scholarly journals Polar bear (Ursus maritimus) use of the Cape Bathurst polynya and flaw lead

2021 ◽  
Author(s):  
Erin M. Henderson ◽  
Andrew E. Derocher
Keyword(s):  
Polar Bear ◽  
Step Length ◽  
Ursus Maritimus ◽  
Polar Bears ◽  
Long Distance ◽  
Subadult Male ◽  
Male And Female ◽  
Habitat Features ◽  
Adult Females ◽  
Pack Ice

The Cape Bathurst polynya and flaw lead (CBP) are major, predictable habitat features with ≤15% ice cover in an otherwise ice-covered Beaufort Sea, and thought to provide hunting opportunities for polar bears (Ursus maritimus Phipps, 1774). We assessed 78 adult (female; with and without cubs) and subadult (male and female) polar bears’ use of the CBP from October – June, 2007–2014. The CBP was up to 725 km wide in autumn, ice-covered in winter, and <306 km wide in spring. Seventy-nine percent (n = 62) of the bears used the CBP (≥1 location <2.4 km, or one 4 h step length, from the CBP). Use was higher for solitary adult females and subadult males, which travelled faster with low turning angles along wider sections than females with offspring and subadult females. Bears were closest to the CBP during the spring hyperphagia season. While a wider CBP did not prevent crossing, bears primarily crossed from the coast towards pack ice at locations 53% narrower than areas not crossed. Bears might avoid crossing when it would require a long-distance swim. The CBP affects polar bear ecology by providing hunting habitat and a corridor that could increase prey encounters but may affect movement.

scholarly journals Predation of Harp Seals, Pagophilus groenlandicus, by Polar Bears, Ursus maritimus, in Svalbard

ARCTIC ◽  
2019 ◽  
Vol 72 (2) ◽  
pp. 197-202 ◽  
Author(s):  
Thomas G. Smith ◽  
Ian Stirling
Keyword(s):  
Sea Ice ◽  
Polar Bear ◽  
Barents Sea ◽  
Population Level ◽  
Open Water ◽  
Ursus Maritimus ◽  
Polar Bears ◽  
Pagophilus Groenlandicus ◽  
Large Numbers ◽  
Pack Ice

Harp seals (Pagophilus groenlandicus) that breed in February and March in the White Sea migrate to open water around Svalbard and Franz Josef Land in the Barents Sea, feeding pelagically while following the receding ice edge northward to the edge of the polar pack. Although harp seals are present throughout the area during the summer, they are primarily pelagic and do not appear to be extensively preyed upon by polar bears (Ursus maritimus). However, occasionally, large numbers of harp seals may haul out and rest on the pack ice or feed in the water below the ice and surface to breathe between the floes. When approached by a polar bear while on the ice, harp seals do not exhibit the instant flight response characteristic of the polar bear’s primary prey species, ringed (Pusa hispida) and bearded seals (Erignathus barbatus). In this situation, polar bears may make multiple kills without either consuming their own prey or scavenging seals killed by other bears. This behavior appears not to frighten other nearby harp seals, whether hauled out on the ice or in the water below the floes. These unusual concentrations of harp seals hauled out on sea ice may be related to the distribution and abundance of fish or other epontic prey. Their lack of an escape response to predators on the surface of the sea ice is probably a result of briefly hauling out in large numbers in spring while whelping on the sea ice in areas where the consequences of potential polar bear predation are insignificant. The rare events of harp seal mortality from bears killing them on the surface of pack ice during the summer do not appear to have a significant impact at the population level of either species.

scholarly journals Iñupiaq Knowledge of Polar Bears (Ursus maritimus) in the Southern Beaufort Sea, Alaska

ARCTIC ◽  
2021 ◽  
Vol 74 (3) ◽  
pp. 239-257
Author(s):  
Karyn D. Rode ◽  
Hannah Voorhees ◽  
Henry P. Huntington ◽  
George M. Durner
Keyword(s):  
Sea Ice ◽  
Polar Bear ◽  
Late Summer ◽  
Beaufort Sea ◽  
Ursus Maritimus ◽  
The Arctic ◽  
Polar Bears ◽  
Structured Interviews ◽  
Ice Breakup ◽  
Pack Ice

Successful wildlife management depends upon coordination and consultation with local communities. However, much of the research used to inform management is often derived solely from data collected directly from wildlife. Indigenous people living in the Arctic have a close connection to their environment, which provides unique opportunities to observe their environment and the ecology of Arctic species. Further, most northern Arctic communities occur within the range of polar bears (nanuq, Ursus maritimus) and have experienced significant climatic changes. Here, we used semi-structured interviews from 2017 to 2019 to document Iñupiaq knowledge of polar bears observed over four decades in four Alaskan communities in the range of the Southern Beaufort Sea polar bear subpopulation: Wainwright, Utqiaġvik, Nuiqsut, and Kaktovik. All but one of 47 participants described directional and notable changes in sea ice, including earlier ice breakup, later ice return, thinner ice, and less multiyear pack ice. These changes corresponded with observations of bears spending more time on land during the late summer and early fall in recent decades—observations consistent with scientific and Indigenous knowledge studies in Alaska, Canada, and Greenland. Participants noted that polar bear and seal body condition and local abundance either varied geographically or exhibited no patterns. However, participants described a recent phenomenon of bears being exhausted and lethargic when arriving on shore in the summer and fall after extensive swims from the pack ice. Further, several participants suggested that maternal denning is occurring more often on land than sea ice. Participants indicated that village and regional governments are increasingly challenged to obtain resources needed to keep their communities safe as polar bears spend more time on land, an issue that is likely to be exacerbated both in this region and elsewhere as sea ice loss continues. 

scholarly journals Long-distance swimming by polar bears (Ursus maritimus) of the southern Beaufort Sea during years of extensive open water

2012 ◽  
Vol 90 (5) ◽  
pp. 663-676 ◽  
Author(s):  
A.M. Pagano ◽  
G.M. Durner ◽  
S.C. Amstrup ◽  
K.S. Simac ◽  
G.S. York
Keyword(s):  
Sea Ice ◽  
Adult Female ◽  
Open Water ◽  
Ursus Maritimus ◽  
Polar Bears ◽  
Long Distance ◽  
Gps Collars ◽  
Movement Data ◽  
Global Positioning ◽  
Ice Conditions

Polar bears ( Ursus maritimus Phipps, 1774) depend on sea ice for catching marine mammal prey. Recent sea-ice declines have been linked to reductions in body condition, survival, and population size. Reduced foraging opportunity is hypothesized to be the primary cause of sea-ice-linked declines, but the costs of travel through a deteriorated sea-ice environment also may be a factor. We used movement data from 52 adult female polar bears wearing Global Positioning System (GPS) collars, including some with dependent young, to document long-distance swimming (>50 km) by polar bears in the southern Beaufort and Chukchi seas. During 6 years (2004–2009), we identified 50 long-distance swims by 20 bears. Swim duration and distance ranged from 0.7 to 9.7 days (mean = 3.4 days) and 53.7 to 687.1 km (mean = 154.2 km), respectively. Frequency of swimming appeared to increase over the course of the study. We show that adult female polar bears and their cubs are capable of swimming long distances during periods when extensive areas of open water are present. However, long-distance swimming appears to have higher energetic demands than moving over sea ice. Our observations suggest long-distance swimming is a behavioral response to declining summer sea-ice conditions.

Research and management of polar bears Ursus maritimus

Polar Record ◽  
1986 ◽  
Vol 23 (143) ◽  
pp. 167-176 ◽  
Author(s):  
Ian Stirling
Keyword(s):  
Natural Resources ◽  
Polar Bear ◽  
World Wide ◽  
Ursus Maritimus ◽  
Polar Bears ◽  
International Agreement ◽  
International Union ◽  
International Coordination ◽  
The 1950S ◽  
Circumpolar Arctic

AbstractThrough the 1950s and 1960s there was a marked increase in recorded numbers of polar bears being killed for their hides, giving rise to world-wide concern that the species might be endangered. At a meeting in Fairbanks, Alaska 1965, representatives of circumpolar arctic nations discussed conservation of polar bears and concluded that international coordination of research and management efforts was essential. Subsequent meetings of scientists engaged in polar bear research were organized every two years by the International Union for the Conservation of Nature and Natural Resources, facilitating exchanges of views and cooperation; as a result, in 1973 the International Agreement on the Conservation of Polar Bears and their Habitats was signed in Oslo, Norway. This paper describes some of the research and management undertaken in the years leading up to the agreement, and initiatives that are continuing because of it.

Consequences of long-distance swimming and travel over deep-water pack ice for a female polar bear during a year of extreme sea ice retreat

Polar Biology ◽  
2011 ◽  
Vol 34 (7) ◽  
pp. 975-984 ◽  
Author(s):  
George M. Durner ◽  
John P. Whiteman ◽  
Henry J. Harlow ◽  
Steven C. Amstrup ◽  
Eric V. Regehr ◽  
...  
Keyword(s):  
Sea Ice ◽  
Deep Water ◽  
Polar Bear ◽  
Long Distance ◽  
Pack Ice ◽  
Ice Retreat ◽  
Female Polar Bear ◽  
Sea Ice Retreat

Trichinella and polar bears: a limited risk for humans

2017 ◽  
Vol 91 (4) ◽  
pp. 440-446 ◽  
Author(s):  
J. Dupouy-Camet ◽  
P. Bourée ◽  
H. Yera
Keyword(s):  
World War Ii ◽  
Polar Bear ◽  
Ursus Maritimus ◽  
The Arctic ◽  
Polar Bears ◽  
World War ◽  
Protected Species ◽  
Brown Bears ◽  
Limited Access ◽  
Human Trichinellosis

AbstractIn this review, we identified 63 cases reported since World War II of human trichinellosis linked to the consumption of parasitized polar bear (Ursus maritimus) meat. This low number contrasts to the numerous cases of human trichinellosis related to consumption of the meat of black (U. americanus) or brown bears (U. arctos). The prevalence of Trichinella infection is high in bears, but larval muscular burden is usually lower in polar bears compared to other bear species. Polar bears, therefore, seem to play a limited role in the transmission of trichinellosis to humans, as native residents living in the Arctic traditionally consume well-cooked bear meat, and travellers and foreign hunters have only limited access to this protected species due to the declining polar bear population.

An observation of possible cannibalism by polar bears (Ursus maritimus)

1985 ◽  
Vol 63 (6) ◽  
pp. 1516-1517 ◽  
Author(s):  
N. J. Lunn ◽  
G. B. Stenhouse
Keyword(s):  
Adult Female ◽  
Adult Male ◽  
Physical Condition ◽  
Polar Bear ◽  
Ursus Maritimus ◽  
Polar Bears ◽  
Ecological Significance ◽  
Natural Conditions ◽  
Old Adult

We observed a case of cannibalism by a 23-year-old adult male polar bear in very poor physical condition on Southampton Island, N.W.T. It had apparently killed an adult female and was feeding on the carcass. Cannibalism among polar bears does occur under natural conditions. It is difficult to document how often this occurs and of what ecological significance it might be.

scholarly journals Long-Distance Movement of a Female Polar Bear from Canada to Russia

ARCTIC ◽  
2017 ◽  
Vol 70 (2) ◽  
pp. 121 ◽  
Author(s):  
Amy C. Johnson ◽  
Jodie D. Pongracz ◽  
Andrew E. Derocher
Keyword(s):  
Home Range ◽  
Sea Ice ◽  
Polar Bear ◽  
Brownian Bridge ◽  
Polar Bears ◽  
Minimum Convex Polygon ◽  
Long Distance ◽  
Movement Model ◽  
Female Polar Bear ◽  
Long Distance Movement

Polar bears (Ursus maritimus) display fidelity to large geographic regions, and their movements are influenced by sea ice distribution. Polar bear subpopulations are moderately distinct from one another, and long-distance movements between subpopulations are rare. We describe and analyze the movements of a female polar bear tracked by satellite telemetry from spring 2009 for 798 days. This female traveled an exceptionally long distance (totaling 11 686 km) from the sea ice off the Yukon Territory, Canada (Southern Beaufort Sea subpopulation) to Wrangel Island, Russia (Chukchi Sea subpopulation). In comparison to other polar bears in this study, this bear traveled farther, moved faster, and had a much larger home range in the first year. Furthermore, the calculation of the home range size by two different methods demonstrated that the commonly used minimum convex polygon method overestimated the home range compared to the less biased Brownian bridge movement model. This female’s long-distance movement was unusual and provides additional evidence for gene flow between subpopulations. Monitoring polar bear movements is useful to track such events, which is especially important at present because sea ice loss due to climate change can affect subpopulation boundaries and influence management.

scholarly journals Testing the hypothesis that routine sea ice coverage of 3-5 mkm2 results in a greater than 30% decline in population size of polar bears (Ursus maritimus)

2017 ◽  
Author(s):  
Susan J Crockford
Keyword(s):  
Sea Ice ◽  
Population Size ◽  
Habitat Loss ◽  
Polar Bear ◽  
Population Decline ◽  
Ursus Maritimus ◽  
The Arctic ◽  
Polar Bears ◽  
Population Declines ◽  
Sea Ice Decline

The polar bear (Ursus maritimus) was the first species to be classified as threatened with extinction based on predictions of future conditions rather than current status. These predictions were made using expert-opinion forecasts of population declines linked to modeled habitat loss – first by the International Union for the Conservation of Nature (IUCN)’s Red List in 2006, and then by the United States Fish and Wildlife Service (USFWS) in 2008 under the Endangered Species Act (ESA), based on data collected to 2005 and 2006, respectively. Both assessments predicted significant population declines of polar bears would result by mid-century as a consequence of summer sea ice extent rapidly reaching 3-5 mkm2 on a regular basis: the IUCN predicted a >30% decline in total population, while the USFWS predicted the global population would decline by 67% (including total extirpation of ten subpopulations within two vulnerable ecoregions). Biologists involved in these conservation assessments had to make several critical assumptions about how polar bears might be affected by future habitat loss, since sea ice conditions predicted to occur by 2050 had not occurred prior to 2006. However, summer sea ice declines have been much faster than expected: low ice levels not expected until mid-century (about 3-5 mkm2) have occurred regularly since 2007. Realization of predicted sea ice levels allows the ‘rapid sea ice decline = population decline’ assumption for polar bears to be treated as a testable hypothesis. Data collected between 2007 and 2015 reveal that polar bear numbers have not declined as predicted and no subpopulation has been extirpated. Several subpopulations expected to be at high risk of decline remained stable and five showed increases in population size. Another at-risk subpopulation was not counted but showed marked improvement in reproductive parameters and body condition with less summer ice. As a consequence, the hypothesis that repeated summer sea ice levels of below 5 mkm2 will cause significant population declines in polar bears is rejected, a result that indicates the ESA and IUCN judgments to list polar bears as threatened based on future risks of habitat loss were scientifically unfounded and that similar predictions for Arctic seals and walrus may be likewise flawed. The lack of a demonstrable ‘rapid sea ice decline = population decline’ relationship for polar bears also potentially invalidates updated survival model outputs that predict catastrophic population declines should the Arctic become ice-free in summer.

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