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Babic NL, Johnstone CP, Reljić S, Sergiel A, Huber Đ, Reina RD. Evaluation of physiological stress in free-ranging bears: current knowledge and future directions. Biol Rev Camb Philos Soc 2023; 98:168-190. [PMID: 36176191 PMCID: PMC10086944 DOI: 10.1111/brv.12902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 08/25/2022] [Accepted: 08/31/2022] [Indexed: 01/12/2023]
Abstract
Stress responses, which are mediated by the neurogenic system (NS) and hypothalamic-pituitary-adrenal (HPA) axis help vertebrates maintain physiological homeostasis. Fight-or-flight responses are activated by the NS, which releases norepinephrine/noradrenaline and epinephrine/adrenaline in response to immediate stressors, whilst the HPA axis releases glucocorticoid hormones (e.g. cortisol and corticosterone) to help mitigate allostatic load. There have been many studies on stress responses of captive animals, but they are not truly reflective of typical ranges or the types of stressors encountered by free-ranging wildlife, such as responses and adaptation to environmental change, which are particularly important from a conservation perspective. As stress can influence the composition of age and sex classes of free-ranging populations both directly and indirectly, ecological research must be prioritised towards more vulnerable taxa. Generally, large predators tend to be particularly at risk of anthropogenically driven population declines because they exhibit reduced behavioural plasticity required to adapt to changing landscapes and exist in reduced geographic ranges, have small population sizes, low fecundity rates, large spatial requirements and occupy high trophic positions. As a keystone species with a long history of coexistence with humans in highly anthropogenic landscapes, there has been growing concern about how humans influence bear behaviour and physiology, via numerous short- and long-term stressors. In this review, we synthesise research on the stress response in free-ranging bear populations and evaluate the effectiveness and limitations of current methodology in measuring stress in bears to identify the most effective metrics for future research. Particularly, we integrate research that utilised haematological variables, cardiac monitors and Global Positioning System (GPS) collars, serum/plasma and faecal glucocorticoid concentrations, hair cortisol levels, and morphological metrics (primarily skulls) to investigate the stress response in ursids in both short- and long-term contexts. We found that in free-ranging bears, food availability and consumption have the greatest influence on individual stress, with mixed responses to anthropogenic influences. Effects of sex and age on stress are also mixed, likely attributable to inconsistent methods. We recommend that methodology across all stress indicators used in free-ranging bears should be standardised to improve interpretation of results and that a wider range of species should be incorporated in future studies.
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Affiliation(s)
- Natarsha L Babic
- School of Biological Sciences, Monash University, 25 Rainforest Walk, Clayton, 3800, Victoria, Australia
| | - Christopher P Johnstone
- School of Biological Sciences, Monash University, 25 Rainforest Walk, Clayton, 3800, Victoria, Australia
| | - Slaven Reljić
- Faculty of Veterinary Medicine, University of Zagreb, Heinzelova 55, Zagreb, 10000, Croatia
| | - Agnieszka Sergiel
- Institute of Nature Conservation, Polish Academy of Sciences, Adama Mickiewicza 33, Krakow, 31120, Poland
| | - Đuro Huber
- Faculty of Veterinary Medicine, University of Zagreb, Heinzelova 55, Zagreb, 10000, Croatia.,Institute of Nature Conservation, Polish Academy of Sciences, Adama Mickiewicza 33, Krakow, 31120, Poland
| | - Richard D Reina
- School of Biological Sciences, Monash University, 25 Rainforest Walk, Clayton, 3800, Victoria, Australia
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2
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Wilson AE, Michaud SA, Jackson AM, Stenhouse G, McClelland CJR, Coops NC, Janz DM. Protein biomarkers in serum as a conservation tool to assess reproduction: a case study on brown bears ( Ursus arctos). CONSERVATION PHYSIOLOGY 2021; 9:coab091. [PMID: 34888057 PMCID: PMC8651255 DOI: 10.1093/conphys/coab091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 10/26/2021] [Accepted: 11/01/2021] [Indexed: 06/13/2023]
Abstract
Monitoring the reproductive characteristics of a species can complement existing conservation strategies by understanding the mechanisms underlying demography. However, methodology to determine important aspects of female reproductive biology is often absent in monitoring programs for large mammals. Protein biomarkers may be a useful tool to detect physiological changes that are indicative of reproductive state. This study aimed to identify protein biomarkers of reproductive status in serum collected from free-ranging female brown bears (Ursus arctos) in Alberta, Canada, from 2001 to 2018. We hypothesized that the expression of proteins related to reproduction in addition to energetics and stress can be used to answer specific management-focused questions: (i) identify when a female is pregnant, (ii) detect if a female is lactating, (iii) determine age of sexual maturity (i.e. primiparity) and (iv) assess female fertility (i.e. reproduction rate). Furthermore, we investigated if silver spoon effects (favourable early life conditions provide fitness benefits through adulthood) could be determined using protein expression. A target panel of 19 proteins with established relationships to physiological function was measured by peptide-based analysis using liquid chromatography and multiple reaction monitoring mass spectrometry and their differential expression was evaluated using a Wilcoxon signed-rank test. We found biomarkers of pregnancy (apolipoprotein B-100 and afamin), lactation (apolipoprotein B-100 and alpha-2-macroglobulin) and sexual maturity (corticosteroid-binding globulin), but there were no statistically significant relationships with protein expression and fertility. The expression of proteins related to reproduction (afamin) and energetics (vitamin-D binding protein) was associated with the nutritional quality of the individual's present habitat rather than their early life habitat. This study highlights potential biomarkers of reproductive status and provides additional methods for monitoring physiological function in wildlife to inform conservation.
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Affiliation(s)
- Abbey E Wilson
- Department of Veterinary Biomedical Sciences, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan S7N 5B4, Canada
| | - Sarah A Michaud
- The University of Victoria Genome BC Proteomics Centre, 4464 Markham St #3101, Victoria, British Columbia V8Z 7X8, Canada
| | - Angela M Jackson
- The University of Victoria Genome BC Proteomics Centre, 4464 Markham St #3101, Victoria, British Columbia V8Z 7X8, Canada
| | - Gordon Stenhouse
- Grizzly Bear Program, fRI Research, 1176 Switzer Drive, Hinton, Alberta T7V 1V3, Canada
| | | | - Nicholas C Coops
- Department of Forest Resource Management, University of British Columbia, 2424 Main Mall, Vancouver, British Columbia V6T 1Z4, Canada
| | - David M Janz
- Department of Veterinary Biomedical Sciences, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan S7N 5B4, Canada
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Wilson AE, Sergiel A, Selva N, Swenson JE, Zedrosser A, Stenhouse G, Janz DM. Correcting for enzyme immunoassay changes in long term monitoring studies. MethodsX 2021; 8:101212. [PMID: 34434735 PMCID: PMC8374155 DOI: 10.1016/j.mex.2021.101212] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 01/02/2021] [Indexed: 11/18/2022] Open
Abstract
Enzyme immunoassays (EIAs) are a common tool for measuring steroid hormones in wildlife due to their low cost, commercial availability, and rapid results. Testing technologies improve continuously, sometimes requiring changes in protocols or crucial assay components. Antibody replacement between EIA kits can cause differences in EIA sensitivity, which can hinder monitoring hormone concentration over time. The antibody in a common cortisol EIA kit used for long-term monitoring of stress in wildlife was replaced in 2014, causing differences in cross reactivity and standard curve concentrations. Therefore, the objective of this study was to develop a method to standardize results following changes in EIA sensitivity. We validated this method using cortisol concentrations measured in the hair of brown bears (Ursus arctos).We used a simple linear regression to model the relationship between cortisol concentrations using kit 1 and kit 2. We found a linear relationship between the two kits (R2 = 0.85) and used the regression equation (kit2 = (0.98 × kit1) + 1.65) to predict cortisol concentrations in re-measured samples. Mean predicted percent error was 16% and 72% of samples had a predicted percent error <20%, suggesting that this method is well-suited for correcting changes in EIA sensitivity.
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Affiliation(s)
- Abbey E. Wilson
- Department of Veterinary Biomedical Sciences, University of Saskatchewan, 44 Campus Drive, Saskatoon, SK S7N 5B3, Canada
- Corresponding author.
| | - Agnieszka Sergiel
- Institute of Nature Conservation, Polish Academy of Sciences, Adama Mickiewicza 33, 31120 Krakow, Poland
| | - Nuria Selva
- Institute of Nature Conservation, Polish Academy of Sciences, Adama Mickiewicza 33, 31120 Krakow, Poland
| | - Jon E. Swenson
- Faculty of Environmental Science and Natural Resource Management, Norwegian University of Life Sciences, Høgskoleveien 12, NO-1432, Norway
| | - Andreas Zedrosser
- Department of Natural Sciences and Environmental Health, University of South-Eastern Norway, Gullbringvegen 36, 3800 Bø, Norway
- Institute for Wildlife Biology and Game Management, University for Natural Resources and Life Sciences, Gregor-Mendel-Straße 33, 1180 Vienna, Austria
| | - Gordon Stenhouse
- fRI Research, Grizzly Bear Program, 1176 Switzer Drive, Hinton T7V 1V3, AB, Canada
| | - David M. Janz
- Department of Veterinary Biomedical Sciences, University of Saskatchewan, 44 Campus Drive, Saskatoon, SK S7N 5B3, Canada
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Christianson D, Coleman TH, Doan Q, Haroldson MA. Physiological consequences of consuming low-energy foods: herbivory coincides with a stress response in Yellowstone bears. CONSERVATION PHYSIOLOGY 2021; 9:coab029. [PMID: 34345432 PMCID: PMC8325456 DOI: 10.1093/conphys/coab029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 03/25/2021] [Accepted: 04/08/2021] [Indexed: 06/13/2023]
Abstract
Meat, fruit, seeds and other high-energy bear foods are often highly localized and briefly available and understanding which factors influence bear consumption of these foods is a common focus of bear conservation and ecology. However, the most common bear foods, graminoids and forbs, are more widespread but of lower quality. We poorly understand how herbage consumption impacts bear physiology, such as endocrine system function that regulates homeostasis and stress responses. Here, we described bear diets with a novel approach, measuring the concentration of chlorophyll in bear scats (faecal chlorophyll) to index the proportion of the recent diet that was composed of leaves from graminoids and forbs. We measured faecal chlorophyll and faecal cortisol in 351 grizzly (Ursus arctos, n = 255) and black bear (Ursus americanus, n = 96) scats from Yellowstone National Park in 2008-2009. We compared models of faecal chlorophyll and faecal cortisol concentrations considering the effects of spatial, dietary, scat and bear-specific factors including species. Faecal chlorophyll levels were the strongest predictor of faecal cortisol in a manner that suggested an endocrine response to a low-energy diet. Both compounds were highest during the spring and early summer months, overlapping the breeding season when higher energy foods were less available. Effects of scat composition, scat weathering, bear age, bear sex, species and other factors that have previously been shown to influence faecal cortisol in bears were not important unless faecal chlorophyll was excluded from models. The top models of faecal chlorophyll suggested grazing was primarily influenced by spatial attributes, with greater grazing closer to recreational trails, implying that elevated cortisol with grazing could be a response to anthropogenic activity. Our results confirm that higher stress hormone concentrations correspond with lower quality diets in bears, particularly grazing, and that faecal chlorophyll shows promise as a metric for studying grazing behaviour and its consequences.
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Affiliation(s)
- David Christianson
- Department of Ecosystem Science and Management, University of Wyoming, Laramie, WY 82071, USA
| | - Tyler H Coleman
- Sequoia-Kings Canyon National Park, National Park Service, 47050 Generals Highway, Three Rivers, CA 93271, USA
| | - Quint Doan
- School of Forestry and Environmental Studies, Yale University, 370 Prospect Street, New Haven CT 06511, USA
| | - Mark A Haroldson
- U.S. Geological Survey, Northern Rocky Mountain Science Center, Interagency Grizzly Bear Study Team, 2327 University Way, Suite 2, Bozeman, MT 59717, USA
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Wilson AE, Wismer D, Stenhouse G, Coops NC, Janz DM. Landscape condition influences energetics, reproduction, and stress biomarkers in grizzly bears. Sci Rep 2021; 11:12124. [PMID: 34108541 PMCID: PMC8190091 DOI: 10.1038/s41598-021-91595-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 05/21/2021] [Indexed: 02/05/2023] Open
Abstract
Environmental change has been shown to influence mammalian distribution, habitat use, and behavior; however, few studies have investigated the impact on physiological function. This study aimed to determine the influence of landscape condition on the expression of target proteins related to energetics, reproduction, and stress in grizzly bears. We hypothesized that changes in landscape condition explains protein expression. Skin biopsies were collected from free-ranging grizzly bears in Alberta, Canada from 2013-2019 (n = 86 individuals). We used an information theoretic approach to develop 11 a priori candidate generalized linear mixed models to explain protein expression. We compared models using Akaike Information Criteria (AICc) weights and averaged models with ΔAICc < 2 for each protein. Food resources, represented by increased distance to coal mines and decreased crown closure, positively influenced energetic proteins (adiponectin and alpha-1-acid glycoprotein). Proteins related to reproduction (ceruloplasmin and serpin B5) were positively associated with increased wetland and upland food resources in addition to movement, but negatively associated with increased distance to roads. One stress related protein, complement C3, was positively influenced by increased percent conifer. Given the need to detect emerging threats to wildlife, we suggest the assessment of physiological function will lead to improved monitoring of species in rapidly changing landscapes.
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Affiliation(s)
- Abbey E. Wilson
- grid.25152.310000 0001 2154 235XDepartment of Veterinary Biomedical Sciences, University of Saskatchewan, 52 Campus Drive, Saskatoon, SK S7N 5B4 Canada ,Toxicology Centre, 44 Campus Drive, Saskatoon, SK S7N 5B3 Canada
| | - Dan Wismer
- fRI Research, Grizzly Bear Program, 1176 Switzer Drive, Hinton, AB T7V 1V3 Canada
| | - Gordon Stenhouse
- fRI Research, Grizzly Bear Program, 1176 Switzer Drive, Hinton, AB T7V 1V3 Canada
| | - Nicholas C. Coops
- grid.17091.3e0000 0001 2288 9830Department of Forest Resource Management, University of British Columbia, 2424 Main Mall, Vancouver, BC V6T 1Z4 Canada
| | - David M. Janz
- grid.25152.310000 0001 2154 235XDepartment of Veterinary Biomedical Sciences, University of Saskatchewan, 52 Campus Drive, Saskatoon, SK S7N 5B4 Canada ,Toxicology Centre, 44 Campus Drive, Saskatoon, SK S7N 5B3 Canada
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Cattet M, Janz DM, Kapronczai L, Erlenbach JA, Jansen HT, Nelson OL, Robbins CT, Stenhouse GB. Cortisol levels in blood and hair of unanesthetized grizzly bears (Ursus arctos) following intravenous cosyntropin injection. Vet Med Sci 2021; 7:2032-2038. [PMID: 33978314 PMCID: PMC8464257 DOI: 10.1002/vms3.523] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 02/23/2021] [Accepted: 04/22/2021] [Indexed: 11/25/2022] Open
Abstract
Hair cortisol concentration (HCC) is being used increasingly to evaluate long‐term stress in many mammalian species. Most of the cortisol is assumed to passively diffuse from circulating blood into hair follicles and gradually accumulate in growing hair. However, our research with free‐ranging grizzly bears (Ursus arctos) suggests HCC increases significantly within several hours following capture, a time too brief to be explained by this mechanism alone. In this study with captive grizzly bears, we sought to determine if a brief spike in blood cortisol concentration, thus mimicking a single stressful event, would cause an increase in HCC over a 7‐day period. To do this, we administered a single intravenous dose (5 μg/kg) of cosyntropin to three captive unanaesthetised adult female grizzly bears on two occasions, during April when hair growth was arrested and during August when hair was growing. In both trials, the cosyntropin caused a two‐fold or greater increase in serum cortisol levels within 1 hr but did not appear to influence HCC at 1, 48, and 168 hr following cosyntropin administration. We conclude the cosyntropin‐induced cortisol spike was likely insignificant when compared to the adrenocortical response that occurs in free‐ranging bears when captured. We suggest further study with a larger sample of captive bears to evaluate the combined effects of anaesthesia and multiple doses of cosyntropin administered over several hours would better simulate the adrenocortical response of free‐ranging grizzly bears during capture.
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Affiliation(s)
- Marc Cattet
- RGL Recovery Wildlife Health & Veterinary Services, Saskatoon, SK, Canada.,Department of Veterinary Pathology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - David M Janz
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada.,Toxicology Centre, University of Saskatchewan, Saskatoon, SK, Canada
| | | | - Joy A Erlenbach
- School of the Environment, Washington State University, Pullman, WA, USA
| | - Heiko T Jansen
- Department of Integrative Physiology and Neuroscience, College of Veterinary Medicine, Washington State University, Pullman, WA, USA
| | - O Lynne Nelson
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA, USA
| | - Charles T Robbins
- School of Biological Sciences, Washington State University, Pullman, WA, USA
| | - Gordon B Stenhouse
- fRI Research, Hinton, AB, Canada.,Alberta Environment & Parks, Edmonton, AB, Canada
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Wilson AE, Michaud SA, Jackson AM, Stenhouse G, Coops NC, Janz DM. Development and validation of protein biomarkers of health in grizzly bears. CONSERVATION PHYSIOLOGY 2020; 8:coaa056. [PMID: 32607241 PMCID: PMC7311831 DOI: 10.1093/conphys/coaa056] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Revised: 04/09/2020] [Accepted: 05/31/2020] [Indexed: 06/11/2023]
Abstract
Large carnivores play critical roles in the maintenance and function of natural ecosystems; however, the populations of many of these species are in decline across the globe. Therefore, there is an urgent need to develop novel techniques that can be used as sensitive conservation tools to detect new threats to the health of individual animals well in advance of population-level effects. Our study aimed to determine the expression of proteins related to energetics, reproduction and stress in the skin of grizzly bears (Ursus arctos) using a liquid chromatography and multiple reaction monitoring mass spectrometry assay. We hypothesized that a suite of target proteins could be measured using this technique and that the expression of these proteins would be associated with biological (sex, age, sample location on body) and environmental (geographic area, season, sample year) variables. Small skin biopsies were collected from free-ranging grizzly bears in Alberta, Canada, from 2013 to 2019 (n = 136 samples from 111 individuals). Over 700 proteins were detected in the skin of grizzly bears, 19 of which were chosen as targets because of their established roles in physiological function. Generalized linear mixed model analysis was used for each target protein. Results indicate that sample year influenced the majority of proteins, suggesting that physiological changes may be driven in part by responses to changes in the environment. Season influenced the expression of proteins related to energetics, reproduction and stress, all of which were lower during fall compared to early spring. The expression of proteins related to energetics and stress varied by geographic area, while the majority of proteins that were affected by biological attributes (age class, sex and age class by sex interaction) were related to reproduction and stress. This study provides a novel method by which scientists and managers can further assess and monitor physiological function in wildlife.
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Affiliation(s)
- Abbey E Wilson
- Department of Veterinary Biomedical Sciences, University of Saskatchewan, 44 Campus Drive, Saskatoon, Saskatchewan S7N 5B3, Canada
| | - Sarah A Michaud
- The University of Victoria Genome BC Proteomics Centre, 4464 Markham St #3101, Victoria, British Columbia V8Z 7X8, Canada
| | - Angela M Jackson
- The University of Victoria Genome BC Proteomics Centre, 4464 Markham St #3101, Victoria, British Columbia V8Z 7X8, Canada
| | - Gordon Stenhouse
- Foothills Research Institute, Grizzly Bear Program, 1176 Switzer Drive, Hinton, Alberta T7V 1V3, Canada
| | - Nicholas C Coops
- Department of Forest Resource Management, University of British Columbia, 2424 Main Mall, Vancouver, British Columbia V6T 1Z4, Canada
| | - David M Janz
- Department of Veterinary Biomedical Sciences, University of Saskatchewan, 44 Campus Drive, Saskatoon, Saskatchewan S7N 5B3, Canada
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