Contrasting Temporal Patterns of Mercury, Niche Dynamics, and Body Fat Indices of Polar Bears and Ringed Seals in a Melting Icescape

2020 ◽  
Vol 54 (5) ◽  
pp. 2780-2789 ◽  
Author(s):  
David J. Yurkowski ◽  
Evan S. Richardson ◽  
Nicholas J. Lunn ◽  
Derek C.G. Muir ◽  
Amy C. Johnson ◽  
...  
Keyword(s):  
Body Fat ◽  
Temporal Patterns ◽  
Polar Bears ◽  
Ringed Seals ◽  
Niche Dynamics

scholarly journals Comparing temporal patterns in body condition of ringed seals living within their core geographic range with those living at the edge

Ecography ◽  
2020 ◽  
Vol 43 (10) ◽  
pp. 1521-1535
Author(s):  
Steven H. Ferguson ◽  
David J. Yurkowski ◽  
Brent G. Young ◽  
Aaron T. Fisk ◽  
Derek C. G. Muir ◽  
...  
Keyword(s):  
Body Condition ◽  
Temporal Patterns ◽  
Geographic Range ◽  
Ringed Seals

Unusual Predation Attempts of Polar Bears on Ringed Seals in the Southern Beaufort Sea: Possible Significance of Changing Spring Ice Conditions

ARCTIC ◽  
2009 ◽  
Vol 61 (1) ◽  
pp. 14 ◽  
Author(s):  
Ian Stirling ◽  
Evan Richardson ◽  
Gregory W. Thiemann ◽  
Andrew E. Derocher
Keyword(s):  
Sea Ice ◽  
Polar Bear ◽  
Foraging Behaviour ◽  
Open Water ◽  
Beaufort Sea ◽  
Polar Bears ◽  
Ringed Seals ◽  
Decadal Scale ◽  
Underlying Causes ◽  
Ice Conditions

In April and May 2003 through 2006, unusually rough and rafted sea ice extended for several tens of kilometres offshore in the southeastern Beaufort Sea from about Atkinson Point to the Alaska border. Hunting success of polar bears (Ursus maritimus) seeking seals was low despite extensive searching for prey. It is unknown whether seals were less abundant in comparison to other years or less accessible because they maintained breathing holes below rafted ice rather than snowdrifts, or whether some other factor was involved. However, we found 13 sites where polar bears had clawed holes through rafted ice in attempts to capture ringed seals (Phoca hispida) in 2005 through 2006 and another site during an additional research project in 2007. Ice thickness at the 12 sites that we measured averaged 41 cm. These observations, along with cannibalized and starved polar bears found on the sea ice in the same general area in the springs of 2004 through 2006, suggest that during those years, polar bears in the southern Beaufort Sea were nutritionally stressed. Searches made farther north during the same period and using the same methods produced no similar observations near Banks Island or in Amundsen Gulf. A possible underlying ecological explanation is a decadal-scale downturn in seal populations. But a more likely explanation is major changes in the sea-ice and marine environment resulting from record amounts and duration of open water in the Beaufort and Chukchi seas, possibly influenced by climate warming. Because the underlying causes of observed changes in polar bear body condition and foraging behaviour are unknown, further study is warranted.

scholarly journals CONCENTRATIONS AND INTERACTIONS OF SELECTED ESSENTIAL AND NON-ESSENTIAL ELEMENTS IN RINGED SEALS AND POLAR BEARS OF ARCTIC ALASKA

2001 ◽  
Vol 37 (4) ◽  
pp. 711-721 ◽  
Author(s):  
Victoria M. Woshner ◽  
Todd M. O'Hara ◽  
Gerald R. Bratton ◽  
Val R. Beasley
Keyword(s):  
Essential Elements ◽  
Polar Bears ◽  
Ringed Seals ◽  
Arctic Alaska

Spatial and temporal patterns of problem polar bears in Churchill, Manitoba

Polar Biology ◽  
2009 ◽  
Vol 32 (10) ◽  
pp. 1529-1537 ◽  
Author(s):  
Lindsay Towns ◽  
A. E. Derocher ◽  
I. Stirling ◽  
N. J. Lunn ◽  
D. Hedman
Keyword(s):  
Temporal Patterns ◽  
Polar Bears ◽  
Spatial And Temporal Patterns

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.

scholarly journals Fatty acid composition of the adipose tissue of polar bears and of their prey: ringed seals, bearded seals and harp seals

2003 ◽  
Vol 265 ◽  
pp. 275-282 ◽  
Author(s):  
O Grahl-Nielsen ◽  
M Andersen ◽  
AE Derocher ◽  
C Lydersen ◽  
Ø Wiig ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Acid Composition ◽  
Polar Bears ◽  
Ringed Seals ◽  
Bearded Seals

Midsummer observations on the behavior of wild polar bears (Ursus maritimus)

1974 ◽  
Vol 52 (9) ◽  
pp. 1191-1198 ◽  
Author(s):  
Ian Stirling
Keyword(s):  
Diurnal Rhythm ◽  
Intraspecific Competition ◽  
Ursus Maritimus ◽  
Polar Bears ◽  
Phoca Hispida ◽  
Devon Island ◽  
Adult Females ◽  
Ringed Seals ◽  
Single Animal ◽  
The Mean

Wild polar bears (Ursus maritimus) were observed from Caswall Tower, Devon Island (74°43′ N; 91°10′ W), from 24 July to 8 August 1973. A total of 602.7 bear hours of observations was recorded. Two types of hunting were observed, stalking and still-hunting. Of 288 hunts observed, 65 (22.6%) were stalks and 233 (77.4%) were still-hunts. All cubs observed hunted, but they exhibited great variety in patience and apparent skill. Scavenging and intraspecific competition for possession of kills were observed. When threatened, adult females with cubs were not subordinate to tears of any other age or sex classes. A diurnal rhythm was recorded in which bears slept most during the latter third of the 24-h cycle and least in the first third. The average of 17 sleeps longer than 60 min was 465 ± 301.3 min.Basking ringed seals (Phoca hispida) alternated between lying flat and raising their heads to look about for predators. The mean duration of the lying and looking phases was 26.3 and 7.0 s respectively (n = 591 and 580). The variation between individual seals was greater than within individuals. If a group of seals hauled out together, all individuals maintained watchful behavior; no single animal acted as a "sentry" for the others.

Sign in / Sign up

Export Citation Format

Share Document