aside from humans, the only threat to polar bears are other polar bears. Polar bear feeding on a caribou carcass, taken July 26, 2010, from the air. We evaluated patterns in the composition of foods in scat to characterize the foraging behaviors that underpin the diet mixing and omnivory observed in polar bears on land in western Hudson Bay. I have to agree with this part of what Andrew Derocher had to say to NBC News reporter John Roach (“As Arctic ice melts, polar bears switch diets to survive, studies say“ January 24, 2014): “Polar bears will eat anything,” he told NBC News. 1. above], Polar bears seem to have taken advantage of the substantial increase in availability of both caribou and snow geese (Table 1). Unlike the case for plants, no spatial patterns were found for animal remains, likely due the animals’ more vagile and ubiquitous distribution. Some prefer den polar bears, instead of bears caught in the open, because they taste better. Is climate change affecting their population? Media outlets that quoted the press release verbatim, as many do these days (e.g. They can grow anywhere from 8 feet to 11 feet in height and about 8 feet in length. Is this just sloppy writing or deliberate misinformation? However, the AMNH press release fails to mention – as the papers it publicizes certainly do – that Western Hudson Bay populations of caribou and snow geese have increased exponentially since a similar polar bear diet study was done in 1968/69.In other words, there were hardly any caribou or geese around back in the late 60s — little wonder polar bears weren’t eating any. Polar bears weigh about 500 to 1,700 pounds, and they live the cold Arctic —in parts of Alaska, Canada, Denmark/Greenland, Norway, and Russia. The scientists at the American Museum of Natural History suggest that polar bears seem to be increasingly rely on caribou in the past 40 years. This is quite unusual in Ursus maritimus for they had never put so much effort in chasing down alternate prey (in the past). Larger land mammals such as caribou and muskox are difficult to catch, as polar bears overheat quickly due to their thick coats, but they stand a better chance when targeting a young or sickly animal. 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