title: Spatial analysis of factors influencing long-term stress in the grizzly bear (Ursus arctos) population of Alberta, Canada.
abstract: Non-invasive measures for assessing long-term stress in free ranging mammals are an increasingly important approach for understanding physiological responses to landscape conditions. Using a spatially and temporally expansive dataset of hair cortisol concentrations (HCC) generated from a threatened grizzly bear (Ursus arctos) population in Alberta, Canada, we quantified how variables representing habitat conditions and anthropogenic disturbance impact long-term stress in grizzly bears. We characterized spatial variability in male and female HCC point data using kernel density estimation and quantified variable influence on spatial patterns of male and female HCC stress surfaces using random forests. Separate models were developed for regions inside and outside of parks and protected areas to account for substantial differences in anthropogenic activity and disturbance within the study area. Variance explained in the random forest models ranged from 55.34% to 74.96% for males and 58.15% to 68.46% for females. Predicted HCC levels were higher for females compared to males. Generally, high spatially continuous female HCC levels were associated with parks and protected areas while low-to-moderate levels were associated with increased anthropogenic disturbance. In contrast, male HCC levels were low in parks and protected areas and low-to-moderate in areas with increased anthropogenic disturbance. Spatial variability in gender-specific HCC levels reveal that the type and intensity of external stressors are not uniform across the landscape and that male and female grizzly bears may be exposed to, or perceive, potential stressors differently. We suggest observed spatial patterns of long-term stress may be the result of the availability and distribution of foods related to disturbance features, potential sexual segregation in available habitat selection, and may not be influenced by sources of mortality which represent acute traumas. In this wildlife system and others, conservation and management efforts can benefit by understanding spatial- and gender-based stress responses to landscape conditions.
authors.affiliation: Spatial Pattern Analysis and Research Lab, Department of Geography, University of Victoria, Victoria, British Columbia, Canada.
authors.forename: Mathieu L
authors.initials: ML
authors.lastname: Bourbonnais
authors.affiliation: Spatial Pattern Analysis and Research Lab, Department of Geography, University of Victoria, Victoria, British Columbia, Canada.
authors.forename: Trisalyn A
authors.initials: TA
authors.lastname: Nelson
authors.affiliation: Canadian Cooperative Wildlife Health Centre, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: Marc R L
authors.initials: MR
authors.lastname: Cattet
authors.affiliation: Applied Conservation Science Lab, Department of Geography, University of Victoria, Victoria, British Columbia, Canada.
authors.forename: Chris T
authors.initials: CT
authors.lastname: Darimont
authors.affiliation: Foothills Research Institute, Hinton, Alberta, Canada.
authors.forename: Gordon B
authors.initials: GB
authors.lastname: Stenhouse
mesh_terms: D000416:Alberta; D000818:Animals; D003247:Conservation of Natural Resources; D005260:Female; D006197:Hair / Q000378:metabolism; D006854:Hydrocortisone / Q000378:metabolism; D008297:Male; D015233:Models, Statistical; D012044:Regression Analysis; D015203:Reproducibility of Results; D062206:Spatial Analysis; D018709:Statistics, Nonparametric; D013312:Stress, Physiological; D013997:Time Factors; D001503:Ursidae / Q000378:metabolism / Q000502:physiology*
chemical_list: D006854:Hydrocortisone