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Fry TL, Friedrichs KR, Ketz AC, Duncan C, Van Deelen TR, Goldberg TL, Atwood TC. Long-term assessment of relationships between changing environmental conditions and the physiology of southern Beaufort Sea polar bears (Ursus maritimus). GLOBAL CHANGE BIOLOGY 2023; 29:5524-5539. [PMID: 37503782 DOI: 10.1111/gcb.16883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 06/28/2023] [Accepted: 06/30/2023] [Indexed: 07/29/2023]
Abstract
Climate change is influencing polar bear (Ursus maritimus) habitat, diet, and behavior but the effects of these changes on their physiology is not well understood. Blood-based biomarkers are used to assess the physiologic health of individuals but their usefulness for evaluating population health, especially as it relates to changing environmental conditions, has rarely been explored. We describe links between environmental conditions and physiologic functions of southern Beaufort Sea polar bears using data from blood samples collected from 1984 to 2018, a period marked by extensive environmental change. We evaluated associations between 13 physiologic biomarkers and circumpolar (Arctic oscillation index) and regional (wind patterns and ice-free days) environmental metrics and seasonal and demographic co-variates (age, sex, season, and year) known to affect polar bear ecology. We observed signs of dysregulation of water balance in polar bears following years with a lower annual Arctic oscillation index. In addition, liver enzyme values increased over time, which is suggestive of potential hepatocyte damage as the Arctic has warmed. Biomarkers of immune function increased with regional-scale wind patterns and the number of ice-free days over the Beaufort Sea continental shelf and were lower in years with a lower winter Arctic oscillation index, suggesting an increased allocation of energetic resources for immune processes under these conditions. We propose that the variation in polar bear immune and metabolic function is likely indicative of physiologic plasticity, a response that allows polar bears to remain in homeostasis even as they experience changes in nutrition and habitat in response to changing environments.
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Affiliation(s)
- Tricia L Fry
- School of Veterinary Medicine, University of Wisconsin, Madison, Wisconsin, USA
| | | | - Alison C Ketz
- Department of Forest and Wildlife Ecology, Wisconsin Cooperative Research Unit, University of Wisconsin, Madison, Wisconsin, USA
| | - Colleen Duncan
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, USA
| | - Timothy R Van Deelen
- Department of Forest and Wildlife Ecology, University of Wisconsin, Madison, Wisconsin, USA
| | - Tony L Goldberg
- School of Veterinary Medicine, University of Wisconsin, Madison, Wisconsin, USA
| | - Todd C Atwood
- U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, USA
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2
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Hostetter NJ, Regehr EV, Wilson RR, Royle JA, Converse SJ. Modeling spatiotemporal abundance and movement dynamics using an integrated spatial capture-recapture movement model. Ecology 2022; 103:e3772. [PMID: 35633152 PMCID: PMC9787655 DOI: 10.1002/ecy.3772] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Revised: 12/21/2021] [Accepted: 01/21/2022] [Indexed: 12/30/2022]
Abstract
Animal movement is a fundamental ecological process affecting the survival and reproduction of individuals, the structure of populations, and the dynamics of communities. Methods to quantify animal movement and spatiotemporal abundances, however, are generally separate and therefore omit linkages between individual-level and population-level processes. We describe an integrated spatial capture-recapture (SCR) movement model to jointly estimate (1) the number and distribution of individuals in a defined spatial region and (2) movement of those individuals through time. We applied our model to a study of polar bears (Ursus maritimus) in a 28,125 km2 survey area of the eastern Chukchi Sea, USA in 2015 that incorporated capture-recapture and telemetry data. In simulation studies, the model provided unbiased estimates of movement, abundance, and detection parameters using a bivariate normal random walk and correlated random walk movement process. Our case study provided detailed evidence of directional movement persistence for both male and female bears, where individuals regularly traversed areas larger than the survey area during the 36-day study period. Scaling from individual- to population-level inferences, we found that densities varied from <0.75 bears/625 km2 grid cell/day in nearshore cells to 1.6-2.5 bears/grid cell/day for cells surrounded by sea ice. Daily abundance estimates ranged from 53 to 69 bears, with no trend across days. The cumulative number of unique bears that used the survey area increased through time due to movements into and out of the area, resulting in an estimated 171 individuals using the survey area during the study (95% credible interval 124-250). Abundance estimates were similar to a previous multiyear integrated population model using capture-recapture and telemetry data (2008-2016; Regehr et al., Scientific Reports 8:16780, 2018). Overall, the SCR-movement model successfully quantified both individual- and population-level space use, including the effects of landscape characteristics on movement, abundance, and detection, while linking the movement and abundance processes to directly estimate density within a prescribed spatial region and temporal period. Integrated SCR-movement models provide a generalizable approach to incorporate greater movement realism into population dynamics and link movement to emergent properties including spatiotemporal densities and abundances.
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Affiliation(s)
- Nathan J. Hostetter
- Washington Cooperative Fish and Wildlife Research Unit, School of Aquatic and Fishery SciencesUniversity of WashingtonSeattleWashingtonUSA,Present address:
United States Geological Survey, North Carolina Cooperative Fish and Wildlife Research Unit, Department of Applied EcologyNorth Carolina State UniversityRaleighNorth CarolinaUSA
| | - Eric V. Regehr
- Applied Physics LaboratoryPolar Science Center, University of WashingtonSeattleWashingtonUSA
| | - Ryan R. Wilson
- Marine Mammals ManagementUnited States Fish and Wildlife ServiceAnchorageAlaskaUSA
| | - J. Andrew Royle
- United States Geological SurveyEastern Ecological Science CenterLaurelMarylandUSA
| | - Sarah J. Converse
- United States Geological Survey, Washington Cooperative Fish and Wildlife Research Unit, School of Environmental and Forest Sciences and School of Aquatic and Fishery SciencesUniversity of WashingtonSeattleWashingtonUSA
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3
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Peacock E. A new polar bear population. Science 2022; 376:1267-1268. [PMID: 35709265 DOI: 10.1126/science.abq5267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Can the international conservation agreement protect these bears?
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Affiliation(s)
- Elizabeth Peacock
- Department of Emergency Medicine, Emory University School of Medicine, Atlanta, GA. USA
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4
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Vongraven D, Derocher AE, Pilfold NW, Yoccoz NG. Polar Bear Harvest Patterns Across the Circumpolar Arctic. FRONTIERS IN CONSERVATION SCIENCE 2022. [DOI: 10.3389/fcosc.2022.836544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Wildlife harvest remains a conservation concern for many species and assessing patterns of harvest can provide insights on sustainability and inform management. Polar bears (Ursus maritimus) are harvested over a large part of their range by local people. The species has a history of unsustainable harvest that was largely rectified by an international agreement that required science-based management. The objective of our study was to examine the temporal patterns in the number of polar bears harvested, harvest sex ratios, and harvest rates from 1970 to 2018. We analyzed data from 39,049 harvested polar bears (annual mean 797 bears) collected from 1970 to 2018. Harvest varied across populations and times that reflect varying management objectives, episodic events, and changes based on new population estimates. More males than females were harvested with an overall M:F sex ratio of 1.84. Harvest varied by jurisdiction with 68.0% of bears harvested in Canada, 18.0% in Greenland, 11.8% in the USA, and 2.2% in Norway. Harvest rate was often near the 4.5% target rate. Where data allowed harvest rate estimation, the target rate was exceeded in 11 of 13 populations with 1–5 populations per year above the target since 1978. Harvest rates at times were up to 15.9% of the estimated population size suggesting rare episodes of severe over-harvest. Harvest rate was unrelated to a proxy for ecosystem productivity (area of continental shelf within each population) but was correlated with prey diversity. In the last 5–10 years, monitored populations all had harvest rates near sustainable limits, suggesting improvements in management. Polar bear harvest management has reduced the threat it once posed to the species. However, infrequent estimates of abundance, new management objectives, and climate change have raised new concerns about the effects of harvest.
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Hayward KM, Clemente-Carvalho RBG, Jensen EL, de Groot PVC, Branigan M, Dyck M, Tschritter C, Sun Z, Lougheed SC. Genotyping-in-thousands by sequencing (GT-seq) of non-invasive fecal and degraded samples: a new panel to enable ongoing monitoring of Canadian polar bear populations. Mol Ecol Resour 2022; 22:1906-1918. [PMID: 35007402 PMCID: PMC9305793 DOI: 10.1111/1755-0998.13583] [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: 06/16/2021] [Revised: 11/25/2021] [Accepted: 12/07/2021] [Indexed: 11/26/2022]
Abstract
Genetic monitoring using noninvasive samples provides a complement or alternative to traditional population monitoring methods. However, next‐generation sequencing approaches to monitoring typically require high quality DNA and the use of noninvasive samples (e.g., scat) is often challenged by poor DNA quality and contamination by nontarget species. One promising solution is a highly multiplexed sequencing approach called genotyping‐in‐thousands by sequencing (GT‐seq), which can enable cost‐efficient genomics‐based monitoring for populations based on noninvasively collected samples. Here, we develop and validate a GT‐seq panel of 324 single nucleotide polymorphisms (SNPs) optimized for genotyping of polar bears based on DNA from noninvasively collected faecal samples. We demonstrate (1) successful GT‐seq genotyping of DNA from a range of sample sources, including successful genotyping (>50% loci) of 62.9% of noninvasively collected faecal samples determined to contain polar bear DNA; and (2) that we can reliably differentiate individuals, ascertain sex, assess relatedness, and resolve population structure of Canadian polar bear subpopulations based on a GT‐seq panel of 324 SNPs. Our GT‐seq data reveal spatial‐genetic patterns similar to previous polar bear studies but at lesser cost per sample and through use of noninvasively collected samples, indicating the potential of this approach for population monitoring. This GT‐seq panel provides the foundation for a noninvasive toolkit for polar bear monitoring and can contribute to community‐based programmes – a framework which may serve as a model for wildlife conservation and management for species worldwide.
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Affiliation(s)
- Kristen M Hayward
- Department of Biology, Queen's University, Kingston, Ontario, Canada
| | | | - Evelyn L Jensen
- School of Natural and Environmental Sciences, Newcastle University, Newcastle, United Kingdom
| | | | - Marsha Branigan
- Department of Environment and Natural Resources, Government of the Northwest Territories, Inuvik, Northwest Territories, Canada
| | - Markus Dyck
- Department of Environment, Government of Nunavut, Igloolik, Nunavut, Canada
| | | | - Zhengxin Sun
- Department of Biology, Queen's University, Kingston, Ontario, Canada
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6
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Hoondert RPJ, Ragas AMJ, Hendriks AJ. Simulating changes in polar bear subpopulation growth rate due to legacy persistent organic pollutants - Temporal and spatial trends. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 754:142380. [PMID: 33254886 DOI: 10.1016/j.scitotenv.2020.142380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 08/18/2020] [Accepted: 09/11/2020] [Indexed: 06/12/2023]
Abstract
Although atmospheric concentrations of many conventional persistent organic pollutants (POPs) have decreased in the Arctic over the past few decades, levels of most POPs and mercury remain high since the 1990s or start to increase again in Arctic areas, especially polar bears. So far, studies generally focused on individual effects of POPs, and do not directly link POP concentrations in prey species to population-specific parameters. In this study we therefore aimed to estimate the effect of legacy POPs and mercury on population growth rate of nineteen polar bear subpopulations. We modelled population development in three scenarios, based on species sensitivity distributions (SSDs) derived for POPs based on ecotoxicity data for endothermic species. In the first scenario, ecotoxicity data for polar bears were based on the HC50 (the concentration at which 50% of the species is affected). The other two scenarios were based on the HC5 and HC95. Considerable variation in effects of POPs could be observed among the scenarios. In our intermediate scenario, we predicted subpopulation decline for ten out of 15 polar bear subpopulations. The estimated population growth rate was least reduced in Gulf of Boothia and Foxe Basin. On average, PCB concentrations in prey (in μg/g toxic equivalency (TEQ)) posed the largest threat to polar bear subpopulations, with negative modelled population growth rates for the majority of subpopulations. We did not find a correlation between modelled population changes and monitored population trends for the majority of chemical-subpopulation combinations. Modelled population growth rates increased over time, implying a decreasing effect of PCBs, DDTs, and mercury. Polar bear subpopulations are reportedly still declining in four out of the seven subpopulations for which sufficient long-term monitoring data is available, as reported by the IUCN-PBSG. This implies that other emerging pollutants or other anthropogenic stressors may affect polar bear subpopulations.
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Affiliation(s)
- Renske P J Hoondert
- Department of Environmental Science, Institute for Wetland and Water Research, Faculty of Science, Radboud University Nijmegen, the Netherlands.
| | - Ad M J Ragas
- Department of Environmental Science, Institute for Wetland and Water Research, Faculty of Science, Radboud University Nijmegen, the Netherlands; Faculty of Management, Science and Technology, Open University, the Netherlands
| | - A Jan Hendriks
- Department of Environmental Science, Institute for Wetland and Water Research, Faculty of Science, Radboud University Nijmegen, the Netherlands
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7
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Dominique M, Letcher RJ, Rutter A, Langlois VS. Comparative review of the distribution and burden of contaminants in the body of polar bears. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:32456-32466. [PMID: 32556983 DOI: 10.1007/s11356-020-09193-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 05/05/2020] [Indexed: 06/11/2023]
Abstract
Historical (or legacy) contaminants, such as metals and persistent organic pollutants (POPs; e.g., polychlorinated biphenyls) have been measured in circumpolar subpopulations of polar bears, especially from Hudson Bay, East Greenland, and Svalbard, but substantially less is currently known about new and/or emerging contaminants such as polychlorinated naphthalenes, current-use pesticides, organotins, and polycyclic aromatic compounds (PACs). The polar bear (Ursus maritimus) is an apex Arctic predator that accumulates high levels of bioaccumulative POPs and mercury (Hg), but there is currently no comprehensive profiling of the present knowledge on contaminants in tissue and body compartments in polar bears. Based on current literature reports and data, and including archived museum samples (as far back as the 1300s) and up to 2018, the aim of this review is to utilize available data to examine the comparative distribution and burden of mainly lipophilic contaminants in kidney, liver, fat, and other body compartments, such as milk, blood, and brain. Highlight outcomes from this review include the following: (1) the kidneys are one of the most important tissue depots of contaminants in polar bears; (2) there is a critical lack of data concerning the presence of metals of concern (other than Hg); and (3) there currently are no data available on the concentrations of many newer and emerging contaminants, such as PACs, which is especially relevant given the increasing oil and gas development in regions, such as the Beaufort Sea (Canada). Additionally, given the vulnerability of polar bear populations worldwide, there is a need to develop non-invasive approaches to monitor contaminant exposure in polar bears.
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Affiliation(s)
- Mélanie Dominique
- Centre Eau Terre Environnement, Institut national de la recherche scientifique (INRS), Québec City, QC, Canada
| | - Robert J Letcher
- Ecotoxicology and Wildlife Health Division, Wildlife and Landscape Science Directorate, Environment and Climate Change Canada, National Wildlife Research Centre, Carleton University, Ottawa, ON, Canada
| | - Allison Rutter
- School of Environmental Studies, Queen's University, Kingston, ON, Canada
| | - Valerie S Langlois
- Centre Eau Terre Environnement, Institut national de la recherche scientifique (INRS), Québec City, QC, Canada.
- Ecotoxicology and Wildlife Health Division, Wildlife and Landscape Science Directorate, Environment and Climate Change Canada, National Wildlife Research Centre, Carleton University, Ottawa, ON, Canada.
- Ecotoxicogenomics and Endocrine Disruption, Centre Eau Terre Environnement, Institut national de la recherche scientifique (INRS), 490, rue de la Couronne, Québec, QC, G1K 9A9, Canada.
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8
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Richardson ES, Davis C, Stirling I, Derocher AE, Lunn NJ, Malenfant RM. Variance in lifetime reproductive success of male polar bears. Behav Ecol 2020. [DOI: 10.1093/beheco/araa074] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
Despite the important role that population density plays in ecological and evolutionary processes, studies of solitary species that occur at low densities remain scarce. In the context of mating systems, density is expected to influence the ability of males to find and monopolize mates, in turn, influencing variance in lifetime mating/reproductive success and the opportunity for selection. Herein, we investigate variance in male lifetime mating success (LMS), lifetime reproductive success (LRS), and the mating system of a sexually dimorphic carnivore that occurs at low densities, the polar bear (Ursus maritimus). Across 17 cohorts, born from 1975 to 1991, male LMS ranged from 0 to10 mates and LRS from 0 to 14 cubs; 40% of known-age males were not known to have reproduced. The opportunity for sexual selection (Is = 1.66, range = 0.60–4.99) and selection (I = 1.76, range: 0.65–4.89) were low compared to species with similar levels of sexual size dimorphism. Skew in male LRS was also low but significant for most cohorts indicating nonrandom reproductive success. Age-specific reproductive success was biased toward males from 11 to 17 years of age, with variation in fecundity (54%) but not longevity (10%) playing an important role in male reproduction. Our results support a growing body of evidence that suggests that male-biased size dimorphism and polygynous mating systems need not be associated with high variance in male mating and/or reproductive success.
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Affiliation(s)
- Evan S Richardson
- Wildlife Research Division, Science and Technology Branch, Environment and Climate Change Canada, Winnipeg, Manitoba, Canada
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Corey Davis
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Ian Stirling
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
- Wildlife Research Division, Science and Technology Branch, Environment and Climate Change Canada, University of Alberta, Edmonton, Alberta, Canada
| | - Andrew E Derocher
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Nicholas J Lunn
- Wildlife Research Division, Science and Technology Branch, Environment and Climate Change Canada, University of Alberta, Edmonton, Alberta, Canada
| | - René M Malenfant
- Department of Biology, University of New Brunswick, Fredericton, New Brunswick, Canada
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Jensen EL, Tschritter C, de Groot PVC, Hayward KM, Branigan M, Dyck M, Clemente‐Carvalho RBG, Lougheed SC. Canadian polar bear population structure using genome-wide markers. Ecol Evol 2020; 10:3706-3714. [PMID: 32313629 PMCID: PMC7160183 DOI: 10.1002/ece3.6159] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 01/23/2020] [Accepted: 02/18/2020] [Indexed: 12/01/2022] Open
Abstract
Predicting the consequences of environmental changes, including human-mediated climate change on species, requires that we quantify range-wide patterns of genetic diversity and identify the ecological, environmental, and historical factors that have contributed to it. Here, we generate baseline data on polar bear population structure across most Canadian subpopulations (n = 358) using 13,488 genome-wide single nucleotide polymorphisms (SNPs) identified with double-digest restriction site-associated DNA sequencing (ddRAD). Our ddRAD dataset showed three genetic clusters in the sampled Canadian range, congruent with previous studies based on microsatellites across the same regions; however, due to a lack of sampling in Norwegian Bay, we were unable to confirm the existence of a unique cluster in that subpopulation. These data on the genetic structure of polar bears using SNPs provide a detailed baseline against which future shifts in population structure can be assessed, and opportunities to develop new noninvasive tools for monitoring polar bears across their range.
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Affiliation(s)
- Evelyn L. Jensen
- Department of BiologyQueen’s UniversityKingstonONCanada
- Present address:
Department of Ecology and Evolutionary BiologyYale UniversityNew HavenCTUSA
| | | | | | | | - Marsha Branigan
- Department of Environment and Natural ResourcesGovernment of the Northwest TerritoriesInuvikNTCanada
| | - Markus Dyck
- Department of EnvironmentGovernment of NunavutIgloolikNUCanada
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Identifying individual polar bears at safe distances: A test with captive animals. PLoS One 2020; 15:e0228991. [PMID: 32053691 PMCID: PMC7018014 DOI: 10.1371/journal.pone.0228991] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 01/28/2020] [Indexed: 11/20/2022] Open
Abstract
The need to recognise individuals in population and behavioural studies has stimulated the development of various identification methods. A commonly used method is to employ natural markers to distinguish individuals. In particular, the automated processing of photographs of study animals has gained interest due to the speed of processing and the ability to handle a high volume of records. However, automated processing requires high-quality photographs, which means that they need to be taken from a specific angle or at close distances. Polar bears Ursus maritimus, for example, may be identified by automated analysis of whisker spot patterns. However, to obtain photographs of adequate quality, the animals need to be closer than is usually possible without risk to animal or observer. In this study we tested the accuracy of an alternative method to identify polar bears at further distances. This method is based on distinguishing a set of physiognomic characteristics, which can be recognised from photographs taken in the field at distances of up to 400 m. During five trials, sets of photographs of 15 polar bears from six zoos, with each individual bear portrayed on different dates, were presented for identification to ten test observers. Among observers the repeatability of the assessments was 0.68 (SE 0.011). Observers with previous training in photogrammetric techniques performed better than observers without training. Experience with observing polar bears in the wild did not improve skills to identify individuals on photographs. Among the observers with photogrammetric experience, the rate of erroneous assessment was on average 0.13 (SE 0.020). For the inexperienced group this was 0.72 (SE 0.018). Error rates obtained with automated whisker spot analysis were intermediate (0.26–0.58). We suggest that wildlife studies will benefit from applying several identification techniques to collect data under different conditions.
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