1
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Fry TL, Friedrichs KR, Ketz AC, Duncan C, Van Deelen TR, Goldberg TL, Atwood TC. Long-term assessment of relationships between changing environmental conditions and the physiology of southern Beaufort Sea polar bears (Ursus maritimus). GLOBAL CHANGE BIOLOGY 2023; 29:5524-5539. [PMID: 37503782 DOI: 10.1111/gcb.16883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 06/28/2023] [Accepted: 06/30/2023] [Indexed: 07/29/2023]
Abstract
Climate change is influencing polar bear (Ursus maritimus) habitat, diet, and behavior but the effects of these changes on their physiology is not well understood. Blood-based biomarkers are used to assess the physiologic health of individuals but their usefulness for evaluating population health, especially as it relates to changing environmental conditions, has rarely been explored. We describe links between environmental conditions and physiologic functions of southern Beaufort Sea polar bears using data from blood samples collected from 1984 to 2018, a period marked by extensive environmental change. We evaluated associations between 13 physiologic biomarkers and circumpolar (Arctic oscillation index) and regional (wind patterns and ice-free days) environmental metrics and seasonal and demographic co-variates (age, sex, season, and year) known to affect polar bear ecology. We observed signs of dysregulation of water balance in polar bears following years with a lower annual Arctic oscillation index. In addition, liver enzyme values increased over time, which is suggestive of potential hepatocyte damage as the Arctic has warmed. Biomarkers of immune function increased with regional-scale wind patterns and the number of ice-free days over the Beaufort Sea continental shelf and were lower in years with a lower winter Arctic oscillation index, suggesting an increased allocation of energetic resources for immune processes under these conditions. We propose that the variation in polar bear immune and metabolic function is likely indicative of physiologic plasticity, a response that allows polar bears to remain in homeostasis even as they experience changes in nutrition and habitat in response to changing environments.
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Affiliation(s)
- Tricia L Fry
- School of Veterinary Medicine, University of Wisconsin, Madison, Wisconsin, USA
| | | | - Alison C Ketz
- Department of Forest and Wildlife Ecology, Wisconsin Cooperative Research Unit, University of Wisconsin, Madison, Wisconsin, USA
| | - Colleen Duncan
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, USA
| | - Timothy R Van Deelen
- Department of Forest and Wildlife Ecology, University of Wisconsin, Madison, Wisconsin, USA
| | - Tony L Goldberg
- School of Veterinary Medicine, University of Wisconsin, Madison, Wisconsin, USA
| | - Todd C Atwood
- U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, USA
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2
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Rode KD, Taras BD, Stricker CA, Atwood TC, Boucher NP, Durner GM, Derocher AE, Richardson ES, Cherry SG, Quakenbush L, Horstmann L, Bromaghin JF. Diet energy density estimated from isotopes in predator hair associated with survival, habitat, and population dynamics. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2023; 33:e2751. [PMID: 36151883 DOI: 10.1002/eap.2751] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 07/29/2022] [Accepted: 08/30/2022] [Indexed: 06/16/2023]
Abstract
Sea ice loss is fundamentally altering the Arctic marine environment. Yet there is a paucity of data on the adaptability of food webs to ecosystem change, including predator-prey interactions. Polar bears (Ursus maritimus) are an important subsistence resource for Indigenous people and an apex predator that relies entirely on the under-ice food web to meet its energy needs. In this study, we assessed whether polar bears maintained dietary energy density by prey switching in response to spatiotemporal variation in prey availability. We compared the macronutrient composition of diets inferred from stable carbon and nitrogen isotopes in polar bear guard hair (primarily representing summer/fall diet) during periods when bears had low and high survival (2004-2016), between bears that summered on land versus pack ice, and between bears occupying different regions of the Alaskan and Canadian Beaufort Sea. Polar bears consumed diets with lower energy density during periods of low survival, suggesting that concurrent increased dietary proportions of beluga whales (Delphinapterus leucas) did not offset reduced proportions of ringed seals (Pusa hispida). Diets with the lowest energy density and proportions from ringed seal blubber were consumed by bears in the western Beaufort Sea (Alaska) during a period when polar bear abundance declined. Intake required to meet energy requirements of an average free-ranging adult female polar bear was 2.1 kg/day on diets consumed during years with high survival but rose to 3.0 kg/day when survival was low. Although bears that summered onshore in the Alaskan Beaufort Sea had higher-fat diets than bears that summered on the pack ice, access to the remains of subsistence-harvested bowhead whales (Balaena mysticetus) contributed little to improving diet energy density. Because most bears in this region remain with the sea ice year round, prey switching and consumption of whale carcasses onshore appear insufficient to augment diets when availability of their primary prey, ringed seals, is reduced. Our results show that a strong predator-prey relationship between polar bears and ringed seals continues in the Beaufort Sea. The method of estimating dietary blubber using predator hair, demonstrated here, provides a new metric to monitor predator-prey relationships that affect individual health and population demographics.
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Affiliation(s)
- Karyn D Rode
- U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, USA
| | - Brian D Taras
- Alaska Department of Fish and Game, Fairbanks, Alaska, USA
| | - Craig A Stricker
- U.S. Geological Survey, Fort Collins Science Center, Fort Collins, Colorado, USA
| | - Todd C Atwood
- U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, USA
| | - Nicole P Boucher
- University of Alberta, Edmonton, Alberta, Canada
- School of Environmental Studies, University of Victoria, Victoria, British Columbia, Canada
| | - George M Durner
- U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, USA
| | | | - Evan S Richardson
- Environment and Climate Change Canada, Science and Technology Branch, Winnipeg, Manitoba, Canada
| | - Seth G Cherry
- University of Alberta, Edmonton, Alberta, Canada
- Parks Canada, East Kootenay, British Columbia, Canada
| | | | - Lara Horstmann
- College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, Alaska, USA
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3
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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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4
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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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5
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Patil VP, Durner GM, Douglas DC, Atwood TC. Modeling the spatial and temporal dynamics of land‐based polar bear denning in Alaska. J Wildl Manage 2022. [DOI: 10.1002/jwmg.22302] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Vijay P. Patil
- Alaska Science Center U.S. Geological Survey 4210 University Drive Anchorage AK 99508 USA
| | - George M. Durner
- Alaska Science Center U.S. Geological Survey 4210 University Drive Anchorage AK 99508 USA
| | - David C. Douglas
- Alaska Science Center U.S. Geological Survey 250 Egan Drive Juneau AK 99801 USA
| | - Todd C. Atwood
- Alaska Science Center U.S. Geological Survey 4210 University Drive Anchorage AK 99508 USA
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6
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Mattisson J, Linnell JDC, Anders O, Belotti E, Breitenmoser‐Würsten C, Bufka L, Fuxjäger C, Heurich M, Ivanov G, Jędrzejewski W, Kont R, Kowalczyk R, Krofel M, Melovski D, Mengüllüoğlu D, Middelhoff TL, Molinari‐Jobin A, Odden J, Ozoliņš J, Okarma H, Persson J, Schmidt K, Vogt K, Zimmermann F, Andrén H. Timing and synchrony of birth in Eurasian lynx across Europe. Ecol Evol 2022; 12:e9147. [PMID: 35923936 PMCID: PMC9339757 DOI: 10.1002/ece3.9147] [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: 04/20/2022] [Revised: 07/07/2022] [Accepted: 07/11/2022] [Indexed: 11/24/2022] Open
Abstract
The ecology and evolution of reproductive timing and synchrony have been a topic of great interest in evolutionary ecology for decades. Originally motivated by questions related to behavioral and reproductive adaptation to environmental conditions, the topic has acquired new relevance in the face of climate change. However, there has been relatively little research on reproductive phenology in mammalian carnivores. The Eurasian lynx (Lynx lynx) occurs across the Eurasian continent, covering three of the four main climate regions of the world. Thus, their distribution includes a large variation in climatic conditions, making it an ideal species to explore reproductive phenology. Here, we used data on multiple reproductive events from 169 lynx females across Europe. Mean birth date was May 28 (April 23 to July 1), but was ~10 days later in northern Europe than in central and southern Europe. Birth dates were relatively synchronized across Europe, but more so in the north than in the south. Timing of birth was delayed by colder May temperatures. Severe and cold weather may affect neonatal survival via hypothermia and avoiding inclement weather early in the season may select against early births, especially at northern latitudes. Overall, only about half of the kittens born survived until onset of winter but whether kittens were born relatively late or early did not affect kitten survival. Lynx are strict seasonal breeders but still show a degree of flexibility to adapt the timing of birth to surrounding environmental conditions. We argue that lynx give birth later when exposed to colder spring temperatures and have more synchronized births when the window of favorable conditions for raising kittens is shorter. This suggests that lynx are well adapted to different environmental conditions, from dry and warm climates to alpine, boreal, and arctic climates. This variation in reproductive timing will be favorable in times of climate change, as organisms with high plasticity are more likely to adjust to new environmental conditions.
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Affiliation(s)
| | - John D. C. Linnell
- Norwegian Institute for Nature Research Trondheim Norway
- Department of Forestry and Wildlife Management Inland Norway University of Applied Sciences Koppang Norway
| | | | - Elisa Belotti
- Department of Research and Nature Protection Šumava National Park Administration Kašperské Hory Czech Republic
- Faculty of Forestry and Wood Sciences Czech University of Life Sciences Prague Prague Czech Republic
| | | | - Ludek Bufka
- Department of Research and Nature Protection Šumava National Park Administration Kašperské Hory Czech Republic
| | | | - Marco Heurich
- Department of Forestry and Wildlife Management Inland Norway University of Applied Sciences Koppang Norway
- Chair of Wildlife Ecology and Management, Faculty of Environment and Natural Resources University of Freiburg Freiburg Germany
- Department of Visitor Management and National Park Monitoring Bavarian Forest National Park Grafenau Germany
| | | | - Włodzimierz Jędrzejewski
- Mammal Research Institute Polish Academy of Sciences Białowieża Poland
- Centro de Ecología Instituto Venezolano de Investigaciones Científicas (IVIC) Caracas Venezuela
| | - Radio Kont
- Department of Zoology, Institute of Ecology and Earth Sciences University of Tartu Tartu Estonia
| | - Rafał Kowalczyk
- Mammal Research Institute Polish Academy of Sciences Białowieża Poland
| | - Miha Krofel
- Department of Forestry and Renewable Forest Resources, Biotechnical Faculty University of Ljubljana Ljubljana Slovenia
| | - Dime Melovski
- Wildlife Sciences Georg‐August University Goettingen Germany
- Macedonian Ecological Society Skopje Macedonia
| | | | | | | | - John Odden
- Norwegian Institute for Nature Research Oslo Norway
| | - Jānis Ozoliņš
- Latvian State Forest Research Institute “Silava” Salaspils Latvia
| | - Henryk Okarma
- Institute of Nature Conservation Polish Academy of Sciences Kraków Poland
| | - Jens Persson
- Grimsö Wildlife Research Station, Department of Ecology Swedish University of Agricultural Sciences Sweden
| | - Krzysztof Schmidt
- Mammal Research Institute Polish Academy of Sciences Białowieża Poland
| | | | | | - Henrik Andrén
- Grimsö Wildlife Research Station, Department of Ecology Swedish University of Agricultural Sciences Sweden
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7
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Woodruff SP, Blank JJ, Wisdom SS, Wilson RR, Durner GM, Atwood TC, Perham CJ, Pohl CHM. Evaluating the efficacy of aerial infrared surveys to detect artificial polar bear dens. WILDLIFE SOC B 2022. [DOI: 10.1002/wsb.1324] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
| | - Justin J. Blank
- Environmental Research and Consulting, LLC Eagle River AK 99577 USA
| | | | | | - George M. Durner
- U.S. Geological Survey, Alaska Science Center Anchorage AK 99508 USA
| | - Todd C. Atwood
- U.S. Geological Survey, Alaska Science Center Anchorage AK 99508 USA
| | - Craig J. Perham
- U.S. Bureau of Land Management, Alaska State Office Anchorage AK 99513 USA
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8
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Babiy UV, Salomashkina VV, Kulemeev PS, Kholodova MV, Gruzdev AR, Regehr EV. First evidence of a brown bear on Wrangel Island, Russia. URSUS 2022. [DOI: 10.2192/ursus-d-20-00024.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
| | | | | | | | | | - Eric V. Regehr
- Polar Science Center, University of Washington, Seattle, Washington, USA
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9
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Woodruff SP, Andersen EM, Wilson RR, Mangipane LS, Miller SB, Klein KJ, Lemons PR. Classifying the effects of human disturbance on denning polar bears. ENDANGER SPECIES RES 2022. [DOI: 10.3354/esr01203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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10
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Atwood TC, Rode KD, Douglas DC, Simac K, Pagano AM, Bromaghin JF. Long-term variation in polar bear body condition and maternal investment relative to a changing environment. Glob Ecol Conserv 2021. [DOI: 10.1016/j.gecco.2021.e01925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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11
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Van der Walt M, Neuman-Lee LA, Terletzky PA, Atwood TC, Gese EM, French SS. Measuring adrenal and reproductive hormones in hair from Southern Beaufort Sea polar bears (Ursus maritimus). Gen Comp Endocrinol 2021; 310:113807. [PMID: 33964286 DOI: 10.1016/j.ygcen.2021.113807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 04/29/2021] [Accepted: 05/03/2021] [Indexed: 11/23/2022]
Abstract
Polar bears (Ursus maritimus) use sea ice to access marine mammal prey. In Alaska's Southern Beaufort Sea, the declining availability of sea ice habitat in summer and fall has reduced opportunities for polar bears to routinely hunt on the ice for seals, their primary prey. This reduced access to prey may result in physiological stress with subsequent potential consequences to reproductive function (physiological changes that accompany reproduction), which can be measured via reproductive hormones. Hormone concentrations in hair can be used as a minimally invasive alternative to serum concentrations, which must come from animal captures. Hair samples also provide a long-term average measurement of hormone concentrations that is not influenced by short-term fluctuations like that of serum. The aim of this study was (1) to determine if a radioimmunoassay could be used to measure adrenal and reproductive hormones in polar bear hair, and (2) to determine what the relationship is between these hormones and other reproductive, condition, and demographic parameters of polar bears. We successfully validated this method for cortisol, progesterone, estradiol, and testosterone through the analysis of hair and serum of 141 free-ranging polar bears. We found that while hair cannot be used to estimate serum hormone concentrations during the breeding season, hormone concentrations in hair can be used to measure reproductive function in polar bears. Further, our findings support trends in previous studies measuring hormone concentrations in serum. We found that adrenal and some reproductive hormones were positively correlated in hair samples of females. Associations between hormone concentrations in hair and serum did not vary relative to reproductive status of adult females. Serum testosterone increased throughout the breeding season for adult males and was significantly associated with body mass index (BMI). Our research supports the use of hair as a measure of reproductive function in polar bears and allows us to monitor the future effects of climate change on polar bear physiology.
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Affiliation(s)
- Marilize Van der Walt
- Department of Biology and the Ecology Center, Utah State University, 5305 Old Main Hill, Logan, UT 84322, USA.
| | - Lorin A Neuman-Lee
- Department of Biology and the Ecology Center, Utah State University, 5305 Old Main Hill, Logan, UT 84322, USA.
| | - Patricia A Terletzky
- Department of Wildland Resources, Utah State University, 5230 Old Main Hill, Logan, UT 84322, USA.
| | - Todd C Atwood
- U.S. Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, AK 99508, USA.
| | - Eric M Gese
- U.S. Department of Agriculture, Wildlife Services, National Wildlife Research Center, Department of Wildland Resources, Utah State University, Logan, UT 84322, USA.
| | - Susannah S French
- Department of Biology and the Ecology Center, Utah State University, 5305 Old Main Hill, Logan, UT 84322, USA
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12
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Van Horn RC, Sheppard JK, Swaisgood RR, Appleton RD, Sanchez RI, Vallejos DJ, Vallejos J, Owen MA. Site characteristics influence Andean bear natal-den selection in dry forest habitat. URSUS 2021. [DOI: 10.2192/ursus-d-19-00036.2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
| | | | | | - Robyn D. Appleton
- Department of Forest and Conservation Sciences, University of British Columbia, BC V6T 1Z4, Canada
| | - R. Isaí Sanchez
- Spectacled Bear Conservation Society, Batán Grande, Lambayeque, Peru
| | - D. José Vallejos
- Spectacled Bear Conservation Society, Batán Grande, Lambayeque, Peru
| | - Javier Vallejos
- Spectacled Bear Conservation Society, Batán Grande, Lambayeque, Peru
| | - Megan A. Owen
- San Diego Zoo Wildlife Alliance, Escondido, CA 92027-7000, USA
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13
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Crupi AP, Gregovich DP, White KS. Steep and deep: Terrain and climate factors explain brown bear (Ursus arctos) alpine den site selection to guide heli-skiing management. PLoS One 2020; 15:e0238711. [PMID: 32966287 PMCID: PMC7511016 DOI: 10.1371/journal.pone.0238711] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 08/21/2020] [Indexed: 11/28/2022] Open
Abstract
Winter recreation and tourism continue to expand worldwide, and where these activities overlap with valuable wildlife habitat, there is greater potential for conservation concerns. Wildlife populations can be particularly vulnerable to disturbance in alpine habitats as helicopters and snowmachines are increasingly used to access remote backcountry terrain. Brown bears (Ursus arctos) have adapted hibernation strategies to survive this period when resources and energy reserves are limited, and disturbance could negatively impact fitness and survival. To help identify areas of potential conflict between helicopter skiing and denning brown bears in Alaska, we developed a model to predict alpine denning habitat and an associated data-based framework for mitigating disturbance activities. Following den emergence in spring, we conducted three annual aerial surveys (2015-2017) and used locations from three GPS-collared bears (2008-2014) to identify 89 brown bear dens above the forest line. We evaluated brown bear den site selection of land cover, terrain, and climate factors using resource selection function (RSF) models. Our top model supported the hypothesis that bears selected dens based on terrain and climate factors that maximized thermal efficiency. Brown bears selected den sites characterized by steep slopes at moderate elevations in smooth, well-drained topographies that promoted vegetation and deep snow. We used the RSF model to map relative probability of den selection and found 85% of dens occurred within terrain predicted as prime denning habitat. Brown bear exposure to helicopter disturbance was evident as moderate to high intensities of helicopter flight tracking data overlapped prime denning habitat, and we quantified where the risk of these impact was greatest. We also documented evidence of late season den abandonment due to disturbance from helicopter skiing. The results from this study provide valuable insights into bear denning habitat requirements in subalpine and alpine landscapes. Our quantitative framework can be used to support conservation planning for winter recreation industries operating in habitats occupied by denning brown bears.
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Affiliation(s)
- Anthony P. Crupi
- Division of Wildlife Conservation, Alaska Department of Fish and Game, Douglas, Alaska, United States of America
| | - David P. Gregovich
- Division of Wildlife Conservation, Alaska Department of Fish and Game, Douglas, Alaska, United States of America
| | - Kevin S. White
- Division of Wildlife Conservation, Alaska Department of Fish and Game, Douglas, Alaska, United States of America
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14
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Erratum. J Wildl Manage 2020. [DOI: 10.1002/jwmg.21889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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15
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Florko KRN, Derocher AE, Breiter CJC, Ghazal M, Hedman D, Higdon JW, Richardson ES, Sahanatien V, Trim V, Petersen SD. Polar bear denning distribution in the Canadian Arctic. Polar Biol 2020. [DOI: 10.1007/s00300-020-02657-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
AbstractDeclines in Arctic sea ice associated with climate change have resulted in habitat loss for ice-adapted species, while facilitating increased human development at higher latitudes. Development increases land-use and shipping traffic, which can threaten ecologically and culturally important species. Female polar bears (Ursus maritimus) and cubs are susceptible to disturbance during denning; a better understanding of denning habitat distribution may aid management. We compiled existing location data on polar bear denning (n = 64 sources) in Canada between 1967 and 2018, including traditional ecological knowledge (TEK) studies, government and consultant reports, peer-reviewed scientific articles, and unpublished data acquired through data-sharing agreements. We synthesized these data to create a map of known denning locations. Most coastal regions in northern Canada supported denning, but large areas exist where denning is unreported. Gaps remain in the knowledge of polar bear denning in Canada and filling these will aid the conservation and management of polar bears in a changing Arctic.
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16
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Pagano AM, Atwood TC, Durner GM, Williams TM. The seasonal energetic landscape of an apex marine carnivore, the polar bear. Ecology 2020; 101:e02959. [DOI: 10.1002/ecy.2959] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 10/22/2019] [Accepted: 11/12/2019] [Indexed: 12/12/2022]
Affiliation(s)
- Anthony M. Pagano
- U.S. Geological SurveyAlaska Science Center4210 University Drive Anchorage Alaska99508USA
- Department of Ecology & Evolutionary Biology University of California Santa Cruz 130 McAllister Way Santa Cruz California95060USA
| | - Todd C. Atwood
- U.S. Geological SurveyAlaska Science Center4210 University Drive Anchorage Alaska99508USA
| | - George M. Durner
- U.S. Geological SurveyAlaska Science Center4210 University Drive Anchorage Alaska99508USA
| | - Terrie M. Williams
- Department of Ecology & Evolutionary Biology University of California Santa Cruz 130 McAllister Way Santa Cruz California95060USA
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17
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Smith TS, Amstrup SC, Kirschhoffer BJ, York G. Efficacy of aerial forward-looking infrared surveys for detecting polar bear maternal dens. PLoS One 2020; 15:e0222744. [PMID: 32106278 PMCID: PMC7046283 DOI: 10.1371/journal.pone.0222744] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 01/06/2020] [Indexed: 11/20/2022] Open
Abstract
Denned polar bears (Ursus maritimus) are invisible under the snow, therefore winter-time petroleum exploration and development activities in northern Alaska have potential to disturb maternal polar bears and their cubs. Previous research determined forward looking infrared (FLIR) imagery could detect many polar bear maternal dens under the snow, but also identified limitations of FLIR imagery. We evaluated the efficacy of FLIR-surveys conducted by oil-field operators from 2004–2016. Aerial FLIR surveys detected 15 of 33 (45%) and missed 18 (55%) of the dens known to be within surveyed areas. While greater adherence to previously recommended protocols may improve FLIR detection rates, the physical characteristics of polar bear maternal dens, increasing frequencies of weather unsuitable for FLIR detections—caused by global warming, and competing false positives are likely to prevent FLIR surveys from detecting maternal dens reliably enough to afford protections consonant with increasing global threats to polar bear welfare.
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Affiliation(s)
- Tom S. Smith
- Wildlife and Wildlands Conservation Program, Brigham Young University, Provo, UT, United States of America
- * E-mail:
| | - Steven C. Amstrup
- Polar Bears International, Bozeman, MT, United States of America
- Department of Zoology and Physiology, University of Wyoming, Laramie, WY, United States of America
| | | | - Geoffrey York
- Polar Bears International, Bozeman, MT, United States of America
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18
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Ware JV, Rode KD, Robbins CT, Leise T, Weil CR, Jansen HT. The Clock Keeps Ticking: Circadian Rhythms of Free-Ranging Polar Bears. J Biol Rhythms 2020; 35:180-194. [DOI: 10.1177/0748730419900877] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Life in the Arctic presents organisms with multiple challenges, including extreme photic conditions, cold temperatures, and annual loss and daily movement of sea ice. Polar bears ( Ursus maritimus) evolved under these unique conditions, where they rely on ice to hunt their main prey, seals. However, very little is known about the dynamics of their daily and seasonal activity patterns. For many organisms, activity is synchronized (entrained) to the earth’s day/night cycle, in part via an endogenous (circadian) timekeeping mechanism. The present study used collar-mounted accelerometer and global positioning system data from 122 female polar bears in the Chukchi and Southern Beaufort Seas collected over an 8-year period to characterize activity patterns over the calendar year and to determine if circadian rhythms are expressed under the constant conditions found in the Arctic. We reveal that the majority of polar bears (80%) exhibited rhythmic activity for the duration of their recordings. Collectively within the rhythmic bear cohort, circadian rhythms were detected during periods of constant daylight (June-August; 24.40 ± 1.39 h, mean ± SD) and constant darkness (23.89 ± 1.72 h). Exclusive of denning periods (November-April), the time of peak activity remained relatively stable (acrophases: ~1200-1400 h) for most of the year, suggesting either entrainment or masking. However, activity patterns shifted during the spring feeding and seal pupping season, as evidenced by an acrophase inversion to ~2400 h in April, followed by highly variable timing of activity across bears in May. Intriguingly, despite the dynamic environmental photoperiodic conditions, unpredictable daily timing of prey availability, and high between-animal variability, the average duration of activity (alpha) remained stable (11.2 ± 2.9 h) for most of the year. Together, these results reveal a high degree of behavioral plasticity in polar bears while also retaining circadian rhythmicity. Whether this degree of plasticity will benefit polar bears faced with a loss of sea ice remains to be determined.
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Affiliation(s)
- Jasmine V. Ware
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington, USA
- Department of Environment, Government of Nunavut, Igloolik, NU, Canada
| | - Karyn D. Rode
- U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, USA
| | - Charles T. Robbins
- School of the Environment and School of Biological Sciences, Washington State University, Pullman, Washington, USA
| | - Tanya Leise
- Department of Mathematics and Statistics, Amherst College, Amherst, Massachusetts, USA
| | - Colby R. Weil
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington, USA
| | - Heiko T. Jansen
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington, USA
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Wilson RR, Durner GM. Seismic Survey Design and Effects on Maternal Polar Bear Dens. J Wildl Manage 2019. [DOI: 10.1002/jwmg.21800] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Ryan R. Wilson
- U.S. Fish and Wildlife Service 1011 E. Tudor Rd. Anchorage AK 99503 USA
| | - George M. Durner
- U.S. Geological Survey, Alaska Science Center 4210 University Dr. Anchorage AK 99508 USA
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