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Goh G, Vesterdorf K, Fuller A, Blache D, Maloney SK. Optimal sampling interval for characterisation of the circadian rhythm of body temperature in homeothermic animals using periodogram and cosinor analysis. Ecol Evol 2024; 14:e11243. [PMID: 38601852 PMCID: PMC11004550 DOI: 10.1002/ece3.11243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 03/19/2024] [Accepted: 03/25/2024] [Indexed: 04/12/2024] Open
Abstract
Core body temperature (T c) is a critical aspect of homeostasis in birds and mammals and is increasingly used as a biomarker of the fitness of an animal to its environment. Periodogram and cosinor analysis can be used to estimate the characteristics of the circadian rhythm of T c from data obtained on loggers that have limited memory capacity and battery life. The sampling interval can be manipulated to maximise the recording period, but the impact of sampling interval on the output of periodogram or cosinor analysis is unknown. Some basic guidelines are available from signal analysis theory, but those guidelines have never been tested on T c data. We obtained data at 1-, 5- or 10-min intervals from nine avian or mammalian species, and re-sampled those data to simulate logging at up to 240-min intervals. The period of the rhythm was first analysed using the Lomb-Scargle periodogram, and the mesor, amplitude, acrophase and adjusted coefficient of determination (R 2) from the original and the re-sampled data were obtained using cosinor analysis. Sampling intervals longer than 60 min did not affect the average mesor, amplitude, acrophase or adjusted R 2, but did impact the estimation of the period of the rhythm. In most species, the period was not detectable when intervals longer than 120 min were used. In all individual profiles, a 30-min sampling interval modified the values of the mesor and amplitude by less than 0.1°C, and the adjusted R 2 by less than 0.1. At a 30-min interval, the acrophase was accurate to within 15 min for all species except mice. The adjusted R 2 increased as sampling frequency decreased. In most cases, a 30-min sampling interval provides a reliable estimate of the circadian T c rhythm using periodogram and cosinor analysis. Our findings will help biologists to select sampling intervals to fit their research goals.
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Affiliation(s)
- Grace Goh
- School of Human SciencesThe University of Western AustraliaCrawleyWestern AustraliaAustralia
| | - Kristine Vesterdorf
- School of Human SciencesThe University of Western AustraliaCrawleyWestern AustraliaAustralia
| | - Andrea Fuller
- Brain Function Research Group, School of Physiology, Faculty of Health SciencesUniversity of the WitwatersrandJohannesburgSouth Africa
| | - Dominique Blache
- School of Agriculture and EnvironmentThe University of Western AustraliaCrawleyWestern AustraliaAustralia
| | - Shane K. Maloney
- School of Human SciencesThe University of Western AustraliaCrawleyWestern AustraliaAustralia
- Brain Function Research Group, School of Physiology, Faculty of Health SciencesUniversity of the WitwatersrandJohannesburgSouth Africa
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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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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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4
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Amstrup SC, Bitz CM. Unlock the Endangered Species Act to address GHG emissions. Science 2023; 381:949-951. [PMID: 37651530 DOI: 10.1126/science.adh2280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Abstract
For the first time, ESA evaluations can include impacts on polar bears from greenhouse gas emissions.
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Affiliation(s)
- Steven C Amstrup
- Polar Bears International, Bozeman, MT, USA
- Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA
| | - Cecilia M Bitz
- Atmospheric Sciences, University of Washington, Seattle, WA, USA
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5
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Improving Animal Wellbeing Using Behavior-Based Methodologies: A Discussion on Enrichment and Bears under Human Care. JOURNAL OF ZOOLOGICAL AND BOTANICAL GARDENS 2023. [DOI: 10.3390/jzbg4010022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2023] Open
Abstract
This communication discusses the Bear Care Group’s “behavior-based” enrichment philosophy, focusing on the importance of enrichment programs built on the knowledge of species’ natural histories, living strategies, and observed daily and seasonal routines. Methods for program development are discussed, detailing the benefits to animal wellbeing, including the reduction of chronic stress and frustration that lead to abnormal or stereotypical behaviors. The concepts are illustrated through a discussion of bear natural history and living strategies, but these methods are applicable to a wide range of taxa. The Bear Care Group encourages facilities to consider behavior-based enrichment programs to promote positive welfare for their animals.
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Kellner A, Atwood TC, Douglas DC, Breck SW, Wittemyer G. High winds and melting sea ice trigger landward movement in a polar bear population of concern. Ecosphere 2023. [DOI: 10.1002/ecs2.4420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Affiliation(s)
- Annie Kellner
- Graduate Degree Program in Ecology Colorado State University Fort Collins Colorado USA
- Department of Fish, Wildlife, and Conservation Biology Colorado State University Fort Collins Colorado USA
| | - Todd C. Atwood
- U.S. Geological Survey Alaska Science Center Anchorage Alaska USA
| | | | - Stewart W. Breck
- USDA‐WS‐National Wildlife Research Center Fort Collins Colorado USA
| | - George Wittemyer
- Graduate Degree Program in Ecology Colorado State University Fort Collins Colorado USA
- Department of Fish, Wildlife, and Conservation Biology Colorado State University Fort Collins Colorado USA
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7
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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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8
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Zhou W, Wang M, Gao K, Gao H, Wei F, Nie Y. Behavioural thermoregulation by montane ungulates under climate warming. DIVERS DISTRIB 2022. [DOI: 10.1111/ddi.13626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Affiliation(s)
- Wenliang Zhou
- Key Laboratory of Animal Ecology and Conservation Biology Institute of Zoology, Chinese Academy of Sciences Beijing China
- Center for Evolution and Conservation Biology Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou) Guangzhou China
| | - Meng Wang
- Key Laboratory of Animal Ecology and Conservation Biology Institute of Zoology, Chinese Academy of Sciences Beijing China
- University of Chinese Academy of Sciences Beijing China
| | - Kai Gao
- Ministry of Education, Key Laboratory for Biodiversity Science and Ecological Engineering, College of Life Sciences Beijing Normal University Beijing China
| | - Hualei Gao
- Key Laboratory of Animal Ecology and Conservation Biology Institute of Zoology, Chinese Academy of Sciences Beijing China
| | - Fuwen Wei
- Key Laboratory of Animal Ecology and Conservation Biology Institute of Zoology, Chinese Academy of Sciences Beijing China
- Center for Evolution and Conservation Biology Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou) Guangzhou China
- University of Chinese Academy of Sciences Beijing China
- Center for Excellence in Animal Evolution and Genetics Chinese Academy of Sciences Kunming China
| | - Yonggang Nie
- Key Laboratory of Animal Ecology and Conservation Biology Institute of Zoology, Chinese Academy of Sciences Beijing China
- University of Chinese Academy of Sciences Beijing China
- Center for Excellence in Animal Evolution and Genetics Chinese Academy of Sciences Kunming China
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9
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Griffen BD, Whiteman JP, Pullan S. Significance of autumn and winter food consumption for reproduction by Southern Beaufort Sea polar bears, Ursus maritimus. Polar Biol 2022. [DOI: 10.1007/s00300-022-03066-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
AbstractPolar bears (Ursus maritimus) in the southern Beaufort Sea experience long annual periods when preferred seal prey are scarce or are unavailable. Consumption of bowhead whale (Balaena mysticetus) carcasses from native Alaskan subsistence hunting is increasingly common for onshore polar bears, yet the energetic consequences of this consumption remain unclear. We use data on bears captured repeatedly over periods that encompassed autumn and winter, combined with calculations, to show that adult female bears likely consume an average of at least 4 seal equivalents during both autumn and winter periods and that considerable variation in energy intake exists across individual bears. We further show that subsistence-caught whale carcasses provide an upper threshold of > 4000 seal equivalents, which could potentially meet mean consumption needs of ~ 80% of the southern Beaufort Sea bear subpopulation during autumn and winter periods. Finally, we modify an existing model to show that observed mass changes over autumn and winter could substantially alter spring foraging habitat choice by females with cubs and the chance that a female with reduced energy reserves would abort a pregnancy or abandon cubs in favor of increasing her own survival; these behaviors could potentially influence population vital rates. Our study highlights the importance of mass dynamics over the autumn and winter months, points to the need for additional data on foraging and energetics over this period, and indicates that the recent declines in polar bear body condition in some subpopulations could have complex effects on reproduction.
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10
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Whiteman JP, Harlow HJ, Durner GM, Regehr EV, Amstrup SC, Pagano AM, Ben‐David M. The acute physiological response of polar bears to helicopter capture. J Wildl Manage 2022; 86:e22238. [PMID: 35915725 PMCID: PMC9324155 DOI: 10.1002/jwmg.22238] [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: 09/04/2021] [Revised: 02/25/2022] [Accepted: 03/29/2022] [Indexed: 11/28/2022]
Abstract
Many wildlife species are live captured, sampled, and released; for polar bears (Ursus maritimus) capture often requires chemical immobilization via helicopter darting. Polar bears reduce their activity for approximately 4 days after capture, likely reflecting stress recovery. To better understand this stress, we quantified polar bear activity (via collar‐mounted accelerometers) and body temperature (via loggers in the body core [Tabd] and periphery [Tper]) during 2–6 months of natural behavior, and during helicopter recapture and immobilization. Recapture induced bouts of peak activity higher than those that occurred during natural behavior for 2 of 5 bears, greater peak Tper for 3 of 6 bears, and greater peak Tabd for 1 of 6 bears. High body temperature (>39.0°C) occurred in Tper for 3 of 6 individuals during recapture and 6 of 6 individuals during natural behavior, and in Tabd for 2 of 6 individuals during recapture and 3 of 6 individuals during natural behavior. Measurements of Tabd and Tper correlated with rectal temperatures measured after immobilization, supporting the use of rectal temperatures for monitoring bear response to capture. Using a larger dataset (n = 66 captures), modeling of blood biochemistry revealed that maximum ambient temperature during recapture was associated with a stress leukogram (7–26% decline in percent lymphocytes, 12–21% increase in percent neutrophils) and maximum duration of helicopter operations had a similar but smaller effect. We conclude that polar bear activity and body temperature during helicopter capture are similar to that which occurs during the most intense events of natural behavior; high body temperature, especially in warm capture conditions, is a key concern; additional study of stress leukograms in polar bears is needed; and additional data collection regarding capture operations would be useful.
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Affiliation(s)
- John P. Whiteman
- Department of Biological Sciences, Old Dominion University Hampton Boulevard Norfolk VA 23529 USA
| | - Henry J. Harlow
- Department of Zoology and Physiology, University of Wyoming University Avenue Laramie WY 82071 USA
| | - George M. Durner
- Alaska Science Center, US Geological Survey University Drive Anchorage AK 99508 USA
| | - Eric V. Regehr
- Polar Science Center University of Washington NE 40th Street Seattle WA 98105 USA
| | | | - Anthony M. Pagano
- Alaska Science Center, US Geological Survey University Drive Anchorage AK 99508 USA
| | - Merav Ben‐David
- Department of Zoology and Physiology, University of Wyoming University Avenue Laramie WY 82071 USA
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11
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Lok R, Woelders T, van Koningsveld MJ, Oberman K, Fuhler SG, Beersma DGM, Hut RA. Bright Light Decreases Peripheral Skin Temperature in Healthy Men: A Forced Desynchrony Study Under Dim and Bright Light (II). J Biol Rhythms 2022; 37:417-428. [PMID: 35723003 PMCID: PMC9326805 DOI: 10.1177/07487304221096948] [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] [Indexed: 11/17/2022]
Abstract
Human thermoregulation is strictly regulated by the preoptic area of the hypothalamus, which is directly influenced by the suprachiasmatic nucleus (SCN). The main input pathway of the SCN is light. Here, thermoregulatory effects of light were assessed in humans in a forced desynchrony (FD) design. The FD experiment was performed in dim light (DL, 6 lux) and bright white light (BL, 1300 lux) in 8 men in a semi-randomized within-subject design. A 4 × 18 h FD protocol (5 h sleep, 13 h wake) was applied, with continuous core body temperature (CBT) and skin temperature measurements at the forehead, clavicles, navel, palms, foot soles and toes. Skin temperature parameters indicated sleep-wake modulations as well as internal clock variations. All distal skin temperature parameters increased during sleep, when CBT decreased. Light significantly affected temperature levels during the wake phase, with decreased temperature measured at the forehead and toes and increased navel and clavicular skin temperatures. These effects persisted when the lights were turned off for sleep. Circadian amplitude of CBT and all skin temperature parameters decreased significantly during BL exposure. Circadian proximal skin temperatures cycled in phase with CBT, while distal skin temperatures cycled in anti-phase, confirming the idea that distal skin regions reflect heat dissipation and proximal regions approximate CBT. In general, we find that increased light intensity exposure may have decreased heat loss in humans, especially at times when the circadian system promotes sleep.
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Affiliation(s)
- R Lok
- Chronobiology Unit, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherland.,Department of Psychiatry and Behavioral Sciences, Stanford University, Palo Alto, California, USA.,University of Groningen, Leeuwarden, the Netherlands
| | - T Woelders
- Chronobiology Unit, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherland
| | - M J van Koningsveld
- Chronobiology Unit, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherland
| | - K Oberman
- Chronobiology Unit, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherland
| | - S G Fuhler
- Chronobiology Unit, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherland
| | - D G M Beersma
- Chronobiology Unit, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherland
| | - R A Hut
- Chronobiology Unit, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherland
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12
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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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13
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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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14
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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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15
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Pagano AM, Durner GM, Atwood TC, Douglas DC. Effects of sea ice decline and summer land use on polar bear home range size in the Beaufort Sea. Ecosphere 2021. [DOI: 10.1002/ecs2.3768] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Anthony M. Pagano
- U.S. Geological Survey Alaska Science Center Anchorage Alaska 99508 USA
| | - George M. Durner
- U.S. Geological Survey Alaska Science Center Anchorage Alaska 99508 USA
| | - Todd C. Atwood
- U.S. Geological Survey Alaska Science Center Anchorage Alaska 99508 USA
| | - David C. Douglas
- U.S. Geological Survey Alaska Science Center Juneau Alaska 99801 USA
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16
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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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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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18
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Petherick AS, Reuther JD, Shirar SJ, Anderson SL, DeSantis LRG. Dietary ecology of Alaskan polar bears (Ursus maritimus) through time and in response to Arctic climate change. GLOBAL CHANGE BIOLOGY 2021; 27:3109-3119. [PMID: 33793039 DOI: 10.1111/gcb.15573] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 01/25/2021] [Indexed: 06/12/2023]
Abstract
Arctic climate change poses serious threats to polar bears (Ursus maritimus) as reduced sea ice makes seal prey inaccessible and marine ecosystems undergo bottom-up reorganization. Polar bears' elongated skulls and reduced molar dentition, as compared to their sister species the grizzly bear (Ursus arctos), are adaptations associated with hunting seals on sea ice and a soft, lipid-rich diet of blubber and meat. With significant declines in sea ice, it is unclear if and how polar bears may be altering their diets. Clarifying polar bear dietary responses to changing climates, both today and in the past, is critical to proper conservation and management of this apex predator. This is particularly important when a dietary strategy may be maladaptive. Here, we test the hypothesis that hard-food consumption (i.e., less preferred foods including bone), inferred from dental microwear texture analysis, increased with Arctic warming. We find that polar bears demonstrate a conserved absence of hard-object feeding in Alaska through time (including approximately 1000 years ago), until the 21st century, consistent with a highly conserved and specialized diet of soft blubber and flesh. Notably, our results also suggest that some 21st-century polar bears may be consuming harder foods (e.g., increased carcass utilization, terrestrial foods including garbage), despite having skulls and metabolisms poorly suited for such a diet. Prior to the 21st century, only polar bears with larger mandibles demonstrated increased hard-object feeding, though to a much lower degree than closely related grizzly bears which regularly consume mechanically challenging foods. Polar bears, being morphologically specialized, have biomechanical constraints which may limit their ability to consume mechanically challenging diets, with dietary shifts occurring only under the most extreme scenarios. Collectively, the highly specialized diets and cranial morphology of polar bears may severely limit their ability to adapt to a warming Arctic.
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Affiliation(s)
- Ansley S Petherick
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Joshua D Reuther
- Archaeology Department, University of Alaska Museum of the North, Fairbanks, AK, USA
- Department of Anthropology, University of Alaska, Fairbanks, AK, USA
| | - Scott J Shirar
- Archaeology Department, University of Alaska Museum of the North, Fairbanks, AK, USA
| | - Shelby L Anderson
- Department of Anthropology, Portland State University, Portland, OR, USA
| | - Larisa R G DeSantis
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
- Department of Earth and Environmental Sciences, Vanderbilt University, Nashville, TN, USA
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19
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Williams CL, Hindle AG. Field Physiology: Studying Organismal Function in the Natural Environment. Compr Physiol 2021; 11:1979-2015. [PMID: 34190338 DOI: 10.1002/cphy.c200005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Continuous physiological measurements collected in field settings are essential to understand baseline, free-ranging physiology, physiological range and variability, and the physiological responses of organisms to disturbances. This article presents a current summary of the available technologies to continuously measure the direct physiological parameters in the field at high-resolution/instantaneous timescales from freely behaving animals. There is a particular focus on advantages versus disadvantages of available methods as well as emerging technologies "on the horizon" that may have been validated in captive or laboratory-based scenarios but have yet to be applied in the wild. Systems to record physiological variables from free-ranging animals are reviewed, including radio (VHF/UFH) telemetry, acoustic telemetry, and dataloggers. Physiological parameters that have been continuously measured in the field are addressed in seven sections including heart rate and electrocardiography (ECG); electromyography (EMG); electroencephalography (EEG); body temperature; respiratory, blood, and muscle oxygen; gastric pH and motility; and blood pressure and flow. The primary focal sections are heart rate and temperature as these can be, and have been, extensively studied in free-ranging organisms. Predicted aspects of future innovation in physiological monitoring are also discussed. The article concludes with an overview of best practices and points to consider regarding experimental designs, cautions, and effects on animals. © 2021 American Physiological Society. Compr Physiol 11:1979-2015, 2021.
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Affiliation(s)
- Cassondra L Williams
- National Marine Mammal Foundation, San Diego, California, USA.,Department of Ecology and Evolutionary Biology, School of Biological Science, University of California Irvine, Irvine, California, USA
| | - Allyson G Hindle
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, USA
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20
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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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21
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Wilsterman K, Ballinger MA, Williams CM. A unifying, eco‐physiological framework for animal dormancy. Funct Ecol 2020. [DOI: 10.1111/1365-2435.13718] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Kathryn Wilsterman
- Biological Sciences University of Montana Missoula MT USA
- Integrative Biology University of California Berkeley CA USA
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22
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Kang H, Qiao Y, Li Y, Qin W, Wu X. Keep Cool: Polyhedral ZnO@ZIF-8 Polymer Coatings for Daytime Radiative Cooling. Ind Eng Chem Res 2020. [DOI: 10.1021/acs.iecr.0c01178] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Hongjun Kang
- MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, Heilongjiang 150001, P.R. China
- School of Materials Science and Engineering, Harbin Institute of Technology, Harbin, Heilongjiang 150001, P.R. China
| | - Yadong Qiao
- MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, Heilongjiang 150001, P.R. China
| | - Yang Li
- MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, Heilongjiang 150001, P.R. China
| | - Wei Qin
- School of Materials Science and Engineering, Harbin Institute of Technology, Harbin, Heilongjiang 150001, P.R. China
| | - Xiaohong Wu
- MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, Heilongjiang 150001, P.R. China
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23
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Weyer NM, Fuller A, Haw AJ, Meyer LCR, Mitchell D, Picker M, Rey B, Hetem RS. Increased Diurnal Activity Is Indicative of Energy Deficit in a Nocturnal Mammal, the Aardvark. Front Physiol 2020; 11:637. [PMID: 32733261 PMCID: PMC7358442 DOI: 10.3389/fphys.2020.00637] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 05/19/2020] [Indexed: 01/30/2023] Open
Abstract
Shifting activity to cooler times of day buffers animals from increased heat and aridity under climate change. Conversely, when resources are limited, some nocturnal species become more diurnal, reducing energetic costs of keeping warm at night. Aardvarks (Orycteropus afer) are nocturnal, obligate ant- and termite-eating mammals which may be threatened directly by increasing heat and aridity, or indirectly by the effects of climate change on their prey. We hypothesised that the minimum 24-h body temperature of aardvarks would decline during energy scarcity, and that aardvarks would extend their active phases to compensate for reduced resource availability, possibly resulting in increased diurnal activity when aardvarks were energetically compromised. To measure their thermoregulatory patterns and foraging activity, we implanted abdominal temperature and activity data loggers into 12 adult aardvarks and observed them for varying durations over 3 years in the Kalahari. Under non-drought conditions, aardvarks tightly controlled their 24-h body temperature rhythm (mean amplitude of the 24-h body temperature rhythm was 1.8 ± 0.3°C during summer and 2.1 ± 0.1°C during winter) and usually were nocturnal. During a summer drought, aardvarks relaxed the precision of body temperature regulation (mean 24-h amplitude 2.3 ± 0.4°C) and those that subsequently died shifted their activity to progressively earlier times of day in the weeks before their deaths. Throughout the subsequent winter, the aardvarks’ minimum 24-h body temperatures declined, causing exaggerated heterothermy (4.7 ± 1.3°C; absolute range 24.7 to 38.8°C), with one individual’s body temperature varying by 11.7°C within 8 h. When body temperatures were low, aardvarks often emerged from burrows during daytime, and occasionally returned before sunset, resulting in completely diurnal activity. Aardvarks also shortened their active periods by 25% during food scarcity, likely to avoid energetic costs incurred by foraging. Despite their physiological and behavioural flexibility, aardvarks were unable to compensate for reduced food availability. Seven study aardvarks and several others died, presumably from starvation. Our results do not bode well for aardvarks facing climate change, and for the many animal species dependent on aardvark burrows for refuge.
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Affiliation(s)
- Nora Marie Weyer
- Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Andrea Fuller
- Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.,Centre for Veterinary Wildlife Studies and Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa
| | - Anna Jean Haw
- Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.,Research Institute of Wildlife Ecology, Department of Integrative Biology and Evolution, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Leith Carl Rodney Meyer
- Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.,Centre for Veterinary Wildlife Studies and Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Pretoria, South Africa
| | - Duncan Mitchell
- Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Mike Picker
- Department of Biological Sciences, Faculty of Science, University of Cape Town, Cape Town, South Africa
| | - Benjamin Rey
- Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.,Laboratoire de Biométrie et Biologie Evolutive, UMR 5558, Université de Lyon, Université Lyon 1, CNRS, Villeurbanne, France
| | - Robyn Sheila Hetem
- Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.,School of Animal, Plant and Environmental Sciences, Faculty of Science, University of the Witwatersrand, Johannesburg, South Africa
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24
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Post E, Alley RB, Christensen TR, Macias-Fauria M, Forbes BC, Gooseff MN, Iler A, Kerby JT, Laidre KL, Mann ME, Olofsson J, Stroeve JC, Ulmer F, Virginia RA, Wang M. The polar regions in a 2°C warmer world. SCIENCE ADVANCES 2019; 5:eaaw9883. [PMID: 31840060 PMCID: PMC6892626 DOI: 10.1126/sciadv.aaw9883] [Citation(s) in RCA: 126] [Impact Index Per Article: 25.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 09/26/2019] [Indexed: 05/21/2023]
Abstract
Over the past decade, the Arctic has warmed by 0.75°C, far outpacing the global average, while Antarctic temperatures have remained comparatively stable. As Earth approaches 2°C warming, the Arctic and Antarctic may reach 4°C and 2°C mean annual warming, and 7°C and 3°C winter warming, respectively. Expected consequences of increased Arctic warming include ongoing loss of land and sea ice, threats to wildlife and traditional human livelihoods, increased methane emissions, and extreme weather at lower latitudes. With low biodiversity, Antarctic ecosystems may be vulnerable to state shifts and species invasions. Land ice loss in both regions will contribute substantially to global sea level rise, with up to 3 m rise possible if certain thresholds are crossed. Mitigation efforts can slow or reduce warming, but without them northern high latitude warming may accelerate in the next two to four decades. International cooperation will be crucial to foreseeing and adapting to expected changes.
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Affiliation(s)
- Eric Post
- Department of Wildlife, Fish, and Conservation Biology, University of California, Davis, Davis, CA 95616, USA
| | - Richard B. Alley
- Department of Geosciences, and Earth and Environmental Systems Institute, The Pennsylvania State University, University Park, PA 16802, USA
| | - Torben R. Christensen
- Department of Bioscience, Arctic Research Centre, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark
| | - Marc Macias-Fauria
- School of Geography and the Environment, University of Oxford, Oxford OX1 3QY, UK
| | - Bruce C. Forbes
- Arctic Centre, University of Lapland, Box 122, FI-96101 Rovaniemi, Finland
| | - Michael N. Gooseff
- Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO 80303, USA
| | - Amy Iler
- Chicago Botanic Garden, 1000 Lake Cook Road, Glencoe, IL 60022, USA
| | - Jeffrey T. Kerby
- Department of Wildlife, Fish, and Conservation Biology, University of California, Davis, Davis, CA 95616, USA
- Neukom Institute for Computational Science, Institute of Arctic Studies, and Environmental Studies Program, Dartmouth College, Hanover, NH 03755, USA
| | - Kristin L. Laidre
- Polar Science Center, Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, WA 98105, USA
| | - Michael E. Mann
- Department of Meteorology and Atmospheric Science and Department of Geosciences, The Pennsylvania State University, University Park, PA 16802, USA
| | - Johan Olofsson
- Department of Ecology and Environmental Science, Umeå University, S-901 87 Umeå, Sweden
| | - Julienne C. Stroeve
- University College London, Bloomsbury, London, UK
- National Snow and Ice Data Center, Boulder, CO 80303, USA
| | - Fran Ulmer
- Chair, U.S. Arctic Research Commission, 420 L Street, Suite 315 Anchorage, AK 99501, USA
- Chair, U.S. Artic Research Commission, 4350 N. Fairfax Drive, Suite 510, Arlington, VA 22203, USA
- Belfer Center for Science and International Affairs John F. Kennedy School of Government, Harvard University, Cambridge, MA 02138, USA
| | - Ross A. Virginia
- Institute of Arctic Studies, and Environmental Studies Program, Dartmouth College, Hanover, NH 03755, USA
| | - Muyin Wang
- Joint Institute for the Study of the Atmosphere and Ocean, University of Washington, Seattle, WA 98195, USA
- National Oceanic and Atmospheric Administration Pacific Marine Environmental Laboratory, Seattle, WA 98115, USA
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25
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Space use patterns affect stable isotopes of polar bears (Ursus maritimus) in the Beaufort Sea. Polar Biol 2019. [DOI: 10.1007/s00300-019-02546-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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26
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Pagano AM, Williams TM. Estimating the energy expenditure of free-ranging polar bears using tri-axial accelerometers: A validation with doubly labeled water. Ecol Evol 2019; 9:4210-4219. [PMID: 31015999 PMCID: PMC6468055 DOI: 10.1002/ece3.5053] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2018] [Revised: 02/13/2019] [Accepted: 02/19/2019] [Indexed: 01/27/2023] Open
Abstract
Measures of energy expenditure can be used to inform animal conservation and management, but methods for measuring the energy expenditure of free-ranging animals have a variety of limitations. Advancements in biologging technologies have enabled the use of dynamic body acceleration derived from accelerometers as a proxy for energy expenditure. Although dynamic body acceleration has been shown to strongly correlate with oxygen consumption in captive animals, it has been validated in only a few studies on free-ranging animals. Here, we use relationships between oxygen consumption and overall dynamic body acceleration in resting and walking polar bears Ursus maritimus and published values for the costs of swimming in polar bears to estimate the total energy expenditure of 6 free-ranging polar bears that were primarily using the sea ice of the Beaufort Sea. Energetic models based on accelerometry were compared to models of energy expenditure on the same individuals derived from doubly labeled water methods. Accelerometer-based estimates of energy expenditure on average predicted total energy expenditure to be 30% less than estimates derived from doubly labeled water. Nevertheless, accelerometer-based measures of energy expenditure strongly correlated (r 2 = 0.70) with measures derived from doubly labeled water. Our findings highlight the strengths and limitations in dynamic body acceleration as a measure of total energy expenditure while also further supporting its use as a proxy for instantaneous, detailed energy expenditure in free-ranging animals.
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Affiliation(s)
- Anthony M. Pagano
- Alaska Science CenterU.S. Geological SurveyAnchorageAlaska
- Present address:
Institute for Conservation ResearchSan Diego Zoo GlobalSan DiegoCalifornia
| | - Terrie M. Williams
- Department of Ecology & Evolutionary BiologyUniversity of California, Santa CruzSanta CruzCalifornia
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27
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Whiteman JP, Harlow HJ, Durner GM, Regehr EV, Amstrup SC, Ben-David M. Heightened Immune System Function in Polar Bears Using Terrestrial Habitats. Physiol Biochem Zool 2019; 92:1-11. [DOI: 10.1086/698996] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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28
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Hall LE, Chalfoun AD. Behavioural plasticity modulates temperature-related constraints on foraging time for a montane mammal. J Anim Ecol 2018; 88:363-375. [PMID: 30449046 DOI: 10.1111/1365-2656.12925] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 09/10/2018] [Indexed: 11/29/2022]
Abstract
Contemporary climate change is altering temperature profiles across the globe. Increasing temperatures can reduce the amount of time during which conditions are suitable for animals to engage in essential activities, such as securing food. Behavioural plasticity, the ability to alter behaviour in response to the environment, may provide animals with a tool to adjust to changes in the availability of suitable thermal conditions. The extent to which individuals can alter fitness-enhancing behaviours, such as food collection, to proximately buffer variation in temperature, however, remains unclear. Even less well understood are the potential performance advantages of flexible strategies among endotherms. We examined the degree to which individuals altered rates of food collection in response to temperature, and two potential benefits, using the American pika (Ochotona princeps), a temperature-sensitive, food-hoarding mammal, as a model. From July-September 2013-2015, we used motion-activated cameras and in situ temperature loggers to examine pika food-caching activity for 72 individuals across 10 sites in the central Rocky Mountains, USA. We quantified % nitrogen by cache volume as a metric of cache quality, and the number of events during which pikas were active in temperatures ≥25°C as a measure of potential thermoregulatory stress. We found a strong negative effect of temperature on the rate at which pikas cached food. Individual responses to temperature varied substantially in both the level of food-collecting activity and in the degree to which individuals shifted activity with warming temperature. After accounting for available foraging time, individuals that exhibited greater plasticity collected a comparable amount of nitrogen, while simultaneously experiencing fewer occasions in which temperatures eclipsed estimated thermal tolerances. By varying food-collection norms of reaction, individuals were able to plastically respond to temperature-driven reductions in foraging time. Through this increased flexibility, individuals amassed food caches of comparable quality, while minimizing exposure to potentially stressful thermal conditions. Our results suggest that, given sufficient resource quality and availability, plasticity in foraging activity may help temperature-limited endotherms adjust to climate-related constraints on foraging time.
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Affiliation(s)
- L Embere Hall
- Wyoming Cooperative Fish and Wildlife Research Unit, Department of Zoology and Physiology and Program in Ecology, University of Wyoming, Laramie, Wyoming
| | - Anna D Chalfoun
- U.S. Geological Survey, Wyoming Cooperative Fish and Wildlife Research Unit, Department of Zoology and Physiology and Program in Ecology, University of Wyoming, Laramie, Wyoming
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29
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Lillie KM, Gese EM, Atwood TC, Sonsthagen SA. Development of on-shore behavior among polar bears ( Ursus maritimus) in the southern Beaufort Sea: inherited or learned? Ecol Evol 2018; 8:7790-7799. [PMID: 30250663 PMCID: PMC6144971 DOI: 10.1002/ece3.4233] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 04/16/2018] [Accepted: 04/20/2018] [Indexed: 11/24/2022] Open
Abstract
Polar bears (Ursus maritimus) are experiencing rapid and substantial changes to their environment due to global climate change. Polar bears of the southern Beaufort Sea (SB) have historically spent most of the year on the sea ice. However, recent reports from Alaska indicate that the proportion of the SB subpopulation observed on-shore during late summer and early fall has increased. Our objective was to investigate whether this on-shore behavior has developed through genetic inheritance, asocial learning, or through social learning. From 2010 to 2013, genetic data were collected from SB polar bears in the fall via hair snags and remote biopsy darting on-shore and in the spring from captures and remote biopsy darting on the sea ice. Bears were categorized as either on-shore or off-shore individuals based on their presence on-shore during the fall. Levels of genetic relatedness, first-order relatives, mother-offspring pairs, and father-offspring pairs were determined and compared within and between the two categories: on-shore versus off-shore. Results suggested transmission of on-shore behavior through either genetic inheritance or social learning as there was a higher than expected number of first-order relatives exhibiting on-shore behavior. Genetic relatedness and parentage data analyses were in concurrence with this finding, but further revealed mother-offspring social learning as the primary mechanism responsible for the development of on-shore behavior. Recognizing that on-shore behavior among polar bears was predominantly transmitted via social learning from mothers to their offspring has implications for future management and conservation as sea ice continues to decline.
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Affiliation(s)
- Kate M. Lillie
- Department of Wildland ResourcesUtah State UniversityLoganUtah
| | - Eric M. Gese
- U.S. Department of AgricultureWildlife ServicesNational Wildlife Research CenterDepartment of Wildland ResourcesUtah State UniversityLoganUtah
| | - Todd C. Atwood
- Alaska Science CenterU.S. Geological SurveyAnchorageAlaska
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Pagano AM, Carnahan AM, Robbins CT, Owen MA, Batson T, Wagner N, Cutting A, Nicassio-Hiskey N, Hash A, Williams TM. Energetic costs of locomotion in bears: is plantigrade locomotion energetically economical? ACTA ACUST UNITED AC 2018; 221:221/12/jeb175372. [PMID: 29921569 DOI: 10.1242/jeb.175372] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2017] [Accepted: 04/21/2018] [Indexed: 02/05/2023]
Abstract
Ursids are the largest mammals to retain a plantigrade posture. This primitive posture has been proposed to result in reduced locomotor speed and economy relative to digitigrade and unguligrade species, particularly at high speeds. Previous energetics research on polar bears (Ursus maritimus) found locomotor costs were more than double predictions for similarly sized quadrupedal mammals, which could be a result of their plantigrade posture or due to adaptations to their Arctic marine existence. To evaluate whether polar bears are representative of terrestrial ursids or distinctly uneconomical walkers, this study measured the mass-specific metabolism, overall dynamic body acceleration, and gait kinematics of polar bears and grizzly bears (Ursus arctos) trained to rest and walk on a treadmill. At routine walking speeds, we found polar bears and grizzly bears exhibited similar costs of locomotion and gait kinematics, but differing measures of overall dynamic body acceleration. Minimum cost of transport while walking in the two species (2.21 J kg-1 m-1) was comparable to predictions for similarly sized quadrupedal mammals, but these costs doubled (4.42 J kg-1 m-1) at speeds ≥5.4 km h-1 Similar to humans, another large plantigrade mammal, bears appear to exhibit a greater economy while moving at slow speeds.
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Affiliation(s)
- Anthony M Pagano
- US Geological Survey, Alaska Science Center, 4210 University Dr., Anchorage, AK 99508, USA .,Department of Ecology & Evolutionary Biology, University of California, Santa Cruz, CA 95060, USA
| | - Anthony M Carnahan
- School of the Environment and School of Biological Sciences, Washington State University, Pullman, WA 99164, USA
| | - Charles T Robbins
- School of the Environment and School of Biological Sciences, Washington State University, Pullman, WA 99164, USA
| | - Megan A Owen
- Institute for Conservation Research, San Diego Zoo Global, San Diego, CA 92027, USA
| | | | - Nate Wagner
- San Diego Zoo Global, San Diego, CA 92027, USA
| | | | | | - Amy Hash
- Oregon Zoo, Portland, OR 97221, USA
| | - Terrie M Williams
- Department of Ecology & Evolutionary Biology, University of California, Santa Cruz, CA 95060, USA
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Affiliation(s)
- John P Whiteman
- Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA.
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Pagano AM, Durner GM, Rode KD, Atwood TC, Atkinson SN, Peacock E, Costa DP, Owen MA, Williams TM. High-energy, high-fat lifestyle challenges an Arctic apex predator, the polar bear. Science 2018; 359:568-572. [DOI: 10.1126/science.aan8677] [Citation(s) in RCA: 92] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 12/19/2017] [Indexed: 11/02/2022]
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Rode KD, Olson J, Eggett D, Douglas DC, Durner GM, Atwood TC, Regehr EV, Wilson RR, Smith T, St. Martin M. Den phenology and reproductive success of polar bears in a changing climate. J Mammal 2018. [DOI: 10.1093/jmammal/gyx181] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Karyn D Rode
- U.S. Geological Survey, Alaska Science Center, Anchorage, AK, USA
| | - Jay Olson
- Brigham Young University, Plant and Wildlife Sciences, Provo, UT, USA
| | - Dennis Eggett
- Center for Collaborative Research and Statistical Consulting, Department of Statistics, Brigham Young University, Provo, UT, USA
| | - David C Douglas
- U.S. Geological Survey, Alaska Science Center, Juneau, AK, USA
| | - George M Durner
- U.S. Geological Survey, Alaska Science Center, Anchorage, AK, USA
| | - Todd C Atwood
- U.S. Geological Survey, Alaska Science Center, Anchorage, AK, USA
| | - Eric V Regehr
- U.S. Fish and Wildlife Service, Marine Mammals Management, Anchorage, AK, USA
| | - Ryan R Wilson
- U.S. Fish and Wildlife Service, Marine Mammals Management, Anchorage, AK, USA
| | - Tom Smith
- Brigham Young University, Plant and Wildlife Sciences, Provo, UT, USA
| | - Michelle St. Martin
- U.S. Fish and Wildlife Service, Marine Mammals Management, Anchorage, AK, USA
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Rode KD, Wilson RR, Douglas DC, Muhlenbruch V, Atwood TC, Regehr EV, Richardson ES, Pilfold NW, Derocher AE, Durner GM, Stirling I, Amstrup SC, St Martin M, Pagano AM, Simac K. Spring fasting behavior in a marine apex predator provides an index of ecosystem productivity. GLOBAL CHANGE BIOLOGY 2018; 24:410-423. [PMID: 28994242 DOI: 10.1111/gcb.13933] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 08/02/2017] [Indexed: 05/27/2023]
Abstract
The effects of declining Arctic sea ice on local ecosystem productivity are not well understood but have been shown to vary inter-specifically, spatially, and temporally. Because marine mammals occupy upper trophic levels in Arctic food webs, they may be useful indicators for understanding variation in ecosystem productivity. Polar bears (Ursus maritimus) are apex predators that primarily consume benthic and pelagic-feeding ice-associated seals. As such, their productivity integrates sea ice conditions and the ecosystem supporting them. Declining sea ice availability has been linked to negative population effects for polar bears but does not fully explain observed population changes. We examined relationships between spring foraging success of polar bears and sea ice conditions, prey productivity, and general patterns of ecosystem productivity in the Beaufort and Chukchi Seas (CSs). Fasting status (≥7 days) was estimated using serum urea and creatinine levels of 1,448 samples collected from 1,177 adult and subadult bears across three subpopulations. Fasting increased in the Beaufort Sea between 1983-1999 and 2000-2016 and was related to an index of ringed seal body condition. This change was concurrent with declines in body condition of polar bears and observed changes in the diet, condition and/or reproduction of four other vertebrate consumers within the food chain. In contrast, fasting declined in CS polar bears between periods and was less common than in the two Beaufort Sea subpopulations consistent with studies demonstrating higher primary productivity and maintenance or improved body condition in polar bears, ringed seals, and bearded seals despite recent sea ice loss in this region. Consistency between regional and temporal variation in spring polar bear fasting and food web productivity suggests that polar bears may be a useful indicator species. Furthermore, our results suggest that spatial and temporal ecological variation is important in affecting upper trophic-level productivity in these marine ecosystems.
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Affiliation(s)
- Karyn D Rode
- U.S. Geological Survey, Alaska Science Center, Anchorage, AK, USA
| | - Ryan R Wilson
- U.S. Fish and Wildlife Service, Marine Mammals Management, Anchorage, AK, USA
| | - David C Douglas
- U.S. Geological Survey, Alaska Science Center, Juneau, AK, USA
| | | | - Todd C Atwood
- U.S. Geological Survey, Alaska Science Center, Anchorage, AK, USA
| | - Eric V Regehr
- U.S. Fish and Wildlife Service, Marine Mammals Management, Anchorage, AK, USA
| | - Evan S Richardson
- Wildlife Research Division, Science and Technology Branch, Environment Canada, Edmonton, AB, Canada
| | - Nicholas W Pilfold
- Institute for Conservation Research, San Diego Zoo Global, Escondido, CA, USA
| | - Andrew E Derocher
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - George M Durner
- U.S. Geological Survey, Alaska Science Center, Anchorage, AK, USA
| | - Ian Stirling
- Wildlife Research Division, Science and Technology Branch, Environment Canada, Edmonton, AB, Canada
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Steven C Amstrup
- Polar Bears International, Bozeman, MT, USA
- Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA
| | - Michelle St Martin
- U.S. Fish and Wildlife Service, Marine Mammals Management, Anchorage, AK, USA
| | - Anthony M Pagano
- U.S. Geological Survey, Alaska Science Center, Anchorage, AK, USA
| | - Kristin Simac
- U.S. Geological Survey, Alaska Science Center, Anchorage, AK, USA
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Whiteman JP, Harlow HJ, Durner GM, Regehr EV, Amstrup SC, Ben-David M. Phenotypic plasticity and climate change: can polar bears respond to longer Arctic summers with an adaptive fast? Oecologia 2017; 186:369-381. [DOI: 10.1007/s00442-017-4023-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 11/22/2017] [Indexed: 02/02/2023]
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Durner GM, Douglas DC, Albeke SE, Whiteman JP, Amstrup SC, Richardson E, Wilson RR, Ben-David M. Increased Arctic sea ice drift alters adult female polar bear movements and energetics. GLOBAL CHANGE BIOLOGY 2017; 23:3460-3473. [PMID: 28586523 DOI: 10.1111/gcb.13746] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 03/17/2017] [Accepted: 04/13/2017] [Indexed: 06/07/2023]
Abstract
Recent reductions in thickness and extent have increased drift rates of Arctic sea ice. Increased ice drift could significantly affect the movements and the energy balance of polar bears (Ursus maritimus) which forage, nearly exclusively, on this substrate. We used radio-tracking and ice drift data to quantify the influence of increased drift on bear movements, and we modeled the consequences for energy demands of adult females in the Beaufort and Chukchi seas during two periods with different sea ice characteristics. Westward and northward drift of the sea ice used by polar bears in both regions increased between 1987-1998 and 1999-2013. To remain within their home ranges, polar bears responded to the higher westward ice drift with greater eastward movements, while their movements north in the spring and south in fall were frequently aided by ice motion. To compensate for more rapid westward ice drift in recent years, polar bears covered greater daily distances either by increasing their time spent active (7.6%-9.6%) or by increasing their travel speed (8.5%-8.9%). This increased their calculated annual energy expenditure by 1.8%-3.6% (depending on region and reproductive status), a cost that could be met by capturing an additional 1-3 seals/year. Polar bears selected similar habitats in both periods, indicating that faster drift did not alter habitat preferences. Compounding reduced foraging opportunities that result from habitat loss; changes in ice drift, and associated activity increases, likely exacerbate the physiological stress experienced by polar bears in a warming Arctic.
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Affiliation(s)
- George M Durner
- U.S. Geological Survey, Alaska Science Center, Anchorage, AK, USA
| | - David C Douglas
- U.S. Geological Survey, Alaska Science Center, Juneau, AK, USA
| | - Shannon E Albeke
- Wyoming Geographic Information Science Center, University of Wyoming, Laramie, WY, USA
| | - John P Whiteman
- Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA
| | | | - Evan Richardson
- Environment and Climate Change Canada, University of Alberta, Edmonton, AB, Canada
| | - Ryan R Wilson
- U.S. Fish and Wildlife Service, Marine Mammals Management, Anchorage, AK, USA
| | - Merav Ben-David
- Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA
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Whiteman JP, Harlow HJ, Durner GM, Regehr EV, Rourke BC, Robles M, Amstrup SC, Ben-David M. Polar bears experience skeletal muscle atrophy in response to food deprivation and reduced activity in winter and summer. CONSERVATION PHYSIOLOGY 2017; 5:cox049. [PMID: 28835844 PMCID: PMC5550809 DOI: 10.1093/conphys/cox049] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 07/05/2017] [Accepted: 07/26/2017] [Indexed: 05/31/2023]
Abstract
When reducing activity and using stored energy during seasonal food shortages, animals risk degradation of skeletal muscles, although some species avoid or minimize the resulting atrophy while experiencing these conditions during hibernation. Polar bears may be food deprived and relatively inactive during winter (when pregnant females hibernate and hunting success declines for other demographic groups) as well as summer (when sea ice retreats from key foraging habitats). We investigated muscle atrophy in samples of biceps femoris collected from free-ranging polar bears in the Southern Beaufort Sea (SBS) throughout their annual cycle. Atrophy was most pronounced in April-May as a result of food deprivation during the previous winter, with muscles exhibiting reduced protein concentration, increased water content, and lower creatine kinase mRNA. These animals increased feeding and activity in spring (when seal prey becomes more available), initiating a period of muscle recovery. During the following ice melt of late summer, ~30% of SBS bears abandon retreating sea ice for land; in August, these 'shore' bears exhibited no muscle atrophy, indicating that they had fully recovered from winter food deprivation. These individuals subsequently scavenged whale carcasses deposited by humans and by October, had retained good muscle condition. In contrast, ~70% of SBS bears follow the ice north in late summer, into deep water with less prey. These 'ice' bears fast; by October, they exhibited muscle protein loss and rapid changes in myosin heavy-chain isoforms in response to reduced activity. These findings indicate that, unlike other bears during winter hibernation, polar bears without food in summer cannot mitigate atrophy. Consequently, prolonged summer fasting resulting from climate change-induced ice loss creates a risk of greater muscle atrophy and reduced abilities to travel and hunt.
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Affiliation(s)
- John P. Whiteman
- Program in Ecology, University of Wyoming, 1000 E. University Avenue, Laramie, WY 82071, USA
- Department of Zoology and Physiology, University of Wyoming, 1000 E. University Avenue, Laramie, WY 82071, USA
| | - Henry J. Harlow
- Department of Zoology and Physiology, University of Wyoming, 1000 E. University Avenue, Laramie, WY 82071, USA
| | - George M. Durner
- U.S. Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, AK 99508, USA
| | - Eric V. Regehr
- Marine Mammals Management, U.S. Fish and Wildlife Service, 1011 East Tudor Road, Anchorage, AK 99503, USA
- Current: Polar Science Center, Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, WA 98105, USA
| | - Bryan C. Rourke
- Department of Biological Sciences, California State University, 1250 Bellflower Blvd, Long Beach, CA 90840, USA
| | - Manuel Robles
- Department of Biological Sciences, California State University, 1250 Bellflower Blvd, Long Beach, CA 90840, USA
| | | | - Merav Ben-David
- Program in Ecology, University of Wyoming, 1000 E. University Avenue, Laramie, WY 82071, USA
- Department of Zoology and Physiology, University of Wyoming, 1000 E. University Avenue, Laramie, WY 82071, USA
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Boyles JG, Bennett NC, Mohammed OB, Alagaili AN. Torpor Patterns in Desert Hedgehogs (Paraechinus aethiopicus) Represent Another New Point along a Thermoregulatory Continuum. Physiol Biochem Zool 2017; 90:445-452. [PMID: 28402233 DOI: 10.1086/691542] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Documenting variation in thermoregulatory patterns across phylogenetically and geographically diverse taxa is key to understanding the evolution of endothermy and heterothermy in birds and mammals. We recorded body temperature (Tb) in free-ranging desert hedgehogs (Paraechinus aethiopicus) across three seasons in the deserts of Saudi Arabia. Modal Tb's (35°-36.5°C) were slightly below normal for mammals but still warmer than those of other hedgehogs. The single maximum Tb recorded was 39.2°C, which is cooler than maximum Tb's recorded in most desert mammals. Desert hedgehogs commonly used torpor during winter and spring but never during summer. Torpor bouts occurred frequently but irregularly, and most lasted less than 24 h. Unlike daily heterotherms, desert hedgehogs did occasionally remain torpid for more than 24 h, including one bout of 101 h. Body temperatures during torpor were often within 2°-3°C of ambient temperature; however, we never recorded repeated bouts of long, predictable torpor punctuated by brief arousal periods similar to those common among seasonal hibernators. Thus, desert hedgehogs can be included on the ever-growing list of species that display torpor patterns intermediate to traditionally defined hibernators and daily heterotherms. Extant hedgehogs are a recent radiation within an ancient family, and the intermediate thermoregulatory pattern displayed by desert hedgehogs is unlike the deeper and more regular torpor seen in other hedgehogs, suggesting that this may be a derived-as opposed to ancestral-trait in this subfamily. We suggest that this family (Erinaceidae) and order (Eulipotyphla) may be important for understanding the evolution of thermoregulatory patterns among Laurasiatheria and mammals in general.
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Affiliation(s)
- Justin G Boyles
- 1 Cooperative Wildlife Research Laboratory, Department of Zoology, Southern Illinois University, Carbondale, Illinois
| | - Nigel C Bennett
- 2 King Saud University Mammals Research Chair, Department of Zoology, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia.,3 Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa
| | - Osama B Mohammed
- 2 King Saud University Mammals Research Chair, Department of Zoology, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
| | - Abdulaziz N Alagaili
- 2 King Saud University Mammals Research Chair, Department of Zoology, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
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Ware JV, Rode KD, Bromaghin JF, Douglas DC, Wilson RR, Regehr EV, Amstrup SC, Durner GM, Pagano AM, Olson J, Robbins CT, Jansen HT. Habitat degradation affects the summer activity of polar bears. Oecologia 2017; 184:87-99. [PMID: 28247129 DOI: 10.1007/s00442-017-3839-y] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 02/09/2017] [Indexed: 01/24/2023]
Abstract
Understanding behavioral responses of species to environmental change is critical to forecasting population-level effects. Although climate change is significantly impacting species' distributions, few studies have examined associated changes in behavior. Polar bear (Ursus maritimus) subpopulations have varied in their near-term responses to sea ice decline. We examined behavioral responses of two adjacent subpopulations to changes in habitat availability during the annual sea ice minimum using activity data. Location and activity sensor data collected from 1989 to 2014 for 202 adult female polar bears in the Southern Beaufort Sea (SB) and Chukchi Sea (CS) subpopulations were used to compare activity in three habitat types varying in prey availability: (1) land; (2) ice over shallow, biologically productive waters; and (3) ice over deeper, less productive waters. Bears varied activity across and within habitats with the highest activity at 50-75% sea ice concentration over shallow waters. On land, SB bears exhibited variable but relatively high activity associated with the use of subsistence-harvested bowhead whale carcasses, whereas CS bears exhibited low activity consistent with minimal feeding. Both subpopulations had fewer observations in their preferred shallow-water sea ice habitats in recent years, corresponding with declines in availability of this substrate. The substantially higher use of marginal habitats by SB bears is an additional mechanism potentially explaining why this subpopulation has experienced negative effects of sea ice loss compared to the still-productive CS subpopulation. Variability in activity among, and within, habitats suggests that bears alter their behavior in response to habitat conditions, presumably in an attempt to balance prey availability with energy costs.
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Affiliation(s)
- Jasmine V Ware
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA, 99164-7620, USA.
| | - Karyn D Rode
- Alaska Science Center, U.S. Geological Survey, 4210 University Dr., Anchorage, AK, 99508, USA
| | - Jeffrey F Bromaghin
- Alaska Science Center, U.S. Geological Survey, 4210 University Dr., Anchorage, AK, 99508, USA
| | - David C Douglas
- Alaska Science Center, U.S. Geological Survey, 250 Egan Drive, Juneau, AK, 99801, USA
| | - Ryan R Wilson
- U.S. Fish and Wildlife Service, 1011 East Tudor Road, MS 341, Anchorage, AK, 99503, USA
| | - Eric V Regehr
- U.S. Fish and Wildlife Service, 1011 East Tudor Road, MS 341, Anchorage, AK, 99503, USA
| | | | - George M Durner
- Alaska Science Center, U.S. Geological Survey, 4210 University Dr., Anchorage, AK, 99508, USA
| | - Anthony M Pagano
- Alaska Science Center, U.S. Geological Survey, 4210 University Dr., Anchorage, AK, 99508, USA
| | - Jay Olson
- Department of Plant and Wildlife Sciences, Brigham Young University, 5049 LSB, Provo, UT, 84602, USA
| | - Charles T Robbins
- School of the Environment and School of Biological Sciences, Washington State University, Pullman, WA, 99164-4236, USA
| | - Heiko T Jansen
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA, 99164-7620, USA
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Laforge MP, Clark DA, Schmidt AL, Lankshear JL, Kowalchuk S, Brook RK. Temporal aspects of polar bear (Ursus maritimus) occurrences at field camps in Wapusk National Park, Canada. Polar Biol 2017. [DOI: 10.1007/s00300-017-2091-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Implications of Rapid Environmental Change for Polar Bear Behavior and Sociality. MARINE MAMMAL WELFARE 2017. [DOI: 10.1007/978-3-319-46994-2_24] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Towards a mechanistic understanding of the responses of large terrestrial mammals to heat and aridity associated with climate change. ACTA ACUST UNITED AC 2016. [DOI: 10.1186/s40665-016-0024-1] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Gormezano LJ, McWilliams SR, Iles DT, Rockwell RF. Costs of locomotion in polar bears: when do the costs outweigh the benefits of chasing down terrestrial prey? CONSERVATION PHYSIOLOGY 2016; 4:cow045. [PMID: 27757238 PMCID: PMC5066388 DOI: 10.1093/conphys/cow045] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Revised: 08/29/2016] [Accepted: 09/11/2016] [Indexed: 06/06/2023]
Abstract
Trade-offs between locomotory costs and foraging gains are key elements in determining constraints on predator-prey interactions. One intriguing example involves polar bears pursuing snow geese on land. As climate change forces polar bears to spend more time ashore, they may need to expend more energy to obtain land-based food. Given that polar bears are inefficient at terrestrial locomotion, any extra energy expended to pursue prey could negatively impact survival. However, polar bears have been regularly observed engaging in long pursuits of geese and other land animals, and the energetic worth of such behaviour has been repeatedly questioned. We use data-driven energetic models to examine how energy expenditures vary across polar bear mass and speed. For the first time, we show that polar bears in the 125-235 kg size range can profitably pursue geese, especially at slower speeds. We caution, however, that heat build-up may be the ultimate limiting factor in terrestrial chases, especially for larger bears, and this limit would be reached more quickly with warmer environmental temperatures.
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Affiliation(s)
- Linda J. Gormezano
- Division of Vertebrate Zoology, American Museum of Natural History, 79th Street and Central Park West, New York, NY 10024, USA
| | - Scott R. McWilliams
- Department of Natural Resources Science, University of Rhode Island, Kingston, RI 02881, USA
| | - David T. Iles
- Department of Wildland Resources and the Ecology Center, 5230 Old Main Hill, Utah State University, Logan, UT 84322-5230, USA
| | - Robert F. Rockwell
- Division of Vertebrate Zoology, American Museum of Natural History, 79th Street and Central Park West, New York, NY 10024, USA
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45
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No safe haven for polar bears in warming Arctic. Nature 2016. [DOI: 10.1038/nature.2016.20590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Pilfold NW, Hedman D, Stirling I, Derocher AE, Lunn NJ, Richardson E. Mass Loss Rates of Fasting Polar Bears. Physiol Biochem Zool 2016; 89:377-88. [DOI: 10.1086/687988] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Atwood TC, Peacock E, McKinney MA, Lillie K, Wilson R, Douglas DC, Miller S, Terletzky P. Rapid Environmental Change Drives Increased Land Use by an Arctic Marine Predator. PLoS One 2016; 11:e0155932. [PMID: 27249673 PMCID: PMC4889047 DOI: 10.1371/journal.pone.0155932] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 05/06/2016] [Indexed: 11/18/2022] Open
Abstract
In the Arctic Ocean’s southern Beaufort Sea (SB), the length of the sea ice melt season (i.e., period between the onset of sea ice break-up in summer and freeze-up in fall) has increased substantially since the late 1990s. Historically, polar bears (Ursus maritimus) of the SB have mostly remained on the sea ice year-round (except for those that came ashore to den), but recent changes in the extent and phenology of sea ice habitat have coincided with evidence that use of terrestrial habitat is increasing. We characterized the spatial behavior of polar bears spending summer and fall on land along Alaska’s north coast to better understand the nexus between rapid environmental change and increased use of terrestrial habitat. We found that the percentage of radiocollared adult females from the SB subpopulation coming ashore has tripled over 15 years. Moreover, we detected trends of earlier arrival on shore, increased length of stay, and later departure back to sea ice, all of which were related to declines in the availability of sea ice habitat over the continental shelf and changes to sea ice phenology. Since the late 1990s, the mean duration of the open-water season in the SB increased by 36 days, and the mean length of stay on shore increased by 31 days. While on shore, the distribution of polar bears was influenced by the availability of scavenge subsidies in the form of subsistence-harvested bowhead whale (Balaena mysticetus) remains aggregated at sites along the coast. The declining spatio-temporal availability of sea ice habitat and increased availability of human-provisioned resources are likely to result in increased use of land. Increased residency on land is cause for concern given that, while there, bears may be exposed to a greater array of risk factors including those associated with increased human activities.
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Affiliation(s)
- Todd C. Atwood
- U.S. Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, AK, 99508, United States of America
- * E-mail:
| | - Elizabeth Peacock
- U.S. Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, AK, 99508, United States of America
| | - Melissa A. McKinney
- University of Connecticut, Center for Environmental Sciences and Engineering and Department of Natural Resources and the Environment, 1376 Storrs Road, Storrs, CT, 06269, United States of America
| | - Kate Lillie
- Utah State University, Department of Wildland Resources, Logan, UT, 84322–5230, United States of America
| | - Ryan Wilson
- U.S. Fish and Wildlife Service, Marine Mammals Management, 1011 E Tudor Road, Anchorage, AK, 99503, United States of America
| | - David C. Douglas
- U.S. Geological Survey, Alaska Science Center, 250 Egan Drive, Juneau, AK, 99801, United States of America
| | - Susanne Miller
- U.S. Fish and Wildlife Service, Marine Mammals Management, 1011 E Tudor Road, Anchorage, AK, 99503, United States of America
| | - Pat Terletzky
- Utah State University, Department of Wildland Resources, Logan, UT, 84322–5230, United States of America
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Sciullo L, Thiemann GW, Lunn NJ. Comparative assessment of metrics for monitoring the body condition of polar bears in western Hudson Bay. J Zool (1987) 2016. [DOI: 10.1111/jzo.12354] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- L. Sciullo
- Department of Biology; York University; Toronto Ontario M3J 1P3 Canada
| | - G. W. Thiemann
- Faculty of Environmental Studies; York University; Toronto Ontario M3J 1P3 Canada
| | - N. J. Lunn
- Wildlife Research Division; Science and Technology Branch; Environment and Climate Change Canada; University of Alberta; Edmonton Alberta T6G 2E9 Canada
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McCue MD, Welch KC. (13)C-Breath testing in animals: theory, applications, and future directions. J Comp Physiol B 2015; 186:265-85. [PMID: 26660654 DOI: 10.1007/s00360-015-0950-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Revised: 11/11/2015] [Accepted: 11/25/2015] [Indexed: 10/22/2022]
Abstract
The carbon isotope values in the exhaled breath of an animal mirror the carbon isotope values of the metabolic fuels being oxidized. The measurement of stable carbon isotopes in carbon dioxide is called (13)C-breath testing and offers a minimally invasive method to study substrate oxidation in vivo. (13)C-breath testing has been broadly used to study human exercise, nutrition, and pathologies since the 1970s. Owing to reduced use of radioactive isotopes and the increased convenience and affordability of (13)C-analyzers, the past decade has witnessed a sharp increase in the use of breath testing throughout comparative physiology--especially to answer questions about how and when animals oxidize particular nutrients. Here, we review the practical aspects of (13)C-breath testing and identify the strengths and weaknesses of different methodological approaches including the use of natural abundance versus artificially-enriched (13)C tracers. We critically compare the information that can be obtained using different experimental protocols such as diet-switching versus fuel-switching. We also discuss several factors that should be considered when designing breath testing experiments including extrinsic versus intrinsic (13)C-labelling and different approaches to model nutrient oxidation. We use case studies to highlight the myriad applications of (13)C-breath testing in basic and clinical human studies as well as comparative studies of fuel use, energetics, and carbon turnover in multiple vertebrate and invertebrate groups. Lastly, we call for increased and rigorous use of (13)C-breath testing to explore a variety of new research areas and potentially answer long standing questions related to thermobiology, locomotion, and nutrition.
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Rode KD, Wilson RR, Regehr EV, St. Martin M, Douglas DC, Olson J. Increased Land Use by Chukchi Sea Polar Bears in Relation to Changing Sea Ice Conditions. PLoS One 2015; 10:e0142213. [PMID: 26580809 PMCID: PMC4651550 DOI: 10.1371/journal.pone.0142213] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 10/19/2015] [Indexed: 11/21/2022] Open
Abstract
Recent observations suggest that polar bears (Ursus maritimus) are increasingly using land habitats in some parts of their range, where they have minimal access to their preferred prey, likely in response to loss of their sea ice habitat associated with climatic warming. We used location data from female polar bears fit with satellite radio collars to compare land use patterns in the Chukchi Sea between two periods (1986–1995 and 2008–2013) when substantial summer sea-ice loss occurred. In both time periods, polar bears predominantly occupied sea-ice, although land was used during the summer sea-ice retreat and during the winter for maternal denning. However, the proportion of bears on land for > 7 days between August and October increased between the two periods from 20.0% to 38.9%, and the average duration on land increased by 30 days. The majority of bears that used land in the summer and for denning came to Wrangel and Herald Islands (Russia), highlighting the importance of these northernmost land habitats to Chukchi Sea polar bears. Where bears summered and denned, and how long they spent there, was related to the timing and duration of sea ice retreat. Our results are consistent with other studies supporting increased land use as a common response of polar bears to sea-ice loss. Implications of increased land use for Chukchi Sea polar bears are unclear, because a recent study observed no change in body condition or reproductive indices between the two periods considered here. This result suggests that the ecology of this region may provide a degree of resilience to sea ice loss. However, projections of continued sea ice loss suggest that polar bears in the Chukchi Sea and other parts of the Arctic may increasingly use land habitats in the future, which has the potential to increase nutritional stress and human-polar bear interactions.
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Affiliation(s)
- Karyn D. Rode
- U.S. Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, Alaska, 99508, United States of America
- * E-mail:
| | - Ryan R. Wilson
- United States Fish and Wildlife Service, Marine Mammals Management, 1011 E Tudor Road, Anchorage, Alaska, 99503, United States of America
| | - Eric V. Regehr
- United States Fish and Wildlife Service, Marine Mammals Management, 1011 E Tudor Road, Anchorage, Alaska, 99503, United States of America
| | - Michelle St. Martin
- United States Fish and Wildlife Service, Marine Mammals Management, 1011 E Tudor Road, Anchorage, Alaska, 99503, United States of America
| | - David C. Douglas
- U.S. Geological Survey, Alaska Science Center, 250 Egan Drive, Juneau, Alaska, 99801, United States of America
| | - Jay Olson
- Brigham Young University, Plant and Wildlife Sciences, 5049 LSB, Provo, Utah, 84602, United States of America
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