1
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Barnas AF, Simone CAB, Geldart EA, Love OP, Jagielski PM, Gilchrist HG, Richardson ES, Dey CJ, Semeniuk CAD. An interspecific foraging association with polar bears increases foraging opportunities for avian predators in a declining Arctic seabird colony. Ecol Evol 2024; 14:e11012. [PMID: 38469043 PMCID: PMC10926061 DOI: 10.1002/ece3.11012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 12/04/2023] [Accepted: 12/06/2023] [Indexed: 03/13/2024] Open
Abstract
Interspecific foraging associations (IFAs) are biological interactions where two or more species forage in association with each other. Climate-induced reductions in Arctic sea ice have increased polar bear (Ursus maritimus) foraging in seabird colonies, which creates foraging opportunities for avian predators. We used drone video of bears foraging within a common eider (Somateria mollissima) colony on East Bay Island (Nunavut, Canada) in 2017 to investigate herring gull (Larus argentatus) foraging in association with bears. We recorded nest visitation by gulls following n = 193 eider flushing events from nests during incubation. The probability of gulls visiting eider nests increased with higher number of gulls present (β = 0.14 ± 0.03 [SE], p < .001) and for nests previously visited by a bear (β = 1.14 ± 0.49 [SE], p < .02). In our model examining the probability of gulls consuming eggs from nests, we failed to detect statistically significant effects for the number of gulls present (β = 0.09 ± 0.05 [SE], p < .07) or for nests previously visited by a bear (β = -0.92 ± 0.71 [SE], p < .19). Gulls preferred to visit nests behind bears (χ2 = 18, df = 1, p < .0001), indicating gulls are risk averse in the presence of polar bears. Our study provides novel insights on an Arctic IFA, and we present evidence that gulls capitalize on nests made available due to disturbance associated with foraging bears, as eiders disturbed off their nest allow gulls easier access to eggs. We suggest the IFA between gulls and polar bears is parasitic, as gulls are consuming terrestrial resources which would have eventually been consumed by bears. This finding has implications for estimating the energetic contribution of bird eggs to polar bear summer diets in that the total number of available clutches to consume may be reduced due to avian predators.
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Affiliation(s)
- Andrew F. Barnas
- Department of Integrative BiologyUniversity of WindsorWindsorOntarioCanada
- School of Environmental StudiesUniversity of VictoriaVictoriaBritish ColumbiaCanada
| | | | - Erica A. Geldart
- Department of Integrative BiologyUniversity of WindsorWindsorOntarioCanada
| | - Oliver P. Love
- Department of Integrative BiologyUniversity of WindsorWindsorOntarioCanada
| | | | - H. Grant Gilchrist
- National Wildlife Research Centre, Science and Technology BranchEnvironment and Climate Change CanadaOttawaOntarioCanada
| | - Evan S. Richardson
- Science and Technology BranchEnvironment and Climate Change CanadaOttawaOntarioCanada
| | - Cody J. Dey
- Department of Integrative BiologyUniversity of WindsorWindsorOntarioCanada
- Science and Technology BranchEnvironment and Climate Change CanadaOttawaOntarioCanada
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2
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Pagano AM, Rode KD, Lunn NJ, McGeachy D, Atkinson SN, Farley SD, Erlenbach JA, Robbins CT. Polar bear energetic and behavioral strategies on land with implications for surviving the ice-free period. Nat Commun 2024; 15:947. [PMID: 38351211 PMCID: PMC10864307 DOI: 10.1038/s41467-023-44682-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 12/21/2023] [Indexed: 02/16/2024] Open
Abstract
Declining Arctic sea ice is increasing polar bear land use. Polar bears on land are thought to minimize activity to conserve energy. Here, we measure the daily energy expenditure (DEE), diet, behavior, movement, and body composition changes of 20 different polar bears on land over 19-23 days from August to September (2019-2022) in Manitoba, Canada. Polar bears on land exhibited a 5.2-fold range in DEE and 19-fold range in activity, from hibernation-like DEEs to levels approaching active bears on the sea ice, including three individuals that made energetically demanding swims totaling 54-175 km. Bears consumed berries, vegetation, birds, bones, antlers, seal, and beluga. Beyond compensating for elevated DEE, there was little benefit from terrestrial foraging toward prolonging the predicted time to starvation, as 19 of 20 bears lost mass (0.4-1.7 kg•day-1). Although polar bears on land exhibit remarkable behavioral plasticity, our findings reinforce the risk of starvation, particularly in subadults, with forecasted increases in the onshore period.
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Affiliation(s)
- Anthony M Pagano
- U. S. Geological Survey, Alaska Science Center, Anchorage, AK, 99508, USA.
| | - Karyn D Rode
- U. S. Geological Survey, Alaska Science Center, Anchorage, AK, 99508, USA
| | - Nicholas J Lunn
- Wildlife Research Division, Science and Technology Branch, Environment and Climate Change Canada, Edmonton, AB, T6G 2E9, Canada
| | - David McGeachy
- Wildlife Research Division, Science and Technology Branch, Environment and Climate Change Canada, Edmonton, AB, T6G 2E9, Canada
| | | | - Sean D Farley
- Alaska Department of Fish and Game, Anchorage, AK, 99518, USA
| | - Joy A Erlenbach
- School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA
- U.S. Fish and Wildlife Service, Kodiak National Wildlife Refuge, Kodiak, AK, 99615, USA
| | - Charles T Robbins
- School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA
- School of the Environment, Washington State University, Pullman, WA, 99164, USA
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3
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Tidière M, Colchero F, Staerk J, Adkesson MJ, Andersen DH, Bland L, Böye M, Brando S, Clegg I, Cubaynes S, Cutting A, De Man D, Derocher AE, Dorsey C, Elgar W, Gaglione E, Anderson Hansen K, Jungheim A, Kok J, Laule G, Goya AL, Miller L, Monreal-Pawlowsky T, Mucha K, Owen MA, Petersen SD, Pilfold N, Richardson D, Richardson ES, Sabo D, Sato N, Shellabarger W, Skovlund CR, Tomisawa K, Trautwein SE, Van Bonn W, Van Elk C, Von Fersen L, Wahlberg M, Zhang P, Zhang X, Conde DA. Survival improvements of marine mammals in zoological institutions mirror historical advances in human longevity. Proc Biol Sci 2023; 290:20231895. [PMID: 37848064 PMCID: PMC10581765 DOI: 10.1098/rspb.2023.1895] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 09/21/2023] [Indexed: 10/19/2023] Open
Abstract
An intense public debate has fuelled governmental bans on marine mammals held in zoological institutions. The debate rests on the assumption that survival in zoological institutions has been and remains lower than in the wild, albeit the scientific evidence in support of this notion is equivocal. Here, we used statistical methods previously applied to assess historical improvements in human lifespan and data on 8864 individuals of four marine mammal species (harbour seal, Phoca vitulina; California sea lion, Zalophus californianus; polar bear, Ursus maritimus; common bottlenose dolphin, Tursiops truncatus) held in zoos from 1829 to 2020. We found that life expectancy increased up to 3.40 times, and first-year mortality declined up to 31%, during the last century in zoos. Moreover, the life expectancy of animals in zoos is currently 1.65-3.55 times longer than their wild counterparts. Like humans, these improvements have occurred concurrently with advances in management practices, crucial for population welfare. Science-based decisions will help effective legislative changes and ensure better implementation of animal care.
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Affiliation(s)
- Morgane Tidière
- Interdisciplinary Centre on Population Dynamics (CPop), University of Southern Denmark, Odense, Denmark
- Department of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense, Denmark
- Conservation and Science Department, Species360, 7900 International Drive, Suite 300, Minneapolis, MN 55425, USA
| | - Fernando Colchero
- Interdisciplinary Centre on Population Dynamics (CPop), University of Southern Denmark, Odense, Denmark
- Department of Mathematics and Computer Science, University of Southern Denmark, Odense, Denmark
- Department of Primate Behavior and Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Pl. 6, 04103 Leipzig, Germany
| | - Johanna Staerk
- Interdisciplinary Centre on Population Dynamics (CPop), University of Southern Denmark, Odense, Denmark
- Department of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense, Denmark
- Conservation and Science Department, Species360, 7900 International Drive, Suite 300, Minneapolis, MN 55425, USA
| | | | - Ditte H. Andersen
- Department of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense, Denmark
| | - Lucie Bland
- Conservation and Science Department, Species360, 7900 International Drive, Suite 300, Minneapolis, MN 55425, USA
- Eureka Publishing, Thornbury, Australia
| | - Martin Böye
- Centre de Recherche et d'Etude pour l'Animal Sauvage, Planète Sauvage, 44710 Port Saint Pere, France
| | - Sabrina Brando
- AnimalConcepts, PO Box 378, 03725 Teulada, Alicante, Spain
| | - Isabella Clegg
- Animal Welfare Expertise, The Knoll, Woodlands, Combe Martin, EX34 0ATLittleton Manor, Winchester SO22 6QU, UK
| | - Sarah Cubaynes
- CEFE, Univ Montpellier, CNRS, EPHE-PSL University, IRD, Montpellier, France
| | - Amy Cutting
- Polar Bear International, PO Box 3008, Bozeman, MT, USA
| | - Danny De Man
- European Association of Zoos and Aquaria (EAZA), Plantage Middelaan 45, 1018-DC Amsterdam, The Netherlands
| | - Andrew E. Derocher
- Department of Biological Sciences, University of Alberta; Edmonton, Alberta, Canada T6G 2E9
| | - Candice Dorsey
- Association of Zoos and Aquariums, 8403 Colesville Road Ste 710, Silver Spring, MD 20910, USA
| | - William Elgar
- Zoo Miami, 12400 SW 152 Street, Miami, FL 33177, USA
| | - Eric Gaglione
- Georgia Aquarium, 225 Baker Street, Atlanta, GA 30313, USA
| | - Kirstin Anderson Hansen
- Department of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense, Denmark
- Marine Biological Research Center, University of Southern Denmark, Hindsholmvej 11, 5300 Kerteminde, Denmark
| | - Allison Jungheim
- Como Park Zoo and Conservatory, 1225 Estabrook Dr., Saint Paul, MN 55103, USA
| | - José Kok
- Ouwehands Zoo, Grebbeweg 111, 3911 AV Rhenen, The Netherlands
| | - Gail Laule
- Mandai Wildlife Group, 80 Mandai Lake Road, Singapore 729826
| | | | - Lance Miller
- Chicago Zoological Society, Brookfield Zoo, Brookfield, IL, USA
| | | | - Katelyn Mucha
- Conservation and Science Department, Species360, 7900 International Drive, Suite 300, Minneapolis, MN 55425, USA
| | - Megan A. Owen
- San Diego Zoo Wildlife Alliance, 15600 San Pasqual Valley Rd., Escondido, CA, USA
| | | | - Nicholas Pilfold
- San Diego Zoo Wildlife Alliance, 15600 San Pasqual Valley Rd., Escondido, CA, USA
| | - Douglas Richardson
- Zoological Consultancy Ltd, Columba Cottage, Mill Rd, Kingussie PH21 1LF, UK
- EAZA Polar Bear EEP, Amsterdam, Netherlands
| | - Evan S. Richardson
- Environment and Climate Change Canada, Unit 150–234 Donald Street, Winnipeg, Manitoba R3C 1M8, Canada
| | - Devon Sabo
- Columbus Zoo and Aquarium, 4850 W. Powell Road, PO Box 400, Powell, OH 43065-0400, USA
| | - Nobutaka Sato
- Asahiyama Zoological Park, Kuranuma, Higasiasahikawacho, Asahikawa city, Japan
| | | | - Cecilie R. Skovlund
- Conservation, Copenhagen Zoo, Roskildevej 38, 2000 Frederiksberg, Denmark
- Section of Animal Welfare and Disease Control, Department of Veterinary and Animal Sciences, University of Copenhagen, Grønnegårdsvej 8, 1870 Frederiksberg, Denmark
| | - Kanako Tomisawa
- Omuta City Zoo, 163 Showa-machi, Omuta, Fukuoka 836-0871, Japan
| | - Sandra E. Trautwein
- Conservation and Science Department, Species360, 7900 International Drive, Suite 300, Minneapolis, MN 55425, USA
| | - William Van Bonn
- A. Watson Armour III, Center for Animal Health and Welfare, Animal Care and Science Division, John G. Shedd Aquarium, Chicago, IL 60605, USA
| | - Cornelis Van Elk
- Independent practitioner, Arendsweg 98, Enschede 7544RM, The Netherlands
| | | | - Magnus Wahlberg
- Department of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense, Denmark
- Marine Biological Research Center, University of Southern Denmark, Hindsholmvej 11, 5300 Kerteminde, Denmark
| | - Peijun Zhang
- Mammal and Marine Bioacoustics Laboratory Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya 572000, People's Republic of China
| | - Xianfeng Zhang
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, People's Republic of China
| | - Dalia A. Conde
- Interdisciplinary Centre on Population Dynamics (CPop), University of Southern Denmark, Odense, Denmark
- Department of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense, Denmark
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4
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Verstege JS, Johnson-Bice SM, Roth JD. Arctic and red fox population responses to climate and cryosphere changes at the Arctic's edge. Oecologia 2023; 202:589-599. [PMID: 37458813 DOI: 10.1007/s00442-023-05418-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 07/01/2023] [Indexed: 07/30/2023]
Abstract
Responses of one species to climate change may influence the population dynamics of others, particularly in the Arctic where food webs are strongly linked. Specifically, changes to the cryosphere may limit prey availability for predators. We examined Arctic (Vulpes lagopus) and red fox (V. vulpes) population dynamics near the southern edge of the Arctic fox distribution using fur harvest records from Churchill, Manitoba, Canada between 1955 and 2012. Arctic foxes showed a declining population trend over time (inferred from harvest records corrected for trapping effort), whereas the red fox population trend was relatively stable. The positive relationship between the annual Arctic and red fox harvests suggested interspecific competition did not promote the Arctic fox decline. To investigate alternative mechanisms, we evaluated the relative influence of sea-ice phenology, snow depth, snow duration, winter thaws, and summer temperature on the harvest dynamics of both species in the most recent 32 years (1980-2012; n = 29) of our data. Arctic fox harvests were negatively related to the length of time Hudson Bay was free of sea ice. Shorter sea ice duration may reduce access to seal carrion as an alternative winter food source when lemming densities decline. Contrary to our prediction, red fox harvest was not related to summer temperature but was positively related to snow depth, suggesting winter prey availability may limit red fox population growth. Predators have an important ecological role, so understanding the influence of changes in the cryosphere on predator-prey interactions may better illuminate the broader influence of climate change on food-web dynamics.
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Affiliation(s)
- Jacqueline S Verstege
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada
| | - Sean M Johnson-Bice
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada
| | - James D Roth
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada.
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5
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Buhler KJ, Dibernardo A, Pilfold NW, Harms NJ, Fenton H, Carriere S, Kelly A, Schwantje H, Aguilar XF, Leclerc LM, Gouin GG, Lunn NJ, Richardson ES, McGeachy D, Bouchard É, Ortiz AH, Samelius G, Lindsay LR, Drebot MA, Gaffney P, Leighton P, Alisauskas R, Jenkins E. Widespread Exposure to Mosquitoborne California Serogroup Viruses in Caribou, Arctic Fox, Red Fox, and Polar Bears, Canada. Emerg Infect Dis 2023; 29:54-63. [PMID: 36573538 PMCID: PMC9796188 DOI: 10.3201/eid2901.220154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Northern Canada is warming at 3 times the global rate. Thus, changing diversity and distribution of vectors and pathogens is an increasing health concern. California serogroup (CSG) viruses are mosquitoborne arboviruses; wildlife reservoirs in northern ecosystems have not been identified. We detected CSG virus antibodies in 63% (95% CI 58%-67%) of caribou (n = 517), 4% (95% CI 2%-7%) of Arctic foxes (n = 297), 12% (95% CI 6%-21%) of red foxes (n = 77), and 28% (95% CI 24%-33%) of polar bears (n = 377). Sex, age, and summer temperatures were positively associated with polar bear exposure; location, year, and ecotype were associated with caribou exposure. Exposure was highest in boreal caribou and increased from baseline in polar bears after warmer summers. CSG virus exposure of wildlife is linked to climate change in northern Canada and sustained surveillance could be used to measure human health risks.
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6
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Wilder JM, Mangipane LS, Atwood T, Kochnev A, Smith T, Vongraven D. Efficacy of bear spray as a deterrent against polar bears. WILDLIFE SOC B 2022. [DOI: 10.1002/wsb.1403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- James M. Wilder
- U.S. Fish and Wildlife Service, Marine Mammals Management 1011 E. Tudor Road Anchorage AK 99503 USA
| | - Lindsey S. Mangipane
- U.S. Fish and Wildlife Service, Marine Mammals Management 1011 E. Tudor Road Anchorage AK 99503 USA
| | - Todd Atwood
- U.S. Geological Survey, Alaska Science Center, 4210 University Drive Anchorage Alaska 99508 USA
| | - Anatoly Kochnev
- Russian Academy of Sciences, Far East Branch, Institute of Biological Problems of the North, Mammals Ecology Lab, 18 Portovaya Street 685000 Magadan Russia
- Beringia National Park, 10 Naberezhnaya Dezhneva 89251 Provideniya Russia
| | - Tom Smith
- Wildlife and Wildlands Conservation Program Brigham Young University 5050 Life Sciences Building Provo Utah 84602 USA
| | - Dag Vongraven
- Norwegian Polar Institute, Fram Center N‐9296 Tromsø Norway
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7
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Himes Boor GK, McGuire TL, Warlick AJ, Taylor RL, Converse SJ, McClung JR, Stephens AD. Estimating reproductive and juvenile survival rates when offspring ages are uncertain: A novel multievent mark‐resight model with beluga whale case study. Methods Ecol Evol 2022. [DOI: 10.1111/2041-210x.14032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
| | | | - Amanda J. Warlick
- School of Aquatic and Fishery Sciences University of Washington Seattle Washington USA
| | | | - Sarah J. Converse
- U.S. Geological Survey, Washington Cooperative Fish and Wildlife Research Unit, School of Environmental and Forest Sciences & School of Aquatic and Fishery Sciences University of Washington Seattle Washington USA
| | - John R. McClung
- The Cook Inlet Beluga Whale Photo‐ID Project Anchorage Alaska USA
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8
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Rode KD, Douglas D, Atwood T, Durner G, Wilson R, Pagano A. Observed and forecasted changes in land use by polar bears in the Beaufort and Chukchi Seas, 1985–2040. Glob Ecol Conserv 2022. [DOI: 10.1016/j.gecco.2022.e02319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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9
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Togunov RR, Derocher AE, Lunn NJ, Auger-Méthé M. Drivers of polar bear behavior and the possible effects of prey availability on foraging strategy. MOVEMENT ECOLOGY 2022; 10:50. [PMID: 36384775 PMCID: PMC9670556 DOI: 10.1186/s40462-022-00351-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 11/09/2022] [Indexed: 06/05/2023]
Abstract
BACKGROUND Change in behavior is one of the earliest responses to variation in habitat suitability. It is therefore important to understand the conditions that promote different behaviors, particularly in areas undergoing environmental change. Animal movement is tightly linked to behavior and remote tracking can be used to study ethology when direct observation is not possible. METHODS We used movement data from 14 polar bears (Ursus maritimus) in Hudson Bay, Canada, during the foraging season (January-June), when bears inhabit the sea ice. We developed an error-tolerant method to correct for sea ice drift in tracking data. Next, we used hidden Markov models with movement and orientation relative to wind to study three behaviors (stationary, area-restricted search, and olfactory search) and examine effects of 11 covariates on behavior. RESULTS Polar bears spent approximately 47% of their time in the stationary drift state, 29% in olfactory search, and 24% in area-restricted search. High energy behaviors occurred later in the day (around 20:00) compared to other populations. Second, olfactory search increased as the season progressed, which may reflect a shift in foraging strategy from still-hunting to active search linked to a shift in seal availability (i.e., increase in haul-outs from winter to the spring pupping and molting seasons). Last, we found spatial patterns of distribution linked to season, ice concentration, and bear age that may be tied to habitat quality and competitive exclusion. CONCLUSIONS Our observations were generally consistent with predictions of the marginal value theorem, and differences between our findings and other populations could be explained by regional or temporal variation in resource availability. Our novel movement analyses and finding can help identify periods, regions, and conditions of critical habitat.
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Affiliation(s)
- Ron R. Togunov
- Institute for the Oceans and Fisheries, The University of British Columbia, V6T 1Z4 Vancouver, Canada
- Department of Zoology, The University of British Columbia, Vancouver, V6T 1Z4 Canada
| | - Andrew E. Derocher
- Department of Biological Sciences, University of Alberta, Edmonton, T6G 2E9 Canada
| | - Nicholas J. Lunn
- Wildlife Research Division, Science and Technology Branch, Environment and Climate Change Canada, Edmonton, T6G 2E9 Canada
| | - Marie Auger-Méthé
- Institute for the Oceans and Fisheries, The University of British Columbia, V6T 1Z4 Vancouver, Canada
- Department of Statistics, The University of British Columbia, Vancouver, V6T 1Z4 Canada
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10
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Naciri M, Aars J, Blanchet MA, Gimenez O, Cubaynes S. Reproductive senescence in polar bears in a variable environment. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.920481] [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
Reproductive senescence is ubiquitous in mammals. However, patterns of senescence vary across reproductive traits, even within populations, perhaps because of differences in selection pressures, physiological constraints, and responses to environmental conditions. We investigated reproductive senescence in wild female polar bears (Ursus maritimus), using 31 years of capture-recapture data from the Svalbard area. We studied the influence of environmental conditions on age-specific litter production and litter size using generalized linear mixed models. Further, using a capture-recapture model that handles the dependency between vital rates of individuals belonging to the same family unit, we assessed maternal-age-related changes in first year cub and litter survival. We provide clear evidence for reproductive senescence in female polar bears. Litter production and litter size peaked in middle-aged females and declined sharply afterward. By contrast cub and litter survival did not decline after prime age. We found no evidence of terminal investment. The reproductive output of all females was affected by sea-ice conditions during the previous year and the Arctic Oscillation, with some effects differing greatly between age groups. Old females were affected the most by environmental conditions. Our results suggest that the decline in reproductive output is a combination of fertility and body-condition senescence, with a weak contribution of maternal-effect senescence, possibly due to benefits of experience. Further, as predicted by evolutionary theory, senescence appears to be a consequence of failures in early stages of the reproductive cycle rather than in late stages, and environmental variation affected old females more than prime-aged females. Our study emphasizes the need to study several reproductive traits and account for environmental variation when investigating reproductive senescence. Differences in senescence patterns across reproductive traits should be interpreted in light of evolutionary theory and while considering underlying physiological drivers.
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11
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Hostetter NJ, Regehr EV, Wilson RR, Royle JA, Converse SJ. Modeling spatiotemporal abundance and movement dynamics using an integrated spatial capture-recapture movement model. Ecology 2022; 103:e3772. [PMID: 35633152 PMCID: PMC9787655 DOI: 10.1002/ecy.3772] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Revised: 12/21/2021] [Accepted: 01/21/2022] [Indexed: 12/30/2022]
Abstract
Animal movement is a fundamental ecological process affecting the survival and reproduction of individuals, the structure of populations, and the dynamics of communities. Methods to quantify animal movement and spatiotemporal abundances, however, are generally separate and therefore omit linkages between individual-level and population-level processes. We describe an integrated spatial capture-recapture (SCR) movement model to jointly estimate (1) the number and distribution of individuals in a defined spatial region and (2) movement of those individuals through time. We applied our model to a study of polar bears (Ursus maritimus) in a 28,125 km2 survey area of the eastern Chukchi Sea, USA in 2015 that incorporated capture-recapture and telemetry data. In simulation studies, the model provided unbiased estimates of movement, abundance, and detection parameters using a bivariate normal random walk and correlated random walk movement process. Our case study provided detailed evidence of directional movement persistence for both male and female bears, where individuals regularly traversed areas larger than the survey area during the 36-day study period. Scaling from individual- to population-level inferences, we found that densities varied from <0.75 bears/625 km2 grid cell/day in nearshore cells to 1.6-2.5 bears/grid cell/day for cells surrounded by sea ice. Daily abundance estimates ranged from 53 to 69 bears, with no trend across days. The cumulative number of unique bears that used the survey area increased through time due to movements into and out of the area, resulting in an estimated 171 individuals using the survey area during the study (95% credible interval 124-250). Abundance estimates were similar to a previous multiyear integrated population model using capture-recapture and telemetry data (2008-2016; Regehr et al., Scientific Reports 8:16780, 2018). Overall, the SCR-movement model successfully quantified both individual- and population-level space use, including the effects of landscape characteristics on movement, abundance, and detection, while linking the movement and abundance processes to directly estimate density within a prescribed spatial region and temporal period. Integrated SCR-movement models provide a generalizable approach to incorporate greater movement realism into population dynamics and link movement to emergent properties including spatiotemporal densities and abundances.
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Affiliation(s)
- Nathan J. Hostetter
- Washington Cooperative Fish and Wildlife Research Unit, School of Aquatic and Fishery SciencesUniversity of WashingtonSeattleWashingtonUSA,Present address:
United States Geological Survey, North Carolina Cooperative Fish and Wildlife Research Unit, Department of Applied EcologyNorth Carolina State UniversityRaleighNorth CarolinaUSA
| | - Eric V. Regehr
- Applied Physics LaboratoryPolar Science Center, University of WashingtonSeattleWashingtonUSA
| | - Ryan R. Wilson
- Marine Mammals ManagementUnited States Fish and Wildlife ServiceAnchorageAlaskaUSA
| | - J. Andrew Royle
- United States Geological SurveyEastern Ecological Science CenterLaurelMarylandUSA
| | - Sarah J. Converse
- United States Geological Survey, Washington Cooperative Fish and Wildlife Research Unit, School of Environmental and Forest Sciences and School of Aquatic and Fishery SciencesUniversity of WashingtonSeattleWashingtonUSA
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12
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Whisker spots on polar bears reveal increasing fluctuating asymmetry. Mamm Biol 2022. [DOI: 10.1007/s42991-022-00294-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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13
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Anthropogenic food: an emerging threat to polar bears. ORYX 2022. [DOI: 10.1017/s0030605322000278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Abstract
Supplemental food from anthropogenic sources is a source of conflict with humans for many wildlife species. Food-seeking behaviours by black bears Ursus americanus and brown bears Ursus arctos can lead to property damage, human injury and mortality of the offending bears. Such conflicts are a well-known conservation management issue wherever people live in bear habitats. In contrast, the use of anthropogenic foods by the polar bear Ursus maritimus is less common historically but is a growing conservation and management issue across the Arctic. Here we present six case studies that illustrate how negative food-related interactions between humans and polar bears can become either chronic or ephemeral and unpredictable. Our examination suggests that attractants are an increasing problem, exacerbated by climate change-driven sea-ice losses that cause increased use of terrestrial habitats by bears. Growing human populations and increased human visitation increase the likelihood of human–polar bear conflict. Efforts to reduce food conditioning in polar bears include attractant management, proactive planning and adequate resources for northern communities to reduce conflicts and improve human safety. Permanent removal of unsecured sources of nutrition, to reduce food conditioning, should begin immediately at the local level as this will help to reduce polar bear mortality.
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14
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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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15
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Autumn migration phenology of polar bears (Ursus maritimus) in Hudson Bay, Canada. Polar Biol 2022. [DOI: 10.1007/s00300-022-03050-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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16
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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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17
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The Adrenal Cortisol Response to Increasing Ambient Temperature in Polar Bears ( Ursus maritimus). Animals (Basel) 2022; 12:ani12060672. [PMID: 35327071 PMCID: PMC8944560 DOI: 10.3390/ani12060672] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 02/28/2022] [Accepted: 03/04/2022] [Indexed: 02/01/2023] Open
Abstract
Our objective was to identify the upper ambient temperature threshold that triggers an increase in cortisol in response to increased thermoregulatory demands in polar bears. The results reported here include endocrine data collected over two years from 25 polar bears housed in 11 accredited zoological institutions across North America. The effects of ambient temperature, sex, age group (juvenile, adult, elderly), breeding season and humidity on fecal cortisol metabolite (FCM) concentrations (N = 8439 samples) were evaluated using linear mixed models. Ambient temperatures were placed into five different categories: <5 °C, 6−10 °C, 11−15 °C, 16−20 °C, and >20 °C. Ambient temperature and humidity had a significant (p < 0.05) effect on FCM concentrations with significant (p < 0.05) interactions of sex, age and breeding season. Once biotic factors were accounted for, there was a significant (p < 0.05) increase in FCM concentrations associated with ambient temperatures above 20 °C in adult polar bears. The implications of these findings for the management of both zoo and wild polar bears are discussed.
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18
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Regehr EV, Runge MC, Von Duyke A, Wilson RR, Polasek L, Rode KD, Hostetter NJ, Converse SJ. Demographic risk assessment for a harvested species threatened by climate change: polar bears in the Chukchi Sea. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2021; 31:e02461. [PMID: 34582601 PMCID: PMC9286533 DOI: 10.1002/eap.2461] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 02/09/2021] [Accepted: 04/05/2021] [Indexed: 06/13/2023]
Abstract
Climate change threatens global biodiversity. Many species vulnerable to climate change are important to humans for nutritional, cultural, and economic reasons. Polar bears Ursus maritimus are threatened by sea-ice loss and represent a subsistence resource for Indigenous people. We applied a novel population modeling-management framework that is based on species life history and accounts for habitat loss to evaluate subsistence harvest for the Chukchi Sea (CS) polar bear subpopulation. Harvest strategies followed a state-dependent approach under which new data were used to update the harvest on a predetermined management interval. We found that a harvest strategy with a starting total harvest rate of 2.7% (˜85 bears/yr at current abundance), a 2:1 male-to-female ratio, and a 10-yr management interval would likely maintain subpopulation abundance above maximum net productivity level for the next 35 yr (approximately three polar bear generations), our primary criterion for sustainability. Plausible bounds on starting total harvest rate were 1.7-3.9%, where the range reflects uncertainty due to sampling variation, environmental variation, model selection, and differing levels of risk tolerance. The risk of undesired demographic outcomes (e.g., overharvest) was positively related to harvest rate, management interval, and projected declines in environmental carrying capacity; and negatively related to precision in population data. Results reflect several lines of evidence that the CS subpopulation has been productive in recent years, although it is uncertain how long this will last as sea-ice loss continues. Our methods provide a template for balancing trade-offs among protection, use, research investment, and other factors. Demographic risk assessment and state-dependent management will become increasingly important for harvested species, like polar bears, that exhibit spatiotemporal variation in their response to climate change.
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Affiliation(s)
- Eric V. Regehr
- Polar Science CenterApplied Physics LaboratoryUniversity of WashingtonSeattleWashington98105USA
| | - Michael C. Runge
- Patuxent Wildlife Research CenterU.S. Geological SurveyLaurelMaryland20708USA
| | - Andrew Von Duyke
- Department of Wildlife ManagementNorth Slope BoroughUtqiaġvikAlaska99723USA
| | - Ryan R. Wilson
- Marine Mammals ManagementU.S. Fish and Wildlife ServiceAnchorageAlaska99503USA
| | - Lori Polasek
- Division of Wildlife ConservationAlaska Department of Fish and GameJuneauAlaska99802USA
| | - Karyn D. Rode
- Alaska Science CenterU.S. Geological SurveyAnchorageAlaska99508USA
| | - Nathan J. Hostetter
- Washington Cooperative Fish and Wildlife Research UnitSchool of Aquatic and Fishery SciencesUniversity of WashingtonSeattleWashington98105USA
| | - Sarah J. Converse
- Washington Cooperative Fish and Wildlife Research UnitSchool of Environmental and Forest Sciences (SEFS) & School of Aquatic and Fishery Sciences (SAFS)U.S. Geological SurveyUniversity of WashingtonSeattleWashington98105USA
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19
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An on-ice aerial survey of the Kane Basin polar bear (Ursus maritimus) subpopulation. Polar Biol 2021; 45:89-100. [PMID: 35125636 PMCID: PMC8776663 DOI: 10.1007/s00300-021-02974-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 10/16/2021] [Accepted: 11/15/2021] [Indexed: 10/28/2022]
Abstract
AbstractThere is an imminent need to collect information on distribution and abundance of polar bears (Ursus maritimus) to understand how they are affected by the ongoing decrease in Arctic sea ice. The Kane Basin (KB) subpopulation is a group of high-latitude polar bears that ranges between High Arctic Canada and NW Greenland around and north of the North Water polynya (NOW). We conducted a line transect distance sampling aerial survey of KB polar bears during 28 April–12 May 2014. A total of 4160 linear kilometers were flown in a helicopter over fast ice in the fjords and over offshore pack ice between 76° 50′ and 80° N′. Using a mark-recapture distance sampling protocol, the estimated abundance was 190 bears (95% lognormal CI: 87–411; CV 39%). This estimate is likely negatively biased to an unknown degree because the offshore sectors of the NOW with much open water were not surveyed because of logistical and safety reasons. Our study demonstrated that aerial surveys may be a feasible method for obtaining abundance estimates for small subpopulations of polar bears.
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20
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Orgeret F, Thiebault A, Kovacs KM, Lydersen C, Hindell MA, Thompson SA, Sydeman WJ, Pistorius PA. Climate change impacts on seabirds and marine mammals: The importance of study duration, thermal tolerance and generation time. Ecol Lett 2021; 25:218-239. [PMID: 34761516 DOI: 10.1111/ele.13920] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 10/01/2021] [Accepted: 10/13/2021] [Indexed: 11/27/2022]
Abstract
Understanding climate change impacts on top predators is fundamental to marine biodiversity conservation, due to their increasingly threatened populations and their importance in marine ecosystems. We conducted a systematic review of the effects of climate change (prolonged, directional change) and climate variability on seabirds and marine mammals. We extracted data from 484 studies (4808 published studies were reviewed), comprising 2215 observations on demography, phenology, distribution, diet, behaviour, body condition and physiology. The likelihood of concluding that climate change had an impact increased with study duration. However, the temporal thresholds for the effects of climate change to be discernibly varied from 10 to 29 years depending on the species, the biological response and the oceanic study region. Species with narrow thermal ranges and relatively long generation times were more often reported to be affected by climate change. This provides an important framework for future assessments, with guidance on response- and region-specific temporal dimensions that need to be considered when reporting effects of climate change. Finally, we found that tropical regions and non-breeding life stages were poorly covered in the literature, a concern that should be addressed to enable a better understanding of the vulnerability of marine predators to climate change.
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Affiliation(s)
- Florian Orgeret
- Marine Apex Predator Research Unit (MAPRU), Department of Zoology, Institute for Coastal and Marine Research, Nelson Mandela University, Port Elizabeth, South Africa
| | - Andréa Thiebault
- Marine Apex Predator Research Unit (MAPRU), Department of Zoology, Institute for Coastal and Marine Research, Nelson Mandela University, Port Elizabeth, South Africa
| | - Kit M Kovacs
- Norwegian Polar Institute, Fram Centre, Tromsø, Norway
| | | | - Mark A Hindell
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
| | | | | | - Pierre A Pistorius
- Marine Apex Predator Research Unit (MAPRU), Department of Zoology, Institute for Coastal and Marine Research, Nelson Mandela University, Port Elizabeth, South Africa.,DST-NRF Centre of Excellence at the FitzPatrick Institute of African Ornithology, Nelson Mandela University, Port Elizabeth, South Africa
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21
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Fatty acid profiles of feeding and fasting bears: estimating calibration coefficients, the timeframe of diet estimates, and selective mobilization during hibernation. J Comp Physiol B 2021; 192:379-395. [PMID: 34687352 DOI: 10.1007/s00360-021-01414-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 09/20/2021] [Accepted: 10/03/2021] [Indexed: 10/20/2022]
Abstract
Accurate information on diet composition is central to understanding and conserving carnivore populations. Quantitative fatty acid signature analysis (QFASA) has emerged as a powerful tool for estimating the diets of predators, but ambiguities remain about the timeframe of QFASA estimates and the need to account for species-specific patterns of metabolism. We conducted a series of feeding experiments with four juvenile male brown bears (Ursus arctos) to (1) track the timing of changes in adipose tissue composition and QFASA diet estimates in response to a change in diet and (2) quantify the relationship between consumer and diet FA composition (i.e., determine "calibration coefficients"). Bears were fed three compositionally distinct diets for 90-120 days each. Two marine-based diets were intended to approximate the lipid content and composition of the wild diet of polar bears (U. maritimus). Bear adipose tissue composition changed quickly in the direction of the diet and showed evidence of stabilization after 60 days. During hibernation, FA profiles were initially stable but diet estimates after 10 weeks were sensitive to calibration coefficients. Calibration coefficients derived from the marine-based diets were broadly similar to each other and to published values from marine-fed mink (Mustela vison), which have been used as a model for free-ranging polar bears. For growing bears on a high-fat diet, the temporal window for QFASA estimates was 30-90 days. Although our results reinforce the importance of accurate calibration, the similarities across taxa and diets suggest it may be feasible to develop a generalized QFASA approach for mammalian carnivores.
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22
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Atkinson SN, Laidre KL, Arnold TW, Stapleton S, Regehr EV, Born EW, Wiig Ø, Dyck M, Lunn NJ, Stern HL, Paetkau D. A novel mark-recapture-recovery survey using genetic sampling for polar bears Ursus maritimus in Baffin Bay. ENDANGER SPECIES RES 2021. [DOI: 10.3354/esr01148] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Changes in sea-ice dynamics are affecting polar bears Ursus maritimus across their circumpolar range, which highlights the importance of periodic demographic assessments to inform management and conservation. We used genetic mark-recapture-recovery to derive estimates of abundance and survival for the Baffin Bay (BB) polar bear subpopulation—the first time this method has been used successfully for this species. Genetic data from tissue samples we collected via biopsy darting were combined with historical physical capture and harvest recovery data. The combined data set consisted of 1410 genetic samples (2011-2013), 914 physical captures (1993-1995, 1997), and 234 harvest returns of marked bears (1993-2013). The estimate of mean subpopulation abundance was 2826 (95% CI = 2284-3367) in 2012-2013. Estimates of annual survival (mean ± SE) were 0.90 ± 0.05 and 0.78 ± 0.06 for females and males age ≥2 yr, respectively. The proportion of total mortality of adult females and males that was attributed to legal harvest was 0.16 ± 0.05 and 0.26 ± 0.06, respectively. Remote sensing sea-ice data, telemetry data, and spatial distribution of onshore sampling indicated that polar bears were more likely to use offshore sea-ice habitat during the 1990s sampling period compared to the 2010s. Furthermore, in the 1990s, sampling of deep fjords and inland areas was limited, and no offshore sampling occurred in either time period, which precluded comparisons of abundance between the 1993-1997 and 2011-2013 study periods. Our findings demonstrate that genetic sampling can be a practical method for demographic assessment of polar bears over large spatial and temporal scales.
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Affiliation(s)
- SN Atkinson
- Wildlife Research Section, Department of Environment, Government of Nunavut, Igloolik, NU X0A 0L0, Canada
| | - KL Laidre
- Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle, WA 98105, USA
- Greenland Institute of Natural Resources, 3900 Nuuk, Greenland
| | - TW Arnold
- Department of Fisheries, Wildlife, and Conservation Biology, University of Minnesota, St. Paul, MN 55108, USA
| | - S Stapleton
- Department of Fisheries, Wildlife, and Conservation Biology, University of Minnesota, St. Paul, MN 55108, USA
| | - EV Regehr
- Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle, WA 98105, USA
| | - EW Born
- Greenland Institute of Natural Resources, 3900 Nuuk, Greenland
| | - Ø Wiig
- Natural History Museum, University of Oslo, 0318, Oslo, Norway
| | - M Dyck
- Wildlife Research Section, Department of Environment, Government of Nunavut, Igloolik, NU X0A 0L0, Canada
| | - NJ Lunn
- Environment and Climate Change Canada, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - HL Stern
- Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle, WA 98105, USA
| | - D Paetkau
- Wildlife Genetics International, Nelson, BC V1L 5P9, Canada
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23
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Pilfold NW, Richardson ES, Ellis J, Jenkins E, Scandrett WB, Hernández‐Ortiz A, Buhler K, McGeachy D, Al‐Adhami B, Konecsni K, Lobanov VA, Owen MA, Rideout B, Lunn NJ. Long-term increases in pathogen seroprevalence in polar bears (Ursus maritimus) influenced by climate change. GLOBAL CHANGE BIOLOGY 2021; 27:4481-4497. [PMID: 34292654 PMCID: PMC8457125 DOI: 10.1111/gcb.15537] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 12/28/2020] [Indexed: 05/10/2023]
Abstract
The influence of climate change on wildlife disease dynamics is a burgeoning conservation and human health issue, but few long-term studies empirically link climate to pathogen prevalence. Polar bears (Ursus maritimus) are vulnerable to the negative impacts of sea ice loss as a result of accelerated Arctic warming. While studies have associated changes in polar bear body condition, reproductive output, survival, and abundance to reductions in sea ice, no long-term studies have documented the impact of climate change on pathogen exposure. We examined 425 serum samples from 381 adult polar bears, collected in western Hudson Bay (WH), Canada, for antibodies to selected pathogens across three time periods: 1986-1989 (n = 157), 1995-1998 (n = 159) and 2015-2017 (n = 109). We ran serological assays for antibodies to seven pathogens: Toxoplasma gondii, Neospora caninum, Trichinella spp., Francisella tularensis, Bordetella bronchiseptica, canine morbillivirus (CDV) and canine parvovirus (CPV). Seroprevalence of zoonotic parasites (T. gondii, Trichinella spp.) and bacterial pathogens (F. tularensis, B. bronchiseptica) increased significantly between 1986-1989 and 1995-1998, ranging from +6.2% to +20.8%, with T. gondii continuing to increase into 2015-2017 (+25.8% overall). Seroprevalence of viral pathogens (CDV, CPV) and N. caninum did not change with time. Toxoplasma gondii seroprevalence was higher following wetter summers, while seroprevalences of Trichinella spp. and B. bronchiseptica were positively correlated with hotter summers. Seroprevalence of antibodies to F. tularensis increased following years polar bears spent more days on land, and polar bears previously captured in human settlements were more likely to be seropositive for Trichinella spp. As the Arctic has warmed due to climate change, zoonotic pathogen exposure in WH polar bears has increased, driven by numerous altered ecosystem pathways.
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Affiliation(s)
- Nicholas W. Pilfold
- Conservation Science and Wildlife HealthSan Diego Zoo Wildlife AllianceEscondidoCAUSA
| | - Evan S. Richardson
- Wildlife Research Division, Science and Technology BranchEnvironment and Climate Change CanadaWinnipegMBCanada
| | - John Ellis
- Department of Veterinary MicrobiologyUniversity of SaskatchewanSaskatoonSKCanada
| | - Emily Jenkins
- Department of Veterinary MicrobiologyUniversity of SaskatchewanSaskatoonSKCanada
| | - W. Brad Scandrett
- Centre for Food‐borne and Animal ParasitologyCanadian Food Inspection AgencySaskatoonSKCanada
| | | | - Kayla Buhler
- Department of Veterinary MicrobiologyUniversity of SaskatchewanSaskatoonSKCanada
| | - David McGeachy
- Wildlife Research Division, Science and Technology BranchEnvironment and Climate Change CanadaEdmontonABCanada
| | - Batol Al‐Adhami
- Centre for Food‐borne and Animal ParasitologyCanadian Food Inspection AgencySaskatoonSKCanada
| | - Kelly Konecsni
- Centre for Food‐borne and Animal ParasitologyCanadian Food Inspection AgencySaskatoonSKCanada
| | - Vladislav A. Lobanov
- Centre for Food‐borne and Animal ParasitologyCanadian Food Inspection AgencySaskatoonSKCanada
| | - Megan A. Owen
- Conservation Science and Wildlife HealthSan Diego Zoo Wildlife AllianceEscondidoCAUSA
| | - Bruce Rideout
- Conservation Science and Wildlife HealthSan Diego Zoo Wildlife AllianceEscondidoCAUSA
| | - Nicholas J. Lunn
- Wildlife Research Division, Science and Technology BranchEnvironment and Climate Change CanadaEdmontonABCanada
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24
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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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25
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Maduna SN, Aars J, Fløystad I, Klütsch CFC, Zeyl Fiskebeck EML, Wiig Ø, Ehrich D, Andersen M, Bachmann L, Derocher AE, Nyman T, Eiken HG, Hagen SB. Sea ice reduction drives genetic differentiation among Barents Sea polar bears. Proc Biol Sci 2021; 288:20211741. [PMID: 34493082 PMCID: PMC8424353 DOI: 10.1098/rspb.2021.1741] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 08/12/2021] [Indexed: 12/24/2022] Open
Abstract
Loss of Arctic sea ice owing to climate change is predicted to reduce both genetic diversity and gene flow in ice-dependent species, with potentially negative consequences for their long-term viability. Here, we tested for the population-genetic impacts of reduced sea ice cover on the polar bear (Ursus maritimus) sampled across two decades (1995-2016) from the Svalbard Archipelago, Norway, an area that is affected by rapid sea ice loss in the Arctic Barents Sea. We analysed genetic variation at 22 microsatellite loci for 626 polar bears from four sampling areas within the archipelago. Our results revealed a 3-10% loss of genetic diversity across the study period, accompanied by a near 200% increase in genetic differentiation across regions. These effects may best be explained by a decrease in gene flow caused by habitat fragmentation owing to the loss of sea ice coverage, resulting in increased inbreeding of local polar bears within the focal sampling areas in the Svalbard Archipelago. This study illustrates the importance of genetic monitoring for developing adaptive management strategies for polar bears and other ice-dependent species.
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Affiliation(s)
- Simo Njabulo Maduna
- Norwegian Institute of Bioeconomy Research, Division of Environment and Natural Resources, Svanhovd, N-9925 Svanvik, Norway
| | - Jon Aars
- Norwegian Polar Institute, N-9296 Tromsø, Norway
| | - Ida Fløystad
- Norwegian Institute of Bioeconomy Research, Division of Environment and Natural Resources, Svanhovd, N-9925 Svanvik, Norway
| | - Cornelya F. C. Klütsch
- Norwegian Institute of Bioeconomy Research, Division of Environment and Natural Resources, Svanhovd, N-9925 Svanvik, Norway
| | | | - Øystein Wiig
- Natural History Museum, University of Oslo, N-0318 Oslo, Norway
| | - Dorothee Ehrich
- Department of Arctic and Marine Biology, UiT Arctic University of Tromsø, N-9037 Tromsø, Norway
| | | | - Lutz Bachmann
- Natural History Museum, University of Oslo, N-0318 Oslo, Norway
| | - Andrew E. Derocher
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2E9
| | - Tommi Nyman
- Norwegian Institute of Bioeconomy Research, Division of Environment and Natural Resources, Svanhovd, N-9925 Svanvik, Norway
| | - Hans Geir Eiken
- Norwegian Institute of Bioeconomy Research, Division of Environment and Natural Resources, Svanhovd, N-9925 Svanvik, Norway
| | - Snorre B. Hagen
- Norwegian Institute of Bioeconomy Research, Division of Environment and Natural Resources, Svanhovd, N-9925 Svanvik, Norway
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Togunov RR, Derocher AE, Lunn NJ, Auger‐Méthé M. Characterising menotactic behaviours in movement data using hidden Markov models. Methods Ecol Evol 2021. [DOI: 10.1111/2041-210x.13681] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ron R. Togunov
- Institute for the Oceans and Fisheries The University of British Columbia Vancouver BC Canada
- Department of Zoology The University of British Columbia Vancouver BC Canada
| | - Andrew E. Derocher
- Department of Biological Sciences University of Alberta Edmonton AB Canada
| | - Nicholas J. Lunn
- Department of Biological Sciences University of Alberta Edmonton AB Canada
- Wildlife Research Division, Science and Technology Branch Environment and Climate Change Canada Edmonton AB Canada
| | - Marie Auger‐Méthé
- Institute for the Oceans and Fisheries The University of British Columbia Vancouver BC Canada
- Department of Statistics University of British Columbia Vancouver BC Canada
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27
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Galicia MP, Thiemann GW, Dyck MG, Ferguson SH. Are tissue samples obtained via remote biopsy useful for fatty acid-based diet analyses in a free-ranging carnivore? J Mammal 2021. [DOI: 10.1093/jmammal/gyab041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Fundamental knowledge on free-ranging animals has been obtained through capture-based studies; however, these may be logistically intensive, financially expensive, and potentially inconsistent with local cultural values. Genetic mark–recapture using remote tissue sampling has emerged as a less invasive alternative to capture-based population surveys but provides fewer opportunities to collect samples and measurements for broader ecological studies. We compared lipid content, fatty acid (FA) composition, and diet estimates from adipose tissue of polar bears (Ursus maritimus) obtained from two collection methods: remote biopsies (n = 138) sampled from helicopters and hunter-collected tissue (n = 499) from bears harvested in Davis Strait and Gulf of Boothia, Nunavut, 2010 – 2018. Lipid content of adipose tissue was lower in remote biopsies than harvest samples likely because remote biopsies removed only the outermost layer of subcutaneous tissue, rather than the more metabolically dynamic innermost tissue obtained from harvest samples. In contrast, FA composition was similar between the two collection methods with relatively small proportional differences in individual FAs. For diet estimates in Davis Strait, collection method was not a predictor of prey contribution to diet. In Gulf of Boothia, collection method was a predictor for some prey types, but the differences were relatively minor; the rank order of prey types was similar (e.g., ringed seal; Pusa hispida was consistently the primary prey in diets) and prey proportions differed by < 6% between the collection methods. Results from both methods showed that diets varied by geographic area, season, year, age class, and sex. Our study demonstrates that adipose tissue from remote biopsy provides reliable estimates of polar bear diet based on FA analysis and can be used to monitor underlying ecological changes in Arctic marine food webs.
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Affiliation(s)
| | - Gregory W Thiemann
- Faculty of Environmental and Urban Change, York University, Toronto, Ontario, Canada
| | - Markus G Dyck
- Wildlife Research Section, Department of Environment, Government of Nunavut, Igloolik, Nunavut, Canada
| | - Steven H Ferguson
- Fisheries and Oceans Canada, Central and Arctic Region, Winnipeg, Manitoba, Canada
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28
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James TD, Salguero-Gómez R, Jones OR, Childs DZ, Beckerman AP. Bridging gaps in demographic analysis with phylogenetic imputation. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2021; 35:1210-1221. [PMID: 33068013 DOI: 10.1111/cobi.13658] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 09/10/2020] [Accepted: 10/08/2020] [Indexed: 06/11/2023]
Abstract
Phylogenetically informed imputation methods have rarely been applied to estimate missing values in demographic data but may be a powerful tool for reconstructing vital rates of survival, maturation, and fecundity for species of conservation concern. Imputed vital rates could be used to parameterize demographic models to explore how populations respond when vital rates are perturbed. We used standardized vital rate estimates for 50 bird species to assess the use of phylogenetic imputation to fill gaps in demographic data. We calculated imputation accuracy for vital rates of focal species excluded from the data set either singly or in combination and with and without phylogeny, body mass, and life-history trait data. We used imputed vital rates to calculate demographic metrics, including generation time, to validate the use of imputation in demographic analyses. Covariance among vital rates and other trait data provided a strong basis to guide imputation of missing vital rates in birds, even in the absence of phylogenetic information. Mean NRMSE for null and phylogenetic models differed by <0.01 except when no vital rates were available or for vital rates with high phylogenetic signal (Pagel's λ > 0.8). In these cases, including body mass and life-history trait data compensated for lack of phylogenetic information: mean normalized root mean square error (NRMSE) for null and phylogenetic models differed by <0.01 for adult survival and <0.04 for maturation rate. Estimates of demographic metrics were sensitive to the accuracy of imputed vital rates. For example, mean error in generation time doubled in response to inaccurate estimates of maturation time. Accurate demographic data and metrics, such as generation time, are needed to inform conservation planning processes, for example through International Union for Conservation of Nature Red List assessments and population viability analysis. Imputed vital rates could be useful in this context but, as for any estimated model parameters, awareness of the sensitivities of demographic model outputs to the imputed vital rates is essential.
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Affiliation(s)
- Tamora D James
- Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield, S10 2TN, U.K
| | - Roberto Salguero-Gómez
- Department of Zoology, University of Oxford, Zoology Research and Administration Building, 11a Mansfield Rd, Oxford, OX1 3SZ, U.K
| | - Owen R Jones
- Interdisciplinary Centre on Population Dynamics (CPop), Department of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense M, Odense, Denmark
| | - Dylan Z Childs
- Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield, S10 2TN, U.K
| | - Andrew P Beckerman
- Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield, S10 2TN, U.K
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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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30
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Bohart AM, Lunn NJ, Derocher AE, McGeachy D. Migration dynamics of polar bears ( Ursus maritimus) in western Hudson Bay. Behav Ecol 2021. [DOI: 10.1093/beheco/araa140] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Migration is predicted to change both spatially and temporally as climate change alters seasonal resource availability. Species in extreme environments are especially susceptible to climate change; hence, it is important to determine environmental and biological variables that influence their migration. Polar bears (Ursus maritimus) are an Arctic apex carnivore whose migration phenology has been affected by climate change and is vulnerable to future changes. Here, we used satellite-linked telemetry collar data from adult female polar bears in western Hudson Bay from 2004 to 2016 and multivariate response regression models to demonstrate that 1) spatial and temporal migration metrics are correlated, 2) ice concentration and wind are important environmental variables that influence polar bear migration in seasonal ice areas, and 3) migration did not vary across the years of our study, highlighting the importance of continued monitoring. Specifically, we found that ice concentration, wind speed, and wind direction affected polar bear migration onto ice during freeze-up and ice concentration and wind direction affected migration onto land during breakup. Bears departed from land earlier with increased wind speed and the effect of wind direction on migration may be linked to prey searching and ice drift. Low ice concentration was associated with higher movement during freeze-up and breakup. Our findings suggest that migration movement may increase in response to climate change as ice concentration and access to prey declines, potentially increasing nutritional stress on bears.
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Affiliation(s)
- Alyssa M Bohart
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Nicholas J Lunn
- Wildlife Research Division, Science and Technology Branch, Environment and Climate Change Canada, University of Alberta, Edmonton, Alberta, Canada
| | - Andrew E Derocher
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - David McGeachy
- Wildlife Research Division, Science and Technology Branch, Environment and Climate Change Canada, University of Alberta, Edmonton, Alberta, Canada
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31
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Rode KD, Regehr EV, Bromaghin JF, Wilson RR, St Martin M, Crawford JA, Quakenbush LT. Seal body condition and atmospheric circulation patterns influence polar bear body condition, recruitment, and feeding ecology in the Chukchi Sea. GLOBAL CHANGE BIOLOGY 2021; 27:2684-2701. [PMID: 33644944 DOI: 10.1111/gcb.15572] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 02/10/2021] [Indexed: 06/12/2023]
Abstract
Polar bears (Ursus maritimus) are experiencing loss of sea ice habitats used to access their marine mammal prey. Simultaneously, ocean warming is changing ecosystems that support marine mammal populations. The interactive effects of sea ice and prey are not well understood yet may explain spatial-temporal variation in the response of polar bears to sea ice loss. Here, we examined the potential combined effects of sea ice, seal body condition, and atmospheric circulation patterns on the body condition, recruitment, diet, and feeding probability of 469 polar bears captured in the Chukchi Sea, 2008-2017. The body condition of ringed seals (Pusa hispida), the primary prey of females and subadults, was related to dietary proportions of ringed seal, feeding probability, and the body condition of females and cubs. In contrast, adult males consumed more bearded seals (Erignathus barbatus) and exhibited better condition when bearded seal body condition was higher. The litter size, number of yearlings per adult female, and the condition of dependent young were higher following winters characterized by low Arctic Oscillation conditions, consistent with a growing number of studies. Body condition, recruitment, and feeding probability were either not associated or negatively associated with sea ice conditions, suggesting that, unlike some subpopulations, Chukchi Sea bears are not currently limited by sea ice availability. However, spring sea ice cover declined 2% per year during our study reaching levels not previously observed in the satellite record and resulting in the loss of polar bear hunting and seal pupping habitat. Our study suggests that the status of ice seal populations is likely an important factor that can either compound or mitigate the response of polar bears to sea ice loss over the short term. In the long term, neither polar bears nor their prey are likely robust to limitless loss of their sea ice habitat.
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Affiliation(s)
- Karyn D Rode
- Alaska Science Center, U.S. Geological Survey, Anchorage, AK, USA
| | - Eric V Regehr
- Polar Science Center, University of Washington, Seattle, WA, USA
| | | | - Ryan R Wilson
- Marine Mammals Management, U.S. Fish and Wildlife Service, Anchorage, AK, USA
| | - Michelle St Martin
- Marine Mammals Management, U.S. Fish and Wildlife Service, Anchorage, AK, USA
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32
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Conn PB, Chernook VI, Moreland EE, Trukhanova IS, Regehr EV, Vasiliev AN, Wilson RR, Belikov SE, Boveng PL. Aerial survey estimates of polar bears and their tracks in the Chukchi Sea. PLoS One 2021; 16:e0251130. [PMID: 33956835 PMCID: PMC8101751 DOI: 10.1371/journal.pone.0251130] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 04/20/2021] [Indexed: 11/19/2022] Open
Abstract
Polar bears are of international conservation concern due to climate change but are difficult to study because of low densities and an expansive, circumpolar distribution. In a collaborative U.S.-Russian effort in spring of 2016, we used aerial surveys to detect and estimate the abundance of polar bears on sea ice in the Chukchi Sea. Our surveys used a combination of thermal imagery, digital photography, and human observations. Using spatio-temporal statistical models that related bear and track densities to physiographic and biological covariates (e.g., sea ice extent, resource selection functions derived from satellite tags), we predicted abundance and spatial distribution throughout our study area. Estimates of 2016 abundance ([Formula: see text]) ranged from 3,435 (95% CI: 2,300-5,131) to 5,444 (95% CI: 3,636-8,152) depending on the proportion of bears assumed to be missed on the transect line during Russian surveys (g(0)). Our point estimates are larger than, but of similar magnitude to, a recent estimate for the period 2008-2016 ([Formula: see text]; 95% CI 1,522-5,944) derived from an integrated population model applied to a slightly smaller area. Although a number of factors (e.g., equipment issues, differing platforms, low sample sizes, size of the study area relative to sampling effort) required us to make a number of assumptions to generate estimates, it establishes a useful lower bound for abundance, and suggests high spring polar bear densities on sea ice in Russian waters south of Wrangell Island. With future improvements, we suggest that springtime aerial surveys may represent a plausible avenue for studying abundance and distribution of polar bears and their prey over large, remote areas.
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Affiliation(s)
- Paul B. Conn
- Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, Washington, United States of America
- * E-mail:
| | - Vladimir I. Chernook
- Ecological Center, Autonomous Non-Commercial Organization, Saint-Petersburg, Russia
| | - Erin E. Moreland
- Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, Washington, United States of America
| | - Irina S. Trukhanova
- North Pacific Wildlife Consulting, LLC, Seattle, Washington, United States of America
| | - Eric V. Regehr
- Marine Mammals Management, United States Fish and Wildlife Service, Anchorage, Alaska, United States of America
- Applied Physics Laboratory, Polar Science Center, University of Washington, Seattle, Washington, United States of America
| | | | - Ryan R. Wilson
- Marine Mammals Management, United States Fish and Wildlife Service, Anchorage, Alaska, United States of America
| | - Stanislav E. Belikov
- All-Russian Research Institute for Nature Protection (Federal State Budgetary Institution), Moscow, Russia
| | - Peter L. Boveng
- Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, Washington, United States of America
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33
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Cubaynes S, Aars J, Yoccoz NG, Pradel R, Wiig Ø, Ims RA, Gimenez O. Modeling the demography of species providing extended parental care: A capture-recapture multievent model with a case study on polar bears ( Ursus maritimus). Ecol Evol 2021; 11:3380-3392. [PMID: 33841791 PMCID: PMC8019049 DOI: 10.1002/ece3.7296] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 01/07/2021] [Accepted: 01/25/2021] [Indexed: 12/26/2022] Open
Abstract
In species providing extended parental care, one or both parents care for altricial young over a period including more than one breeding season. We expect large parental investment and long-term dependency within family units to cause high variability in life trajectories among individuals with complex consequences at the population level. So far, models for estimating demographic parameters in free-ranging animal populations mostly ignore extended parental care, thereby limiting our understanding of its consequences on parents and offspring life histories.We designed a capture-recapture multievent model for studying the demography of species providing extended parental care. It handles statistical multiple-year dependency among individual demographic parameters grouped within family units, variable litter size, and uncertainty on the timing at offspring independence. It allows for the evaluation of trade-offs among demographic parameters, the influence of past reproductive history on the caring parent's survival status, breeding probability, and litter size probability, while accounting for imperfect detection of family units. We assess the model performance using simulated data and illustrate its use with a long-term dataset collected on the Svalbard polar bears (Ursus maritimus).Our model performed well in terms of bias and mean square error and in estimating demographic parameters in all simulated scenarios, both when offspring departure probability from the family unit occurred at a constant rate or varied during the field season depending on the date of capture. For the polar bear case study, we provide estimates of adult and dependent offspring survival rates, breeding probability, and litter size probability. Results showed that the outcome of the previous reproduction influenced breeding probability.Overall, our results show the importance of accounting for i) the multiple-year statistical dependency within family units, ii) uncertainty on the timing at offspring independence, and iii) past reproductive history of the caring parent. If ignored, estimates obtained for breeding probability, litter size, and survival can be biased. This is of interest in terms of conservation because species providing extended parental care are often long-living mammals vulnerable or threatened with extinction.
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Affiliation(s)
- Sarah Cubaynes
- CEFEUniv MontpellierCNRSEPHE‐PSL UniversityIRDUniv Paul Valéry Montpellier 3MontpellierFrance
| | - Jon Aars
- Norwegian Polar InstituteFRAM CentreTromsøNorway
| | - Nigel G. Yoccoz
- Department of Arctic and Marine BiologyUiT The Arctic University of NorwayTromsøNorway
| | - Roger Pradel
- CEFEUniv MontpellierCNRSEPHE‐PSL UniversityIRDUniv Paul Valéry Montpellier 3MontpellierFrance
| | - Øystein Wiig
- Natural History MuseumUniversity of OsloOsloNorway
| | - Rolf A. Ims
- Department of Arctic and Marine BiologyUiT The Arctic University of NorwayTromsøNorway
| | - Olivier Gimenez
- CEFEUniv MontpellierCNRSEPHE‐PSL UniversityIRDUniv Paul Valéry Montpellier 3MontpellierFrance
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Pagano AM, Williams TM. Physiological consequences of Arctic sea ice loss on large marine carnivores: unique responses by polar bears and narwhals. J Exp Biol 2021; 224:224/Suppl_1/jeb228049. [PMID: 33627459 DOI: 10.1242/jeb.228049] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Rapid environmental changes in the Arctic are threatening the survival of marine species that rely on the predictable presence of the sea ice. Two Arctic marine mammal specialists, the polar bear (Ursus maritimus) and narwhal (Monodon monoceros), appear especially vulnerable to the speed and capriciousness of sea ice deterioration as a consequence of their unique hunting behaviors and diet, as well as their physiological adaptations for slow-aerobic exercise. These intrinsic characteristics limit the ability of these species to respond to extrinsic threats associated with environmental change and increased industrial activity in a warming Arctic. In assessing how sea ice loss may differentially affect polar bears that hunt on the ice surface and narwhals that hunt at extreme depths below, we found that major ice loss translated into elevated locomotor costs that range from 3- to 4-fold greater than expected for both species. For polar bears this instigates an energy imbalance from the combined effects of reduced caloric intake and increased energy expenditure. For narwhals, high locomotor costs during diving increase the risk of ice entrapment due to the unreliability of breathing holes. These species-specific physiological constraints and extreme reliance on the polar sea ice conspire to make these two marine mammal specialists sentinels of climate change within the Arctic marine ecosystem that may foreshadow rapid changes to the marine ecosystem.
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Affiliation(s)
- Anthony M Pagano
- Institute for Conservation Research, San Diego Zoo Global, San Diego, CA 92027, USA
| | - Terrie M Williams
- University of California, Santa Cruz, Department of Ecology and Evolutionary Biology, Santa Cruz, CA 95060, USA
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35
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Gissi E, Manea E, Mazaris AD, Fraschetti S, Almpanidou V, Bevilacqua S, Coll M, Guarnieri G, Lloret-Lloret E, Pascual M, Petza D, Rilov G, Schonwald M, Stelzenmüller V, Katsanevakis S. A review of the combined effects of climate change and other local human stressors on the marine environment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 755:142564. [PMID: 33035971 DOI: 10.1016/j.scitotenv.2020.142564] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 09/11/2020] [Accepted: 09/21/2020] [Indexed: 06/11/2023]
Abstract
Climate change (CC) is a key, global driver of change of marine ecosystems. At local and regional scales, other local human stressors (LS) can interact with CC and modify its effects on marine ecosystems. Understanding the response of the marine environment to the combined effects of CC and LS is crucial to inform marine ecosystem-based management and planning, yet our knowledge of the potential effects of such interactions is fragmented. At a global scale, we explored how cumulative effect assessments (CEAs) have addressed CC in the marine realm and discuss progress and shortcomings of current approaches. For this we conducted a systematic review on how CEAs investigated at different levels of biological organization ecological responses, functional aspects, and the combined effect of CC and HS. Globally, the effects of 52 LS and of 27 CC-related stressors on the marine environment have been studied in combination, such as industrial fisheries with change in temperature, or sea level rise with artisanal fisheries, marine litter, change in sediment load and introduced alien species. CC generally intensified the effects of LS at species level. At trophic groups and ecosystem levels, the effects of CC either intensified or mitigated the effects of other HS depending on the trophic groups or the environmental conditions involved, thus suggesting that the combined effects of CC and LS are context-dependent and vary among and within ecosystems. Our results highlight that large-scale assessments on the spatial interaction and combined effects of CC and LS remain limited. More importantly, our results strengthen the urgent need of CEAs to capture local-scale effects of stressors that can exacerbate climate-induced changes. Ultimately, this will allow identifying management measures that aid counteracting CC effects at relevant scales.
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Affiliation(s)
- Elena Gissi
- IUAV University of Venice, Tolentini 191, Santa Croce, 30135 Venice, Italy.
| | - Elisabetta Manea
- IUAV University of Venice, Tolentini 191, Santa Croce, 30135 Venice, Italy
| | - Antonios D Mazaris
- Department of Ecology, School of Biology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Simonetta Fraschetti
- Università Federico II di Napoli, Napoli, Italy; Consorzio Universitario per le Scienze del Mare, P.le Flaminio 9, 00196 Rome, Italy; Stazione Zoologica Anton Dohrn, Napoli, Italy
| | - Vasiliki Almpanidou
- Department of Ecology, School of Biology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Stanislao Bevilacqua
- Department of Life Sciences, University of Trieste, Trieste, Italy; Consorzio Universitario per le Scienze del Mare, P.le Flaminio 9, 00196 Rome, Italy
| | - Marta Coll
- Institute of Marine Science, ICM-CSIC, Passeig Marítim de la Barceloneta, no 37-49, 08003 Barcelona, Spain; Ecopath International Initiative, Barcelona, Spain
| | - Giuseppe Guarnieri
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Lecce, Italy; Consorzio Universitario per le Scienze del Mare, P.le Flaminio 9, 00196 Rome, Italy
| | - Elena Lloret-Lloret
- Institute of Marine Science, ICM-CSIC, Passeig Marítim de la Barceloneta, no 37-49, 08003 Barcelona, Spain; Ecopath International Initiative, Barcelona, Spain
| | - Marta Pascual
- Basque Centre for Climate Change (BC3), Edificio Sede N°1 Planta 1/Parque Científico UPV-EHU, Barrio Sarriena, s/n, 48940 Leioa, Bizkaia, Spain
| | - Dimitra Petza
- Department of Marine Sciences, University of the Aegean, University Hill, 81100 Mytilene, Greece; Directorate for Fisheries Policy & Fishery Resources Utilisation, Directorate General for Fisheries, Ministry of Rural Development & Food, 150 Syggrou Avenue, 17671 Athens, Greece
| | - Gil Rilov
- Israel Oceanographic and Limnological Research, National Institute of Oceanography, P.O. Box 8030, Haifa 31080, Israel
| | - Maura Schonwald
- Israel Oceanographic and Limnological Research, National Institute of Oceanography, P.O. Box 8030, Haifa 31080, Israel
| | | | - Stelios Katsanevakis
- Department of Marine Sciences, University of the Aegean, University Hill, 81100 Mytilene, Greece
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36
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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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Clark D, Artelle K, Darimont C, Housty W, Tallio C, Neasloss D, Schmidt A, Wiget A, Turner N. Grizzly and polar bears as nonconsumptive cultural keystone species. Facets (Ott) 2021. [DOI: 10.1139/facets-2020-0089] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Grizzly bears and polar bears often serve as ecological “flagship species” in conservation efforts, but although consumptively used in some areas and cultures they can also be important cultural keystone species even where not hunted. We extend the application of established criteria for defining cultural keystone species to also encompass species with which cultures have a primarily nonconsumptive relationship but that are nonetheless disproportionately important to well-being and identity. Grizzly bears in coastal British Columbia are closely linked to many Indigenous Peoples (including the Haíɫzaqv (Heiltsuk), Kitasoo/Xai’xais, and Nuxalk First Nations), where they are central to the identity, culture, and livelihoods of individuals, families, Chiefs, and Nations. Polar bears in Churchill, Manitoba, provide another example as a cultural keystone species for a mixed Indigenous and non-Indigenous community in which many of the livelihood benefits from the species are mediated by economic transactions in a globalized tourism market. We discuss context specificity and questions of equity in sharing of benefits from cultural keystone species. Our expanded definition of cultural keystone species gives broader recognition of the beyond-ecological importance of these species to Indigenous Peoples, which highlights the societal and ecological importance of Indigenous sovereignty and could facilitate the increased cross-cultural understanding critical to reconciliation.
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Affiliation(s)
- Douglas Clark
- School of Environment & Sustainability, University of Saskatchewan, 117 Science Place, Saskatoon, SK S7N 5C8, Canada
| | - Kyle Artelle
- Department of Geography, University of Victoria, PO Box 1700 STN CSC, Victoria, BC V8W 2Y2, Canada
- Raincoast Conservation Foundation, PO Box 952, Bella Bella, BC V0T 1Z0, Canada
| | - Chris Darimont
- Department of Geography, University of Victoria, PO Box 1700 STN CSC, Victoria, BC V8W 2Y2, Canada
- Raincoast Conservation Foundation, PO Box 952, Bella Bella, BC V0T 1Z0, Canada
- Hakai Institute, PO Box 25039, Campbell River, BC V9W 0B7, Canada
| | - William Housty
- Heiltsuk Integrated Resource Management Department, PO Box 731, Bella Bella, BC V0T 1Z0, Canada
| | - Clyde Tallio
- Nuxalk Nation, PO Box 65, Bella Coola, BC V0T 1C0, Canada
| | - Douglas Neasloss
- Kitasoo/Xai’xais Stewardship Authority, PO Box 119, Klemtu, BC V0T 1L0, Canada
| | - Aimee Schmidt
- The T’akhu  Tlén Conservancy, 371-108 Elliott Street, Whitehorse, YT Y1A 6C4, Canada
| | - Andrew Wiget
- New Mexico State University (Emeritus), 109 Beryl Street, White Rock, NM 87547, USA
| | - Nancy Turner
- School of Environmental Studies (Emeritus), University of Victoria, PO Box 1700 STN CSC, Victoria, BC V8W 2Y2, Canada
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Johnson AC, Reimer JR, Lunn NJ, Stirling I, McGeachy D, Derocher AE. Influence of sea ice dynamics on population energetics of Western Hudson Bay polar bears. CONSERVATION PHYSIOLOGY 2020; 8:coaa132. [PMID: 33408870 PMCID: PMC7772618 DOI: 10.1093/conphys/coaa132] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 10/23/2020] [Accepted: 12/07/2020] [Indexed: 05/27/2023]
Abstract
The Arctic marine ecosystem has experienced extensive changes in sea ice dynamics, with significant effects on ice-dependent species such as polar bears (Ursus maritimus). We used annual estimates of the numbers of bears onshore in the core summering area, age/sex structure and body condition data to estimate population energy density and storage energy in Western Hudson Bay polar bears from 1985 to 2018. We examined intra-population variation in energetic patterns, temporal energetic trends and the relationship between population energetics and sea ice conditions. Energy metrics for most demographic classes declined over time in relation to earlier sea ice breakup, most significantly for solitary adult females and subadult males, suggesting their greater vulnerability to nutritional stress than other age/sex classes. Temporal declines in population energy metrics were related to earlier breakup and longer lagged open-water periods, suggesting multi-year effects of sea ice decline. The length of the open-water period ranged from 102 to 166 days and increased significantly by 9.9 days/decade over the study period. Total population energy density and storage energy were significantly lower when sea ice breakup occurred earlier and the lagged open-water period was longer. At the earliest breakup and a lagged open-water period of 180 days, population energy density was predicted to be 33% lower than our minimum estimated energy density and population storage energy was predicted to be 40% lower than the minimum estimated storage energy. Consequently, over the study, the total population energy density declined by 53% (mean: 3668 ± 386 MJ kg-1/decade) and total population storage energy declined by 56% (mean: 435900 ± 46770 MJ/decade). This study provides insights into ecological mechanisms linking population responses to sea ice decline and highlights the significance of maintaining long-term research programs.
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Affiliation(s)
- Amy C Johnson
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Jody R Reimer
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
- Department of Mathematics, University of Utah, Salt Lake City, UT 84112, USA
| | - Nicholas J Lunn
- Environment and Climate Change Canada, CW-422 Biological Sciences Building, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Ian Stirling
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
- Environment and Climate Change Canada, CW-422 Biological Sciences Building, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - David McGeachy
- Environment and Climate Change Canada, CW-422 Biological Sciences Building, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Andrew E Derocher
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
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Heemskerk S, Johnson AC, Hedman D, Trim V, Lunn NJ, McGeachy D, Derocher AE. Temporal dynamics of human-polar bear conflicts in Churchill, Manitoba. Glob Ecol Conserv 2020. [DOI: 10.1016/j.gecco.2020.e01320] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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40
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Laidre KL, Atkinson SN, Regehr EV, Stern HL, Born EW, Wiig Ø, Lunn NJ, Dyck M, Heagerty P, Cohen BR. Transient benefits of climate change for a high-Arctic polar bear (Ursus maritimus) subpopulation. GLOBAL CHANGE BIOLOGY 2020; 26:6251-6265. [PMID: 32964662 DOI: 10.1111/gcb.15286] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 05/18/2020] [Indexed: 06/11/2023]
Abstract
Kane Basin (KB) is one of the world's most northerly polar bear (Ursus maritimus) subpopulations, where bears have historically inhabited a mix of thick multiyear and annual sea ice year-round. Currently, KB is transitioning to a seasonally ice-free region because of climate change. This ecological shift has been hypothesized to benefit polar bears in the near-term due to thinner ice with increased biological production, although this has not been demonstrated empirically. We assess sea-ice changes in KB together with changes in polar bear movements, seasonal ranges, body condition, and reproductive metrics obtained from capture-recapture (physical and genetic) and satellite telemetry studies during two study periods (1993-1997 and 2012-2016). The annual cycle of sea-ice habitat in KB shifted from a year-round ice platform (~50% coverage in summer) in the 1990s to nearly complete melt-out in summer (<5% coverage) in the 2010s. The mean duration between sea-ice retreat and advance increased from 109 to 160 days (p = .004). Between the 1990s and 2010s, adult female (AF) seasonal ranges more than doubled in spring and summer and were significantly larger in all months. Body condition scores improved for all ages and both sexes. Mean litter sizes of cubs-of-the-year (C0s) and yearlings (C1s), and the number of C1s per AF, did not change between decades. The date of spring sea-ice retreat in the previous year was positively correlated with C1 litter size, suggesting smaller litters following years with earlier sea-ice breakup. Our study provides evidence for range expansion, improved body condition, and stable reproductive performance in the KB polar bear subpopulation. These changes, together with a likely increasing subpopulation abundance, may reflect the shift from thick, multiyear ice to thinner, seasonal ice with higher biological productivity. The duration of these benefits is unknown because, under unmitigated climate change, continued sea-ice loss is expected to eventually have negative demographic and ecological effects on all polar bears.
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Affiliation(s)
- Kristin L Laidre
- Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle, WA, USA
- Greenland Institute of Natural Resources, Nuuk, Greenland
| | - Stephen N Atkinson
- Wildlife Research Section, Department of Environment, Government of Nunavut, Igloolik, NU, Canada
| | - Eric V Regehr
- Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle, WA, USA
| | - Harry L Stern
- Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle, WA, USA
| | - Erik W Born
- Greenland Institute of Natural Resources, Nuuk, Greenland
| | - Øystein Wiig
- Natural History Museum, University of Oslo, Oslo, Norway
| | - Nicholas J Lunn
- Environment and Climate Change Canada, University of Alberta, Edmonton, AB, Canada
| | - Markus Dyck
- Wildlife Research Section, Department of Environment, Government of Nunavut, Igloolik, NU, Canada
| | - Patrick Heagerty
- Department of Biostatistics, University of Washington, Seattle, WA, USA
| | - Benjamin R Cohen
- Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle, WA, USA
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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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Boonstra R, Bodner K, Bosson C, Delehanty B, Richardson ES, Lunn NJ, Derocher AE, Molnár PK. The stress of Arctic warming on polar bears. GLOBAL CHANGE BIOLOGY 2020; 26:4197-4214. [PMID: 32364624 DOI: 10.1111/gcb.15142] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 04/15/2020] [Accepted: 04/23/2020] [Indexed: 05/25/2023]
Abstract
Arctic ecosystems are changing rapidly in response to climate warming. While Arctic mammals are highly evolved to these extreme environments, particularly with respect to their stress axis, some species may have limited capacity to adapt to this change. We examined changes in key components of the stress axis (cortisol and its carrier protein-corticosteroid binding globulin [CBG]) in polar bears (Ursus maritimus) from western Hudson Bay (N = 300) over a 33 year period (1983-2015) during which time the ice-free period was increasing. Changing sea ice phenology limits spring hunting opportunities and extends the period of onshore fasting. We assessed the response of polar bears to a standardized stressor (helicopter pursuit, darting, and immobilization) during their onshore fasting period (late summer-autumn) and quantified the serum levels of the maximum corticosteroid binding capacity (MCBC) of CBG, the serum protein that binds cortisol strongly, and free cortisol (FC). We quantified bear condition (age, sex, female with cubs or not, fat condition), sea ice (breakup in spring-summer, 1 year lagged freeze-up in autumn), and duration of fasting until sample collection as well as cumulative impacts of the latter environmental traits from the previous year. Data were separated into "good" years (1983-1990) when conditions were thought to be optimal and "poor" years (1991-2015) when sea ice conditions deteriorated and fasting on land was extended. MCBC explained 39.4% of the variation in the good years, but only 28.1% in the poor ones, using both biological and environmental variables. MCBC levels decreased with age. Changes in FC were complex, but more poorly explained. Counterintuitively, MCBC levels increased with increased time onshore, 1 year lag effects, and in poor ice years. We conclude that MCBC is a biomarker of stress in polar bears and that the changes we document are a consequence of climate warming.
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Affiliation(s)
- Rudy Boonstra
- Centre for the Neurobiology of Stress, Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, Canada
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, Canada
| | - Korryn Bodner
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, Canada
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada
| | - Curtis Bosson
- Centre for the Neurobiology of Stress, Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, Canada
| | - Brendan Delehanty
- Centre for the Neurobiology of Stress, Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, Canada
| | - Evan S Richardson
- Wildlife Research Division, Science and Technology Branch, Environment and Climate Change Canada, Winnipeg, MB, Canada
| | - Nicholas J Lunn
- Environment and Climate Change Canada, Biological Sciences Building, University of Alberta, Edmonton, AB, Canada
| | - Andrew E Derocher
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Péter K Molnár
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, Canada
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada
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Biddlecombe BA, Bayne EM, Lunn NJ, McGeachy D, Derocher AE. Comparing sea ice habitat fragmentation metrics using integrated step selection analysis. Ecol Evol 2020; 10:4791-4800. [PMID: 32551061 PMCID: PMC7297736 DOI: 10.1002/ece3.6233] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 02/21/2020] [Accepted: 03/10/2020] [Indexed: 11/06/2022] Open
Abstract
Habitat fragmentation occurs when continuous habitat gets broken up as a result of ecosystem change. While commonly studied in terrestrial ecosystems, Arctic sea ice ecosystems also experience fragmentation, but are rarely studied in this context. Most fragmentation analyses are conducted using patch-based metrics, which are potentially less suitable for sea ice that has gradual changes between sea ice cover, than distinct "long-term" patches. Using an integrated step selection analysis, we compared the descriptive power of a patch-based metric to a more novel metric, the variation in local spatial autocorrelation over time. We used satellite telemetry data from 39 adult female polar bears (Ursus maritimus) in Hudson Bay to examine their sea ice habitat using Advanced Microwave Scanning Radiometer 2 data during sea ice breakup in May through July from 2013-2018. Spatial autocorrelation resulted in better model fits across 64% of individuals, although both metrics were more effective in describing movement patterns than habitat selection. Variation in local spatial autocorrelation allows for the visualization of sea ice habitat at complex spatial and temporal scales, condensing a targeted time period of habitat that would otherwise have to be analyzed daily.
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Affiliation(s)
| | - Erin M. Bayne
- Department of Biological SciencesUniversity of AlbertaEdmontonAlbertaCanada
| | - Nicholas J. Lunn
- Wildlife Research Division, Science and Technology BranchEnvironment and Climate Change CanadaEdmontonABCanada
| | - David McGeachy
- Wildlife Research Division, Science and Technology BranchEnvironment and Climate Change CanadaEdmontonABCanada
| | - Andrew E. Derocher
- Department of Biological SciencesUniversity of AlbertaEdmontonAlbertaCanada
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Laidre KL, Atkinson S, Regehr EV, Stern HL, Born EW, Wiig Ø, Lunn NJ, Dyck M. Interrelated ecological impacts of climate change on an apex predator. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2020; 30:e02071. [PMID: 31925853 PMCID: PMC7317597 DOI: 10.1002/eap.2071] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 09/12/2019] [Accepted: 11/11/2019] [Indexed: 05/29/2023]
Abstract
Climate change has broad ecological implications for species that rely on sensitive habitats. For some top predators, loss of habitat is expected to lead to cascading behavioral, nutritional, and reproductive changes that ultimately accelerate population declines. In the case of the polar bear (Ursus maritimus), declining Arctic sea ice reduces access to prey and lengthens seasonal fasting periods. We used a novel combination of physical capture, biopsy darting, and visual aerial observation data to project reproductive performance for polar bears by linking sea ice loss to changes in habitat use, body condition (i.e., fatness), and cub production. Satellite telemetry data from 43 (1991-1997) and 38 (2009-2015) adult female polar bears in the Baffin Bay subpopulation showed that bears now spend an additional 30 d on land (90 d in total) in the 2000s compared to the 1990s, a change closely correlated with changes in spring sea ice breakup and fall sea ice formation. Body condition declined for all sex, age, and reproductive classes and was positively correlated with sea ice availability in the current and previous year. Furthermore, cub litter size was positively correlated with maternal condition and spring breakup date (i.e., later breakup leading to larger litters), and negatively correlated with the duration of the ice-free period (i.e., longer ice-free periods leading to smaller litters). Based on these relationships, we projected reproductive performance three polar bear generations into the future (approximately 35 yr). Results indicate that two-cub litters, previously the norm, could largely disappear from Baffin Bay as sea ice loss continues. Our findings demonstrate how concurrent analysis of multiple data types collected over long periods from polar bears can provide a mechanistic understanding of the ecological implications of climate change. This information is needed for long-term conservation planning, which includes quantitative harvest risk assessments that incorporate estimated or assumed trends in future environmental carrying capacity.
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Affiliation(s)
- Kristin L. Laidre
- Polar Science CenterApplied Physics LaboratoryUniversity of WashingtonSeattleWashington98105USA
| | - Stephen Atkinson
- Wildlife Research SectionDepartment of EnvironmentGovernment of NunavutP.O. Box 209IgloolikNunavutX0A 0L0Canada
| | - Eric V. Regehr
- Polar Science CenterApplied Physics LaboratoryUniversity of WashingtonSeattleWashington98105USA
| | - Harry L. Stern
- Polar Science CenterApplied Physics LaboratoryUniversity of WashingtonSeattleWashington98105USA
| | - Erik W. Born
- Greenland Institute of Natural ResourcesP.O. Box 5703900NuukGreenland
| | - Øystein Wiig
- Natural History MuseumUniversity of OsloP.O. Box 1172BlindernN‐0318OsloNorway
| | - Nicholas J. Lunn
- Environment and Climate Change CanadaCW‐422 Biological Sciences BuildingUniversity of AlbertaEdmontonAlbertaT6G 2E9Canada
| | - Markus Dyck
- Wildlife Research SectionDepartment of EnvironmentGovernment of NunavutP.O. Box 209IgloolikNunavutX0A 0L0Canada
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Yurkowski DJ, Richardson ES, Lunn NJ, Muir DCG, Johnson AC, Derocher AE, Ehrman AD, Houde M, Young BG, Debets CD, Sciullo L, Thiemann GW, Ferguson SH. Contrasting Temporal Patterns of Mercury, Niche Dynamics, and Body Fat Indices of Polar Bears and Ringed Seals in a Melting Icescape. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:2780-2789. [PMID: 32046488 DOI: 10.1021/acs.est.9b06656] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Polar bears (Ursus maritimus) and ringed seals (Pusa hispida) have a strong predator-prey relationship and are facing climate-associated Arctic habitat loss and harmful dietary exposure to total mercury (THg) and other pollutants. However, little is known about whether both species inhabiting the same area exhibit similar temporal patterns in Hg concentration, niche dynamics, and body fat indices. We used THg, δ13C, and δ15N values of western Hudson Bay polar bear hair (2004-2016) and ringed seal muscle samples (2003-2015) to investigate temporal trends of these variables and multidimensional niche metrics, as well as body fat indices for both species. We found a decline in THg concentration (by 3.8% per year) and δ13C (by 1.5‰) in ringed seals suggesting a change in feeding habits and carbon source use over time, whereas no significant changes occurred in polar bears. In contrast, the polar bear 3-dimensional niche size decreased by nearly half with no change in ringed seal niche size. The δ13C spacing between both species increased by approximately 1.5× suggesting different responses to annual changes in sympagic-pelagic carbon source production. Ringed seal body fat index was higher in years of earlier sea ice breakup with no change occurring in polar bears. These findings indicate that both species are responding differently to a changing environment suggesting a possible weakening of their predator-prey relationship in western Hudson Bay.
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Affiliation(s)
- David J Yurkowski
- University of Manitoba, Winnipeg, Manitoba MB R3T 2N2, Canada
- Fisheries and Oceans Canada, Winnipeg, Manitoba MB R3T 2N6, Canada
| | - Evan S Richardson
- Environment and Climate Change Canada, Winnipeg, Manitoba MB R3B 2B4, Canada
| | - Nicholas J Lunn
- Environment and Climate Change Canada, Edmonton, Alberta AB T5J 0J4, Canada
| | - Derek C G Muir
- Environment and Climate Change Canada, Burlington, Ontario ON L7S 1A1, Canada
| | - Amy C Johnson
- University of Alberta, Edmonton, Alberta AB T6G 2R3, Canada
| | | | - Ashley D Ehrman
- Fisheries and Oceans Canada, Winnipeg, Manitoba MB R3T 2N6, Canada
| | - Magali Houde
- Environment and Climate Change Canada, Montreal, Quebec QC H2Y 2E7, Canada
| | - Brent G Young
- Fisheries and Oceans Canada, Winnipeg, Manitoba MB R3T 2N6, Canada
| | | | - Luana Sciullo
- York University, Toronto, Ontario ON M3J 1P3, Canada
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Galicia MP, Thiemann GW, Dyck MG. Correlates of seasonal change in the body condition of an Arctic top predator. GLOBAL CHANGE BIOLOGY 2020; 26:840-850. [PMID: 31465583 DOI: 10.1111/gcb.14817] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 07/26/2019] [Indexed: 06/10/2023]
Abstract
Climate-driven sea ice loss has led to changes in the timing of key biological events in the Arctic, however, the consequences and rate of these changes remain largely unknown. Polar bears (Ursus maritimus) undergo seasonal changes in energy stores in relation to foraging opportunities and habitat conditions. Declining sea ice has been linked to reduced body condition in some subpopulations, however, the specific timing and duration of the feeding period when bears acquire most of their energy stores and its relationship to the timing of ice break-up is poorly understood. We used community-based sampling to investigate seasonality in body condition (energy stores) of polar bears in Nunavut, Canada, and examined the influence of sea ice variables. We used adipose tissue lipid content as an index of body condition for 1,206 polar bears harvested from 2010-2017 across five subpopulations with varying seasonal ice conditions: Baffin Bay (October-August), Davis Strait and Foxe Basin (year-round), Gulf of Boothia and Lancaster Sound (August-May). Similar seasonal patterns were found in body condition across subpopulations with bears at their nadir of condition in the spring, followed by fat accumulation past break-up date and subsequent peak body condition in autumn, indicating that bears are actively foraging in late spring and early summer. Late season feeding implies that even minor advances in the timing of break-up may have detrimental effects on foraging opportunities, body condition, and subsequent reproduction and survival. The magnitude of seasonal changes in body condition varied across the study area, presumably driven by local environmental conditions. Our results demonstrate how community-based monitoring of polar bears can reveal population-level responses to climate warming in advance of detectable demographic change. Our data on the seasonal timing of polar bear foraging and energy storage should inform predictive models of the effects of climate-mediated sea ice loss.
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Affiliation(s)
| | | | - Markus G Dyck
- Wildlife Research Station, Department of Environment, Government of Nunavut, Igloolik, NU, Canada
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48
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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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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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Routti H, Atwood TC, Bechshoft T, Boltunov A, Ciesielski TM, Desforges JP, Dietz R, Gabrielsen GW, Jenssen BM, Letcher RJ, McKinney MA, Morris AD, Rigét FF, Sonne C, Styrishave B, Tartu S. State of knowledge on current exposure, fate and potential health effects of contaminants in polar bears from the circumpolar Arctic. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 664:1063-1083. [PMID: 30901781 DOI: 10.1016/j.scitotenv.2019.02.030] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 02/01/2019] [Accepted: 02/02/2019] [Indexed: 05/03/2023]
Abstract
The polar bear (Ursus maritimus) is among the Arctic species exposed to the highest concentrations of long-range transported bioaccumulative contaminants, such as halogenated organic compounds and mercury. Contaminant exposure is considered to be one of the largest threats to polar bears after the loss of their Arctic sea ice habitat due to climate change. The aim of this review is to provide a comprehensive summary of current exposure, fate, and potential health effects of contaminants in polar bears from the circumpolar Arctic required by the Circumpolar Action Plan for polar bear conservation. Overall results suggest that legacy persistent organic pollutants (POPs) including polychlorinated biphenyls, chlordanes and perfluorooctane sulfonic acid (PFOS), followed by other perfluoroalkyl compounds (e.g. carboxylic acids, PFCAs) and brominated flame retardants, are still the main compounds in polar bears. Concentrations of several legacy POPs that have been banned for decades in most parts of the world have generally declined in polar bears. Current spatial trends of contaminants vary widely between compounds and recent studies suggest increased concentrations of both POPs and PFCAs in certain subpopulations. Correlative field studies, supported by in vitro studies, suggest that contaminant exposure disrupts circulating levels of thyroid hormones and lipid metabolism, and alters neurochemistry in polar bears. Additionally, field and in vitro studies and risk assessments indicate the potential for adverse impacts to polar bear immune functions from exposure to certain contaminants.
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Affiliation(s)
- Heli Routti
- Norwegian Polar Institute, Fram Centre, NO-9296 Tromsø, Norway.
| | - Todd C Atwood
- U.S. Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, AK 99508, USA
| | - Thea Bechshoft
- Department of Bioscience, Arctic Research Centre (ARC), Faculty of Science and Technology, Aarhus University, Frederiksborgvej 399, PO Box 358, DK-4000 Roskilde, Denmark
| | - Andrei Boltunov
- Marine Mammal Research and Expedition Center, 36 Nahimovskiy pr., Moscow 117997, Russia
| | - Tomasz M Ciesielski
- Department of Biology, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Jean-Pierre Desforges
- Department of Bioscience, Arctic Research Centre (ARC), Faculty of Science and Technology, Aarhus University, Frederiksborgvej 399, PO Box 358, DK-4000 Roskilde, Denmark
| | - Rune Dietz
- Department of Bioscience, Arctic Research Centre (ARC), Faculty of Science and Technology, Aarhus University, Frederiksborgvej 399, PO Box 358, DK-4000 Roskilde, Denmark
| | | | - Bjørn M Jenssen
- Department of Biology, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway; Department of Bioscience, Arctic Research Centre (ARC), Faculty of Science and Technology, Aarhus University, Frederiksborgvej 399, PO Box 358, DK-4000 Roskilde, Denmark; Department of Arctic Technology, University Centre in Svalbard, PO Box 156, NO-9171 Longyearbyen, Norway
| | - Robert J Letcher
- Ecotoxicology and Wildlife Heath Division, Wildlife and Landscape Science Directorate, Environment and Climate Change Canada, National Wildlife Research Centre, Carleton University, 1125 Colonel By Dr., Ottawa, Ontario K1A 0H3, Canada
| | - Melissa A McKinney
- Department of Natural Resource Sciences, McGill University, Ste.-Anne-de-Bellevue, QC H9X 3V9, Canada
| | - Adam D Morris
- Ecotoxicology and Wildlife Heath Division, Wildlife and Landscape Science Directorate, Environment and Climate Change Canada, National Wildlife Research Centre, Carleton University, 1125 Colonel By Dr., Ottawa, Ontario K1A 0H3, Canada
| | - Frank F Rigét
- Department of Bioscience, Arctic Research Centre (ARC), Faculty of Science and Technology, Aarhus University, Frederiksborgvej 399, PO Box 358, DK-4000 Roskilde, Denmark
| | - Christian Sonne
- Department of Bioscience, Arctic Research Centre (ARC), Faculty of Science and Technology, Aarhus University, Frederiksborgvej 399, PO Box 358, DK-4000 Roskilde, Denmark
| | - Bjarne Styrishave
- Toxicology and Drug Metabolism Group, Department of Pharmacy, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen OE, Denmark
| | - Sabrina Tartu
- Norwegian Polar Institute, Fram Centre, NO-9296 Tromsø, Norway
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