The influence of climate variability on polar bear (Ursus maritimus) and ringed seal (Pusa hispida) population dynamics

2006 ◽  
Vol 84 (3) ◽  
pp. 357-364 ◽  
Author(s):  
A Rosing-Asvid
Keyword(s):  
Polar Bear ◽  
Ursus Maritimus ◽  
Early Spring ◽  
Ringed Seal ◽  
Polar Bears ◽  
Lactation Period ◽  
Long Time ◽  
Pusa Hispida ◽  
By Catch ◽  
Catch Statistics

Unusually high polar bear (Ursus maritimus Phipps, 1774) predation on ringed seal (Pusa hispida (Schreber, 1775)) pups and increased survival of polar bear cubs during mild springs is documented in published articles. Strong predation on newborn ringed seal pups in early spring, however, is likely to lower the overall energy intake of polar bears if ringed seal pups are their main food, because the energetic value of ringed seal pups increases 7–8 times during the 6 week lactation period. So although hunting success in early spring increases cub survival during the period after den emergence,when they are most vulnerable, it is likely to increase the number of starving bears later in the season. This negative-feedback effect of strong spring predation will not occur in areas where other seal species are abundant during summer, and polar bears in such areas are likely to exhibit population growth during periods with milder springs, at least until the ringed seal population has been depleted. Long time series of population estimates that can be used to test this hypothesis do not exist, but it is strongly supported by catch statistics for polar bears and ringed seals from east Greenland.

The breeding habitat of the ringed seal (Phoca hispida). The birth lair and associated structures

1975 ◽  
Vol 53 (9) ◽  
pp. 1297-1305 ◽  
Author(s):  
Thomas G. Smith ◽  
Ian Stirling
Keyword(s):  
Ursus Maritimus ◽  
Ringed Seal ◽  
Breeding Habitat ◽  
Polar Bears ◽  
Alopex Lagopus ◽  
Phoca Hispida ◽  
Arctic Foxes ◽  
Different Types ◽  
Amundsen Gulf

The subnivean lairs of the ringed seal (Phoca hispida) were studied in the Amundsen Gulf and Prince Albert Sound areas from 1971 through 1974. The structure of several different types of lairs are described. The existence of a birth-lair complex consisting of several closely adjacent lairs appears likely. The spacial distribution of lairs and lair types found on refrozen leads and in pressure ridges is described. Lairs were more abundant in inshore ice than in offshore ice. The function of subnivean lairs appears to be to provide thermal shelter, especially for neonate seals, and protection from predation by arctic foxes (Alopex lagopus) and polar bears (Ursus maritimus).

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.

The caloric value of whole ringed seals (Phoca hispida) in relation to polar bear (Ursus maritimus) ecology and hunting behavior

1975 ◽  
Vol 53 (8) ◽  
pp. 1021-1027 ◽  
Author(s):  
Ian Stirling ◽  
Eoin H. McEwan
Keyword(s):  
Total Body Water ◽  
Polar Bear ◽  
Fat Body ◽  
Ursus Maritimus ◽  
Ringed Seal ◽  
Body Water ◽  
Phoca Hispida ◽  
Hunting Behavior ◽  
Wet Weight ◽  
Total Body

Throughout its circumpolar range, the polar bear (Ursus maritimus) feeds predominantly on the ringed seal (Phoca hispida). Despite seasonal variation in availability and distribution of seals, polar bears prefer to eat mainly the fat, often leaving substantial portions of seal meat and blubber. In the present study, 12 seals were minced and analyzed for water, fat, protein, and ash contents. The percentage composition varied from 23 to 58% protein, 34 to 76% fat, 2 to 5.5% ash, and 47.4 to 69.5% total body water. The caloric values varied from 2.3 to 5.3 kcal/g wet weight. Relationships between total body water and fat (%), body water (litres) and protein (kg) are presented. These results are discussed in relation to the ecology and hunting behavior of the polar bear.

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 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.

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.

Relationships between estimates of ringed seal (Phoca hispida) and polar bear (Ursus maritimus) populations in the Canadian Arctic

1995 ◽  
Vol 52 (12) ◽  
pp. 2594-2612 ◽  
Author(s):  
Ian Stirling ◽  
Nils Are Øritsland
Keyword(s):  
Metabolic Rate ◽  
Population Size ◽  
Polar Bear ◽  
Population Level ◽  
Ursus Maritimus ◽  
Polar Bears ◽  
Phoca Hispida ◽  
Ringed Seals ◽  
Reproductive Rates ◽  
The Relationship

Analysis of estimates of population size of ringed s,eals (Phoca hispida) and polar bears (Ursus maritimus) from several areas indicated that estimates of one predicted the range of expected population size of the other in areas where ringed seals constitute the primary prey. In some areas, the closeness of this relationship indicates where estimates of either seals or bears may be inaccurate. The number of seals required to support a population of polar bears of predetermined size was estimated independently using both behavioral and energetic data. Behavioral estimates of the number of seals killed may overestimate energetic requirements and vice versa. Predation and energy matrices indicated that high levels of predation on seals are sustainable only if most animals killed are young-of-the-year. The field metabolic rate of the polar bear appears to be about twice the basal metabolic rate. Densities of seals vary in response to overall productivity of the ecosystem in different areas, and fluctuations in their numbers and reproductive rates between years can be used to monitor changes in productivity of the ecosystem. These changes also cause variation in productivity of bears, which indicates the sensitivity, at the population level, of the relationship between ringed seals and polar bears.

Monitoring of helminthiasis of the polar bear (Ursus maritimus) in the wild and zoos of Russia

2021 ◽  
Vol 1 (4) ◽  
pp. 63-66
Author(s):  
N. V. Esaulova ◽  
◽  
S. V. Naydenko ◽  
O. G. Rudakova ◽  
◽  
...  
Keyword(s):  
Polar Bear ◽  
Wild Population ◽  
Ursus Maritimus ◽  
Polar Bears ◽  
Fecal Samples ◽  
Helminth Eggs ◽  
Franz Josef Land ◽  
In The Wild ◽  
Invasion Analysis ◽  
Baylisascaris Transfuga

The article provides information on monitoring studies of polar bear helminthiasis in the wild population of Franz Josef Land and in zoos in Russia. Wild bears were found to be free from invasion. Analysis of fecal samples from polar bears from 17 zoos showed that the total extensiveness of the invasion was 21%, 2 types of helminths were identified: Baylisascaris transfuga and Diphyllobothrium sp. Samples with helminth eggs were found in zoos in Nizhny Novgorod, Rostov-on-Don, Penza, Udmurtia, Khabarovsk, Novosibirsk, Kazan, Krasnoyarsk, Moscow, Volokolamsk, Seversk, Perm.

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