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Rode KD, Taras BD, Stricker CA, Atwood TC, Boucher NP, Durner GM, Derocher AE, Richardson ES, Cherry SG, Quakenbush L, Horstmann L, Bromaghin JF. Diet energy density estimated from isotopes in predator hair associated with survival, habitat, and population dynamics. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2023; 33:e2751. [PMID: 36151883 DOI: 10.1002/eap.2751] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 07/29/2022] [Accepted: 08/30/2022] [Indexed: 06/16/2023]
Abstract
Sea ice loss is fundamentally altering the Arctic marine environment. Yet there is a paucity of data on the adaptability of food webs to ecosystem change, including predator-prey interactions. Polar bears (Ursus maritimus) are an important subsistence resource for Indigenous people and an apex predator that relies entirely on the under-ice food web to meet its energy needs. In this study, we assessed whether polar bears maintained dietary energy density by prey switching in response to spatiotemporal variation in prey availability. We compared the macronutrient composition of diets inferred from stable carbon and nitrogen isotopes in polar bear guard hair (primarily representing summer/fall diet) during periods when bears had low and high survival (2004-2016), between bears that summered on land versus pack ice, and between bears occupying different regions of the Alaskan and Canadian Beaufort Sea. Polar bears consumed diets with lower energy density during periods of low survival, suggesting that concurrent increased dietary proportions of beluga whales (Delphinapterus leucas) did not offset reduced proportions of ringed seals (Pusa hispida). Diets with the lowest energy density and proportions from ringed seal blubber were consumed by bears in the western Beaufort Sea (Alaska) during a period when polar bear abundance declined. Intake required to meet energy requirements of an average free-ranging adult female polar bear was 2.1 kg/day on diets consumed during years with high survival but rose to 3.0 kg/day when survival was low. Although bears that summered onshore in the Alaskan Beaufort Sea had higher-fat diets than bears that summered on the pack ice, access to the remains of subsistence-harvested bowhead whales (Balaena mysticetus) contributed little to improving diet energy density. Because most bears in this region remain with the sea ice year round, prey switching and consumption of whale carcasses onshore appear insufficient to augment diets when availability of their primary prey, ringed seals, is reduced. Our results show that a strong predator-prey relationship between polar bears and ringed seals continues in the Beaufort Sea. The method of estimating dietary blubber using predator hair, demonstrated here, provides a new metric to monitor predator-prey relationships that affect individual health and population demographics.
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Affiliation(s)
- Karyn D Rode
- U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, USA
| | - Brian D Taras
- Alaska Department of Fish and Game, Fairbanks, Alaska, USA
| | - Craig A Stricker
- U.S. Geological Survey, Fort Collins Science Center, Fort Collins, Colorado, USA
| | - Todd C Atwood
- U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, USA
| | - Nicole P Boucher
- University of Alberta, Edmonton, Alberta, Canada
- School of Environmental Studies, University of Victoria, Victoria, British Columbia, Canada
| | - George M Durner
- U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, USA
| | | | - Evan S Richardson
- Environment and Climate Change Canada, Science and Technology Branch, Winnipeg, Manitoba, Canada
| | - Seth G Cherry
- University of Alberta, Edmonton, Alberta, Canada
- Parks Canada, East Kootenay, British Columbia, Canada
| | | | - Lara Horstmann
- College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, Alaska, USA
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2
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Smith MEK, Horstmann L, Stimmelmayr R. Stable isotope differences of polar bears in the Southern Beaufort Sea and Chukchi Sea. J Wildl Manage 2022. [DOI: 10.1002/jwmg.22225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Malia E. K. Smith
- College of Fisheries and Ocean Sciences, University of Alaska Fairbanks 2120 Koyukuk Drive Fairbanks AK 99775 USA
| | - Lara Horstmann
- College of Fisheries and Ocean Sciences, University of Alaska Fairbanks 2120 Koyukuk Drive Fairbanks AK 99775 USA
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3
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Laidre KL, Supple MA, Born EW, Regehr EV, Wiig Ø, Ugarte F, Aars J, Dietz R, Sonne C, Hegelund P, Isaksen C, Akse GB, Cohen B, Stern HL, Moon T, Vollmers C, Corbett-Detig R, Paetkau D, Shapiro B. Glacial ice supports a distinct and undocumented polar bear subpopulation persisting in late 21st-century sea-ice conditions. Science 2022; 376:1333-1338. [PMID: 35709290 DOI: 10.1126/science.abk2793] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Polar bears are susceptible to climate warming because of their dependence on sea ice, which is declining rapidly. We present the first evidence for a genetically distinct and functionally isolated group of polar bears in Southeast Greenland. These bears occupy sea-ice conditions resembling those projected for the High Arctic in the late 21st century, with an annual ice-free period that is >100 days longer than the estimated fasting threshold for the species. Whereas polar bears in most of the Arctic depend on annual sea ice to catch seals, Southeast Greenland bears have a year-round hunting platform in the form of freshwater glacial mélange. This suggests that marine-terminating glaciers, although of limited availability, may serve as previously unrecognized climate refugia. Conservation of Southeast Greenland polar bears, which meet criteria for recognition as the world's 20th polar bear subpopulation, is necessary to preserve the genetic diversity and evolutionary potential of the species.
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Affiliation(s)
- Kristin L Laidre
- Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle, WA 98105, USA.,Greenland Institute of Natural Resources, 3900 Nuuk, Greenland
| | - Megan A Supple
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Erik W Born
- Greenland Institute of Natural Resources, 3900 Nuuk, Greenland
| | - Eric V Regehr
- Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle, WA 98105, USA
| | - Øystein Wiig
- Natural History Museum, University of Oslo, Blindern, NO-0318 Oslo, Norway
| | - Fernando Ugarte
- Greenland Institute of Natural Resources, 3900 Nuuk, Greenland
| | - Jon Aars
- Norwegian Polar Institute, Fram Centre, NO-9296 Tromsø, Norway
| | - Rune Dietz
- Department of Ecoscience and Arctic Research Centre, Aarhus University, DK-4000 Roskilde, Denmark
| | - Christian Sonne
- Department of Ecoscience and Arctic Research Centre, Aarhus University, DK-4000 Roskilde, Denmark
| | - Peter Hegelund
- Greenland Institute of Natural Resources, 3900 Nuuk, Greenland
| | - Carl Isaksen
- Greenland Institute of Natural Resources, 3900 Nuuk, Greenland
| | | | - Benjamin Cohen
- Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle, WA 98105, USA
| | - Harry L Stern
- Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle, WA 98105, USA
| | - Twila Moon
- National Snow and Ice Data Center, Cooperative Institute for Research In Environmental Sciences (CIRES), University of Colorado, Boulder, CO 80309, USA
| | - Christopher Vollmers
- Department of Biomolecular Engineering, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Russ Corbett-Detig
- Department of Biomolecular Engineering, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - David Paetkau
- Wildlife Genetics International, Nelson, BC V1L 5P9, Canada
| | - Beth Shapiro
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA.,Howard Hughes Medical Institute, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
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4
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Vongraven D, Derocher AE, Pilfold NW, Yoccoz NG. Polar Bear Harvest Patterns Across the Circumpolar Arctic. FRONTIERS IN CONSERVATION SCIENCE 2022. [DOI: 10.3389/fcosc.2022.836544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Wildlife harvest remains a conservation concern for many species and assessing patterns of harvest can provide insights on sustainability and inform management. Polar bears (Ursus maritimus) are harvested over a large part of their range by local people. The species has a history of unsustainable harvest that was largely rectified by an international agreement that required science-based management. The objective of our study was to examine the temporal patterns in the number of polar bears harvested, harvest sex ratios, and harvest rates from 1970 to 2018. We analyzed data from 39,049 harvested polar bears (annual mean 797 bears) collected from 1970 to 2018. Harvest varied across populations and times that reflect varying management objectives, episodic events, and changes based on new population estimates. More males than females were harvested with an overall M:F sex ratio of 1.84. Harvest varied by jurisdiction with 68.0% of bears harvested in Canada, 18.0% in Greenland, 11.8% in the USA, and 2.2% in Norway. Harvest rate was often near the 4.5% target rate. Where data allowed harvest rate estimation, the target rate was exceeded in 11 of 13 populations with 1–5 populations per year above the target since 1978. Harvest rates at times were up to 15.9% of the estimated population size suggesting rare episodes of severe over-harvest. Harvest rate was unrelated to a proxy for ecosystem productivity (area of continental shelf within each population) but was correlated with prey diversity. In the last 5–10 years, monitored populations all had harvest rates near sustainable limits, suggesting improvements in management. Polar bear harvest management has reduced the threat it once posed to the species. However, infrequent estimates of abundance, new management objectives, and climate change have raised new concerns about the effects of harvest.
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5
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Performance of helicopter-based biopsy darting of polar bears (Ursus maritimus) on the spring sea ice. EUR J WILDLIFE RES 2021. [DOI: 10.1007/s10344-021-01550-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Bromaghin JF, Douglas DC, Durner GM, Simac KS, Atwood TC. Survival and abundance of polar bears in Alaska's Beaufort Sea, 2001-2016. Ecol Evol 2021; 11:14250-14267. [PMID: 34707852 PMCID: PMC8525099 DOI: 10.1002/ece3.8139] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 08/02/2021] [Accepted: 09/06/2021] [Indexed: 12/20/2022] Open
Abstract
The Arctic Ocean is undergoing rapid transformation toward a seasonally ice-free ecosystem. As ice-adapted apex predators, polar bears (Ursus maritimus) are challenged to cope with ongoing habitat degradation and changes in their prey base driven by food-web response to climate warming. Knowledge of polar bear response to environmental change is necessary to understand ecosystem dynamics and inform conservation decisions. In the southern Beaufort Sea (SBS) of Alaska and western Canada, sea ice extent has declined since satellite observations began in 1979 and available evidence suggests that the carrying capacity of the SBS for polar bears has trended lower for nearly two decades. In this study, we investigated the population dynamics of polar bears in Alaska's SBS from 2001 to 2016 using a multistate Cormack-Jolly-Seber mark-recapture model. States were defined as geographic regions, and we used location data from mark-recapture observations and satellite-telemetered bears to model transitions between states and thereby explain heterogeneity in recapture probabilities. Our results corroborate prior findings that the SBS subpopulation experienced low survival from 2003 to 2006. Survival improved modestly from 2006 to 2008 and afterward rebounded to comparatively high levels for the remainder of the study, except in 2012. Abundance moved in concert with survival throughout the study period, declining substantially from 2003 and 2006 and afterward fluctuating with lower variation around an average of 565 bears (95% Bayesian credible interval [340, 920]) through 2015. Even though abundance was comparatively stable and without sustained trend from 2006 to 2015, polar bears in the Alaska SBS were less abundant over that period than at any time since passage of the U.S. Marine Mammal Protection Act. The potential for recovery is likely limited by the degree of habitat degradation the subpopulation has experienced, and future reductions in carrying capacity are expected given current projections for continued climate warming.
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Affiliation(s)
| | | | | | | | - Todd C. Atwood
- U.S. Geological SurveyAlaska Science CenterAnchorageAKUSA
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7
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Diet composition and body condition of polar bears (Ursus maritimus) in relation to sea ice habitat in the Canadian High Arctic. Polar Biol 2021. [DOI: 10.1007/s00300-021-02891-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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8
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Age-structured Jolly-Seber model expands inference and improves parameter estimation from capture-recapture data. PLoS One 2021; 16:e0252748. [PMID: 34106979 PMCID: PMC8189494 DOI: 10.1371/journal.pone.0252748] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 05/22/2021] [Indexed: 11/19/2022] Open
Abstract
Understanding the influence of individual attributes on demographic processes is a key objective of wildlife population studies. Capture-recapture and age data are commonly collected to investigate hypotheses about survival, reproduction, and viability. We present a novel age-structured Jolly-Seber model that incorporates age and capture-recapture data to provide comprehensive information on population dynamics, including abundance, age-dependent survival, recruitment, age structure, and population growth rates. We applied our model to a multi-year capture-recapture study of polar bears (Ursus maritimus) in western Hudson Bay, Canada (2012–2018), where management and conservation require a detailed understanding of how polar bears respond to climate change and other factors. In simulation studies, the age-structured Jolly-Seber model improved precision of survival, recruitment, and annual abundance estimates relative to standard Jolly-Seber models that omit age information. Furthermore, incorporating age information improved precision of population growth rates, increased power to detect trends in abundance, and allowed direct estimation of age-dependent survival and changes in annual age structure. Our case study provided detailed evidence for senescence in polar bear survival. Median survival estimates were lower (<0.95) for individuals aged <5 years, remained high (>0.95) for individuals aged 7–22 years, and subsequently declined to near zero for individuals >30 years. We also detected cascading effects of large recruitment classes on population age structure, which created major shifts in age structure when these classes entered the population and then again when they reached prime breeding ages (10–15 years old). Overall, age-structured Jolly-Seber models provide a flexible means to investigate ecological and evolutionary processes that shape populations (e.g., via senescence, life expectancy, and lifetime reproductive success) while improving our ability to investigate population dynamics and forecast population changes from capture-recapture data.
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9
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Weegman MD, Arnold TW, Clark RG, Schaub M. Partial and complete dependency among data sets has minimal consequence on estimates from integrated population models. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2021; 31:e2258. [PMID: 33176007 DOI: 10.1002/eap.2258] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 08/28/2020] [Accepted: 09/09/2020] [Indexed: 06/11/2023]
Abstract
Integrated population models (IPMs) are widely used to combine disparate data sets in joint analysis to better understand population dynamics and provide guidance for conservation activities. An often-cited assumption of IPMs is independence among component data sets within the combined likelihood. Dependency among data sets should lead to underestimation of variance and bias because individuals contribute data to more than one data set. In practice, studied individuals often occur in multiple data sets in IPMs (i.e., overlap), which is one way for the independence assumption to be violated. Such cases have the potential to dissuade practitioners and limit application of IPMs to solve emerging ecological problems. We assessed precision and bias of demographic rates estimated from IPMs using a complete gradient (0-100%) of overlap among data sets, wide ranges in demographic rates (e.g., survival 0.1-0.8) and sample sizes (100-1,200 individuals) and variable data sources. We compared results from our simulations with those from IPMs constructed using empirical data on tree swallows (Tachycineta bicolor) where data sets either had complete overlap or included different individuals. Contrary to previous investigators, we found no substantive bias or uncertainty in any demographic rate from IPMs derived from data sets with complete overlap. While variability in demographic rates was greater at low sample sizes (i.e., low capture, recapture, and survey probabilities), there were negligible differences in the posterior mean or root mean square error of demographic rates among IPMs with strong dependence vs. complete independence among data sets. Our simulations suggest IPMs can be designed using only capture-recapture data or harvest and capture-recovery data where population estimates are obtained from the same data as survival and productivity data. While we encourage researchers to carefully consider the modeling approach best suited for their data sets, our results suggest that dependence among data sets does not generally compromise IPM estimates. Thus, violation of the independence assumption should not dissuade researchers from the application of IPMs in ecological research.
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Affiliation(s)
- Mitch D Weegman
- School of Natural Resources, University of Missouri, Columbia, Missouri, 65211, USA
| | - Todd W Arnold
- Department of Fisheries, Wildlife and Conservation Biology, University of Minnesota, St. Paul, Minnesota, 55108, USA
| | - Robert G Clark
- Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan, S7N 5E2, Canada
- Prairie and Northern Wildlife Research Centre, Environment and Climate Change Canada, Saskatoon, Saskatchewan, S7N 0X4, Canada
| | - Michael Schaub
- Swiss Ornithological Institute, Sempach, 6204, Switzerland
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10
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Hoondert RPJ, Ragas AMJ, Hendriks AJ. Simulating changes in polar bear subpopulation growth rate due to legacy persistent organic pollutants - Temporal and spatial trends. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 754:142380. [PMID: 33254886 DOI: 10.1016/j.scitotenv.2020.142380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 08/18/2020] [Accepted: 09/11/2020] [Indexed: 06/12/2023]
Abstract
Although atmospheric concentrations of many conventional persistent organic pollutants (POPs) have decreased in the Arctic over the past few decades, levels of most POPs and mercury remain high since the 1990s or start to increase again in Arctic areas, especially polar bears. So far, studies generally focused on individual effects of POPs, and do not directly link POP concentrations in prey species to population-specific parameters. In this study we therefore aimed to estimate the effect of legacy POPs and mercury on population growth rate of nineteen polar bear subpopulations. We modelled population development in three scenarios, based on species sensitivity distributions (SSDs) derived for POPs based on ecotoxicity data for endothermic species. In the first scenario, ecotoxicity data for polar bears were based on the HC50 (the concentration at which 50% of the species is affected). The other two scenarios were based on the HC5 and HC95. Considerable variation in effects of POPs could be observed among the scenarios. In our intermediate scenario, we predicted subpopulation decline for ten out of 15 polar bear subpopulations. The estimated population growth rate was least reduced in Gulf of Boothia and Foxe Basin. On average, PCB concentrations in prey (in μg/g toxic equivalency (TEQ)) posed the largest threat to polar bear subpopulations, with negative modelled population growth rates for the majority of subpopulations. We did not find a correlation between modelled population changes and monitored population trends for the majority of chemical-subpopulation combinations. Modelled population growth rates increased over time, implying a decreasing effect of PCBs, DDTs, and mercury. Polar bear subpopulations are reportedly still declining in four out of the seven subpopulations for which sufficient long-term monitoring data is available, as reported by the IUCN-PBSG. This implies that other emerging pollutants or other anthropogenic stressors may affect polar bear subpopulations.
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Affiliation(s)
- Renske P J Hoondert
- Department of Environmental Science, Institute for Wetland and Water Research, Faculty of Science, Radboud University Nijmegen, the Netherlands.
| | - Ad M J Ragas
- Department of Environmental Science, Institute for Wetland and Water Research, Faculty of Science, Radboud University Nijmegen, the Netherlands; Faculty of Management, Science and Technology, Open University, the Netherlands
| | - A Jan Hendriks
- Department of Environmental Science, Institute for Wetland and Water Research, Faculty of Science, Radboud University Nijmegen, the Netherlands
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11
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Florko KRN, Thiemann GW, Bromaghin JF. Drivers and consequences of apex predator diet composition in the Canadian Beaufort Sea. Oecologia 2020; 194:51-63. [PMID: 32897468 DOI: 10.1007/s00442-020-04747-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 08/28/2020] [Indexed: 10/23/2022]
Abstract
Polar bears (Ursus maritimus) rely on annual sea ice as their primary habitat for hunting marine mammal prey. Given their long lifespan, wide geographic distribution, and position at the top of the Arctic marine food web, the diet composition of polar bears can provide insights into temporal and spatial ecosystem dynamics related to climate-mediated sea ice loss. Polar bears with the greatest ecological constraints on diet composition may be most vulnerable to climate-related changes in ice conditions and prey availability. We used quantitative fatty acid signature analysis (QFASA) to estimate the diets of polar bears (n = 419) in two western Canadian Arctic subpopulations (Northern Beaufort Sea and Southern Beaufort Sea) from 1999 to 2015. Polar bear diets were dominated by ringed seal (Pusa hispida), with interannual, seasonal, age- and sex-specific variation. Foraging area and sea ice conditions also affected polar bear diet composition. Most variation in bear diet was explained by longitude, reflecting spatial variation in prey availability. Sea ice conditions (extent, thickness, and seasonal duration) declined throughout the study period, and date of sea ice break-up in the preceding spring was positively correlated with female body condition and consumption of beluga whale (Delphinapterus leucas), suggesting that bears foraged on beluga whales during entrapment events. Female body condition was positively correlated with ringed seal consumption, and negatively correlated with bearded seal consumption. This study provides insights into the complex relationships between declining sea ice habitat and the diet composition and foraging success of a wide-ranging apex predator.
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Affiliation(s)
- Katie R N Florko
- Department of Biology, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada.
| | - Gregory W Thiemann
- Faculty of Environmental Studies, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada
| | - Jeffrey F Bromaghin
- Alaska Science Center, U.S. Geological Survey, 4210 University Drive, Anchorage, AK, 99508, USA
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12
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Reimer JR, Mangel M, Derocher AE, Lewis MA. Modeling optimal responses and fitness consequences in a changing Arctic. GLOBAL CHANGE BIOLOGY 2019; 25:3450-3461. [PMID: 31077520 DOI: 10.1111/gcb.14681] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Accepted: 04/29/2019] [Indexed: 06/09/2023]
Abstract
Animals must balance a series of costs and benefits while trying to maximize their fitness. For example, an individual may need to choose how much energy to allocate to reproduction versus growth, or how much time to spend on vigilance versus foraging. Their decisions depend on complex interactions between environmental conditions, behavioral plasticity, reproductive biology, and energetic demands. As animals respond to novel environmental conditions caused by climate change, the optimal decisions may shift. Stochastic dynamic programming provides a flexible modeling framework with which to explore these trade-offs, but this method has not yet been used to study possible changes in optimal trade-offs caused by climate change. We created a stochastic dynamic programming model capturing trade-off decisions required by an individual adult female polar bear (Ursus maritimus) as well as the fitness consequences of her decisions. We predicted optimal foraging decisions throughout her lifetime as well as the energetic thresholds below which it is optimal for her to abandon a reproductive attempt. To explore the effects of climate change, we shortened the spring feeding period by up to 3 weeks, which led to predictions of riskier foraging behavior and higher reproductive thresholds. The resulting changes in fitness may be interpreted as a best-case scenario, where bears adapt instantaneously and optimally to new environmental conditions. If the spring feeding period was reduced by 1 week, her expected fitness declined by 15%, and if reduced by 3 weeks, expected fitness declined by 68%. This demonstrates an effective way to explore a species' optimal response to a changing landscape of costs and benefits and highlights the fact that small annual effects can result in large cumulative changes in expected lifetime fitness.
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Affiliation(s)
- Jody R Reimer
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
- Department of Mathematical and Statistical Sciences, University of Alberta, Edmonton, AB, Canada
| | - Marc Mangel
- Institute of Marine Sciences and Department of Applied Mathematics and Statistics, University of California, Santa Cruz, Santa Cruz, California
- Department of Biology, University of Bergen, Bergen, Norway
| | - Andrew E Derocher
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Mark A Lewis
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
- Department of Mathematical and Statistical Sciences, University of Alberta, Edmonton, AB, Canada
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13
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Durner GM, Douglas DC, Atwood TC. Are polar bear habitat resource selection functions developed from 1985-1995 data still useful? Ecol Evol 2019; 9:8625-8638. [PMID: 31410267 PMCID: PMC6686286 DOI: 10.1002/ece3.5401] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 05/20/2019] [Accepted: 05/28/2019] [Indexed: 02/04/2023] Open
Abstract
Greenhouse-gas-induced warming in the Arctic has caused declines in sea ice extent and changed its composition, raising concerns by all circumpolar nations for polar bear conservation.Negative impacts have been observed in three well-studied polar bear subpopulations. Most subpopulations, however, receive little or no direct monitoring, hence, resource selection functions (RSF) may provide a useful proxy of polar bear distributions. However, the efficacy of RSFs constructed from past data, that is, reference RSFs, may be degraded under contemporary conditions, especially in a rapidly changing environment.We assessed published Arctic-wide reference RSFs using tracking data from adult female polar bears captured in the Beaufort Sea. We compared telemetry-derived seasonal distributions of polar bears to RSF-defined optimal sea ice habitat during the period of RSF model development, 1985-1995, and two subsequent periods with diminished sea ice: 1996-2006 and 2007-2016. From these comparisons, we assessed the applicability of the reference RSFs for contemporary polar bear conservation.In the two decades following the 1985-1995 reference period, use and availability of optimal habitat by polar bears declined during the ice melt, ice minimum, and ice growth seasons. During the ice maximum season (i.e., winter), polar bears used the best habitat available, which changed relatively little across the three decades of study. During the ice melt, ice minimum, and ice growth seasons, optimal habitat in areas used by polar bears decreased and was displaced north and east of the Alaska Beaufort Sea coast. As optimal habitat diminished in these seasons, polar bears expanded their range and occupied greater areas of suboptimal habitat.Synthesis and applications: Sea ice declines due to climate change continue to challenge polar bears and their conservation. The distribution of Southern Beaufort Sea polar bears remained similar during the ice maximum season, so the reference RSFs developed from data collected >20 years ago continue to accurately model their winter distribution. In contrast, reference RSFs for the ice transitional and minimum seasons showed diminished predictive efficacy but were useful in revealing that contemporary polar bears have been increasingly forced to use suboptimal habitats during those seasons.
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Affiliation(s)
| | | | - Todd C. Atwood
- Alaska Science CenterU.S. Geological SurveyAnchorageAlaskaUSA
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14
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Behaviour and characteristics of mating polar bears (Ursus maritimus) in the Beaufort Sea, Canada. Polar Biol 2019. [DOI: 10.1007/s00300-019-02485-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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15
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Hamilton SG, Derocher AE. Assessment of global polar bear abundance and vulnerability. Anim Conserv 2018. [DOI: 10.1111/acv.12439] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- S. G. Hamilton
- Department of Biological Sciences University of Alberta Edmonton AB Canada
| | - A. E. Derocher
- Department of Biological Sciences University of Alberta Edmonton AB Canada
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16
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Rode KD, Wilson RR, Douglas DC, Muhlenbruch V, Atwood TC, Regehr EV, Richardson ES, Pilfold NW, Derocher AE, Durner GM, Stirling I, Amstrup SC, St Martin M, Pagano AM, Simac K. Spring fasting behavior in a marine apex predator provides an index of ecosystem productivity. GLOBAL CHANGE BIOLOGY 2018; 24:410-423. [PMID: 28994242 DOI: 10.1111/gcb.13933] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 08/02/2017] [Indexed: 05/27/2023]
Abstract
The effects of declining Arctic sea ice on local ecosystem productivity are not well understood but have been shown to vary inter-specifically, spatially, and temporally. Because marine mammals occupy upper trophic levels in Arctic food webs, they may be useful indicators for understanding variation in ecosystem productivity. Polar bears (Ursus maritimus) are apex predators that primarily consume benthic and pelagic-feeding ice-associated seals. As such, their productivity integrates sea ice conditions and the ecosystem supporting them. Declining sea ice availability has been linked to negative population effects for polar bears but does not fully explain observed population changes. We examined relationships between spring foraging success of polar bears and sea ice conditions, prey productivity, and general patterns of ecosystem productivity in the Beaufort and Chukchi Seas (CSs). Fasting status (≥7 days) was estimated using serum urea and creatinine levels of 1,448 samples collected from 1,177 adult and subadult bears across three subpopulations. Fasting increased in the Beaufort Sea between 1983-1999 and 2000-2016 and was related to an index of ringed seal body condition. This change was concurrent with declines in body condition of polar bears and observed changes in the diet, condition and/or reproduction of four other vertebrate consumers within the food chain. In contrast, fasting declined in CS polar bears between periods and was less common than in the two Beaufort Sea subpopulations consistent with studies demonstrating higher primary productivity and maintenance or improved body condition in polar bears, ringed seals, and bearded seals despite recent sea ice loss in this region. Consistency between regional and temporal variation in spring polar bear fasting and food web productivity suggests that polar bears may be a useful indicator species. Furthermore, our results suggest that spatial and temporal ecological variation is important in affecting upper trophic-level productivity in these marine ecosystems.
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Affiliation(s)
- Karyn D Rode
- U.S. Geological Survey, Alaska Science Center, Anchorage, AK, USA
| | - Ryan R Wilson
- U.S. Fish and Wildlife Service, Marine Mammals Management, Anchorage, AK, USA
| | - David C Douglas
- U.S. Geological Survey, Alaska Science Center, Juneau, AK, USA
| | | | - Todd C Atwood
- U.S. Geological Survey, Alaska Science Center, Anchorage, AK, USA
| | - Eric V Regehr
- U.S. Fish and Wildlife Service, Marine Mammals Management, Anchorage, AK, USA
| | - Evan S Richardson
- Wildlife Research Division, Science and Technology Branch, Environment Canada, Edmonton, AB, Canada
| | - Nicholas W Pilfold
- Institute for Conservation Research, San Diego Zoo Global, Escondido, CA, USA
| | - Andrew E Derocher
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - George M Durner
- U.S. Geological Survey, Alaska Science Center, Anchorage, AK, USA
| | - Ian Stirling
- Wildlife Research Division, Science and Technology Branch, Environment Canada, Edmonton, AB, Canada
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Steven C Amstrup
- Polar Bears International, Bozeman, MT, USA
- Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA
| | - Michelle St Martin
- U.S. Fish and Wildlife Service, Marine Mammals Management, Anchorage, AK, USA
| | - Anthony M Pagano
- U.S. Geological Survey, Alaska Science Center, Anchorage, AK, USA
| | - Kristin Simac
- U.S. Geological Survey, Alaska Science Center, Anchorage, AK, USA
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17
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Weegman MD, Arnold TW, Dawson RD, Winkler DW, Clark RG. Integrated population models reveal local weather conditions are the key drivers of population dynamics in an aerial insectivore. Oecologia 2017; 185:119-130. [PMID: 28573381 DOI: 10.1007/s00442-017-3890-8] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 05/24/2017] [Indexed: 12/01/2022]
Abstract
Changes to weather patterns under a warming climate are complex: while warmer temperatures are expected virtually worldwide, decreased mean precipitation is expected at mid-latitudes. Migratory birds depend on broad-scale weather patterns to inform timing of movements, but may be more susceptible to local weather patterns during sedentary periods. We constructed Bayesian integrated population models (IPMs) to assess whether continental or local weather effects best explained population dynamics in an environmentally sensitive aerial insectivorous bird, the tree swallow (Tachycineta bicolor), along a transcontinental gradient from British Columbia to Saskatchewan to New York, and tested whether population dynamics were synchronous among sites. Little consistency existed among sites in the demographic rates most affecting population growth rate or in correlations among rates. Juvenile apparent survival at all sites was stable over time and greatest in New York, whereas adult apparent survival was more variable among years and sites, and greatest in British Columbia and Saskatchewan. Fledging success was greatest in Saskatchewan. Local weather conditions explained significant variation in adult survival in Saskatchewan and fledging success in New York, corroborating the hypothesis that local more than continental weather drives the population dynamics of this species and, therefore, demographic synchrony measured at three sites was limited. Nonetheless, multi-population IPMs can be a powerful tool for identifying correlated population trajectories caused by synchronous demographic rates, and can pinpoint the scale at which environmental drivers are responsible for changes. We caution against applying uniform conservation actions for populations where synchrony does not occur or is not fully understood.
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Affiliation(s)
- Mitch D Weegman
- Department of Fisheries, Wildlife and Conservation Biology, University of Minnesota, St. Paul, MN, 55108, USA. .,Department of Biology, University of Saskatchewan, Saskatoon, SK, S7N 5E2, Canada. .,School of Natural Resources, University of Missouri, Columbia, MO, 65211, USA.
| | - Todd W Arnold
- Department of Fisheries, Wildlife and Conservation Biology, University of Minnesota, St. Paul, MN, 55108, USA
| | - Russell D Dawson
- Ecosystem Science and Management Program, University of Northern British Columbia, Prince George, BC, V2N 4Z9, Canada
| | - David W Winkler
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, 14853, USA.,Cornell Lab of Ornithology, Cornell University, Ithaca, NY, 14850, USA
| | - Robert G Clark
- Prairie and Northern Wildlife Research Centre, Environment and Climate Change Canada, Saskatoon, SK, S7N 0X4, Canada
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18
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Regehr EV, Wilson RR, Rode KD, Runge MC, Stern HL. Harvesting wildlife affected by climate change: a modelling and management approach for polar bears. J Appl Ecol 2017; 54:1534-1543. [PMID: 29081540 PMCID: PMC5637955 DOI: 10.1111/1365-2664.12864] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2016] [Accepted: 12/22/2016] [Indexed: 11/29/2022]
Abstract
The conservation of many wildlife species requires understanding the demographic effects of climate change, including interactions between climate change and harvest, which can provide cultural, nutritional or economic value to humans.We present a demographic model that is based on the polar bear Ursus maritimus life cycle and includes density-dependent relationships linking vital rates to environmental carrying capacity (K). Using this model, we develop a state-dependent management framework to calculate a harvest level that (i) maintains a population above its maximum net productivity level (MNPL; the population size that produces the greatest net increment in abundance) relative to a changing K, and (ii) has a limited negative effect on population persistence.Our density-dependent relationships suggest that MNPL for polar bears occurs at approximately 0·69 (95% CI = 0·63-0·74) of K. Population growth rate at MNPL was approximately 0·82 (95% CI = 0·79-0·84) of the maximum intrinsic growth rate, suggesting relatively strong compensation for human-caused mortality.Our findings indicate that it is possible to minimize the demographic risks of harvest under climate change, including the risk that harvest will accelerate population declines driven by loss of the polar bear's sea-ice habitat. This requires that (i) the harvest rate - which could be 0 in some situations - accounts for a population's intrinsic growth rate, (ii) the harvest rate accounts for the quality of population data (e.g. lower harvest when uncertainty is large), and (iii) the harvest level is obtained by multiplying the harvest rate by an updated estimate of population size. Environmental variability, the sex and age of removed animals and risk tolerance can also affect the harvest rate. Synthesis and applications. We present a coupled modelling and management approach for wildlife that accounts for climate change and can be used to balance trade-offs among multiple conservation goals. In our example application to polar bears experiencing sea-ice loss, the goals are to maintain population viability while providing continued opportunities for subsistence harvest. Our approach may be relevant to other species for which near-term management is focused on human factors that directly influence population dynamics within the broader context of climate-induced habitat degradation.
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Affiliation(s)
- Eric V Regehr
- U.S. Fish and Wildlife Service Anchorage AK USA.,Present address: University of Washington Seattle WA USA
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19
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Ware JV, Rode KD, Bromaghin JF, Douglas DC, Wilson RR, Regehr EV, Amstrup SC, Durner GM, Pagano AM, Olson J, Robbins CT, Jansen HT. Habitat degradation affects the summer activity of polar bears. Oecologia 2017; 184:87-99. [PMID: 28247129 DOI: 10.1007/s00442-017-3839-y] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 02/09/2017] [Indexed: 01/24/2023]
Abstract
Understanding behavioral responses of species to environmental change is critical to forecasting population-level effects. Although climate change is significantly impacting species' distributions, few studies have examined associated changes in behavior. Polar bear (Ursus maritimus) subpopulations have varied in their near-term responses to sea ice decline. We examined behavioral responses of two adjacent subpopulations to changes in habitat availability during the annual sea ice minimum using activity data. Location and activity sensor data collected from 1989 to 2014 for 202 adult female polar bears in the Southern Beaufort Sea (SB) and Chukchi Sea (CS) subpopulations were used to compare activity in three habitat types varying in prey availability: (1) land; (2) ice over shallow, biologically productive waters; and (3) ice over deeper, less productive waters. Bears varied activity across and within habitats with the highest activity at 50-75% sea ice concentration over shallow waters. On land, SB bears exhibited variable but relatively high activity associated with the use of subsistence-harvested bowhead whale carcasses, whereas CS bears exhibited low activity consistent with minimal feeding. Both subpopulations had fewer observations in their preferred shallow-water sea ice habitats in recent years, corresponding with declines in availability of this substrate. The substantially higher use of marginal habitats by SB bears is an additional mechanism potentially explaining why this subpopulation has experienced negative effects of sea ice loss compared to the still-productive CS subpopulation. Variability in activity among, and within, habitats suggests that bears alter their behavior in response to habitat conditions, presumably in an attempt to balance prey availability with energy costs.
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Affiliation(s)
- Jasmine V Ware
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA, 99164-7620, USA.
| | - Karyn D Rode
- Alaska Science Center, U.S. Geological Survey, 4210 University Dr., Anchorage, AK, 99508, USA
| | - Jeffrey F Bromaghin
- Alaska Science Center, U.S. Geological Survey, 4210 University Dr., Anchorage, AK, 99508, USA
| | - David C Douglas
- Alaska Science Center, U.S. Geological Survey, 250 Egan Drive, Juneau, AK, 99801, USA
| | - Ryan R Wilson
- U.S. Fish and Wildlife Service, 1011 East Tudor Road, MS 341, Anchorage, AK, 99503, USA
| | - Eric V Regehr
- U.S. Fish and Wildlife Service, 1011 East Tudor Road, MS 341, Anchorage, AK, 99503, USA
| | | | - George M Durner
- Alaska Science Center, U.S. Geological Survey, 4210 University Dr., Anchorage, AK, 99508, USA
| | - Anthony M Pagano
- Alaska Science Center, U.S. Geological Survey, 4210 University Dr., Anchorage, AK, 99508, USA
| | - Jay Olson
- Department of Plant and Wildlife Sciences, Brigham Young University, 5049 LSB, Provo, UT, 84602, USA
| | - Charles T Robbins
- School of the Environment and School of Biological Sciences, Washington State University, Pullman, WA, 99164-4236, USA
| | - Heiko T Jansen
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA, 99164-7620, USA
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20
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Lunn NJ, Servanty S, Regehr EV, Converse SJ, Richardson E, Stirling I. Demography of an apex predator at the edge of its range: impacts of changing sea ice on polar bears in Hudson Bay. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2016; 26:1302-1320. [PMID: 27755745 DOI: 10.1890/15-1256] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 11/30/2015] [Accepted: 12/01/2015] [Indexed: 05/25/2023]
Abstract
Changes in the abundance and distribution of wildlife populations are common consequences of historic and contemporary climate change. Some Arctic marine mammals, such as the polar bear (Ursus maritimus), may be particularly vulnerable to such changes due to the loss of Arctic sea ice. We evaluated the impacts of environmental variation on demographic rates for the Western Hudson Bay (WH), polar bear subpopulation from 1984 to 2011 using live-recapture and dead-recovery data in a Bayesian implementation of multistate capture-recapture models. We found that survival of female polar bears was related to the annual timing of sea ice break-up and formation. Using estimated vital rates (e.g., survival and reproduction) in matrix projection models, we calculated the growth rate of the WH subpopulation and projected population responses under different environmental scenarios while accounting for parametric uncertainty, temporal variation, and demographic stochasticity. Our analysis suggested a long-term decline in the number of bears from 1185 (95% Bayesian credible interval [BCI] = 993-1411) in 1987 to 806 (95% BCI = 653-984) in 2011. In the last 10 yr of the study, the number of bears appeared stable due to temporary stability in sea ice conditions (mean population growth rate for the period 2001-2010 = 1.02, 95% BCI = 0.98-1.06). Looking forward, we estimated long-term growth rates for the WH subpopulation of ~1.02 (95% BCI = 1.00-1.05) and 0.97 (95% BCI = 0.92-1.01) under hypothetical high and low sea ice conditions, respectively. Our findings support previous evidence for a demographic linkage between sea ice conditions and polar bear population dynamics. Furthermore, we present a robust framework for sensitivity analysis with respect to continued climate change (e.g., to inform scenario planning) and for evaluating the combined effects of climate change and management actions on the status of wildlife populations.
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Affiliation(s)
- Nicholas J Lunn
- Wildlife Research Division, Science & Technology Branch, Environment and Climate Change Canada, CW405 Biological Sciences Centre, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada
| | - Sabrina Servanty
- Colorado Cooperative Fish and Wildlife Research Unit, Colorado State University, Fort Collins, Colorado, 80523, USA
- Patuxent Wildlife Research Center, US Geological Survey, 12100 Beech Forest Road, Laurel, Maryland, 20708, USA
| | - Eric V Regehr
- Marine Mammals Management, US Fish and Wildlife Service, 1011 East Tudor Road, Anchorage, Alaska, 99503, USA
| | - Sarah J Converse
- Patuxent Wildlife Research Center, US Geological Survey, 12100 Beech Forest Road, Laurel, Maryland, 20708, USA
| | - Evan Richardson
- Wildlife Research Division, Science & Technology Branch, Environment and Climate Change Canada, CW405 Biological Sciences Centre, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada
| | - Ian Stirling
- Wildlife Research Division, Science & Technology Branch, Environment and Climate Change Canada, CW405 Biological Sciences Centre, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada
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21
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Atwood TC, Marcot BG, Douglas DC, Amstrup SC, Rode KD, Durner GM, Bromaghin JF. Forecasting the relative influence of environmental and anthropogenic stressors on polar bears. Ecosphere 2016. [DOI: 10.1002/ecs2.1370] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Affiliation(s)
- Todd C. Atwood
- Alaska Science CenterU.S. Geological Survey Anchorage Alaska 99508 USA
| | - Bruce G. Marcot
- Pacific Northwest Research StationU.S.D.A. Forest Service Portland Oregon 97208 USA
| | - David C. Douglas
- Alaska Science CenterU.S. Geological Survey Juneau Alaska 99801 USA
| | | | - Karyn D. Rode
- Alaska Science CenterU.S. Geological Survey Anchorage Alaska 99508 USA
| | - George M. Durner
- Alaska Science CenterU.S. Geological Survey Anchorage Alaska 99508 USA
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22
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York J, Dowsley M, Cornwell A, Kuc M, Taylor M. Demographic and traditional knowledge perspectives on the current status of Canadian polar bear subpopulations. Ecol Evol 2016; 6:2897-924. [PMID: 27069588 PMCID: PMC4804000 DOI: 10.1002/ece3.2030] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Revised: 01/21/2016] [Accepted: 01/23/2016] [Indexed: 11/05/2022] Open
Abstract
Subpopulation growth rates and the probability of decline at current harvest levels were determined for 13 subpopulations of polar bears (Ursus maritimus) that are within or shared with Canada based on mark-recapture estimates of population numbers and vital rates, and harvest statistics using population viability analyses (PVA). Aboriginal traditional ecological knowledge (TEK) on subpopulation trend agreed with the seven stable/increasing results and one of the declining results, but disagreed with PVA status of five other declining subpopulations. The decline in the Baffin Bay subpopulation appeared to be due to over-reporting of harvested numbers from outside Canada. The remaining four disputed subpopulations (Southern Beaufort Sea, Northern Beaufort Sea, Southern Hudson Bay, and Western Hudson Bay) were all incompletely mark-recapture (M-R) sampled, which may have biased their survival and subpopulation estimates. Three of the four incompletely sampled subpopulations were PVA identified as nonviable (i.e., declining even with zero harvest mortality). TEK disagreement was nonrandom with respect to M-R sampling protocols. Cluster analysis also grouped subpopulations with ambiguous demographic and harvest rate estimates separately from those with apparently reliable demographic estimates based on PVA probability of decline and unharvested subpopulation growth rate criteria. We suggest that the correspondence between TEK and scientific results can be used to improve the reliability of information on natural systems and thus improve resource management. Considering both TEK and scientific information, we suggest that the current status of Canadian polar bear subpopulations in 2013 was 12 stable/increasing and one declining (Kane Basin). We do not find support for the perspective that polar bears within or shared with Canada are currently in any sort of climate crisis. We suggest that monitoring the impacts of climate change (including sea ice decline) on polar bear subpopulations should be continued and enhanced and that adaptive management practices are warranted.
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Affiliation(s)
- Jordan York
- Department of Geography and the Environment Lakehead University 955 Oliver Road Thunder Bay ON P7B 5E1 Canada
| | - Martha Dowsley
- Department of Geography and the Environment Lakehead University 955 Oliver Road Thunder Bay ON P7B 5E1 Canada
| | - Adam Cornwell
- Department of Geography and the Environment Lakehead University 955 Oliver Road Thunder Bay ON P7B 5E1 Canada
| | - Miroslaw Kuc
- Miroslaw Kuc PH 205-942 Yonge Street Toronto ON M4W 3S8 Canada
| | - Mitchell Taylor
- Department of Geography and the Environment Lakehead University 955 Oliver Road Thunder Bay ON P7B 5E1 Canada
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23
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LaRue MA, Stapleton S, Porter C, Atkinson S, Atwood T, Dyck M, Lecomte N. Testing methods for using high-resolution satellite imagery to monitor polar bear abundance and distribution. WILDLIFE SOC B 2015. [DOI: 10.1002/wsb.596] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Michelle A. LaRue
- Department of Earth Sciences; University of Minnesota; Minneapolis MN 55455 USA
| | - Seth Stapleton
- Department of Fisheries, Wildlife and Conservation Biology; University of Minnesota; St. Paul MN 55108 USA
| | - Claire Porter
- Polar Geospatial Center; University of Minnesota; St. Paul MN 55108 USA
| | - Stephen Atkinson
- Department of Environment; Government of Nunavut; Igloolik Nunavut X0A 0L0 Canada
| | - Todd Atwood
- United States Geological Survey; Alaska Science Center; Anchorage AK 99508 USA
| | - Markus Dyck
- Department of Environment; Government of Nunavut; Igloolik Nunavut X0A 0L0 Canada
| | - Nicolas Lecomte
- Department of Environment; Government of Nunavut; Igloolik Nunavut X0A 0L0 Canada
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24
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Laidre KL, Stern H, Kovacs KM, Lowry L, Moore SE, Regehr EV, Ferguson SH, Wiig Ø, Boveng P, Angliss RP, Born EW, Litovka D, Quakenbush L, Lydersen C, Vongraven D, Ugarte F. Arctic marine mammal population status, sea ice habitat loss, and conservation recommendations for the 21st century. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2015; 29:724-37. [PMID: 25783745 PMCID: PMC5008214 DOI: 10.1111/cobi.12474] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Revised: 11/18/2014] [Accepted: 12/06/2014] [Indexed: 05/05/2023]
Abstract
Arctic marine mammals (AMMs) are icons of climate change, largely because of their close association with sea ice. However, neither a circumpolar assessment of AMM status nor a standardized metric of sea ice habitat change is available. We summarized available data on abundance and trend for each AMM species and recognized subpopulation. We also examined species diversity, the extent of human use, and temporal trends in sea ice habitat for 12 regions of the Arctic by calculating the dates of spring sea ice retreat and fall sea ice advance from satellite data (1979-2013). Estimates of AMM abundance varied greatly in quality, and few studies were long enough for trend analysis. Of the AMM subpopulations, 78% (61 of 78) are legally harvested for subsistence purposes. Changes in sea ice phenology have been profound. In all regions except the Bering Sea, the duration of the summer (i.e., reduced ice) period increased by 5-10 weeks and by >20 weeks in the Barents Sea between 1979 and 2013. In light of generally poor data, the importance of human use, and forecasted environmental changes in the 21st century, we recommend the following for effective AMM conservation: maintain and improve comanagement by local, federal, and international partners; recognize spatial and temporal variability in AMM subpopulation response to climate change; implement monitoring programs with clear goals; mitigate cumulative impacts of increased human activity; and recognize the limits of current protected species legislation.
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Affiliation(s)
- Kristin L Laidre
- Polar Science Center, Applied Physics Laboratory, 1013 NE 40th Street, University of Washington, Seattle, WA, 98105, U.S.A
- Greenland Institute of Natural Resources, P.O. Box 570, 3900, Nuuk, Greenland
| | - Harry Stern
- Polar Science Center, Applied Physics Laboratory, 1013 NE 40th Street, University of Washington, Seattle, WA, 98105, U.S.A
| | - Kit M Kovacs
- Norwegian Polar Institute, Fram Centre, N-9296, Tromsø, Norway
| | - Lloyd Lowry
- School of Fisheries and Ocean Sciences, University of Alaska, 73-4388, Paiaha Street, Kailua Kona, HI 96740, U.S.A
| | - Sue E Moore
- National Marine Fisheries Service, National Oceanographic and Atmospheric Administration, 7600 Sand Point Way NE, Seattle, WA, 98115, U.S.A
| | - Eric V Regehr
- U.S. Fish and Wildlife Service, 1011 East Tudor Road, Anchorage, AK, 99503, U.S.A
| | - Steven H Ferguson
- Fisheries and Oceans Canada, Freshwater Institute, 501 University Crescent, Winnipeg, MB, R3T 2N6, Canada
| | - Øystein Wiig
- Natural History Museum, University of Oslo, P.O. Box 1172, Blindern, N-0318, Oslo, Norway
| | - Peter Boveng
- National Marine Mammal Laboratory, Alaska Fisheries Science Center, National Oceanic and Atmospheric Administration, 7600, Sand Point Way NE, Seattle, WA 98115, U.S.A
| | - Robyn P Angliss
- National Marine Mammal Laboratory, Alaska Fisheries Science Center, National Oceanic and Atmospheric Administration, 7600, Sand Point Way NE, Seattle, WA 98115, U.S.A
| | - Erik W Born
- Greenland Institute of Natural Resources, P.O. Box 570, 3900, Nuuk, Greenland
| | - Dennis Litovka
- ChukotTINRO, P.O. Box 29, Str. Otke, 56, Anadyr, Chukotka, 689000, Russia
| | - Lori Quakenbush
- Alaska Department of Fish and Game, 1300 College Road, Fairbanks, AK, 99701, U.S.A
| | | | - Dag Vongraven
- Norwegian Polar Institute, Fram Centre, N-9296, Tromsø, Norway
| | - Fernando Ugarte
- Greenland Institute of Natural Resources, P.O. Box 570, 3900, Nuuk, Greenland
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25
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Rogers MC, Peacock E, Simac K, O’Dell MB, Welker JM. Diet of female polar bears in the southern Beaufort Sea of Alaska: evidence for an emerging alternative foraging strategy in response to environmental change. Polar Biol 2015. [DOI: 10.1007/s00300-015-1665-4] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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26
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Pilfold NW, Derocher AE, Stirling I, Richardson E. Multi-temporal factors influence predation for polar bears in a changing climate. OIKOS 2015. [DOI: 10.1111/oik.02000] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Andrew E. Derocher
- Dept of Biological Sciences; Univ. of Alberta; Edmonton, AB T6G 2E9 Canada
| | - Ian Stirling
- Dept of Biological Sciences; Univ. of Alberta; Edmonton, AB T6G 2E9 Canada
- Wildlife Research Division; Science and Technology Branch, Environment Canada; Edmonton, AB T6G 2E9 Canada
| | - Evan Richardson
- Wildlife Research Division; Science and Technology Branch, Environment Canada; Edmonton, AB T6G 2E9 Canada
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27
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Peacock E, Sonsthagen SA, Obbard ME, Boltunov A, Regehr EV, Ovsyanikov N, Aars J, Atkinson SN, Sage GK, Hope AG, Zeyl E, Bachmann L, Ehrich D, Scribner KT, Amstrup SC, Belikov S, Born EW, Derocher AE, Stirling I, Taylor MK, Wiig Ø, Paetkau D, Talbot SL. Implications of the circumpolar genetic structure of polar bears for their conservation in a rapidly warming Arctic. PLoS One 2015; 10:e112021. [PMID: 25562525 PMCID: PMC4285400 DOI: 10.1371/journal.pone.0112021] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Accepted: 09/19/2014] [Indexed: 11/18/2022] Open
Abstract
We provide an expansive analysis of polar bear (Ursus maritimus) circumpolar genetic variation during the last two decades of decline in their sea-ice habitat. We sought to evaluate whether their genetic diversity and structure have changed over this period of habitat decline, how their current genetic patterns compare with past patterns, and how genetic demography changed with ancient fluctuations in climate. Characterizing their circumpolar genetic structure using microsatellite data, we defined four clusters that largely correspond to current ecological and oceanographic factors: Eastern Polar Basin, Western Polar Basin, Canadian Archipelago and Southern Canada. We document evidence for recent (ca. last 1–3 generations) directional gene flow from Southern Canada and the Eastern Polar Basin towards the Canadian Archipelago, an area hypothesized to be a future refugium for polar bears as climate-induced habitat decline continues. Our data provide empirical evidence in support of this hypothesis. The direction of current gene flow differs from earlier patterns of gene flow in the Holocene. From analyses of mitochondrial DNA, the Canadian Archipelago cluster and the Barents Sea subpopulation within the Eastern Polar Basin cluster did not show signals of population expansion, suggesting these areas may have served also as past interglacial refugia. Mismatch analyses of mitochondrial DNA data from polar and the paraphyletic brown bear (U. arctos) uncovered offset signals in timing of population expansion between the two species, that are attributed to differential demographic responses to past climate cycling. Mitogenomic structure of polar bears was shallow and developed recently, in contrast to the multiple clades of brown bears. We found no genetic signatures of recent hybridization between the species in our large, circumpolar sample, suggesting that recently observed hybrids represent localized events. Documenting changes in subpopulation connectivity will allow polar nations to proactively adjust conservation actions to continuing decline in sea-ice habitat.
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Affiliation(s)
- Elizabeth Peacock
- Alaska Science Center, US Geological Survey, Anchorage, Alaska, United States of America
- Department of Environment, Government of Nunavut, Igloolik, Nunavut, Canada
- * E-mail:
| | - Sarah A. Sonsthagen
- Alaska Science Center, US Geological Survey, Anchorage, Alaska, United States of America
| | - Martyn E. Obbard
- Ontario Ministry of Natural Resources and Forestry, Peterborough, Ontario, Canada
| | - Andrei Boltunov
- All-Russian Research Institute for Nature Protection, Moscow, Russian Federation
| | - Eric V. Regehr
- US Fish and Wildlife Service, Marine Mammals Management, Anchorage, Alaska, United States of America
| | | | - Jon Aars
- Norwegian Polar Institute, Tromsø, Norway
| | | | - George K. Sage
- Alaska Science Center, US Geological Survey, Anchorage, Alaska, United States of America
| | - Andrew G. Hope
- Alaska Science Center, US Geological Survey, Anchorage, Alaska, United States of America
| | - Eve Zeyl
- Natural History Museum, University of Oslo, Oslo, Norway
| | - Lutz Bachmann
- Natural History Museum, University of Oslo, Oslo, Norway
| | | | - Kim T. Scribner
- Department of Zoology, Michigan State University, East Lansing, Michigan, United States of America
| | - Steven C. Amstrup
- Polar Bears International, Bozeman, Montana, United States of America
| | - Stanislav Belikov
- All-Russian Research Institute for Nature Protection, Moscow, Russian Federation
| | - Erik W. Born
- Greenland Institute of Natural Resources, Copenhagen, Denmark
| | - Andrew E. Derocher
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Ian Stirling
- Science & Technology Branch, Environment Canada, Edmonton, Alberta, Canada
| | - Mitchell K. Taylor
- Faculty of Science and Environmental Studies, Lakehead University, Thunder Bay, Ontario, Canada
| | - Øystein Wiig
- Natural History Museum, University of Oslo, Oslo, Norway
| | - David Paetkau
- Wildlife Genetics International, Nelson, British Columbia, Canada
| | - Sandra L. Talbot
- Alaska Science Center, US Geological Survey, Anchorage, Alaska, United States of America
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Wilson RR, Horne JS, Rode KD, Regehr EV, Durner GM. Identifying polar bear resource selection patterns to inform offshore development in a dynamic and changing Arctic. Ecosphere 2014. [DOI: 10.1890/es14-00193.1] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Rode KD, Regehr EV, Douglas DC, Durner G, Derocher AE, Thiemann GW, Budge SM. Variation in the response of an Arctic top predator experiencing habitat loss: feeding and reproductive ecology of two polar bear populations. GLOBAL CHANGE BIOLOGY 2014; 20:76-88. [PMID: 23913506 DOI: 10.1111/gcb.12339] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 07/20/2013] [Indexed: 06/02/2023]
Abstract
Polar bears (Ursus maritimus) have experienced substantial changes in the seasonal availability of sea ice habitat in parts of their range, including the Beaufort, Chukchi, and Bering Seas. In this study, we compared the body size, condition, and recruitment of polar bears captured in the Chukchi and Bering Seas (CS) between two periods (1986-1994 and 2008-2011) when declines in sea ice habitat occurred. In addition, we compared metrics for the CS population 2008-2011 with those of the adjacent southern Beaufort Sea (SB) population where loss in sea ice habitat has been associated with declines in body condition, size, recruitment, and survival. We evaluated how variation in body condition and recruitment were related to feeding ecology. Comparing habitat conditions between populations, there were twice as many reduced ice days over continental shelf waters per year during 2008-2011 in the SB than in the CS. CS polar bears were larger and in better condition, and appeared to have higher reproduction than SB bears. Although SB and CS bears had similar diets, twice as many bears were fasting in spring in the SB than in the CS. Between 1986-1994 and 2008-2011, body size, condition, and recruitment indices in the CS were not reduced despite a 44-day increase in the number of reduced ice days. Bears in the CS exhibited large body size, good body condition, and high indices of recruitment compared to most other populations measured to date. Higher biological productivity and prey availability in the CS relative to the SB, and a shorter recent history of reduced sea ice habitat, may explain the maintenance of condition and recruitment of CS bears. Geographic differences in the response of polar bears to climate change are relevant to range-wide forecasts for this and other ice-dependent species.
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Affiliation(s)
- Karyn D Rode
- Marine Mammals Management, U. S. Fish and Wildlife Service, 1011 E Tudor Road, Anchorage, AK, 99502, USA
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Bromaghin JF, McDonald TL, Amstrup SC. Plausible combinations: An improved method to evaluate the covariate structure of Cormack-Jolly-Seber mark-recapture models. ACTA ACUST UNITED AC 2013. [DOI: 10.4236/oje.2013.31002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Robbins CT, Lopez-Alfaro C, Rode KD, Tøien Ø, Nelson OL. Hibernation and seasonal fasting in bears: the energetic costs and consequences for polar bears. J Mammal 2012. [DOI: 10.1644/11-mamm-a-406.1] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Vongraven D, Aars J, Amstrup S, Atkinson SN, Belikov S, Born EW, DeBruyn TD, Derocher AE, Durner G, Gill M, Lunn N, Obbard ME, Omelak J, Ovsyanikov N, Peacock E, Richardson E, Sahanatien V, Stirling I, Wiig Ø. A circumpolar monitoring framework for polar bears. URSUS 2012. [DOI: 10.2192/ursus-d-11-00026.1] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Rode KD, Peacock E, Taylor M, Stirling I, Born EW, Laidre KL, Wiig Ø. A tale of two polar bear populations: ice habitat, harvest, and body condition. POPUL ECOL 2011. [DOI: 10.1007/s10144-011-0299-9] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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