Movements of Walruses Radio-tagged in Bristol Bay, Alaska

Jay, Chadwick V.; Hills, Susan L.

doi:10.14430/arctic410

Cited by 10 publications

(17 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Homing behaviour, i.e. the use of a previously occupied home range, has been reported previously for Pacific walruses (Jay & Hills 2005) and for 1 male Atlantic walrus in Greenland (Born et al 256 Table 2. Odobenus rosmarus.…”

Section: Discussionmentioning

confidence: 62%

“…Fay 1982), inferences from isotope patterns in teeth (Stewart et al 2003), as well as some dedicated studies of behaviour and demographics (e.g. Miller 1982, Miller & Boness 1983, Born & Knutsen 1992, Knutsen 1993, Gjertz & Wiig 1995, Sjare & Stirling 1996, Wiig et al 1996, Jay & Hills 2005, Lydersen et al 2008. Not surprisingly, most of the available behavioural information about walruses is restricted to the seasons in which there is daylight in the High Arctic (i.e.…”

Section: Introductionmentioning

confidence: 99%

“…These large animals are not easily anesthetised, and they are very rough on instruments. Previous telemetry studies have been attempted in both Atlantic (Born & Knutsen 1992, Wiig et al 1996, Born et al 2005, Born & Acquarone 2007 and Pacific walruses (Jay & Hills 2005). However, the durations of data records have not been long enough to reveal breeding locations in most cases, at-sea position data have not been received by the satellite platform and relatively little habitat analysis has been conducted.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Deep into the ice: over-wintering and habitat selection in male Atlantic walruses

Freitas¹,

Kovacs²,

Ims³

et al. 2009

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

New technological developments in animal-borne satellite-tracking devices in combination with increased access to satellite-based environmental data are creating new possibilities for studying movement patterns and habitat selection by animals in remote, logistically challenging environments. In the present study, we report the first year-round data on movement patterns of walruses in the High Arctic, including at-sea positions. Using first-passage times (FPT) to study habitat use and quantifying habitat selection using mixed-effects Cox proportional hazards models, we dispelled the conventional perception that seasonal movement patterns of Atlantic walruses are simply a result of them following the retraction and expansion of annually formed sea ice. Walruses in this study (n = 17 males) actively moved into areas of high ice concentration (> 90%) during winter; travelling far into the ice pack, as far as 600 km from ice-free water. Additionally, high inter-annual, seasonal site fidelity was documented. Seasonal differences in habitat use patterns were also observed. In summer, when walruses feed intensively, FPTs were affected by water depth and distance to the coast (R 2 = 0.571), but these variables had no effect on walrus habitat use in winter. Sea ice concentration was the most important environmental condition during the winter season (R 2 = 0.162), though there are clearly other factors influencing where individuals occur in winter that are currently unaccounted for in these analyses. The male walruses in this study did not do much benthic diving during winter, suggesting that they did not feed often during the time that they are known to breed. Instead, they remained in areas with high ice coverage, far from their coastal summering areas, spending much of their time hauled out or in surface waters.KEY WORDS: Cox proportional hazards models · First-passage time · Odobenus rosmarus rosmarus · Random-effects models · Satellite telemetry · Site fidelity Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 375: [247][248][249][250][251][252][253][254][255][256][257][258][259][260][261] 2009 highly mobile Arctic marine mammals, leaving winter ecology and habitat use largely enigmatic for many species. The new possibilities to study these 'problematic' animals and the environmental conditions they experience by using remote methods are very timely, because the Arctic is currently undergoing dramatic environmental change (ACIA 2005, Solomon et al. 2007). Monitoring a resident population's responses will provide considerable insight into their adaptability and permit assessments of their survival potential.Walruses Odobenus rosmarus are full-time residents of the Arctic. Our current knowledge of their movement patterns and habitat selection choices is a composite built from bits of information from many, different sources, including aboriginal hunting knowledge and catch records (e.g. Lønø 1972, Fay 1982, Fay et al. 1984, natural history observations, some o...

show abstract

Section: Discussionmentioning

confidence: 62%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Deep into the ice: over-wintering and habitat selection in male Atlantic walruses

Freitas¹,

Kovacs²,

Ims³

et al. 2009

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

show abstract

“…Bering Sea coastal haulouts are dominated by adult males. Some coastal haulouts are no longer used (Jay and Hills ) and numbers of animals at other haulouts have steadily declined by 2–3% each year over the last three decades (Sell and Weiss ; Winfree ; Zdor et al. ); however, new haulouts have formed during that same period.…”

Section: Resultsmentioning

confidence: 99%

“…). These walruses tend to use summer haulout sites repeatedly and exhibit fidelity to those sites (Jay and Hills ). However, haulout use is dynamic with numbers of animals fluctuating daily and the abandonment and formation of haulouts is likely dictated by prey availability, human disturbance, coastal development, etc.…”

Section: Pacific Walrus Ecology and Behaviormentioning

confidence: 99%

Pacific Walrus and climate change: observations and predictions

MacCracken

2012

Ecology and Evolution

View full text Add to dashboard Cite

The extent and duration of sea-ice habitats used by Pacific walrus (Odobenus rosmarus divergens) are diminishing resulting in altered walrus behavior, mortality, and distribution. I document changes that have occurred over the past several decades and make predictions to the end of the 21st century. Climate models project that sea ice will monotonically decline resulting in more ice-free summers of longer duration. Several stressors that may impact walruses are directly influenced by sea ice. How these stressors materialize were modeled as most likely-case, worst-case, and best-case scenarios for the mid- and late-21st century, resulting in four comprehensive working hypotheses that can help identify and prioritize management and research projects, identify comprehensive mitigation actions, and guide monitoring programs to track future developments and adjust programs as needed. In the short term, the most plausible hypotheses predict a continuing northward shift in walrus distribution, increasing use of coastal haulouts in summer and fall, and a population reduction set by the carrying capacity of the near shore environment and subsistence hunting. Alternatively, under worst-case conditions, the population will decline to a level where the probability of extinction is high. In the long term, walrus may seasonally abandon the Bering and Chukchi Seas for sea-ice refugia to the northwest and northeast, ocean warming and pH decline alter walrus food resources, and subsistence hunting exacerbates a large population decline. However, conditions that reverse current trends in sea ice loss cannot be ruled out. Which hypothesis comes to fruition depends on how the stressors develop and the success of mitigation measures. Best-case scenarios indicate that successful mitigation of unsustainable harvests and terrestrial haulout-related mortalities can be effective. Management and research should focus on monitoring, elucidating effects, and mitigation, while ultimately, reductions in greenhouse gas emissions are needed to reduce sea-ice habitat losses.

show abstract

Resource partitioning between Pacific walruses and bearded seals in the Alaska Arctic and sub-Arctic

et al. 2017

View full text Add to dashboard Cite

Climate-mediated changes in the phenology of Arctic sea ice and primary production may alter benthic food webs that sustain populations of Pacific walruses (Odobenus rosmarus divergens) and bearded seals (Erignathus barbatus). Interspecific resource competition could place an additional strain on ice-associated marine mammals already facing loss of sea ice habitat. Using fatty acid (FA) profiles, FA trophic markers, and FA stable carbon isotope analyses, we found that walruses and bearded seals partitioned food resources in 2009-2011. Interspecific differences in FA profiles were largely driven by variation in non-methylene FAs, which are markers of benthic invertebrate prey taxa, indicating varying consumption of specific benthic prey. We used Bayesian multi-source FA stable isotope mixing models to estimate the proportional contributions of particulate organic matter (POM) from sympagic (ice algal), pelagic, and benthic sources to these apex predators. Proportional contributions of FAs to walruses and bearded seals from benthic POM sources were high [44 (17-67)% and 62 (38-83)%, respectively] relative to other sources of POM. Walruses also obtained considerable contributions of FAs from pelagic POM sources [51 (32-73)%]. Comparison of δC values of algal FAs from walruses and bearded seals to those from benthic prey from different feeding groups from the Chukchi and Bering seas revealed that different trophic pathways sustained walruses and bearded seals. Our findings suggest that (1) resource partitioning may mitigate interspecific competition, and (2) climate change impacts on Arctic food webs may elicit species-specific responses in these high trophic level consumers.

show abstract

Movements of Walruses Radio-tagged in Bristol Bay, Alaska

Cited by 10 publications

References 10 publications

Deep into the ice: over-wintering and habitat selection in male Atlantic walruses

Deep into the ice: over-wintering and habitat selection in male Atlantic walruses

Pacific Walrus and climate change: observations and predictions

Resource partitioning between Pacific walruses and bearded seals in the Alaska Arctic and sub-Arctic

Contact Info

Product

Resources

About