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Andrew E. Derocher - One of the best experts on this subject based on the ideXlab platform.
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the stress of arctic warming on Polar Bears
Global Change Biology, 2020Co-Authors: Rudy Boonstra, Andrew E. Derocher, Evan S. Richardson, Nicholas J. Lunn, Korryn Bodner, Curtis O Bosson, Brendan Delehanty, Peter K MolnarAbstract:Arctic ecosystems are changing rapidly in response to climate warming. While Arctic mammals are highly evolved to these extreme environments, particularly with respect to their stress axis, some species may have limited capacity to adapt to this change. We examined changes in key components of the stress axis (cortisol and its carrier protein-corticosteroid binding globulin [CBG]) in Polar Bears (Ursus maritimus) from western Hudson Bay (N = 300) over a 33 year period (1983-2015) during which time the ice-free period was increasing. Changing sea ice phenology limits spring hunting opportunities and extends the period of onshore fasting. We assessed the response of Polar Bears to a standardized stressor (helicopter pursuit, darting, and immobilization) during their onshore fasting period (late summer-autumn) and quantified the serum levels of the maximum corticosteroid binding capacity (MCBC) of CBG, the serum protein that binds cortisol strongly, and free cortisol (FC). We quantified bear condition (age, sex, female with cubs or not, fat condition), sea ice (breakup in spring-summer, 1 year lagged freeze-up in autumn), and duration of fasting until sample collection as well as cumulative impacts of the latter environmental traits from the previous year. Data were separated into "good" years (1983-1990) when conditions were thought to be optimal and "poor" years (1991-2015) when sea ice conditions deteriorated and fasting on land was extended. MCBC explained 39.4% of the variation in the good years, but only 28.1% in the poor ones, using both biological and environmental variables. MCBC levels decreased with age. Changes in FC were complex, but more poorly explained. Counterintuitively, MCBC levels increased with increased time onshore, 1 year lag effects, and in poor ice years. We conclude that MCBC is a biomarker of stress in Polar Bears and that the changes we document are a consequence of climate warming.
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Variation in habitat use of Beaufort Sea Polar Bears
Polar Biology, 2020Co-Authors: Amy C. Johnson, Andrew E. DerocherAbstract:Habitat loss and climate change are major processes affecting biodiversity, especially in the Arctic which is experiencing rapid sea ice decline. Loss of sea ice habitat for ice-dependent species such as Polar Bears ( Ursus maritimus ) has been associated with declines in body condition, reproductive output, survival, and abundance. Monitoring habitat use can therefore provide insights into population responses to sea ice loss, especially for vulnerable demographic groups such as subadults. Here, we used resource selection functions to examine habitat selection patterns of subadult male and female ( n = 21) and adult female ( n = 37) Polar Bears in the Southern Beaufort Sea population from 2007 to 2011. We found that Polar Bears displayed broad similarities in seasonal habitat selection by using nearshore areas in winter/spring and ranging farther offshore into the multiyear ice in summer/autumn. However, there were differences in habitat use among age, sex, and reproductive classes. Adult females with cubs-of-the-year differed the most among classes and selected landfast ice in spring, allowing them to hunt for seal birth lairs while reducing risk of intra-specific predation. Adult females with older cubs and solitary adult females used active sea ice, which allowed them to hunt adult seals, while subadult females used a mix of active and landfast ice. Subadult males had similar selection for landfast ice as females with cubs-of-the-year, potentially as a mechanism to reduce intra-specific competition and/or kleptoparasitism. The Arctic faces continued warming and understanding variation in habitat use patterns can assist in identifying which Bears are most vulnerable to loss of different sea ice habitats.
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Behaviour and characteristics of mating Polar Bears (Ursus maritimus) in the Beaufort Sea, Canada
Polar Biology, 2019Co-Authors: B. A. Biddlecombe, Andrew E. Derocher, E. S. Richardson, I. StirlingAbstract:The dynamic sea ice habitat of Polar Bears ( Ursus maritimus ) influences their mating behaviour because it makes the distribution of mates unpredictable. Pronounced sexual dimorphism of Polar Bears likely results from a polygynous mating system, where intrasexual competition between males influences reproductive access to females. We examine aspects of the mating behaviour of Polar Bears in the Beaufort Sea, Canada, from 1970 to 2014 based on 135 breeding pairs observed from March through May. Mean age of paired females and paired males was 9.7 and 11.5 years, respectively. Paired males were older (by 2.2 years) and had significantly higher mass (71 kg) than unpaired males suggesting a polygynous mating system in which larger, dominant, and potentially experienced males monopolise access to females. Our binomial logistic regression suggested age was the most important factor in predicting pairing in males, which can be explained by the correlation between age and body size. Paired females had significantly higher labial development than lone females, suggesting that labial swelling is heightened during mating. Taken together, these observed characteristics suggest a polygynous mating system in Polar Bears, providing further insight into potential mating system variation across their range.
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Mass Loss Rates of Fasting Polar Bears.
Physiological and biochemical zoology : PBZ, 2016Co-Authors: Nicholas W. Pilfold, Andrew E. Derocher, Ian Stirling, Daryll Hedman, Nicholas J. Lunn, Evan RichardsonAbstract:AbstractPolar Bears (Ursus maritimus) have adapted to an annual cyclic regime of feeding and fasting, which is extreme in seasonal sea ice regions of the Arctic. As a consequence of climate change, sea ice breakup has become earlier and the duration of the open-water period through which Polar Bears must rely on fat reserves has increased. To date, there is limited empirical data with which to evaluate the potential energetic capacity of Polar Bears to withstand longer fasts. We measured the incoming and outgoing mass of inactive Polar Bears (n = 142) that were temporarily detained by Manitoba Conservation and Water Stewardship during the open-water period near the town of Churchill, Manitoba, Canada, in 2009–2014. Polar Bears were given access to water but not food and held for a median length of 17 d. Median mass loss rates were 1.0 kg/d, while median mass-specific loss rates were 0.5%/d, similar to other species with high adiposity and prolonged fasting capacities. Mass loss by unfed captive adult male...
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home ranges in moving habitats Polar Bears and sea ice
Ecography, 2016Co-Authors: Mark A Lewis, Marie Augermethe, Andrew E. DerocherAbstract:Home range size estimates are often used to assess the amount of space required for animals to perform the activities essential for their survival and reproduction. However, in moving environments, traditional home range estimates may be ill suited to this task. In particular, traditional home range estimates are inaccurate representations of the space required by Polar Bears Ursus maritimus. The sea ice is the prime foraging platform of Polar Bears, and estimating the amount of ice encountered by Bears may provide a better approximation of space use. We develop a technique to make these estimates. Our results confirm that Polar Bears use more space than terrestrial carnivores to find the resources and conditions they require. We also show that the traditional geographic home range can underestimate both the movement of Bears and the amount of space encountered. Moreover, area of ice encountered increased with ice drift, indicating that Bears living on highly mobile ice might be exposed to higher energetic costs, and potentially larger energetic gains, than Bears inhabiting more stable ice. The methods and concepts presented here can serve as a foundation for new approaches to study the space use of the many species living in moving environments.
Ian Stirling - One of the best experts on this subject based on the ideXlab platform.
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Mass Loss Rates of Fasting Polar Bears.
Physiological and biochemical zoology : PBZ, 2016Co-Authors: Nicholas W. Pilfold, Andrew E. Derocher, Ian Stirling, Daryll Hedman, Nicholas J. Lunn, Evan RichardsonAbstract:AbstractPolar Bears (Ursus maritimus) have adapted to an annual cyclic regime of feeding and fasting, which is extreme in seasonal sea ice regions of the Arctic. As a consequence of climate change, sea ice breakup has become earlier and the duration of the open-water period through which Polar Bears must rely on fat reserves has increased. To date, there is limited empirical data with which to evaluate the potential energetic capacity of Polar Bears to withstand longer fasts. We measured the incoming and outgoing mass of inactive Polar Bears (n = 142) that were temporarily detained by Manitoba Conservation and Water Stewardship during the open-water period near the town of Churchill, Manitoba, Canada, in 2009–2014. Polar Bears were given access to water but not food and held for a median length of 17 d. Median mass loss rates were 1.0 kg/d, while median mass-specific loss rates were 0.5%/d, similar to other species with high adiposity and prolonged fasting capacities. Mass loss by unfed captive adult male...
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effects of climate warming on Polar Bears a review of the evidence
Global Change Biology, 2012Co-Authors: Ian Stirling, Andrew E. DerocherAbstract:Climate warming is causing unidirectional changes to annual patterns of sea ice distribution, structure, and freeze-up. We summarize evidence that documents how loss of sea ice, the primary habitat of Polar Bears (Ursus maritimus), negatively affects their long-term survival. To maintain viable subpopulations, Polar Bears depend on sea ice as a platform from which to hunt seals for long enough each year to accumulate sufficient energy (fat) to survive periods when seals are unavailable. Less time to access to prey, because of progressively earlier breakup in spring, when newly weaned ringed seal (Pusa hispida) young are available, results in longer periods of fasting, lower body condition, decreased access to denning areas, fewer and smaller cubs, lower survival of cubs as well as Bears of other age classes and, finally, subpopulation decline toward eventual extirpation. The chronology of climate-driven changes will vary between subpopulations, with quantifiable negative effects being documented first in the more southerly subpopulations, such as those in Hudson Bay or the southern Beaufort Sea. As the Bears' body condition declines, more seek alternate food resources so the frequency of conflicts between Bears and humans increases. In the most northerly areas, thick multiyear ice, through which little light penetrates to stimulate biological growth on the underside, will be replaced by annual ice, which facilitates greater productivity and may create habitat more favorable to Polar Bears over continental shelf areas in the short term. If the climate continues to warm and eliminate sea ice as predicted, Polar Bears will largely disappear from the southern portions of their range by mid-century. They may persist in the northern Canadian Arctic Islands and northern Greenland for the foreseeable future, but their long-term viability, with a much reduced global population size in a remnant of their former range, is uncertain.
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age and sex composition of seals killed by Polar Bears in the eastern beaufort sea
PLOS ONE, 2012Co-Authors: Nicholas W. Pilfold, Andrew E. Derocher, Ian Stirling, Evan Richardson, Dennis AndriashekAbstract:Background Polar Bears (Ursus maritimus) of the Beaufort Sea enter hyperphagia in spring and gain fat reserves to survive periods of low prey availability. We collected information on seals killed by Polar Bears (n = 650) and hunting attempts on ringed seal (Pusa hispida) lairs (n = 1396) observed from a helicopter during Polar bear mark-recapture studies in the eastern Beaufort Sea in spring in 1985–2011. We investigated how temporal shifts in ringed seal reproduction affect kill composition and the intraspecific vulnerabilities of ringed seals to Polar bear predation. Principal Findings Polar Bears primarily preyed on ringed seals (90.2%) while bearded seals (Erignathus barbatus) only comprised 9.8% of the kills, but 33% of the biomass. Adults comprised 43.6% (150/344) of the ringed seals killed, while their pups comprised 38.4% (132/344). Juvenile ringed seals were killed at the lowest proportion, comprising 18.0% (62/344) of the ringed seal kills. The proportion of ringed seal pups was highest between 2007–2011, in association with high ringed seal productivity. Half of the adult ringed seal kills were ≥21 years (60/121), and kill rates of adults increased following the peak of parturition. Determination of sex from DNA revealed that Polar Bears killed adult male and adult female ringed seals equally (0.50, n = 78). The number of hunting attempts at ringed seal subnivean lair sites was positively correlated with the number of pup kills (r2 = 0.30, P = 0.04), but was not correlated with the number of adult kills (P = 0.37). Conclusions/Significance Results are consistent with decadal trends in ringed seal productivity, with low numbers of pups killed by Polar Bears in spring in years of low pup productivity, and conversely when pup productivity was high. Vulnerability of adult ringed seals to predation increased in relation to reproductive activities and age, but not gender.
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Fasting physiology of Polar Bears in relation to environmental change and breeding behavior in the Beaufort Sea
Polar Biology, 2009Co-Authors: Seth G. Cherry, Andrew E. Derocher, Ian Stirling, Evan S. RichardsonAbstract:We examined the use of the ratio of serum urea to serum creatinine as a physiological biomarker of fasting to monitor temporal patterns in the feeding ecology of Polar Bears ( Ursus maritimus ). Blood was collected from 436 Polar Bears in the eastern Beaufort Sea during April and May of 1985–1986 and 2005–2006. The proportions of Polar Bears fasting were 9.6% in 1985, 10.5% in 1986, 21.4% in 2005, and 29.3% in 2006. We used stepwise logistic regression analysis to evaluate factors that could influence the binary response variable of fasting or not fasting. Significant predictor variables of fasting were: the 2005 and 2006 capture years, solitary adult male Bears, and adult male Bears that were accompanying an estrous female. The increased number of Polar Bears in a physiological fasting state from all sex, age, and reproductive classes in 2005 and 2006 corresponded with broad scale changes in Arctic sea ice composition, which may have affected prey availability. The higher proportion of adult males fasting from all years was attributed to spring breeding behavior.
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Quantitative Support for a Subjective Fatness Index for Immobilized Polar Bears
Journal of Wildlife Management, 2008Co-Authors: Ian Stirling, Gregory W Thiemann, Evan RichardsonAbstract:Adequate stores of body fat are essential for survival and reproduction of Polar Bears (Ursus maritimus). However, Polar bear body fat levels can be difficult to quantify in the field. For >30 years, biologists have subjectively estimated relative fatness of immobilized Polar Bears by assigning individuals a rating from 1 to 5, with 1 being leanest and 5 most obese. Although previous studies suggested this fatness index (FI) rating accurately reflects large-scale differences in body condition, its relationship to more quantitative measures of condition has not been explored. We compared the FI rating of individual Polar Bears in western Hudson Bay and the Beaufort Sea to 2 quantitative measures of body condition: the Quetelet Index (ratio of mass to length2) and the relative lipid content of adipose tissue. We found a significant relationship between FI rating and both Quetelet Index values and adipose lipid content. Our data demonstrate that the FI rating accurately reflects overall body condition, regardless of Polar bear age, sex, or nutritional phase. We suggest that continued field use of the FI rating could provide valuable information on ecological effects of large-scale environmental change on Polar bear populations.
Steven C. Amstrup - One of the best experts on this subject based on the ideXlab platform.
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can Polar Bears use terrestrial foods to offset lost ice based hunting opportunities
Frontiers in Ecology and the Environment, 2015Co-Authors: Karyn D. Rode, Charles T Robbins, Lynne Nelson, Steven C. AmstrupAbstract:Increased land use by Polar Bears (Ursus maritimus) due to climate-change-induced reduction of their sea-ice habitat illustrates the impact of climate change on species distributions and the difficulty of conserving a large, highly specialized carnivore in the face of this global threat. Some authors have suggested that terrestrial food consumption by Polar Bears will help them withstand sea-ice loss as they are forced to spend increasing amounts of time on land. Here, we evaluate the nutritional needs of Polar Bears as well as the physiological and environmental constraints that shape their use of terrestrial ecosystems. Only small numbers of Polar Bears have been documented consuming terrestrial foods even in modest quantities. Over much of the Polar bear's range, limited terrestrial food availability supports only low densities of much smaller, resident brown Bears (Ursus arctos), which use low-quality resources more efficiently and may compete with Polar Bears in these areas. Where consumption of terr...
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a bayesian network modeling approach to forecasting the 21st century worldwide status of Polar Bears
Geophysical monograph, 2013Co-Authors: Steven C. Amstrup, Bruce G Marcot, David C DouglasAbstract:To inform the U.S. Fish and Wildlife Service decision, whether or not to list Polar Bears as threatened under the Endangered Species Act (ESA), we projected the status of the world's Polar Bears (Ursus maritimus) for decades centered on future years 2025, 2050, 2075, and 2095. We defined four ecoregions based on current and projected sea ice conditions: seasonal ice, Canadian Archipelago, Polar basin divergent, and Polar basin convergent ecoregions. We incorporated general circulation model projections of future sea ice into a Bayesian network (BN) model structured around the factors considered in ESA decisions. This first-generation BN model combined empirical data, interpretations of data, and professional judgments of one Polar bear expert into a probabilistic framework that identifies causal links between environmental stressors and Polar bear responses. We provide guidance regarding steps necessary to refine the model, including adding inputs from other experts. The BN model projected extirpation of Polar Bears from the seasonal ice and Polar basin divergent ecoregions, where ≈2/3 of the world's Polar Bears currently occur, by mid century. Projections were less dire in other ecoregions. Decline in ice habitat was the overriding factor driving the model outcomes. Although this is a first-generation model, the dependence of Polar Bears on sea ice is universally accepted, and the observed sea ice decline is faster than models suggest. Therefore, incorporating judgments of multiple experts in a final model is not expected to fundamentally alter the outlook for Polar Bears described here.
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Hematology of Southern Beaufort Sea Polar Bears (2005–2007): Biomarker for an Arctic Ecosystem Health Sentinel
EcoHealth, 2010Co-Authors: Cassandra M Kirk, Steven C. Amstrup, Rhonda Swor, Darce Holcomb, Todd M. O’haraAbstract:Declines in sea-ice habitats have resulted in declining stature, productivity, and survival of Polar Bears in some regions. With continuing sea-ice declines, negative population effects are projected to expand throughout the Polar bear’s range. Precise causes of diminished Polar bear life history performance are unknown, however, climate and sea-ice condition change are expected to adversely impact Polar bear ( Ursus maritimus ) health and population dynamics. As apex predators in the Arctic, Polar Bears integrate the status of lower trophic levels and are therefore sentinels of ecosystem health. Arctic residents feed at the apex of the ecosystem, thus Polar Bears can serve as indicators of human health in the Arctic. Despite their value as indicators of ecosystem welfare, population-level health data for U.S. Polar Bears are lacking. We present hematological reference ranges for southern Beaufort Sea Polar Bears. Hematological parameters in southern Beaufort Sea Polar Bears varied by age, geographic location, and reproductive status. Total leukocytes, lymphocytes, monocytes, eosinophils, and serum immunoglobulin G were significantly greater in males than females. These measures were greater in nonlactating females ages ≥5, than lactating adult females ages ≥5, suggesting that females encumbered by young may be less resilient to new immune system challenges that may accompany ongoing climate change. Hematological values established here provide a necessary baseline for anticipated changes in health as arctic temperatures warm and sea-ice declines accelerate. Data suggest that females with dependent young may be most vulnerable to these changes and should therefore be a targeted cohort for monitoring in this sentinel.
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hematology of southern beaufort sea Polar Bears 2005 2007 biomarker for an arctic ecosystem health sentinel
Ecohealth, 2010Co-Authors: Cassandra M Kirk, Steven C. Amstrup, Rhonda Swor, Darce Holcomb, Todd M OharaAbstract:Declines in sea-ice habitats have resulted in declining stature, productivity, and survival of Polar Bears in some regions. With continuing sea-ice declines, negative population effects are projected to expand throughout the Polar bear’s range. Precise causes of diminished Polar bear life history performance are unknown, however, climate and sea-ice condition change are expected to adversely impact Polar bear (Ursus maritimus) health and population dynamics. As apex predators in the Arctic, Polar Bears integrate the status of lower trophic levels and are therefore sentinels of ecosystem health. Arctic residents feed at the apex of the ecosystem, thus Polar Bears can serve as indicators of human health in the Arctic. Despite their value as indicators of ecosystem welfare, population-level health data for U.S. Polar Bears are lacking. We present hematological reference ranges for southern Beaufort Sea Polar Bears. Hematological parameters in southern Beaufort Sea Polar Bears varied by age, geographic location, and reproductive status. Total leukocytes, lymphocytes, monocytes, eosinophils, and serum immunoglobulin G were significantly greater in males than females. These measures were greater in nonlactating females ages ≥5, than lactating adult females ages ≥5, suggesting that females encumbered by young may be less resilient to new immune system challenges that may accompany ongoing climate change. Hematological values established here provide a necessary baseline for anticipated changes in health as arctic temperatures warm and sea-ice declines accelerate. Data suggest that females with dependent young may be most vulnerable to these changes and should therefore be a targeted cohort for monitoring in this sentinel.
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dietary biomagnification of organochlorine contaminants in alaskan Polar Bears
Canadian Journal of Zoology, 2008Co-Authors: Torsten W. Bentzen, Erich H Follmann, Steven C. Amstrup, G.s. York, Matthew J. Wooller, Derek C G Muir, Todd M OharaAbstract:Concentrations of organochlorine contaminants in the adipose tissue of Polar Bears (Ursus maritimus Phipps, 1774) vary throughout the Arctic. The range in concentrations has not been explained fully by bear age, sex, condition, location, or reproductive status. Dietary pathways expose Polar Bears to a variety of contaminant profiles and concentrations. Prey range from lower trophic level bowhead whales (Balaena mysticetus L., 1758), one of the least contaminated marine mammals, to highly contaminated upper trophic level ringed seals (Phoca hispida (Schreber, 1775)). We used δ15N and δ13C signatures to estimate the trophic status of 42 Polar Bears sampled along Alaska’s Beaufort Sea coast to determine the relationship between organochlorine concentration and trophic level. The δ15N values in the cellular portions of blood ranged from 18.2‰ to 20.7‰. We found strong positive relationships between concentrations of the most recalcitrant polychlorinated biphenyls (PCBs) and δ15N values in models incorporating...
Øystein Wiig - One of the best experts on this subject based on the ideXlab platform.
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Sexual dimorphism and the mating ecology of Polar Bears (Ursus maritimus) at Svalbard
Behavioral Ecology and Sociobiology, 2010Co-Authors: Andrew E. Derocher, Magnus Andersen, Øystein Wiig, Jon AarsAbstract:We assessed the role of size, mass, and age in mating and non-mating Polar Bears ( Ursus maritimus ) at Svalbard, Norway, during the spring breeding season. The ratio of male to female mass, in male-female pairs, ranged from 1.00 to 3.02 ( $$ \overline x = 1.99 $$ ) indicating that mating males were larger than mating females but with substantial variation. Paired males were older than unpaired males and male mass was related to age. However, males paired with females were not significantly different in body mass from those males caught alone. Wounds and scars resulting from fights between males began at about 6 years of age and peaked at about 17 and 20 years of age, respectively. The frequency of broken canines in males, presumably due to increased male-male conflicts, increased with age but showed little increase in females. The wide range of male size in male-female pairs and the age-related signs of injury suggest that male Polar Bears engage in both scramble competition and contest competition for access to breeding females. The mating system of Polar Bears is variable but is best described as female defense polygyny or serial monogamy.
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Effects of climate change on Polar Bears.
Science Progress, 2008Co-Authors: Øystein Wiig, Jon Aars, Erik W. BornAbstract:In this article, we review the effects on Polar Bears of global warming that have already been observed, and try to evaluate what may happen to the Polar Bears in the future. Many researchers have predicted a wide range of impacts of climate change on Polar bear demography and conditions. A predicted major reduction in sea ice habitat will reduce the availability of ice associated seals, the main prey of Polar Bears, and a loss and fragmentation of Polar bear habitat will ultimately lead to large future reductions in most subpopulations. It is likely that Polar Bears will be lost from many areas where they are common today and also that the total population will change into a few more distinctly isolated populations.
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SEXUAL DIMORPHISM OF Polar Bears
Journal of Mammalogy, 2005Co-Authors: Andrew E. Derocher, Magnus Andersen, Øystein WiigAbstract:Sexual dimorphism in body mass, body length, head width, head length, and foreleg guard hair length of Polar Bears (Ursus maritimus) was examined from live-captured Polar Bears in Svalbard, Norway. Limited evidence of sexual dimorphism was apparent in cubs shortly after den emergence but was marked after the 1st year of life. Sexual dimorphism in adults resulted from both a higher growth rate and prolonged growth period in males. In mature animals, sexual dimorphism was greatest in mass, followed by foreleg guard hair length, head width, body length, and head length. Foreleg guard hair length was age related and hypothesized to be a form of ornamentation. Geographic variation in sexual dimorphism was evident for mass and body length for seven different populations but there was no evidence of a hyperallometric relationship in sexual dimorphism.
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Are Polar Bears threatened
Science (New York N.Y.), 2005Co-Authors: Øystein WiigAbstract:Nunavut, Canada, has increased the harvest quota for the 12 subpopulations of Polar Bears found within the territory from 403 in 2004 to 518 in 2005 partly based on the perception by Inuit (not supported by scientific data) that some subpopulations have been increasing under the historical harvest
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SEROLOGIC SURVEY FOR SELECTED VIRUS INFECTIONS IN Polar Bears AT SVALBARD
Journal of wildlife diseases, 2005Co-Authors: Morten Tryland, Øystein Wiig, Erkki Neuvonen, Anita Huovilainen, Hannele Tapiovaara, Albert D. M. E. Osterhaus, Andrew E. DerocherAbstract:Polar Bears (Ursus maritimus) were chemically immobilized and sampled at Svalbard, Norway, and on the pack ice in the Barents Sea from late March to mid-May between 1990 and 1998. Plasma samples were tested for the presence of antibodies to canine distemper virus (CDV), calicivirus, phocid herpesvirus type 1 (PhHV-1), and rabies virus. A seroprevalence of 8% to CDV and 2% to calicivirus were found, whereas no antibodies were detected against PhHV-1 or rabies virus. This serologic survey indicates that Polar Bears in this region are exposed to morbillivirus and calicivirus, although the nature of these viruses and infections are unknown. Morbillivirus and calicivirus are potential pathogens in seals, but it is unknown whether they may cause health problems in Polar Bears.
Cassandra M Kirk - One of the best experts on this subject based on the ideXlab platform.
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Hematology of Southern Beaufort Sea Polar Bears (2005–2007): Biomarker for an Arctic Ecosystem Health Sentinel
EcoHealth, 2010Co-Authors: Cassandra M Kirk, Steven C. Amstrup, Rhonda Swor, Darce Holcomb, Todd M. O’haraAbstract:Declines in sea-ice habitats have resulted in declining stature, productivity, and survival of Polar Bears in some regions. With continuing sea-ice declines, negative population effects are projected to expand throughout the Polar bear’s range. Precise causes of diminished Polar bear life history performance are unknown, however, climate and sea-ice condition change are expected to adversely impact Polar bear ( Ursus maritimus ) health and population dynamics. As apex predators in the Arctic, Polar Bears integrate the status of lower trophic levels and are therefore sentinels of ecosystem health. Arctic residents feed at the apex of the ecosystem, thus Polar Bears can serve as indicators of human health in the Arctic. Despite their value as indicators of ecosystem welfare, population-level health data for U.S. Polar Bears are lacking. We present hematological reference ranges for southern Beaufort Sea Polar Bears. Hematological parameters in southern Beaufort Sea Polar Bears varied by age, geographic location, and reproductive status. Total leukocytes, lymphocytes, monocytes, eosinophils, and serum immunoglobulin G were significantly greater in males than females. These measures were greater in nonlactating females ages ≥5, than lactating adult females ages ≥5, suggesting that females encumbered by young may be less resilient to new immune system challenges that may accompany ongoing climate change. Hematological values established here provide a necessary baseline for anticipated changes in health as arctic temperatures warm and sea-ice declines accelerate. Data suggest that females with dependent young may be most vulnerable to these changes and should therefore be a targeted cohort for monitoring in this sentinel.
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hematology of southern beaufort sea Polar Bears 2005 2007 biomarker for an arctic ecosystem health sentinel
Ecohealth, 2010Co-Authors: Cassandra M Kirk, Steven C. Amstrup, Rhonda Swor, Darce Holcomb, Todd M OharaAbstract:Declines in sea-ice habitats have resulted in declining stature, productivity, and survival of Polar Bears in some regions. With continuing sea-ice declines, negative population effects are projected to expand throughout the Polar bear’s range. Precise causes of diminished Polar bear life history performance are unknown, however, climate and sea-ice condition change are expected to adversely impact Polar bear (Ursus maritimus) health and population dynamics. As apex predators in the Arctic, Polar Bears integrate the status of lower trophic levels and are therefore sentinels of ecosystem health. Arctic residents feed at the apex of the ecosystem, thus Polar Bears can serve as indicators of human health in the Arctic. Despite their value as indicators of ecosystem welfare, population-level health data for U.S. Polar Bears are lacking. We present hematological reference ranges for southern Beaufort Sea Polar Bears. Hematological parameters in southern Beaufort Sea Polar Bears varied by age, geographic location, and reproductive status. Total leukocytes, lymphocytes, monocytes, eosinophils, and serum immunoglobulin G were significantly greater in males than females. These measures were greater in nonlactating females ages ≥5, than lactating adult females ages ≥5, suggesting that females encumbered by young may be less resilient to new immune system challenges that may accompany ongoing climate change. Hematological values established here provide a necessary baseline for anticipated changes in health as arctic temperatures warm and sea-ice declines accelerate. Data suggest that females with dependent young may be most vulnerable to these changes and should therefore be a targeted cohort for monitoring in this sentinel.