Polar bears observed climbing steep slopes to graze on scurvy grass in Svalbard

Stempniewicz, Lech

doi:10.1080/17518369.2017.1326453

Cited by 7 publications

(5 citation statements)

References 34 publications

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“…Sometimes, they catch birds at sea by attacking them from below the water or chasing them across the water (Stempniewicz 2006;Stempniewicz et al 2014). Polar bears also eat marine and terrestrial plants (Russell 1975;Gormezano and Rockwell 2013;Stempniewicz 2017).…”

Section: Introductionmentioning

confidence: 99%

Yes, they can: polar bears Ursus maritimus successfully hunt Svalbard reindeer Rangifer tarandus platyrhynchus

2021

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The polar bear Ursus maritimus is one of the species most endangered by the rapidly declining sea–ice cover in the Arctic, which they use as a platform to hunt fatty, high-energy seals. In recent decades, more polar bears have been forced to remain longer on land, so their access to seals is limited. The importance of terrestrial food to polar bears is disputable, and more data are needed. Terrestrial ungulates could be an attractive substitute prey for them. Svalbard reindeer Rangifer tarandus platyrhynchus are prevalent and their distribution is completely within the range of polar bears. They constitute an attractive potential prey offering a significant energy return. Pre-2000 sources state that polar bears do not attack Svalbard reindeer. This report is the first description and documentation of the complete course of a polar bear hunt for adult reindeer in Hornsund, SW Spitsbergen, and also of the bear’s hunting behaviour and the reindeer’s response. Further, we report several other recent instances of bear–reindeer interactions in Svalbard, suggesting that polar bears now hunt reindeer more frequently than they used to. This increase in hunting is probably linked to the reduced ice cover, with bears spending more time on land, and a growing reindeer population. This study adds to earlier papers on how polar bears in Svalbard have increasingly shifted to a more terrestrial diet, and indicates that they may have an enhanced role as an apex predator in the terrestrial ecosystem.

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Section: Introductionmentioning

confidence: 99%

Yes, they can: polar bears Ursus maritimus successfully hunt Svalbard reindeer Rangifer tarandus platyrhynchus

2021

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“…For some bears, bearded seals Eri gnathus barbatus may also be im portant in summer (Derocher et al 2002, Iversen et al 2013, as they may often rest on pieces of glacier ice, or even on land, thus being more accessible than ringed seals Phoca hispida in the periods with little or no sea ice. However, due to longer ice-free periods, the importance of land-based prey items has increased in the diet of Barents Sea polar bears (Gormezano & Rockwell 2013, Herreman & Peacock 2013, Iversen et al 2013, Prop et al 2015, Tartu et al 2016, Stempniewicz 2017.…”

Section: Discussionmentioning

confidence: 99%

“…It is a highly variable and productive environment subject to extreme oscillations in ice cover, fresh water inflow and surface salinity (Falk-Petersen et al 1998). In the Svalbard region, individual space-use strategies have been stable through years, and the number of coastal bears (close to 300) did not change significantly from autumn 2004 to autumn 2015 (Aars et al 2017, Tartu et al 2018 despite the profound changes in sea ice availability in much of the region that occurred in 2007(Hamilton et al 2015. This suggests that these strategies correspond to 2 stable ecotypes and is supported by DNA sampling and mark−recapture analysis (Aars et al 2017).…”

Section: Introductionmentioning

confidence: 99%

Space-use strategy affects energy requirements in Barents Sea polar bears

Blanchet

Aars

Andersen

et al. 2020

Mar. Ecol. Prog. Ser.

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Polar bears Ursus maritimus are currently facing rapid environmental changes with loss of sea ice and shifts in their prey distribution. Two distinct ecotypes exist in the Barents Sea, where sea ice is decreasing at the highest rate in the Arctic. Coastal bears remain within the Archipelago of Svalbard year-round, whereas offshore bears follow the marginal ice zone (MIZ). We explored these 2 ecotypes’ habitat use, activity and energy needs as well as seasonal variation within these parameters. During the period from 2011-2018, adult female polar bears were equipped with GPS collars and activity sensors (n = 84); 46 of these were equipped with conductivity switches to record aquatic behaviour. Offshore bears travelled longer distances at a higher speed on land and at sea away from land and had a higher activity rate compared to coastal bears. This translated into higher overall energy expenditure. Offshore bears also undertook more distant and energetically costly trips from land to the MIZ, swimming in open water. Both ecotypes showed similar seasonal patterns of activity and movement consistent with their life history linked to sea ice phenology. Despite higher energy expenditure, the offshore strategy seemed to be as profitable as the coastal one as females had marginally better spring body condition, likely due to their specialized high caloric diet of seals throughout the year. However, both ecotypes are currently experiencing habitat changes. Future studies should aim to predict how rapidly declining sea ice in the Barents Sea may challenge polar bears energetically during the coming decades.

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“…Nevertheless, the increasing length of time polar bears spend on land [31,32], coupled with the extent to which they are witnessed feeding on terrestrial diet items (e.g. [26,27,[33][34][35]), necessitates examining their foraging performance (i.e. decision-making heuristics) as efforts to conserve this species have become an international priority [36].…”

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confidence: 99%

“…Understanding polar bears' foraging performance in terrestrial environments is especially important given that terrestrial resources may require different foraging tactics (e.g. climbing cliffs [34]; grazing [35] and chasing prey [37]), and a different suite of environmental stimuli (hereafter 'cues') than what polar bears use to catch seals on the sea-ice [38], potentially affecting their ability to maximize energetic returns. Specifically, reports of polar bears foraging on eggs in avian colonies have increased in recent years as changes in sea-ice phenology have now temporally aligned the onshore arrival of bears to the breeding schedule of birds, in some areas of the Arctic [34,[39][40][41][42][43].…”

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Polar bears are inefficient predators of seabird eggs

et al. 2021

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Climate-mediated sea-ice loss is disrupting the foraging ecology of polar bears ( Ursus maritimus ) across much of their range. As a result, there have been increased reports of polar bears foraging on seabird eggs across parts of their range. Given that polar bears have evolved to hunt seals on ice, they may not be efficient predators of seabird eggs. We investigated polar bears' foraging performance on common eider ( Somateria mollissima ) eggs on Mitivik Island, Nunavut, Canada to test whether bear decision-making heuristics are consistent with expectations of optimal foraging theory. Using aerial-drones, we recorded multiple foraging bouts over 11 days, and found that as clutches were depleted to completion, bears did not exhibit foraging behaviours matched to resource density. As the season progressed, bears visited fewer nests overall, but marginally increased their visitation to nests that were already empty. Bears did not display different movement modes related to nest density, but became less selective in their choice of clutches to consume. Lastly, bears that capitalized on visual cues of flushing eider hens significantly increased the number of clutches they consumed; however, they did not use this strategy consistently or universally. The foraging behaviours exhibited by polar bears in this study suggest they are inefficient predators of seabird eggs, particularly in the context of matching behaviours to resource density.

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Polar bears observed climbing steep slopes to graze on scurvy grass in Svalbard

Cited by 7 publications

References 34 publications

Yes, they can: polar bears Ursus maritimus successfully hunt Svalbard reindeer Rangifer tarandus platyrhynchus

Yes, they can: polar bears Ursus maritimus successfully hunt Svalbard reindeer Rangifer tarandus platyrhynchus

Space-use strategy affects energy requirements in Barents Sea polar bears

Polar bears are inefficient predators of seabird eggs

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